Journal of Ethnopharmacology 102 (2005) 239245

Antidiabetic activities of aqueouleavala a

watha,. Box 14

May 2t 2005

Abstract

Leaves of d in tractivity has hereforbetle leaves. ed dia(HWE) and and Cdose-dependent manner. In glucose tolerance test, both extracts markedly reduced the external glucose load. The antidiabetic activity of HWEis comparable to that of CEE. Moreover, HWE failed to inhibit the glucose absorption from the small intestine of rats. Both extracts werefound to be non-toxic and well tolerated after following chronic oral administration (no overt signs of toxicity, hepatotoxicity or renotoxicity).However, the weight of the spleen had increased in treated groups possibly indicating lymphoproliferative activity. It is concluded that HWEand CEE o 2005 Pu

Keywords:

1. Introd

Pipersemi woopapillosenate, simLeaves o1.21.8 mvery rare(Jayaweebetle is cPhilippinchief conknown asbrown liqterpenes a

CorrespE-mail a

0378-8741/doi:10.1016f Piper betle leaves possess safe and strong antidiabetic activity.blished by Elsevier Ireland Ltd.

Piper betle leaves; Hypoglycaemia; Antihyperglycaemia; Toxicity

uction

betle Linn. (Piperaceae) is a perennial dioecious,dy climber. Stems strongly swollen at the nodes,when young, soon entirely glabrous. Leaves alter-ple and yellowish green to bright green in color.f fertile branches with a petiole 12 cm long,m thick when dry and glabrous at maturity. Berriesly produced, concrescent into a fleshy spadixra, 1982; Dassanayake and Fosberg, 1987). Piperultivated in Sri Lanka, India, Malay Peninsula,

e Islands and East Africa (Jayaweera, 1982). Thestituent of the leaves of this plant is a volatile oilbetel oil. The volatile oil is bright yellow to darkuid possessing a clove like flavor and consists ofnd phenols (Jayaweera, 1982; Anonymous, 1992).

onding author. Tel.: +94 1 503 399.ddress: wdr@zoology.cmb.ac.lk (W.D. Ratnasooriya).

The volatile oil of Sri Lankan Piper betle leaves consists ofhigh content of safrol. In addition, eugenol, allyl diacetoxybenzene and chavibitol acetate were identified as other majorconstituents of the betel oil (Kumaratunga, 2003). Accordingto the preliminary screening studies carried out at Indus-trial Technology Institute, polyphenols, alkaloids, steroids,saponins and tannins were found in the Piper betle leaves(Anonymous, 2004).

Experimentally, leaves of Piper betle are known as betelleaves are shown to possess antimicrobial (Tewari andNayak, 1991), gastroprotective (Majumdar et al., 2003),wound healing (Santhanam and Nagarajan, 1990), hepato-protective (Saravanan et al., 2002), antioxidant (Choudharyand Kale, 2002; Saravanan et al., 2002; Santhakumariet al., 2003), anti-fertility on male rats (Ratnasooriya andPremakumara, 1997) and antimotility effects on washedhuman spermatozoa (Ratnasooriya et al., 1990). In Asiancountries betel leaves are used for chewing and are cred-ited with many medicinal properties such as digestive, stim-

$ see front matter 2005 Published by Elsevier Ireland Ltd./j.jep.2005.06.016extracts of Piper betleL.S.R. Arambewela a, L.D.A.M. Arawwaw

a Industrial Technology Institute, Bauddhaloka Mab Department of Zoology, University of Colombo, P.O

Received 22 October 2004; received in revised form 10Available online 1 Augus

Piper betle (Piperaceae) possess several bioactivities and are usenot been scientifically investigated so far. The aim of this study tThis was tested in normoglycaemic and strepozotocin (STZ)-induccold ethanolic extract (CEE). In normoglycaemic rats, both HWEs and ethanolices in rats, W.D. Ratnasooriya b,

Colombo 7, Sri Lanka90, Colombo 3, Sri Lanka

005; accepted 15 June 2005

aditional medicinal systems. However, its antidiabetice, was to investigate the antidiabetic activity of Piperbetic rats using oral administration of hot water extractEE significantly lowered the blood glucose level in a

