Indian Journal of Experimental Biology Vol. 40, June 2002, pp. 639-655

Immune system and antioxidants, especially those derived from Indian medicinal plants

T P A Devasagayam & K B Sainis

Cell Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085, India

During the functioning of the immune system, such as in phagocytosis, reactive oxygen and nitrogen species are gener­ated. If they are left unchecked they can affect the components of the immune system by inducing oxidative damage. This is more so in the elderly or during inflammation where there is excess generation of these reactive species than can be taken care of by the defenses in the form of antioxidants. Dietary supplementation with antioxidants may greatly help in such con­ditions. There are some indications of possible benefits of antioxidant supplementation. Natural compounds from medicinal plants having antioxidant and immunomodulatory activities have potential as therapeutic agents in this regard. Indian me­dicinal plants with these activities have been identified and their antioxidant and immunomodulatory effects reviewed. The possible future prospects in this regard are also outlined.

During the last 30 years immunology has witnessed an explosion of knowledge and experimental skills that has expanded our view of the immune system and means of searching for its structures and functions in an impressive way. The basic function of the immune system is to protect against foreign pathogens and infectious agents. This is achieved either through in­nate or natural immunological mechanisms which essentially serve as a short term first line of defense or through elaborate adaptive mechanisms which are highly specific, complex and are marked by diversity and memory. In both types of immunity, cells and molecules play important roles. While in natural or innate responses the cellular players are monocytes, macro phages , polymorphonuclear phagocytes and natural killer cells, in the adaptive immunity the piv­otal role is played by two classes of lymphocytes, viz., T (thymus derived) and B (Bursa - or bone mar­row derived) cells and .these are assisted by accessory cells such as antigen presenting cells. Further, the cel­lular dichotomy in adaptive immune responses is also reflected in functional division of labour as the T cells serve as effectors of cell-mediated immune responses such as delayed type hypersensitivity and killing of virus infected cells and also as helpers for the produc­tion of highly specific proteins, called antibodies, by the B lymphocytes. These antibodies possess binding sites complementary to the antigen and are responsi-

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ble for their removal from the system. The molecular constituents of the natural immune system are the complement proteins some of which help in opsonisa­tion of foreign bacteria, lysozyme, defensin peptides, certain cytokines, etc l

.3

.

While the natural immune mechanisms have been considered by and large non-specific with respect to the antigen, interesting new data have revealed pattern recognition by certain receptors such as toll receptors, mannose receptors etc4

. The adaptive immunity, on the other hand, relies heavily on the selection of anti­gen specific clones (clonal selection) and their expan­sion through activation, proliferation and differentia­tion5

. An overwhelming majority of T -cells recognize only peptide antigens in association with one's own major histocompatibility (MHC) complex antigens on the antigen presenting cells, with the help of clonally distributed T-cell receptors (TCR). A few T cells may recognize non-peptide antigens in association with other cell surface molecules6

. T cells differentiate in inflammatory or cytotoxic sub-types. B cells, on the other hand, recognize any type of antigen (protein, lipid, carbohydrate etc.) with the help of clonally dis­tributed B cell receptors which consist of surface bound antibody molecules in association with signal­transduction facilitating molecules and differentiate into antibody producing plasma cells. The repertoire of antigen specific receptors and antibodies is very diverse (>1012 possible molecules of antibodies and even more for TCR) and they are assembled by pro­cesses of recombination and gene rearrangements

640 INDIAN J EXP BIOL, JUNE 2002

(VOl recombination) from mUltiple copies of differ­ent gene segments, junctional diversity, combinatorial diversity and somatic hypermutation (in case of BCR and antibodies) i.2.

Another set of molecules whose role has come to light in recent years is cytokines. These are elaborated by different types of cells, may act in autocrine, paracrine or endocrine manner, stimulate or regulate the growth and functions of nearby cells through spe­cific receptors and are highly potent as they are effec­tive in picomolar quantities. They are truly the lan­guage of communication between cells of the immune system. Some of them produce inflammation and some are chemotactic (chemokines) and these may facilitate innate immune reactions. Interleukins constitute one of the classes of cytokines .

In adaptive immunity, the activation of the antigen specific T or B cells by the specific antigen involves two signals. The first signal is the binding of the MHC associated epitope to its specific receptor on T cells or the direct binding of the epitope to B cells. The second is the binding of co-stimulatory molecules on the antigen presenting cells/helper T cells/antigen itself to their corresponding ligands on the T or B cells which have recognized the antigen. In absence of this second (co-stimulatory) signal the immunocom­petent cell is rendered functionally inactive or aner­gic7

. Some of the cytokines play an important role in the expansion of antigen activated T cells and B cells.

It is obvious that immune system has potential to go astray and harm the host himself. This can be in the form of allergy or autoimmunity. Yet another form-its basic rejection function e .g. transplant re­jection, is a major hurdle in the effort to replace mal­functioning tissues or organs. All these situations de­mand regulation or modulation of immune responses. Likewise, one may need to boost or stimulate the im­mune system so as to facilitate effective vaccination against infective agents or to combat the deleteri ous aftermath of immunosuppressive radiotherapy . It is in the quest of suitable immunomodulators that natural products derived from medicinal pl ants provide a vast resource to draw upon .

Free radical generation in the immune system During normal biochemical reactions in our body

there is a generation of reactive oxygen and nitrogen species (ROS and RNS). This gets enhanced during patho-physiological conditions creating 'oxidative stress'. During this phenomenon cellular constituents get altered resulting in various diseased states. This

may be effectively neutralized, by enhancing the cel­lular defenses, in the form of antioxidants8

-11 . Reac­

tive species are also generated during ' phagocytosis ', a manifestation of innate immunity. The migration of leukocytes at an inflammatory site results in phagocy­tosis with the release of enzymes and cytokines from both macrophages and neutrophils. Phagocytosis stimulates various independent processes, especially "respiratory burst", which results from activation of NADPH oxidase, an enzyme normally inactive in resting cells. The generation of ROS begins with the rapid uptake of oxygen and activation of NADPH oxidase and the production of the superoxide free

radical (0 i).

oxidase) 20" + NADP+ + H + 2

Superoxide is then rapidly converted to hydrogen peroxide (H20 2) by superoxide dismu ~ase (SOD)

20 -2' +2H+ SOD) H ° +0 2 2 2

These ROS can act by either of the two oxygen­dependent mechanisms resulting in the destruction of the microorganism or other foreign matter. The reac­tive species can also be generated by the myeloper­oxidase-halide-H20 2 system. The neutrophil cyto­plasmic granules contain the enzyme myeloperoxi­dase (MPO). In presence of chloride ion, which is Ubiquitous, hydrogen peroxide is converted to hy­pochlorous acid (HOCl), a potent oxidant and anti-microbial agent l2

. .

Cl -+ H 20 2+ H + MPO) HOCI + H20

The MPO-independent mechanism, though not as important as the previous one, is still essential. ROS are generated from superoxide and H20 2 produced via 'respiratory burst' by Fenton (A) and/or Haber-Weiss (B) reactions l3

.

(A) H20

2 +Fe 2+ -7 'OH+OH - +Fc 3+

(B) 0 ; +H 20 2-7'OH+OH - +O z

Reactive nitrogen species are also important. The free radical nitric oxide (NO"), first described as endo­thel ium-derived relaxation factor (EDRF), is pro­duced from arginine by nitric oxide synthase (NOS)

L - Arg + 0 2 + NADPH NOS ) NO' + citrulline

An inducible nitric oxide synthase (iNOS) is capable of continuously producing large amounts of NO'. In activated immune cells, it acts as a 'killer molecule' 14.

DEY ASAGA Y AM & SAINTS: IMMUNOMODULATION AND ANTIOXIDANTS 641

Although the direct toxicity of NO" is modest, it gets greatly increased when it reacts with superoxide to form peroxynitrite, a very strong oxidant.

NO" + O~ ---j ONOO -

Peroxynitrite can react with aromatic amino acid residues to form nitrotyrosine, which can lead to en­zyme inactivation ,s.'6 . It can also kill E. coli cells di­rectlyl7. However, nitric oxide is an important cyto­toxic effector molecule in defense against tumour cells, various protozoa, fungi, helminths, and myco­bacteria ' 8. '9 .

Modulation by antioxidants Cellular components of immune system are rich in

polyunsaturated fatty acids and these are very much susceptible to oxidative attack resulting in highly damaging lipid peroxidation. The peroxidation prod­ucts formed are also highly cytotoxic. This phenome­non may result in increased prostaglandin levels that are strong immunomodulators. More ROS and radi­cal-derived products are also generated during the action of lipoxygenase and cycloxygenase. The in­creased endogenous ROS present during ageing and various disease states affect integral membrane func­tion, including the cell-mediated immune reaction involving phagocyte membrane NADPH oxidase that depends on the triggering of protein kinase C to pro­duce superoxide. Depressed immunocompetence as­sociated with ageing, various diseases, and poor nutri­tion may result from an excess generation of ROS due to the down-regulation of these two enzymes. Various antioxidants may prevent and/or correct immune dys­function. These include the intracellular superoxide dismutase, catalase, glutathione peroxidase and glu­tathione besides the dietary or oral supplements in the form of vitamin C, vitamin E, ~-carotene, zinc and selenium2o

.21

•

Catalase inactivates H20 2 formed by SOD by con­verting it to water and oxygen. Glutathione peroxi­dase in the presence of glutathione, converts H20 2 to water. Zinc is an essential trace element, being a co­factor for about 200 human enzymes, including cyto­plasmic antioxidant Cu-Zn SO~. Selenium is also an essential trace element and a co-factor for glutathione peroxidase. Vitamin E is an efficient lipid soluble an­tioxidant that functions as a 'chain breaker' during lipid peroxidation in cell membranes and various lipid particles including LOL22

. Vitamin C (ascorbic acid) is a water-soluble free radical scavenger23 and it also regenerates vitamin E in cell membranes in combina-

tion with glutathione or corripounds capable of donat­ing reducing equivalents and maintains LDL particle integri ty24.2s. This vitamin is important in neutrophil functions. Beta-carotene, lycopene, lutein and other carotenoids function as important antioxidants and they quench singlet oxygen and peroxyl radicals26

.