240 L.S.R. Arambewela et al. / Journal of Ethnopharmacology 102 (2005) 239245

ulative, carminative and aphrodisiac (Anonymous, 1992).However, Sri Lankan betel inhibits male sexual behavior inrats and possesses antiaphrodisiac activity (Ratnasooriya andPremakumfor cough aadults. It isgiven for gapurulent ulbetle is notmedicinalleaves maytosum (Peuand Daradkshown to hwas undertto lower blcaemic andoral adminIn additionchronic adm

2. Materia

2.1. Plant

Piper bmarkets inleaves weremunagamaGardens, P01) was dColombo 7

2.2. Anima

Healthy200250 g)housed undaccess to peand tap wa

2.3. Prepa

2.3.1. PrepPiper be

and cut intwith 2.5 L oconcentrate(yield 26.2use.

2.3.2. PrepPiper be

and cut intowith ethano

(2830 C). The extraction was filtered and the filtrate wasevaporated to dryness under reduced pressure at 50 C (yield15.6%, w/w, dry weight basis) and stored at 4 C until use.

Admin

oses oprepa

ps (n =arableacolo

; Sara

Evalu

. Effe

inety sllowelood w). Immy in towing m), 3 (

mg/kgE) an

collecatmen

. Effeis wasincethis drats w

l groupllowiE), 3

e). Onkg of). Blommedly inte

. Effeof STZZ (Si

lved inwards,

rat unSweeles ws were>200ted. Tps (n =p1 (1ara, 1996). Further betel juice is given to childrennd administered to the eye for night blindness inused to treat catarrh and diphtheria. The leaves arestric and lung disorders in children and applied to

cers (Jayaweera, 1982). To our knowledge, Piperrecommended as a antidiabetic agent in traditionalsystems. However, it is possible that Piper betlepossess antidiabetic properties as Piper sarmen-ngvicha et al., 1998) and Piper longum (Purohita, 1999) close relatives of the plant, have been

ave antidiabetic properties. Therefore, this studyaken to investigate the ability of Piper betle leavesood glucose levels. This was tested in normogly-streptozotocin (STZ)-induced diabetic rats using

istration of hot water and cold ethanolic extracts., the toxicity of the extracts was also tested using

inistration.

ls and methods

material

etle leaves were purchased from main vegetableWestern province of Sri Lanka in May 2002. Theidentified and authenticated by Mr. D.H.P. Pera-

, Curator of National Herbarium, Royal Botanicaleradeniya, Sri Lanka. A voucher specimen (PSeposited in the Industrial Technology Institute,, Sri Lanka.

ls

adult cross-bred male albino rats (weighingwere used throughout the experiment. They wereer standard environmental conditions with freelleted food (Vet House Ltd., Colombo, Sri Lanka)

ter.

ration of plant extracts

aration of hot water extract (HWE)tle leaves were air dried for 35 days in the shadeo small pieces. Five hundred grams were boiledf distilled water for 4 h. The hot water extract wasd under vacuum at 60 C, freeze-dried at 20 C

%, w/w, dry weight basis) and stored at 4 C until

aration of cold ethanolic extract (CEE)tle leaves were air dried for 35 days in the shadesmall pieces. Five hundred grams were maceratedl (80%, v/v) and kept for 48 h at room temperature

2.4.

Dwere

groucomppharm2000

2.5.

2.5.1level

Nwas a

sia, b1994domlfolloHWE(100of CEwere

or tre

2.5.2Th

CEEwitheightequathe foof HWtamid5 ml/1994rats ihour

2.5.3level

STdissoafterof the(MacsamplevellevelselecgrouGrouistration of extracts

f 100, 200, 300 and 1500 mg/kg of HWE and CEEred in 1 ml of DW and given orally to separate12 or 6/group/extract) of rats. Doses selected wereto what has been generally used in investigatinggical activities of herbal extracts (Grover et al.,

vanan et al., 2002).

ation of antidiabetic activity

ct of HWE and CEE on fasting blood glucose

ix rats were fasted overnight for 16 h, but waterd. Using aseptic precautions, under ether anesthe-as collected from their tails (Fernandopulle et al.,ediately afterwards, these rats were divided ran-8 groups and treated orally (n = 12/group) in theanner. Group 1 (1 ml of DW), 2 (100 mg/kg of

200 mg/kg of HWE), 4 (300 mg/kg of HWE), 5of CEE), 6 (200 mg/kg of CEE), 7 (300 mg/kg

d 8 (22.5 mg/kg of tolbutamide). Blood samplested from tails 2, 4 and 6 h post-treatment with DWts for the determination of serum glucose levels.

ct of HWE and CEE on oral glucose tolerances investigated using 200 mg/kg of both HWE andthe maximum hypoglycaemic activity was evidentose in normoglycaemic fasted rats. In brief, fortyere fasted for 16 h and assigned randomly into 4s (n = 12/group). These rats were orally treated in

ng manner: Group 1 (1 ml of DW), 2 (200 mg/kg(200 mg/kg of CEE) and 4 (22.5 mg/kg of tolbu-e hour later, all these rats were orally loaded with

50% (w/v) glucose solution (Fernandopulle et al.,od samples were collected from the tails of theseiately prior to commencement of treatment and atrvals up to 3 h after glucose challenge.

ct of the HWE and CEE on blood glucose-induced diabetic rats

gma Chemical Company St. Louis MO, USA) was0.1 M cold citrate buffer (pH = 4.5). Immediately

50 mg/kg dose of STZ was injected to the tail veinder mild ether anesthesia with aseptic precautions

ney et al., 1995). Seventy-two hours later, bloodere collected from tails of these rats and glucose

determined. Twelve rats having blood glucosemg/dl and showing polydipsia and polyuria werehese rats were assigned randomly to two equal6/group) and treated in the following manner.

ml of DW) and 2 (200 mg/kg of HWE). Blood

L.S.R. Arambewela et al. / Journal of Ethnopharmacology 102 (2005) 239245 241

samples were then collected from tails of these rats 2 and 4 hpost-treatment and serum glucose levels were determined.

2.5.4. BlooIn all th

drawn eacand serum3000 rpm fsamples wmethod usiCo. AntriuCooperatio

2.6. Deteractivity

The antiCEE. Theretigate the mthe best po

2.6.1. Effecontent

Twelve(n = 6/grou200 mg/kgfor 42 conswere sacrifiers and skeblood. Glyctometric mBriefly, 100boiling KOwas addedcooled anddiscarded.milliliters oice bath, toat 100 C fan ice bathspectropho

2.6.2. EffeTwelve

domly in t200 mg/kgand 1 ml o10 ml/kg of2 h, these awere exposone cut endthe other eand supernwas then es(Dharmasir

2.6.3. Evaluation of antioxidant activityAntioxidant activity of CEE was measured using two

assays: thiobarbitiuric acid reactive substances (TBARS)man eH) scaol, bu

(w/valculabancelex attive scuring

in kat 5

Toxico

e heas (ner. G1500een 10gical sossesEE. R

vert stremormalitthalmise gror voca

ater iatmenof uri

n daycollecanestEDTAbloo

ation w). Otheraturt 320analy

feraseinine uAntriCorp

fter dm ans, hea

vesicleides

for gs werrecordd samplingese experiments, approximately 0.5 ml blood wash time from the tail using aseptic precautionswas separated immediately by centrifuging at

or 15 min. The glucose concentration in the serumas analyzed immediately by the glucose oxidaseng Randox assay kit (Randox Laboratories Ltd.,m, UK) and a spectrophotometer (V500 Jascon, Tokyo, Japan).

mination of the mode of hypoglycaemic

diabetic effect of HWE was comparable to that offore, 200 mg/kg dose of HWE was used to inves-ode of antidiabetic activity as this dose showed

tential in both extracts.