These compounds modulate host defense systems. Supplementation with other antioxidants, especially from natural sources, like medicinal plants will also greatly help in boosting the immune system.

Chronic inflammatory disorders such as rheuma­toid arthritis, asthma, psoriasis and inflammatory bowel disease result in the production of several cyto­kines. These can recruit activated inflammatory and immune cells to the involved site and thereby may amplify and perpetuate the inflammatory process27. The transcription factor NF-KB governs the expres­sion of several genes . some of which encode cyto­kines, chemokines, cell adhesion molecules, growth factors, and some acute phase proteins in health and in some diseases. The agents that activate this factor include ionizing radiation, H20 2, 'OH and ozone. An­tioxidant prevention of NF-KB activation may be beneficial in suppressing toxic/septic shock, acute inflammatory responses, graft-vs-host reactions, and radiation damage28

• Hence immunomodulation can go hand in hand with antioxidant activity.

Effect of immunomodulatory agents Immunomodulatory agents can enhance or inhibit

the immunological responsiveness of an organism by interfering with its regulatory mechanisms. These may be antigen independent and may directly induce production of mediators and effector molecules by the immunocompetent cells. This type of antigen­independent immunity is thus distinct from the one achieved by conventional immunization or by passive immunization using antibodies29

. The primary target of the immunomodulatory compounds is be~eved to be the macrophages, which playa key role in the gen­eration of an immune response. It is known that the activated macrophages display not only increased phagocytosis and intra-cellular killing of pathogens by producing effector molecules like free radicals and nitric oxide, but also produce cytokines like tumor necrosis factor (TN F)-a, and interleukin (lL)-l, IL-6, IL-12 etc30

. These cytokines may, in turn, activate T cells or NK cells.

The immunomodulatory agents may selectively ac­tivate either cell mediated or humoral immunity by

642 INDIAN J EXP SIOL, JUNE 2002

stimulati ng either T HI or T H2 type of cell response, respectively. It is now realized that enhancement of T Hi type of T cell response may be of therapeutic sig­nificance for a variety of intracellular pathogens, like protozoan parasites or mycobacteria; whereas T H2 type of response may be beneficial against extra­cellular pathogens. Recent progress in our understand­ing of the immune system has also opened many pos­sibilities for the selective immunosuppression. Selec­tive immunosuppression by agents inhibiting signal transduction pathways for T cell activation, consid­ered as a therapeutic strategy against graft rejection or autoimmune diseases, has already been demon­strated3

'. Oxidative stress may influence the immune system either by hyperexcitation to cause autoimmune disorders or suppress it, resulting in higher suscepti­bility to infections. Excited mental states such as vari­ous forms of stress are now known to enhance the generation of excessive free radicals in the biological systems and these free radicals lead to several disor­ders. Ayurvedic rasayana drugs may playa major role in handling these problems. However, their full poten­tial still remains to be explored.

Inmmnomodulation by natural products The modulation of immune response by using me­

dicinal plant products as a possible therapeutic meas­ure has become a subject of active scientific investi­gations. The basic concept has, however, existed in the ancient Vedic scripture, the Ayurveda, and has been practiced in Indian traditional medicine for many centuries. This ancient system of medicine that evolved in India thousands of years ago, probably represented the first record of scientific medicine in the history of the world. The story goes that the sages converged on the snow-clad slopes of the Himalayas to discuss ways to alleviate human misery. They, then approached the gods who taught them this elaborate science in a highly simplified way. The two main ap­proaches to illness in Ayurveda are preventive and curative. The main reason for the sages' request to the gods was to avoid diseases and remain fit for a long time. Hence the major approach to therapy in Ay­urveda is one which emphasizes prevention. The sec­ond approach is the curative one, i.e. that which at­tempts to alleviate diseases after they have occurred29

.

According to the Ayurvedic theory, a harmonious balance between three humors of the body viz. ' Vayu', 'Pitta' and 'Kaf' is needed for positive health; imbalance of these may cause disease(s). A signifi-

cant part of Ayurvedic therapeutics is preventive in nature. It aims to promote positive health. An entire section of the Materia Medica of Ayurveda termed 'Rasayanas' is devoted to enhancement of body's re­sistance. The prescribed procedures include not only drugs but also daily routine including exercise, diet and nutrition besides mental attitude and discipline3o.

One of the therapeutic strategies in Ayurvedic medi­cine is to increase body's natural resi stance to the dis­ease causing agent rather than directly neutralizing the agent itself. In practice, this is achieved by using ex­tracts of various plant materials called rasayanas. The claims of the Rasayana therapy are far reaching: In terms of Charaka, by using Rasayana therapy, one obtains longevity, regains youth, get:; sharp memory and intellect, freedom from diseases, lustrous com­plexion and the 'strength of a horse'. In order to un­derstand the concept of Rasayana and draw parallels in contemporary science, we have to become familiar with some of the basic principles of Ay urveda, which is termed as ' science of life'. Credited with divine origins, this science rests on the dosha-dhatu-mala tripod. There are three doshas, namely vayu, pitta and kaf, each with specific characteristics and fu nctions. There are seven dhatus or tissues. Formed by assimi­lation of dietary items, the tissues infl uence the char­acteristics and behaviour of the doshas . The dhatus are arranged in hierarchical fashion- rasadhatu being the primordial tissue. The rasadhatu has been likened to the plasma, although its exact interpretation re­mains elusive. The tissues receive nu trients from the rasadhatu, picking up the components they need. It is obvious then, that the quality of the rasadhatu is very important and also follows that it would influence the working of subsequent tissues. Drugs that improve the quality of this rasadhatu and thereby of the entire body are the Rasayanas. This term Rasayana has been split up into 'Rasa' and 'Ayana' meaning the path the Rasa takes. Several plants are described to have Rasayana properties. On ingesting (he appropriate formulation of the Rasayana in the appropriate season by the appropriate person, the beneficial effects of Rasayana are seen29

•

Immunomodulation, especially using Rasayana drugs , could provide an alternative to conventional chemotherapy under the conditions of impaired im­mune responsiveness or following organ transplanta­tion3

'. This concept of using rasayanas for health, also gains a little more credibility, when we realize that herbal antioxidants concurrently exhibit significant

DEVASAGA YAM & SAINlS : IMMUNOMODULATION AND ANTIOXIDANTS 643

immunomodulatory activities, like in Shilajit and Chyawanprash Awaleha31 . Further, Indian medicinal plants are a rich source of substances that are claimed to induce paraimmunity, the non-specific immuno­modulation of essentially granulocytes, macrophages, natural killer cells and complement functions32-34. Similar immunomodulatory properties have also been reported in the natural products from various plants from other countries35-39. Agarwal & Singh30 have reviewed Indian medicinal plants that have immuno­modulatory properties.

Medicinal plants with immunomodulatory and antioxidant activities

The following plants (with common/ayurvedic names in brackets) are known to have potent immu­nomodulatory and/or antioxidant activities.: Aconitum heterophyllum (Ativisha), Allium sativum (Lahsuna), Allium cepa (Onion), Aloe vera (Ghritkumari), An­drographis paniculata (Kalmegh), Asparagus ra­cemosus (Shatavari), Azadirachta indica (Nimba or Neem) , Berberis aristata, Boswellia serrata, Corcho­rus olitorius, Curcuma longa (Haridra), Emblica offi­cinalis (Amlaki), Glycyrrhiza glabra (Yashtimadhu), Gmeline arborea (Gambhari), Hemidesmus indicus (Shariba), Holarrhena antidysenterica (Kutaja), Mangifera indica (Amra), Nyctanthes arbortristis, Oldenlandia corymbosa, Picrorhiza kurroa (Kattu­karohini), Piper betel (Tamalpatra, Peepal), Piper longum (Pippali), Randia dumatorum (Madanphala), Sphaeranthus indicus (Mundi), Terminalia chebula, Tinospora cordifolia (Guduchi), Tylophora indica (An ant mool), Viscum album, Withania somnifera (Ashwagandha) and Zingiber aromaticum31

•

Details of data available on medicinal, immuno­modulatory and antioxidant properties of some se­lected plants are listed below, in alphabetical order. Please also refer to Table I for an abridged version of the same.

Aloe vera (Ghritkumari) This plant is extensively used in skin care prepara­

tions and other health products. Shamman et al.40

have studied the effects of Aloe vera gel extract sup­plementation on hepatocarcinogenesis induced by diethylnitrosamine and 2-acetyldminofluorene in male Sprague-Dawley rats. The severity of the carcino­genesis process was determined by measuring the in­crease in gamma-glutamyl transpeptidase and the pla­cental form of glutathione S-transferase, hi stochemi-

cally in situ and in plasma and liver fractions. Sup­plementation with Aloe vera gel extract in the dis­eased rats suppressed this increase significantly.

In traditional South-East Asian medicine the thera­peutic value of the parenchymatous leaf-gel of Aloe vera for inflammation-based diseases was reported. Extracts from the leaf-gel contains glutathione per­oxidase activitl l

. The low molecular weight con­stituents of this extract inhibit the release of reacti ve oxygen species (ROS) by phorbol myristic acetate (PMA)-stimulated human polymorphonuclear leuco­cytes (PMN). These compounds also inhibit the ROS­dependent extracellular effects of PMN such as lysis of red blood cells. However, the capacity of the PMN to phagocytose and kill microorganisms is not af­fected. The inhibitory effect of these compounds has been shown to be the indirect result of the diminished availability of intracellular free Ca2

+ (ref. 42).

Allium sativum (Lahsuna, garlic) and Allium cepa (onion)

Garlic is another herb with proclaimed Rasayana effect in Ayurveda. Garlic and onion (Allium cepa) are among the oldest of all cultivated plants. Both have been used as medicinal agents for thousands of years and shown to have applications as antimicro­bial, anti thrombotic, antitumor, hypolipidaemic, an­tiarthritic and hypoglycemic agents. These effects have been linked to their influence on eicosanoid me­tabolism that influences immune functions in various ways43. Nicotine, a major component of tobacco, is partly responsible for the development of atheroscle­rosis. The antioxidant effects of oils isolated from onion and garlic on nicotine-induced lipid peroxida­tion in rat tissues were studied. Lipid peroxidation was significantly increased in the tissues of nicotine­treated rats. Both the garlic oil and onion oil supple­mentation to nicotine-treated rats increased resistance to lipid peroxidation. With garlic oil or onion oil sup­plementation, nicotine-treated rats showed increased activities of antioxidant enzymes and increased con­centrations of glutathione44 .

Through a series of investigations, garlic was also found to exert a diverse range of health promoting effects. It was found to enhance human immune func­tions, by stimulating peripheral blood mononuclear cells in vitro29

. Pre-treatment with garlic led to a pro­tecti ve effect on heart, Ii ver and pancreas agai nst iso­proterenol induced damage. Garlic extract and S-allyl cysteine isolated from garlic were noted to protect

644 INDIAN J EXP BIOL, JUNE 2002

Table 1-Immunomodulating and antioxidant activities of some medicinal plants

Plant/compound Medicinal effects Immunomodulation Antioxidant effect Reference

Aconitum heterophylulll Stimulate macrophages & 31 phagocytic activi ty

Aconitum heterophylum Immunomodulating activity 29

Aglaia roxburghiana (fruit For inflammatory diseases Decrease lipid peroxidation 67 extract)

Aloe vera (leaf extract) Glutathione peroxidase 41 activity

Aloe vera (leaf gel extract) Inhibit ROS generation by 42 stimulated PMN

Aloe vera (leaf gel extract) Inhibits hepatocarci nogene- 40 sis with vitamin C

Allium sativulll Protects against Enhanced immune func- 45 isoproterenol tions

Allium sativulll (dially l Anticarcinogenic in mouse 45 sulphide) skin

Allium sativum Cardioprotective, anti- Related to eicosanoid 43 thrombotic Antimicrobial, metabolism & immune antiarthritic & functions hypoglycaemic

Alliulll sativum (allicin) Induce apoptosis in cancer Increase free radica l pro- 46 cells duction

Allium sativum (oil) Decrease lipid peroxidation 44 Increase antioxidant en-zymes

Allium cepa Cardioprotective, anti- Related to eicosanoid 43 thrombotic Antimicrobial, metabolism & immune antiarthritic & hypoglycae- functions mic

Andrographis paniculata Treatment for snake bite 47

Andrographis paniculata DTH response non-specific 48

(andrographolids)

Andrographis paniculata Decreased Ca2+ overloading Decreased lipid peroxida- 49

(nees) in sarcolemma tion

Asparagus racemosus Stimulate macrophages & 31 Phagocytic ac tivity

Asparagus racemosus Has immunomodulatory 31 compounds

Asparagus racemosus Reduce effect of stressors Macrophage activation & 91 genotypic adaptation

Asparagus racemosus Reduce suppression of 50 chemotactic Act;vity & production of IL-IrrNF-a

Asparagus racemosus Immunomodulator 90

Azadirachta indica Activates T HI type of T cell 31

Response (IL-2, IFN-y, IFN-a)

Azadirachta indica (leaf Effective for infections Immunomodulat ion-diff. 53

extract) Types

Azadirachta indica (dry Immunomodulation in 57

leaves) poultry

(Contd)

DEVASAG A YAM & SAINIS : IMMUNOMODULATION AND ANTIOXIDANTS 645

Table I-(Contd)

Pl an t/compound Medicinal effects Immunomod ul ati on Antioxidant effect Reference

Azadirachta indica Anti-innammatory ac ti vi ty Decrease li pid perox idation 58 (alcoholic ext. ) Azadirachta indica (oil ) Non--specific immunostimu- 59

lant Azadirachta indica (seed Decrease lipoxygenase 61 ext. ) (antiox idant principle) acti vity

Decrease lipid perox idati on Boswellia serrata Immunomodul ating ac ti vity 3 1 Butea monospermea Immunostimulant 6 1 Corchorus olitorius Mitogenic ac tivity 94 Curcuma longa (turmeric) Immunomodulatory com- 31

pounds Curcuma longa (antiox i- Inhibits lipid perox idati on 6 1 dant protein) protects SH & Ca2

+ ATPase Curcuma longa Anticancer effec ts Inhibits superoxide production Decreases lipid perox ida- 62 (curcuminoids) tion Curcuma longa (curcumin) Anticancer effects Anti-innammatory Increases GSH-dependent 69

Enzy mes Curcuma longa (curcumin) Anticancer effects Anti-innammatory Antiox idant effec ts 64 Curcuma longa (curcu min) Antiin fec tious Anti-innammatory . 65

modulates Curcuma longa (yakuchi- Anticancer/anti-stress Anti -i nnammatory 11 0 none AlB) Eclipta alba Antihyperglycaemic 10 1 Emblica officina/is Immunomodulatory com- 31

pounds Emblica officina/is Reduce stress Macrophage activati on & geno 9 1

typic adaptation Emblica officinalis Decreases li pid perox ida- 66 (ascorbic acid Conjugated ti on to gallic acid) Increased SOD, catalse &

Gper Emblica officinalis (embli- Decreases lipid perox ida- 67 canin punigluconin & tion pedunculagin)

Emblica officinalis (fruit For innammatory diseases Decreases lipid peroxida- 67 extrac t) ti on Emblica officinalis Antibacterial 68 Euonymus pendllius (bark For innammatory di seases Decreases lipid perox ida- 67 extract) ti on Glycyrrhiza g/abra May have antiox idant 73 (nvanoids) effects Glycyrrhiza glabra Antiox idant effects 69 (glabridin) Glycyrrhiza glabra (shoot Sti mulate macrophages 72 & root polysaccharide fraction) Glycyrrhiza glabra Inhibits LDL ox idation 74 (glabridin) Glycyrrhiza glabra (7 Inhibits LDL ox idat ion & 75 polyphenols) Destruction of ~-carotene Hollarhena anidysel11rica Immunomodul atoryactivity 31 Hemidesmus indicus (or- Viper-venom inhibitory 74 ganic ac id from root) acti vity Hemidesnlus indiclIs Viper-venom neutra lizing 75 (2-hydroxy-4-methoxy ac ti vit y bcnzoic acid) (Col/td)

646 INDIAN J EXP BIOL, JUNE 2002

Table I-(Contd)

Plant/compound Mcdicinal eFfects Immunomodulation Antioxidant effect Reference

Hemideslllus indicus Anti -inflammatory, anti- Inhibits lipid peroxidation 76 (2-hydroxy-4-methoxy pyretic ac tivity increases SOD benzoic acid) Nyclanlhes arbor-Irislis Hepatoprotective, an- Strong immunostimulant 77

tileishmanial, anti viral, antiamoebic, anti fu ngal

Nyctan/hes arbor-/rislis Depleti on of TNF-a 78 Ocimum sanclum Immunomodulatory com- 31

pounds Picrorhiza kurroa Immunomodulatory activity 31 Piper Ion gum Immunomodul atory com- 31

pounds Piper IOllgUiIl Rcduce effect of stressors Synthesize prostaglandins 9 1 Picrorhiza kurroa Chemotactic ac tivity & pro- 50

duction ofTNF- a inhibi ted Picrorhiza kurroa Anti -hyperglycaemic ef- 101

fect Terminalia chebl.lla Reduce effect of stressors Synthesize prostaglandins 9 1 Terlllillalia chebula Antibacterial 68 Terminalia belerica Antibac teri al 26 Tillospora cordifolia Anti bacterial Stimulates macrophages 31 Tinospora cordifolia Non-specific immunomodu la- 94

ti on Tinospora cordifolia Reduce effect of st ressors Macrophage acti vity & geno- 9 1

typic adaptation Tinospora cordifolia Chemotacti c ac ti vity & pro- 50

duction of TNF-a inhibited

Tillospora cordifolia Immunomodulator 90 Tillospora cordifolia Improves surgical out- 96

come Tillospora malabarica (and Polyclonal B cell activators 94 its polysaccharides) Tillospora cordifolia (sy- Anti-complementary 97 ringen cordiol) ac ti vity Tinospora cordifolia (root) Increase levels of glu- 99

tathi one and vitamin C Tillospora cordifolia Reduce toxic effects of Inhi bits lipid perox idation 100

Cyclophosphamide Tillospora cordifolia Antihyperglycaemic effect 10 1 Viscllm albul11 Mitogenic ac ti vity 94 Wi/hania somllifera Anti bacterial Stimulates macrophages 31 Wi/hallia sOlllllifera Immunomodulatory 31

compounds Wilhan ia sOlllnifera Reduce effect of stressors Synthesize prostaglandins 9 1 Wilhall ia sOlllnifera Chemotactic ac tivity & pro- 50

ducti on ofTNF-a Inhi bited Wi/hallia solllnifera Antihyperglycaemic 99 Wi/hall ia sOlll l1 ifera Anti-in fl ammatory Protects glu tathione & 105

enzy mes Wi/hal1ia somnifera Anti-stress, ant i- Immunomodulatory Increase antiox idant ::11- 109 (si toindosides withaferin infl am matory zy mes A) Anti-aging effects Zillgifer arolllalicll/ll Immunomoc!u latory 29 Zillgifer officillale Anti --nflammatory, 108

anti-<:ancer Anti-stress, anti-f!rolirerati ve

DEY ASAGA Y AM & SAINIS : IMMUNOMODULATION AND ANTIOXIDANTS 647

pulmonary endothelial cells in vitro against hydrogen peroxide induced oxidative damage. Enhanced cell viability and an inhibition of lactate dehydrogenase and lipid peroxidation were also reported29. Diallyl sulfide, a sulfur-containing volatile compound in gar­lic, exerts anticarcinogenic activity in various rodent tumor models45 . Allicin from garlic has been found to induce programmed cell death and therefore, arrest of proliferation in cancer cells46 . Such compounds can thus also exercise immunosuppressive effects.