ct on liver and skeletal muscle glycogen

rats were assigned randomly into two equal groupsp). One group was orally administrated with theof HWE and the other with 1 ml of DW dailyecutive days. On day 1 post-treatment, these ratsced with chloroform and portions of their liv-letal muscles were removed and blotted free ofogen content was determined using a spectropho-

ethod as described in detail by Borst et al. (2000).mg of each organ was digested with 2 ml of 30%

H, and cooled. Three milliliters of 95% ethanoland heated until bubbles were formed. These werecentrifuge (at 1000 rpm for 5 min) and supernatantThe residue was dissolved in 5 ml of DW. Fourf anthrone reagent was added and immersed in anprevent excessive heating. Tubes were incubatedor 4 min for color development and immersed in. Absorbance was measured at 620 nm using atometer.

ct on glucose absorption from intestinemale rats were fasted for 16 h and divided ran-o two equal groups (n = 6/group). The dose ofof HWE was orally administered to one groupf DW to the other group. Thirty minutes later,50% glucose solution was given orally. Followingnimals were sacrificed and their small intestinesed. Fifty milliliters of DW was then infused fromof the intestine and the content was collected at

nd. This was centrifuged at 3000 rpm for 5 minatant discarded. Glucose level in the supernatanttimated using Randox kit and spectrophotometeri, 2001).

(Dor(DPPcontr0.01%and cabsorcompeffecmeas

DPPHBHT

2.7.

Thgroupmann

and (betwicolothat pand Cfor otion,abnoexopintentail oand wof trecolor

Owas

etherpart,whitecentr1993temption awere

transcreatLtd.,Jasco

Aroforglandinaldidyminedorganweret al., 1995) and 2,2-diphenyl-1-picrylhydrazylvenging assay (Singh et al., 2002). As the positive

tylated hydroxy toluene (BHT) was used. In brief,) of CEE and BHT were used in the TBARS assayted the antioxidant index (AI) by measuring theof thiobarbitiuric acidmalondialdehyde color 532 nm. In DPPH scavenging assay, the meanavenging concentration (EC50) was calculated bythe absorbance of the remaining concentrations ofnown concentrations of (050g/ml) of CEE and17 nm.

logical studies

lthy male rats were randomly divided into three= 9/group) and treated orally in the followingroup 1 (1 ml of DW), 2 (1500 mg/kg of HWE)mg/kg of CEE) per day for 42 consecutive days:00 and 11:00 h. The dose, which was used in tox-tudies, was more than 7-folds higher to the dosesed maximum antidiabetic activity in both HWEats were checked twice daily (9:00 and 16:00 h)

igns of toxicity (salivation, diarrohoea, lacryma-rs, ataxia, yellowing of hair, loss of hair, posturalies or behavioral changes), stress (fur erection ora) and aversive behaviors (biting paw and penis,oming behavior, scratching behavior, licking atlization) mortality. Percentage weight gain, foodntake were determined weekly during the periodt for each group. The consistency of faeces andne were noted daily.1 post-treatment, approximately 2 ml of blood

ted from the tail of the treated rats under mildhesia and divided into two equal parts. To one

was added and red blood cell (RBC) counts,d cell (WBC) counts and hemoglobin (Hb) con-

ere determined using standard procedures (Ghai,er part was allowed to clot (2530 min.) at roome (2830 C) and subjected to 15 min. centrifuga-0 rpm for the collection of serum. Serum sampleszed for concentrations of serum aspartate amino-(AST), alanine aminotransferase (ALT), urea andsing Randox enzyme kits (Randox Laboratories

um, UK) and a spectrophotometer (JascoV500,oration, Tokyo, Japan).rawing blood, rats were sacrificed with chlo-d weighed. The liver, kidneys, testes, adrenalrt, spleen, vasa deferentia, prostate glands, sem-s together with coagulating glands, cauda epi-and caput plus corpus epididymides were exam-ross external pathological abnormalities. Thesee removed, blotted free of blood and wet weightsed. Weights of the organs were expressed as a per-

242 L.S.R. Arambewela et al. / Journal of Ethnopharmacology 102 (2005) 239245

centage of the body weight. The stomachs were also removed,opened along the greater curvature and observed for any gas-tric lesions.