Andrographis panicuiata (Kalmegh) This plant is credited with anti-snake venom activi­

ties. Prolonged survival was observed when extracts were administered to mice before or after treatment with different elapid or crotalid venoms47. Ethanolic extract and purified diterpene andrographolides in­duced significant stimulation of antibody and delayed type hypersensitivity (DTH) response to sheep red blood cells in mice. The plant preparations also stimu­lated nonspecific immune responses in the animals as measured in terms of macrophage migration inhibi­tion (MMI), phagocytosis of 14C-Ieucine labelled Es­cherichia coli and proliferation of splenic lympho­cytes. The stimulation of both antigen specific and nonspecific immune responses was, however, of lower order with andrographolide than with the ex­tract, suggesting thereby that substance(s) other than andrographolide present in the extract may also be contributing towards immunostimulation48

. In rats treated with Andrographis paniculata nees the activ­ity of Ca2+-ATPase and Na+-K+ ATPase increased remarkably, and lipid peroxidation decreased signifi­cantl/9.

Asparagus racemosus (Shatavari) The aqueous extract of whole plant of Asparagus

racemosus administered orally to experimental ani­mals, protected against exposure to a variety of bio­logical, physical and chemical stresses. Studies on the mechanisms of action revealed that it produced im­munostimulation. Treatment with A. racemosus sig­nificantly inhibited suppression of chemotactic activ­ity and production of IL-l and TNF-a. by murine macrophages induced by 17 weeks of treatment with ochratoxin A (OT A)5o. Thatte and Dahanuakar51 have studied the protective effects of aqueous extracts of A. racemosus and three other plants against the myelo­suppressive effects of single and double doses of

cyclophosphamide in mice. Kamat et at. 52 have exam­ined the antioxidant effects of crude extract as well as purified polysaccharide fraction of A. racemosus against membrane damage induced in rat mitochon­dria and liver by free radicals generated during y­irradiation. They found that these materials had potent antioxidant properties in vitro.

Azadirachta indica (Neem) Neem has been reported to exert several therapeu­

tic effects. Aqueous extract of Neem bark acted as immunomodulator, as assessed by alternative and classical C pathway activities, migration inhibition factor and chemiluminescence assay for phagocytic activity. There is a very wide spectrum of infectious and non-infectious diseases against which prepara­tions from A. indica are reported to be efficacious. Hence, it was suspected that the general immunopo­tentiating ability could be one of the mechanisms by which it ameliorates these disease conditions.

Using the haemolytic plaque assay technique, an aqueous extract of A. indica bark was shown to en­hance the immune response of BALB/C mice to sheep red blood cells in vivo53

. Neem extracts/oil also have been found to have anti-fertility effect and were pro­posed to stimulate local immunity in the uterine waIl 54

-50.

In another studi7, the effects of feeding powdered dry leaves of Neem were investigated on humoral and cell mediated immune responses, in a flock of broilers which had survived an outbreak of infectious bursal disease (IBD). The treatment significantly enhanced the antibody titre against new castle disease virus an­tigen and also potentiated the inflammatory reactions to l-chloro-2,4-dinitrobenzene in the skin contact sen­sitivity test. The water-soluble constituents of the al­coholic extract of Neem leaves exerted significant antiinflammatory activity in cotton pellet granuloma assay in rats57. The extract also inhibited synthesis of DNA and RNA as well as reduced the level of lipid peroxide(s)58.

In yet another study, the animals were treated in­traperitoneally with the neem oi159. Peritoneal macro­phages exhibited enhanced phagocytic activity and expression of MHC class-II antigens. Neem oil treat­ment also induced the production of gamma inter­feron. Spleen cells showed a significantly higher pro­liferative response to Con A and tetanus toxoid IT ill vitro (IT) compared to that of the controls. Pre­treatment with neem oil, however, did not augment

648 INDIAN J EXP SIOL, JUNE 2002

the anti-IT antibody response. These data suggested that neem oil acts as a non-specific immunostimulant for cell-mediated immune (CMI) mechanisms. This was further supported by the observations that in vitro treatment of mouse splenocytes with neem leaf extract stimulated production of IL-2, IFN-y and TNF-a re­flecting activation of T/-II type of T cell response31

•

An antioxidant principle was isolated from Neem seed using high pressure liquid chromatography with a hy­drophobic reverse-phase column6o. It was found to be a potent inhibitor of plant lipoxygenases. However, such data on mammalian systems are not yet available.

Curcuma Zonga (Turmeric) Turmeric has several components with immuno­

modulatory and antioxidant properti es. Selvam et al. 61

have iso lated turmeric ant i-oxidant protein (TAP) from the aqueous extract of turmeric. The protein showed a concentration-dependent inhibitory effect on lipid peroxidation. Ca2+-ATPase of rat brain ho­mogenate was protected to nearly 50% of the initial act ivity from the lipid peroxidant induced inact ivati on by this protein. This protection of Ca2+-ATPase activ­ity was found to be associated with the preven tion of loss of -SH groups.

Turmeric contains several small molecular weight components with antioxidant, medicinal and immu­nomodulatory acti viti es62

. Natural curcuminoids, iso­lated from turmeric, were compared for their cyto­toxic, tumour reducing and antioxidant ac ti viti es. These compounds were also checked for their poten­tial use as anti-promoters. The curcuminoids inhibited lipid perox idation besides the production of superox­ides and hydrox yl rad ical.

Curcumin, an anti ox idan t present in turmeric, has been shown to inhibit chemical carcinogenesis in animal models and has been shown to be an an ti­infl ammatory agent. It modulates glutathione (GSH)­linked detoxification mechanisms in rats. Singhal et a/.63 have examined the effects of curcumin on GSH­linked enzymes in K562 human erythroleukemia cells. These results suggest that glutathione s­transfe rases (GST) playa major role in detoxification of lip id peroxidation products in K562 cells, and that these enzymes are modulated by curcumin. It is re­ported to inhibit chemically induced carcinogenesis in the sk in , forestomach, and co lon when it is admini s­tered during initi ation and/or postinitiation stages64

•

The inhibition of apoptosis by curcumin in rat thymo­cytes was accompani ed by parti al suppress ion of AP-

1 activity. Complete suppression of AP-l activity was observed in Con A-treated, proliferating thymo­cytes65. The capacity of curcumin to inhibit both cell growth and death strongly implies that these two bio­logical processes share a common pathway at some point and that curcumin affects a common step, pre­sumably involving modulation of the AP-l t,:anscrip­tion factor.

EmbZica offlcinalis (Amlaki) Fruits of Amlaki have been used in Ayurveda as a

potent Rasayana and also for treatment of diseases of diverse etiology. It is an acknowledged rich source of Vitam in C. The role of vitamin C as a potent antioxi­dant has been well documented. Unlike other citrus fruits, Amlaki fruits have ascorbic ac id conjugated to ga llic acid and reducing sugars, fo rming a tannoid complex. Such complex of vitamin C is known to be more stable. It has been suggested that, due to an in­ternal mechani sm, tannoid complex liberates the nas­cent ascorbic ac id into the body. The antioxidant ac­tivity of tannoid active principles of E. officina/is con­sisting of emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin (14%), was investigated on the basis of their effects on rat brain frontal cortical and stri atal concent r::! ions of the ox i­dative free radical scavenging enzymes, superox ide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and lipid peroxidation, in terms of thiobarbituric acid-reacti ve product ,66. The active tannoids of E. officinalis (EOT), induced an increase in both frontal cortical and striatal SOD, CAT and GPX activity , with concomitant decrease in lipid per­oxidation in these brain areas when administered once daily fo r 7 days. Acute single administrati on of EOT had insigni fica nt effects. The resul ts ind icate that the antiox idant activity of E. officinalis may res ide in the tan noids which have vitamin C-Iike properti es, rather than vitamin C itself.

The extract obtai ned from E. officinalis fruits also inhibited lipid peroxidation. The extract is tradit ion­ally used to treat inflammatory diseases67 . Alcoholic extract of E. offic in a lis, was found to show potent bactericidal act ivitl8

.

GZycyrrlziza gZabra (Yashtimadhu) Glabridin, an isoflavan isolated from Glycyrrhiza

glabra (licorice) root, and its derivatives have been reported to inhibit the oxidation of LDL induced by copper ions or medi ated by macrophages69. The anti ­ox idant effect of glabridin on LDL ox idati on appears

DEY ASAGA YAM & SAINIS : IMMUNOMODULATION AND ANTIOXIDANTS 649

to reside mainly in the 2' hydroxyl moiety of the isoflavan. The effect of the consumption of glabridin, on the susceptibility of LDL to oxidation was also studied in atherosclerotic apolipoprotein E deficient mice. The in vivo and in vitro inhibitory activities may be related to the absorption or binding of glabridin to the LDL particle and subsequent protec­tion of LDL from oxidation and by protecting LDL associated carotenoids 70.

The study by Vaya et al. 71 also analyzed the anti­oxidative properties of natural compounds from the root of licorice toward LDL oxidation. Seven con­stituents, with antioxidant capacity were isolated from G. glabra. The isolated compounds were identified as the isoflavans hispaglabridin A, hispaglabridin B, glabridin, and 4'-O-methylglabridin, the two chal­cones, isoprenyJchaJcone derivative and isoliquiriti­genin, and the isoflavone, formononetin . Among these compounds, glabridin constituted the major amount in the crude extract (11.6%, w/w) as detected by HPLC analysis. The antioxidative capacities of the isolated compounds (1-7) were tested against beta-carotene destruction and LDL oxidation. These results suggest that the first 6 constituents were very potent antioxi­dants with glabridin being the most abundant and po­tent antioxidant. As LDL oxidation is a key event in the formation of the early atherosclerotic lesion, the use of these natural antioxidants may prove beneficial to attenuate atherosclerosis.

Nose et al. 72 have investigated the effects of crude polysaccharide fractions obtained from the shoot and hairy root of Glycyrrhiza sp. grown under aseptic conditions on murine peritoneal macrophage function. All crude polysaccharide fractions induced nitric ox­ide production by murine peritoneal macrophages in vitro.

From the air-dried roots of G. glabra L. (Legumi­nosae) five new flavonoid compounds named glu­coliquiritin apioside (a flavonone bisdesmoside), prenyllicoflavone A (a bisprenylflavone), shinflavone (a prenylated pyranoflavanone), shinpterocarpin and I-methoxyphaseollin (both pyranopterocarpans), were isolated together with 8 known saponins, 7 known flavonoid glycosides, and 11 flavonoids73

. The struc­tures of the new potent antioxidant compounds have been elucidated on the basis of their chemical and physicochemical properties.

Hemidesmus indicus (Shariba) Hemidesmus indicus is known for its use in the

treatment for snakebites. An organic acid, isolated and

purified from the root extract possessed viper venom inhibitory activity74. The compound (designated HI­RVIF) was isolated by solvent extraction, silica gel column chromatography and thin layer chromatogra­phy, and was homogeneous in nature. The adjuvant effect of 2-hydroxy-4-methoxy benzoic acid from H. indicus in the generation of anti venom antiserum was explored by Alam et al. 75. The antiserum raised in presence of the compound showed the higher neu­tralization capacity (lethal and hemorrhage) when compared with the antiserum raised with venom alone. The pure compound potentiated the neutraliza­tion of the lethal action of venom by commercial equine polyvalent snake venom antiserum in experi­mental models. The same authors have also shown that it possessed potent anti-inflammatory, antipyretic and antioxidant properties76

. The compound effec­tively neutralized inflammation induced by Vipera russelli venom in male albino mice. It also neutralized free radical formation as estimated by TBARS and enhanced the activity of antioxidant enzyme superox­ide dismutase. The anti-snake venom activity of thi s compound may at least be partly mediated through the above physiological process.

Nyctanthes arbor-tristis (Harsingar) Nyctanthes arbor-tristis L. (Oleaceae), a plant

widely used in the traditional medicinal systems of India, has been reported to possess hepatoprotective, antileishmanial, antiviral and antifungal activities. Strong stimulation of antigen specific and non­specific immunity, as evidenced by increases in hu­moral and delayed type hypersensitivity (DTH) re­sponse to sheep red blood cells (SRBC) and increased macrophage migration inhibition (MMI), has been demonstrated in mice fed 50% ethanolic extract of seeds, flowers and leaves of this plant77

• Maximum activity was found in the seeds in which the active principle(s) appear to be mainly associated with lip­ids. The immunostimulant substance(s) found in N. arbor-tristis L. are likely to play an important role in its antiamoebic, antileishmanial, antiviral and certain other activities.

The effect of the water soluble fraction of the etha­nol extract of N. arbor-tristis on TNF-a level in the plasma of arthritic and soluble protein A (SpA)­treated BALB/C mice has been studied78

. Oral ad­ministration of this fraction in arthritic mice showed a consistent depletion of TNF-a from the host plasma. A similar depletion of TNF-a in the plasma of SpA-

650 INDIAN J EXP BIOL, JUNE 2002

treated mice has been observed. The extract also re­duced plasma interferon-gamma level but the plasma IgM and IgG levels were not affected.

Piper longultl (PippaJi) Pippali rasayana (PR), an Ayurvedic herbal medi­

cine, prepared from Piper Longul1l (Pippali) and Butea lI1onosperma (Palash), and prescribed for the treat­ment of chronic dysentery and worm infestations was tested for anti-giardial and immuno-stimulatory activ­ity in mice, infected with Giardia Lamblia tropho­zoites. It produced up to 98% recovery from the infec­tion 79. The rasayana had no killing effect on the para­site in vitro. It significantly increased macrophage migration inhibition and phagocytic activity, thus in­dicating activation of T cells. Enhancement of host resistance as a consequence could be one of the possi­ble mechanisms contributing towards the recovery of animals from the giardial infection after the treatment with thi s rasayana.

Tinospora cordifolia (Guduchi) Tillospora cordiJolia is a plant widely used in Ay­

urveda and is known as AmritaiGulvellGulanchai Guduchi. T cordifolia is claimed to be useful, in Ay­urvedic literature, for treatment of jaundice, skjn dis­eases, diabetes, anaemia, emaciation and infections8o

.

'Guduchisatwa' , a starchy water extract prepared from it is recommended for its bitter principle and is used as a tonic vitalizer, anti-diabetic, diuretic, an ti -phlogistic and anti-allergic agent8

1.82 . On oral feeding, aqueous extracts of T. cordiJolia exhibited anti-bacterial, anti­phlogistic, analgesic and anti-pyretic activities. It was reported to mediate augmentation of neutrophils and activation of macrophages in abdominal sep­sis/infection and in cyclophosphamjde mediated leuko­penia/ neutropenia82

.83

. Other related studies also show the medicinal propelties of T. cordiJolia84

.85

Dahanukar and co-workers have exami ned various b f·· · I . f T d; r. I' 5 1.86·88 R ge t ene ICla propertIes 0 . cor IJO La . e e al.89

.9o have reported that T. cordiJolia provides pro­

tection against experimental infections in mice. Pre­treatment with T. cordifolia reduced mortali ty in mjce injected with E. coli intraperitoneally, abdominal sep­sis and candida infection. They have also shown that the plant extract specificall y stimulates macrophages and enhanced their phagocytic activity and intracellu­lar killing activity. Immunosuppression associated with deranged hepatic function and sepsis results in poor surgical outcome in obstructive jaundice. T cordiJolia was reported to improve surgical out-

come by strengthening host defenses89. The protection

offered by T. cordiJoLia against stress induced gastric mucosal damage was lost if macrophage act ivity was blocked. Recent data from this group suggest that T. cordifolia may induce adaptation91 .'.J:i .

An in vitro assay technique was used to determine the phagocytic and microbicidal activ ity of a mono­cyte-macrophage cell line using Candida species as test organ isms. The degree of activation of macro­phages induced by metronidazole and T. cordifolia was compared with that induced by a standard immu­nomodulator muramyl-dipeptide'J2. All the three test agents increased the phagocytic and killing capacity of macrophages in a dose dependent manner up to a certain dose, beyond which either of these acti vities plateaued or decreased.

The effect of dry stem crude extracts of T. cordifolia and another locally available species T. malabarica on lymphocytes of mice and humans was examined

9496 T k' . . "t by Sainis and cowokers . . a II1g mltogel1lc actlvl y as a bioassay purification of the active principles was attempted. The data obtained show that dry stem crude extracts of T. cordiJolia and T. rnalabarica con­tain polyclonal B cell activator(s) t;lat are polysaccha­rides in nature. Thus in addition to macrophages and PMN , B lymphocytes can also serve as targets for action of Tinospora extract. Partial structural charac­terization of these polysaccharides has been can-ied out. The mitogenic activity was very much more pro­nounced against mouse B cells compared to human B cell s. Further, after treatment of mice with the puri­fied component G 1-4A, both humoral response to SRBC, and T cell response to protei n antigen and mi­togen in vitro were enhanced. Studies on the binding of this immunomodulator showed that in addition to a subpopulation of B cells a vast majority of murine macrophages had binding sites for it97

.

Two active principles of T. cordifolia were found to possess anticomplementary and immunomodula­tory activities98

. Syringin and cordiol inhibited the in vitro haemolysis of antibody-comed sheep erythro­cytes by guinea pig serum. The reduced haemolysis was attributed to the inhibition of the C3-convertase of the classical complement pathway. The compounds also gave rise to sign ificant increases in IgG antibod­ies in serum and cell-mediated immunity.

Antioxidant properties of various components from T. cordiJolia have been reported. Oral administration of an aqueous T. cordifolia root extract for 6 weeks resulted in a decrease in the levels of plasma lipid

DEV ASAGA YAM & SA IN IS : IMMUNOMODULATION AND ANTIOXIDANTS 651

peroxidation, ceruloplasmin and alpha-tocopherol in alloxan diabetic rats99

. The root extract also caused an increase in the levels of glutathione and vitamin C in alloxan diabetes. Transina a herbal preparation con­taining T. cordifolia induced a dose-related decrease in streptozotocin (STZ) induced hyperglycemia and attenuation of STZ induced decrease in islet SOD activity 100. This indicates that the anti-hyperglycemic effect of transina may be due to free radical scaveng­ing activity. The hyperglycemic activity of STZ may be the consequence of decrease in islet SOD activity leading to the accumulation of free radicals in islet beta-cells.

Extract of T. cordifolia has been shown to inhibit the lipid peroxidation and formation of superoxide, and hydroxyl radicals in vitro l o l

• Administration of the extract partially reduced the elevated lipid perox­ides in serum. Tinospora extract may be useful in re­ducing the chemotoxicity induced by free radical . forming chemicals like cyclophosphamide. Several glycosides with potential antioxidant activity were also isolated, as polyacetates, from the n-BuOH frac­tion of the T. cordifolia stems. The structures of three new norditerpene, furan glycosides cordifoliside A, B and C have been established by 1 D and 2D NMR spectroscopyl02. Other related compounds, with po­tenti al beneficial effects, were also isolated 103.104. Fur­ther studies need to be carried out for providing evi­dence for the antioxidant effect of these compounds.