2.8. Statistical analysis

Data are given as mean S.E.M. Statistical comparisonswere made using one way ANOVA followed by Tukeys fam-ily error test. A P-value 0.05 was considered as significant.Dose dependencies were determined by regression coeffi-cients (r2).

3. Results

3.1. Effect on fasting blood glucose levels

The effects of Piper betle HWE and CEE on the fastingblood glucose levels are shown in Figs. 1 and 2. All dosesof HWE significantly (P < 0.05) reduced the blood glucoselevels up to 4 h except the lowest dose, which impaired theblood glucose level only up to 2 h. On the other hand, alldoses of CEE significantly (P < 0.05) impaired blood glu-cose levels up to 4 h. This impairment of blood glucoselevels of both extracts were marked and dose-dependent(HWE: r2 = second hour:1, fourth hour:1; CEE: r2 = secondhour:1, fourth hour:1) at each time point. The maximumhypoglycaemic activity was induced by 200 mg/kg dose of

both extracts at 2 h (HWE by 24%; CEE by 26%). Therewas no significant (P > 0.05) difference between the over-all hypoglycaemic activities of HWE and CEE. Hypogly-caemic activity of tolbutamide, the reference drug, was com-parable to that of 200 and 300 mg/kg doses of CEE and200 mg/kg dose of HWE. However, the effects of other testeddoses of Piper betle extracts were inferior to the referencedrug.

3.2. Effect on glucose tolerance test

Both HWE and CEE significantly (P < 0.05) improved theglucose tolerance test up to 3 h (Table 1). HWE and CEEshowing approximately 14, 11, 10% and 16, 12, 11% reduc-tion in glycaemia from control values at the 1, 2 and 3 h,respectively. Tolbutamide also improved the glucose toler-ance test up to 3 h. This impairment was comparable to thatof Piper betle extracts.

3.3. Effect of blood glucose level on STZ-induceddiabetic rats

The results are summarized in Table 2. As shown,200 mg/kg dose of HWE significantly (P < 0.05) reduced thehyperglycaemia induced by STZ (control versus treatment;2 h: 239.3 10.8 mg/dl versus 158.8 21.6 mg/dl and 4 h:242.9 17.9 mg/dl versus 154.8 20.3 mg/dl).

Fig. 1. Effect ood gwith controls:of oral administration of hot water extract (HWE) of Piper betle leaves on bl*P < 0.05.lucose level of fasted rats (mean S.E.M., n = 12). As compared

L.S.R. Arambewela et al. / Journal of Ethnopharmacology 102 (2005) 239245 243

Fig. 2. Effect es on bcompared wit

Table 1Effect of hot w

Dose

Control (1 mlHWE (200 mgCEE (200 mgTolbutamide (DW, distilled

* P < 0.05, a

3.4. Effect

HWE tglycogencontrol ve65.8 2.9sus treatme100 mg).

Table 2Effect of oral aPiper betle lerats (mean SDose

ControlHWE

* P < 0.05, aof oral administration of cold etahnolic extract (CEE) of Piper betle leavh controls: *P < 0.05.ater extract (HWE) and cold ethanolic extract (CEE) of Piper betle leaves on oralGlucose concentration (mg/dl)Pre-treatment Time following 50

1 h

DW) 88.3 2.2 159.2 4.4/kg) 91.6 2.6 132.6 3.9*

/kg) 92.0 2.5 136.9 2.9*22.5 mg/kg) 89.4 2.5 135.2 2.7*water.s compared with controls

of liver and skeletal muscle glycogen content

reatment significantly (P < 0.05) increased thecontent of both skeletal muscle (by 44%;rsus treatment: 45.8 3.1g/100 mg versusg/100 mg) and liver (by 105%; control ver-nt: 54.0 3.6g/100 mg versus 110.8 6.6g/

dministration of 200 mg/kg dose of hot water extract (HWE) ofaves on blood glucose level of streptozotocin-induced diabetic

.E.M., n = 6)Glucose concentration (mg/dl)Pre-treatment Post-treatment (h)

2 h 4 h

228.0 13.2 239.3 10.8 242.9 17.9230.2 16.2 158.8 21.6* 154.8 20.3*

s compared with controls.