Wilhania somnifera (Ashwagandha) Withania somniJera effectively inhibits inflamma­

tory process. It can also bring about a specific reduc­tion in a-2 macroglobulin synthesis, unlike the con­ventionally used NSAIDS and has significant antioxi­dant activity. It gave significant protection against depletion of glutathione peroxidase and glutathione induced by exposure to UY-300 nm. The granuloma formation inhibiting activity of various fractions of an extract of the aerial parts of W. somnifera was estab­lished using subcutaneous cotton-pellet implantation in rats 105. Antiinflammatory activity was attributed to the high content of biologically active steroids in the plant, of which withaferin A (a steroidal lactone) is known to be a major component. This compound also has radiosensitizing effect in cancer cells '06.

The aqueous suspension of the root extract W. somnifera was evaluated for its effect on lipid peroxi­dation in lipopolysaccharide-treated animals lO7 . Si­multaneous oral administration of ashwagandha (100 mg/kg) prevented the rise in lipid peroxidation in rab-

bits and mice. The antiinflammatory property of root powder has been shown by Begum et al. 108 in a rat model of arthritis.

Antioxidant activity of active principles of W. SOI11-

nifera, consisting of equimolar concentrations of si­toindosides YII-X and withaferin A, was investigated for their effects on rat brain frontal cortical and stri­atal concentrations of superoxide di smutase, catalase and glutathione peroxidase ,08

. Active glycowithano­lides, administered once daily for 21 days, induced a dose-related increase in SOD, CAT and GPX activity in frontal cortex and striatum, which was statistically significant on days 14 and 21. At the lower dose of WSG on GPX, the effect was evident only on day 21 (ref. 109). Antioxidant effect of active principles of W. somnifera may explain, at least in part, the re­ported antistress, immunomodulatory, cogl1ltlon­facilitating, anti-inflammatory and anti-ageing effects produced by them in experimental animals, and in clinical situations"o.

Zingiber officinale Plants of ginger family (Zingiberaceae) have been

frequently and widely used as spices and also, in tra­ditional oriental medicine3 1

. Yakuchinone A [1-(4'­hydrox y-3' -methox yphen y I )-7 -phen y 1-3-heptanone] and yakuchinone B [1-(4'-hydroxy-3'-methoxyphenyl)-7-phenylhept-l-en-3-one] present in Alpinia oxyphylla Miquel (Zingiberaceae) have inhibitory effects on phorbol ester-induced inflammation and skin carcino­genesis in mice, and oxidative stress in vitro. These diarylheptanoids suppress phorbol ester-induced act i­vation of ornithine decarboxylase and production of tumor necrosis factor-alpha or interleukin-l alpha and their mRNA expression. They also nullified the phor­bol ester-stimulated induction of activator protein-l (AP-I) in cultured human promyelocytic leukemia (HL-60) cells. In addition, both yakuchinone A and B induced apoptotic death in HL-60 cells. Ginger (Zingiber officinale Roscoe, Zingiberaceae) contains such pungent ingredients as [6]-gingerol and [6]­paradol, which also have anti-tumor promotional and anti proli ferati ve effects29

.

Nitric oxide and imrnunomodulation Recent studies have shown that in addition to reac­

tive oxygen intermediates, macrophages may also produce reactive nitrogen intermediates (RNIs), espe­cially nitric oxide (NO), as effector molecules. NO is a labile and highly reactive gas and acts as cytotoxic/

652 INDIAN J EXP BIOL, JUNE 2002

cytostatic effector molecule against tumor cells and various intracellular and extracellular pathogens. One of the possible therapeutic strategies against tumours and infections, could be to upregulate or restore pro­duction of NO in tumor-bearing or parasitized hosts. Studies by Upadhyay III indicate that modulation of NO production using plant deri ved immunomodula­tors could provide a cost effective and less toxic alter­native to chemotherapy against tumor and infections or such molecules can be used in conjunction with anti-tumor or antibiotic drugs for a synergistic action.

Conclusions and future prospects Considering the entire array of components in­

volved in the immune system, it presents as a com­plex, but precisely interwoven network of biochemj­cal mechanisms. It is vulnerable to oxidative stress fro m reactive oxygen and nitrogen species, which have the potential to damage various biological mole­cules produced during the functioning of the immune system. During certain diseased states as well as dur­ing ageing there is a need for boosting the antioxidant availability and thereby potenti ating the immune mechanisms. In this context immunomodulators hav­ing antioxidant abilities, especially derived from In­dian medicinal plants have considerable potenti al. In this rev iew we have identifi ed certain extracts/com­pounds from several medic inal plants which display both immunomodulating and antioxidant effects.

These immunomodulating compounds can also act as adjuvants, or inhibit the immune response. The low molecular weight immunosuppresants can inhibit cell proliferation or may bring about selective inhibition of events in signal transduction pathways. The immu­nostimulants may have potential applications follow­ing radiotherapy and in ageing.

There is a lot more to be done to understand the mechanisms behind these effects as well as to employ them as possible therapeutic agents. A systematic ap­proach is needed for identifying active constituents from different medicinal plants and their multifarious effects, both toxic and beneficial , using modern tech­niques. A multidisciplinary approach will be more rewarding in this direction. Since Rasayana drugs are capable of influencing the biological systems in a multidimensional manner, it is equally worthwhile to examine them for other effects, such as anti-stress, adaptogenic and anti-ageing activities. The task is quite demanding since each plant in the Rasayana category contains a plethora of constituents with simi­lar, synergistic or antagonistic properties.

Acknowledgement Thanks are due to Ms. Jai C. Tilak for help in the

preparation of manuscript.

References I Kuby J, Immunology, 3'd Edition, (W H Freeman & Co,

New York), 1997.

2 Janeway Jr. C A & Travers P, Immunobiology: The im­mune system in health and disease, (Current Biology Ltd.lBlackwell Scientific/ Garland Publishers, New York) , 1994.

3 Mossman T R & Coffman R L, Th 1 and Th2 cells: differ­ent pattern of Iy mphokine secre tion lead to different func­tional properties, Annu Rev Immunol, I' (1989) 145.

4 Medzhitov R, Preston-Hurlburt P & Janeway CA Jr. , A human analog of Drosophil a toll prote in signal ac ti vation of adaptive immunity , Nature, 388 (1997) 394.

5 Burnett F M, Clonal selection theory, (Cambridge Univer­s ity Press, London), 1959.

6 Fairhurst R M, Wang C, Seiling P, Modlin R L & Braun J, CD 1 rest ricted T cell s and resistant to polysaccharide en­capsulated bacteria, Immun ology Today, 19 ( 1998) 257.

7 Schwartz R H, Costimulation of T I) mphocytes : The ro le of CD28, CTLA-4 and B7/BB I in interleukin-2 production and immunotherapy , Cell, 71 (1992) 1065.

8 Devasagayam T P A & Kesavan PC , Radioprotective and an tioxidant action of caffeine : Mechanistic considerati ons, Indian J Exp Bioi, 34 (1996) 291.

9 Devasagayam T P A, Molecu lar damage by reactive oxy­gen spec ies: Its possible role in health and disease. in Bio­logical concepts in radiotherapy, edited by BB Singh & 0 Bhattacharjee (Narosa Publi shing House, New Delhi) , 1995, 102.

10 Devasagayam T P A & Kamat J P, Free rad icals and ant i­oxidants and human di sease, EMSI Newslell, 23 (2000) 3.

11 Thomas C E & Kalyanaraman B (editors) Oxygen radicals and the disease process, (Harvard Academic Publi shers, The Netherlands), 1997.

12 Babior B M, Oxidants from phagocytes: agents of defense and dest ruction, Blood, 64 (1984) 959.

13 Knight J A, The aging process. in : Free radicals, antioxi­dants, aging, and disease (AACC Press, Washington, DC) 1999,64.

14 Anggard E, Nitric oxide: Mediator, murderer .. and medi­cine, Lancet, 343 (1994) 199.

15 Ischiropoulos H, Zhu L, Chen J, Tsai M, Martin J C, Smith C 0 & Beckman JS, Peroxynitrite mediated ty rosine nitra­t;0n catalyzed by superoxide dism.l tase, Arch Biochem Biophys, 298 (1992) 431.

16 Viner R I, Ferrington 0 A, Huhmer A F R, Bigelow 0 J & Schoneich C, Accumulation of nitrotyrosine on the SERCA2a isoform of SR Ca-ATPase of rat skeletal muscle during aging : a peroxynitrite-mediated process, FEBS Lell, 377 (1996) 286.

17 Zhu L, Gunn C & Beckman J S , Bactericidal acti vity of peroxynitrite, Arch Biochem Biophys, 298 (1992) 452.

18 Moncada S, Palmer R M J & Higgs E A, N itric oxide: Physiology, pathophysiology, and pharmacology, Pharm­col Rev, 43 (1991) 109.

DEVASAGA Y AM & SAINIS: IMMUNOMODULATION AND ANTIOXIDANTS 653

19 Nathan C F & Hibbs J B, Role of nitric oxide sy nthesis in macrophage antimicrobial ac tivity, Curr Opin Immunol, 3 (1991) 65.

20 Knight J A, Review: Free Radi cals, antiox idants, and the immune system, Ann Clin Lab Sci, 30 (2000) 145.

21 de La Fuente M & Victor V M, Anti-ox idants as modula­tors of immune function, Imlnunol Cell Bioi, 78 (2000) 49.

22 Meydani S N & Haytek M, Vitamin E and the immune re­sponse, in Il1fernational conference on nutrition, imll1unity, and illness in the elderly edited by R K Chandra (A RTS Biomedical Publ , St. Johns, Newfoundl and) 1992, 105.

23 Frei B, England L & Ames B N, Ascorbate is an out­standing ant iox idant in human pl asma, Proc Natl Acad Sci-USA, 88 (1991) 11003.

24 Niki E, Interaction of ascorbate and alpha tocopherol, Ann NY Acad Sci, 498 ( 1987) 186.

25 Diaz M N, Frei B, Vita J A & Keaney J F, Antioxidants and atherosclerotic heart di sease, N Engl J Med, 337 (1997) 408.

26 Palozza P & Krinsky N I, Antioxidant effects of carote­noids in vivo and in vitro: An overview, Meth EnzYl11ol, 2 13 (1992)403.

27 Brennan F M, Mai ni R N & Feldman M, Cytokine ex pres­sion in chron ic inflammatory di sease, Br Med Bull, 51 (1995) 368.

28 Baeuerle P A & Henkel T, Function and activation of NF­kappa B in the immune system, Annu Rev Il11l11l1nol, 12 (1994) 141.

29 Upadhyay S N, Il1ll11un ol11odulation, (Narosa Publi shing House, New Delhi), 1997.

30 Agarwal S S & Singh V K, Immunomodu lators: A review of studies on Indian medicinal plants and synthetic pep­tides. Part I: Med icinal Plants, Proc Indian Natl Sci Acad B, 65 ( 1999) 179.

3 1 Thalle U & Dahanukar S, Rasayana concept: clues from immunomodulatory therapy, in Il1ll11unol1lodulation, ed ited by S N Upadhyay , (Narosa Publishing House, New Delhi ), 1997,141.

32 Ganguly T & Sainis KB , Inhibition of cellul ar immune re­sponses by Tylophora il1dicu in experimental models, Phy­tOl11edicine, 8 (200 I) (in press).

33 Ganguly T, Badheka L P & Saini s KB, Immunomodulatory effects of Tylophora indica on conA induced Iymphopro­liferation, Phytomedic:ine, 8 (200 I) (in press).

34 Hadden J W, Immunostimulants, Trends Phamwcol Sci, 14 (1993) 169.

35 Puhlmann J, Knaus U, Tubaro L, Schaefer W & Wagner H, Immunologically ac ti ve metall ic ion containing polysac­charides of Achyrocline satureioides, Phytochemisl1Y 31 (1992) 26 17.

36 Sendl A, Mulinaci N, Vincieri F F & Wagner H, Anti­inflammatory and immunologically ac ti ve polysaccharides of SeduIII telephium, Phytochel1l istry, 4 ( 1993) 1357.

37 Wagner H, Search for pl ant deri ved natural products with immunostimulatory acti vi ty (recent advances) . Pure Appl Chem, 62 (1990) 1217.

38 Wagner H & Proksh A, Immunostimulatory drugs of fungi and higher plants. in : Economic and medicinal plant research, Vol. I. (Academic Press, London-New York), 1985, 11 3.

39 Wagncr H, Stuppner H, Schafer W & Zenk M, Immu­nologically ac ti ve polysaccharidcs of Echinacea purpllrea cell cultures, Phytochemistry, 27 (1988) 119.

40 Shamaan N A. , Kadir K A, Rahmat A & Ngah W Z, Vita­min C and Aloe vera supplementation protects from chemical hepatocarcinogenesis in the rat , Nlltrition, 14 (1998) 846.

41 Sabeh F, Wright T & Norton S J, Purification and charac­terization of a glutathione peroxidase from the Aloe vera plant , En zyme Protein , 47 ( 1993) 92.

42 't-Hart L A, Nibbering P H, van den Barselaar M T, van Dijk H, van den Berg A J & Labadie R P, Effects of low molecular weight constituents from Aloe vera gel on oxida­tive metaboli sm and cytotoxic and bactericidal acti vities of human neutrophil s, Int J IlIImunophannacol, 12 (1990) 427.

43 Ali M, Thomson M & Afzal M, Garlic and onions: their ef­fect on eicosanoid metabolism and its clini cal relevance, Prostaglandins Leukot Essent Fatty Acids, 62 (2000) 55.

44 Helen A, Rajasree C R, Krishnak umar K, Augusti K T & Vijayammal P L, Antiox idant role of oil s isolated from garlic (A llium sativul1l Linn) and onion (A llium cepa Linn) on nicotine-induced lipid peroxidation. Vet HUIIl Toxicol, 41 (1999) 3 16.

45 Singh A & Shukla Y, Antitumor act ivity of dially l sulfide in two-stage mouse sk in model of carcinogenesis, Biollled Environ Sci, II (1998) 258.

46 Thalle U, Bagadey S & Dahanukar S, Modulation of pro­grammed cell death by medicinal plants, Cell Mol Bioi Noisy Ie grand, 46 (2000) 199.

47 Martz W, Plants with a reputati on against snakebite, Toxi­con, 30 (1992) 1131.

48 Puri A, Saxena R, Saxena R P, Saxena K C, Srivastava V & Tandon J S, Immunostimulant agents from Andro­graph is paniculata, J Nat Prod, 56 (1993) 995.

49 Guo Z L, Zhao H Y & Zheng X H, An experimental study of the mechanism of Andrographis paniculata nees (APN) in alleviating the Ca2+-overloading in the process of myo­cardial ischemic reperfusion, J Tongji Med Univ, 15 (1995) 205.

50 Dhuley J N, Effect of some Indian herbs on macroph age functions in ochratox in A treated mice, J Ethnophannacol, 58 (1997) 15.

51 Thalle U & Dahanukar S A, Comparative study of immu­nomodulatory activity of Indian medicinal pl ants, Lithium carbonate and Gluean, Meth Find Exp Clin Phannacol, 10 ( 1988) 639.

52 Kamat J P, Boloor K K, Devasagayam T P A & Venkatachalam S R, Antioxidant properties of Asparagus racemosus against damage induced by y-radi ati on in rat li ver mitochondria, J Ethnopharmacol, 71 (2000) 425.

53 Njiro S M & Kofi Tsekpo M W, Effect of an aqueous ex­trac t of Azadirachta indica on the immune response in mice, Onderstepoort J Vet Res, 66 (1999) 59.

54 Upadhya:' S N, Dhawan S, Garg S & Talwar G P, Immu­nomodulatory effects of neem (Azadirachta indica) oil. Int J Il1lmunopharmacol, 14 ( 1992) 11 87.

55 Upadh yay S N, Dhawan S, Sharma M G & Talwar G P, Long- term contracepti ve effects of intrau terine ncem treatment (lUNT) in bonnet monkeys: An alternate to in­trauterine contraceptive dev ices (lUCD), Contraception, 49 (1994) 161.

56 Upadhyay S N, Dhawan S & Talwar G P, Antifertility ef­fects of neem (Azadirachta indica) oil in male rats by

654 INDIAN J EXP BIOL, JUNE 2002

single intra-vas admini stration: an alternate approach to vasectomy, J Alldrol, 14 ( 1993) 275.

57 Sadekar R D, Kolte A Y, Barmase B S & Desai V F, Im­munopotentiating effects of Azadirachla indica (Neem) dry leaves powder in broilers, naturally infected with IBD vi­rus, Indian J Exp Bioi, 36 (1998) 1151 .

58 Chattopadhyay R R, Possible biochemical mode of anti­inflammatory ac tion of Azadirachla indica A. Juss. in rats, Illdian J Exp Bioi, 36 (1998) 41 8.

59 Upadhyay S N, Dhawan S, Garg S & Talwar G P, Immu­nomodulatory effects of ncem (Azadirachta indica) oil , fill J Il1llllunopharlllacol, 14 (1992) 11 87.

60 Rao A D, Devi K N & Thyagaraju K, Isolation of an tiox i­dant principle from Azadirachta seed kernels: determina­tion of its role on plant lipoxygenases, J EnZYllle Illhib, 14 (1998) 85.

6 1 Selvam R, Subramanian L, Gayathri R & Angayarkanni N, The anti-oxidant act ivity of turmeri c (Cu rcllllla longa), J Elhllopharmacol, 47 ( 1995) 59.

62 Ruby A J, Kuttan G, Babu K D, Rajasekharan K N & Kut­tan R, Anti-tumour and antiox idant ac ti vity of natural cur­cuminoids, Callcer Lell , 94 ( 1995) 79.

63 Singhal S S, Awasth i S, Pandya U, Piper J T, Saini M K, Cheng J Z & Awasthi Y C, The effect of curcumin on glu­tath ione- linked enzymes in K562 human leukemia cell s, Toxicol Lell, 109 (1999) 87 .

64 Kawamori T, Lubet R, Steele V E, Kelloff G J, Kaskey R 13 , Rao C V & Reddy B S, Chemopreventive effect of cur­cu min, a naturally occurring anti-inflammatory agent , dur­ing the promotion/progression stages of colon cancer, Call­cer Res, 59 ( 1999) 597.

65 Sikora E, Bielak Z A, Piwocka K, Skierski J & Radziszewska E, Inhibition of proliferation and apoptosis of human and rat T lymphocytes by curcumin, a curry pigment, Biochelll Phanllacol, 54 ( 1997) 899.

66 Bhattacharya A, Chatterjee A, Ghosal S & Bhattacharya S K, Antioxidant activity of ac ti ve tannoid principles of EI11-blica officinalis (amla), Indian J Exp Bioi, 37 (1999) 676.

67 Kumar KC S & Muller K, Medicinal plants from Nepal , II. Eval uation as inhibitors of lipid peroxidat ion in biologica l membranes, J Elhlloplwnnacol, 64 ( 1999) 135.

68 Ahmad I, Mehmood Z & Mohammad F, Screening of some Indian medicinal plants fo r their antimicrobial properties, J Elhnopharmacol, 62 (1998) 183.

69 Belinky P A, Aviram M, Mahmood S & Vaya J, Structural aspects of the inhibitory effect of glabridin on LDL oxida­tion, Free Radic Bioi Med, 24 (1998) 1419.

70 Belinky P A, Aviram M, Fuhrman B, Rosenblat M & Vaya J, The antioxidative effects of the isofl avan glabridin on endogenous constituents of LDL during its oxidation, Alherosclerosis, 137(1) (1998) 49-61.

71 Vaya J, Belinky P A & Aviram M, Antioxidant consti tu­ents from licorice roots: isolation, structure elucidation and antioxidative capacity toward LDL oxidation, Free Radic Bioi Med, 23 (1997) 302.

72 Nose M, Terawaki K, Oguri K, Ogihara Y, Yoshimatsu K & Shimomura K, Activati on of macrophages by crude polysaccharide fractions obtained from shoots of Clycyr­rhiza glabra and hairy roots of Clycyrrhiza uralensis in vi­tro, Bioi Pharl1l BIIII, 2 1 ( 1998) I I 10.

73 Kitagawa I, Chen W Z, Hori K, Harada E, Yasuda N, Yoshikawa M & Ren J, Chemical studies of Chinese licorice-roots . I. Eluc idation of five new fl avonoid constituents from the roots of Clycyrrhiza glabra L. collected in Xinj iang, CIr elli Phar", Bull Tokyo, 42 (1994)

74 roam M I, Auddy B & Gomes A, Isolat ion, purification and partial characterization of viper venom inhi bi ting fac­tor from the root extract of the Indian medicinal plant sar­saparilla (Hemidesmus indicus R. Br.), Toxicon, 32 ( 1994) 1551.

75 Alam M I & Gomes A, Adju vant effects and antiserum ac­tion potenti ation by a (herbal) compound 2-hydroxy-4-methoxy benzoic acid isolated from the root extract of the Indian medi cinal pl ant 'sarsapari lla' (Hemidesl1lus illdicus R. Br.), ToxicolI , 36 ( 1998) 1423.

76 Alam M I & Gomes A, Viper venom-i nduced infl amma­tion and inhibition of free radical formation by pure com­pound (2-hydroxy-4- methoxy benzoic ac id) isolated and purified from anantamul (Hel1l ideSllllls indicus R. BR) root ex trac t, Toxicon , 36 ( 1998) 207.

77 Puri A, Saxena R, Saxena R P, Saxena K C, Srivastava V & Tandon J S, Immunostimulalll activi ty of Nyclamhes ar­bor-Irislis L, J Elhnopharlllacol, 42 (1994) 31.

78 Paul 13 N & Saxena A K, Depletion of tumor necrosis fac­tor-alpha in mice by Nyclanlhes arbor-Irislis, J EI/'IIIo ­pharmacol, 56 (1997) 153.

79 Agarwal A K, Singh M, Gupta N, S.1Xena R, Puri A, Verma A K, Saxe na R P, Dubey C B & Saxena K C, Man­agement of giardiasis by an immuno-modul atory herba l drug Pippal i rasayana, J Elhnophanl1acol, 44 ( 1994) 143.

80 Kirtikar K R & Basu B D, (edi tors) indian medicinal plallls, Vols 1&2 (L M Basu, All ahabad), 1984.

81 Gupta S S, Verma S C L, Garg V P & Rai M, Anti-di abetic effects of Tinospora cordi/olia, Part I. Effect on fast ing blood sugar level, glucose tolerance and adrenaline in­duced hyperglycaemia, Indiall J Med Res, 55 (1967) 733 .

82 Shah D S & Pandya D C, A preliminary study about the ant i- inflammatory activity of Tin ospora cordi/olia , J Res Ind Med Yoga HOllleo, II ( 1976) 77.

83 Pendse V K, Mahawar M M, Khanna N K, Somani K C & Gautam S K, Anti-inflammatory and rel ated activity of wa­ter extract of Tillospora cordi/olia (Tc-We) - "Neem Giloe", fndian Drugs, 19 ( 1981) 14.

84 Singh K P, Gupta A S, Pendse V K, Mahatma 0 P, Bhan­dari D S & Mahawar M M, Experimental and clinical stud­ies on Tillospora cordi/alia, J Res Ind Med, 10,9.

85 Zhao T, Wang X, Rimando A M & Che C, Folk lore me­dicinal plants: Tin ospora sagillala var. cra valliana and Mahonia bealei, P/cl/lta Medica, 57 (1991) 505.

86 Thatte U, Chhabria S S, Dahanukar S A, Isaac A, Rcge N N & Karandikar S M, Immunomodulating effects of As­paragus racenlOSUS, Tillospora cordi/olia and Wilhania S011111i/era (Part II)., Abstract No. 53: Presented at the ' In­ternational Symposium of Immunological adjuvants and modulators of non-specific resistance to microbial in fec­tions, Columbia, Maryland, U.S .A., 1986.

87 Thatle U, Chhabria S S, Karandikar S lv1 & Dahanukar S A, Immunotherapeutic modification of Escherichia coli abdomi nal sepsis and mortality in mice by Indi an medici­nal plants, Ind Drugs, 25 ( 1987) 95.

88 Thatte U & Dahanukar S A, Immunotherapeut ic mod i fi ca-

DEY ASAGA Y AM & SAINIS : IMMUNOMODULATION AND ANTIOXIDANTS 655

tion of experimental infcctions by Indian medicinal plants, PhylOlherap Res, 3 ( 1989) 43 .

89 Katiyar C K, Brindavanam N B, Tiwari P & Narayana D B A, Immunomodulator products from Ayurveda: currcnt status and future perspectives, in Imllllln omodulalioll, edited by S N Upadhyay, (Narosa Publishing House, New Delhi), 1997, 163.

90 Rege N, Bapat R D, Koti R, Desai N K & Dahanukar S, Immunotherapy with Tinospora cordiJolia: a new lead in the management of obst ructive jaundice. Illdian J Casu'o­enlerol, 12 (1993) 5.

91 Rege N N, Thatte U M & Dahanukar S A, Adaptogenic properties of six rasayana herbs used in Ayurvedic medi­cine, Phylolher Res, 13 ( 1999) 275.

92 Rege N N & Dahanukar S A, Quantitation of microbicidal activity of mononuclear phagocytes: an ill vilro technique, J Poslgrad Med, 39 (1993) 22.

93 Upadhyay S N, Therapeutic potential of immunomodula­tory agents from plant products, in 1lIIl1lllnoll1oduialioll, ed­ited by S N Upadhyay, (Narosa Publi shing House, New Delhi),1997, pp.149.

94 Sainis K B, Sumariwala P F, Goel A, Chintalwar G J, Si­pahimalani A T & Banerji A, Immunomodulatory proper­ties of stem extracts of Tillospora cordifolia: Cell targets and active principles, in Immunomodulaliol1, edited by S N Upadhyay , (Narosa Publi shing House. New Delhi), 1997, 155 .

95 Sainis K B, Ramakrishnan R, Sumariwala P F, Sipahima­lani A T, Chintalwar G J & Banerji A, Further studies on immunomodulation by natural products from Tinospora cordiJolia , in Imlllull opharlllGcology: Slralegies fro illlI1lLl­

nolherapy , edited by S N Upadhyay , (Narosa Publi shing House, New Delhi), 1999.

96 Chintalwar G J, Jain A, Sipahimalani A T, Banelji A, Su­mariwala P, Ramakrishnan R & Sainis K B, An immu­nologically active arabinogalactan from Tillospora cordifo­lia , PhylOchemislry, 52 (1999) 1089.

97 Rupal Ramakrishnan , "Studies on the interactions of natu­ral products from Tillospora cordiJolia on immune system. Ph.D. Thesis submitted to the University of Mumbai , Mumbai , India, 2001.

98 Kapil A & Sharma S, Iml11unopotentiating compounds from Tin ospora cordiJolia, J EI/lIlopharlllacoi, 58 (1997) 89.

99 Prince P S & Menon Y P, Antioxidant activity of Tillo­spora cordiJolia roots in experimental diabetes, J Elhno­pharmacol, 65 (1999) 277.

100 Mathew S & Kuttan G, Antioxidant ac tivity of Tinospora cordiJolia and its usefulness in the ame liorati on of cyclo­phosphamide induced toxicity, J Exp Clill Cancer Res. 16 ( 1997) 407.

101 Bhattacharya S K, Satyan K S & Chakrabarti A, Effect of Trasina, an Ayurvedic herbal formulation, on pancreatic is­let superoxide disl11utase activity in hyperglycael11ic rats, Indian J Exp Bioi, 35 ( 1997) 297.

102 Gangan Y D, Pradhan P, Sipahil11alani A T & Banerji A, Cordifoli sides A, B, C: norditerpene furan glycosides from Tillospora cordiJolia, Phylochelllislry, 37 ( 1994) 78 1.

103 Sipahimalani AT, Norr H & Wagner H, Phenylpropanoid glycosides and tetrahydroOurofuran lignan glycosides from the adaptogenie plant drugs Tinospora cordiJolia and Dry­petes roxburghii., Planta Medica, 60 (1994) 596.

104 Rao Y E & Rao Y M, Studies on the polysaccharide prepa­ration (G uduchisatwa) derived from Tillospora cordifolia,. Indiall J PharmaceLllical Sci, 43 (1981) 131 .

105 al Hindawi M K, al Khafaji S H & Abdu l Nabi M H, Anti­granul oma activity of Iraqi Withania solllnifera, J Elhllo­phanllaco/, 37 ( 1992) 113.

106 UmaDevi P, Sharada A C & Solomon F E, III vivo growth inhibitory and rad iosens itizing effects of Withaferin-A on mouse Ehrlich ascites carcinoma, Cancer Letl, 95 (1995) 189.

107 Begum Y H & Sadique J, Long-term effect of herbal drug Wilhania sOll/lIiJera on adj uvant-induced arthritis in rats, Indian J Exp Bioi, 26 (1988) 877.

108 Dhuley J N, Effect of ashwagandha on lipid perox idation in stress-i nduced ani mals, J Ellmophanllacoi, 60 (1998) 173.

109 Bhattacharya S K, Satyan K S & Ghosal S, Antioxidant ac­ti vity of glycowithanolides from Wilhallia sOlllniJera, In ­dian J Exp Bioi , 35 ( 1997) 236.

110 Surh Y, Molecular mechanisms of chemopreventive effects of selected dietary and medicinal phenolic substances, Shinlim-dong, Kwanak-gu, Seoul , South Korea. MUIaI Res, 428 (1999) 305.

III Upadhyay S N, Imfllllnopharmacology: Slralegies f or illl­munotherapy, (Narosa Publishing House, New Delhi ), 1999.