3.5. EffectHWE tr

glucose abthe treated36.8 1.6

3.6. Antiox

CEE pothat of BH37.8 versusversus BHT

3.7. Toxico

There wFurther Pipmal food inwere not sThe consislood glucose level of fasted rats (mean S.E.M., n = 12). Asglucose tolerance test (mean S.E.M., n = 12)

% oral glucose load (h)2 h 3 h

145.5 4.1 134.0 4.6127.7 3.8* 119.1 3.4*129.1 2.1* 120.3 3.5*124.9 2.3* 106.6 3.3*

on glucose absorption from intestineeatment did not significantly (P > 0.05) inhibit thesorption from the lumen of the intestine between

and control groups (control versus treatment:mg/ml versus 38.9 1.8 mg/ml).

idant activity

ssessed a higher antioxidant activity compared toT in both TBARS assay (AI: CEE versus BHT;32.7) and DPPH scavenging assay (EC50: CEE; 6.2g/ml versus 8.3g/ml).

logical studies

ere no treatment-related deaths with either extract.er betle HWE and CEE treated rats showed nor-take, water intake, and their percent weight gain

ignificantly (P > 0.05) reduced (data not shown).tency of faeces and colour of urine of HWE and

244 L.S.R. Arambewela et al. / Journal of Ethnopharmacology 102 (2005) 239245

CEE treated rats were essentially similar to those of controls.Furthermore, neither extract of Piper betle induced any overtsigns of toxicity, stress or aversive behaviors.

None oany of theters investiined appeaicant alternthe treatedgroups, sigdent whentreatment vversus 0.2treatment v0.23 0.00lesions wer

4. Discuss

Overallbetle leavetested in fcaemic actiby loweringrats). Thefasted normup to 4 h apglycaemicthat of tolbsulphonylu

In glucolowered thther HWESTZ-inducversibly dacreas (Macendocrineabetic activering the balso suggesactivity. Swater extraet al., 199(Purohit anPiper betlesarmentosulevels in STgle dose ofantihypergthree plantical constitmon. The lthe presencpyrrole amChantrapro

and Finlay, 1995) while the fruits of Piper longum containsvolatile oil, piperine and starch (Shankaracharya et al., 1997).Further, it is possible that both HWE and CEE may act as a

in secrd for s

sulphWE fthe lu

mulatiis anoits itsay restal muari et a

et al.esis. Kperoxn is onperoxtive drevenHWEjudge

ditionxidantnsionely, thper beper bts evensignslevelslevelibit m; Ratnars toer, boh posson, our betle

its thherbal

owled

e auody,

ssistine Res

rence

J.C., Hblishersf the extracts significantly (P > 0.05) changedserum parameters and haematological parame-gated (data not shown). All the organs exam-red normal in treated rats. There was no signif-ation (P > 0.05) in the organ weights betweengroups except for the spleen. In both treatmentnificant increase in weight of the spleen was evi-compared with respective control groups (HWE:ersus control: 0.54 0.01 g/100 g body weight

3 0.00 g/100 g body weight, by 235%; CEE:ersus control: 0.50 0.01 g body weight versusg/100 g body weight, by 217%). Further gastric

e not observed in any of the treated rats.

ion

results show that both HWE and CEE of Pipers possess marked hypoglycaemic activity (whenasted normoglycaemic rats) and antihypergly-vity (by improvement of glucose tolerance test andthe blood glucose levels in STZ-induced diabetic

hypoglycaemic effect of Piper betle extracts onoglycaemic rats were dose-dependent and lastedart from the lowest dose of HWE. Further, hypo-potential of HWE and CEE were comparable toutamide, the reference hypoglycaemic drug of

rea type (Rang et al., 1995).se tolerance test, HWE, CEE and tolbutamide

e external glucose level in a similar manner. Fur-significantly reduced the blood glucose level ofed diabetic rats a dose, which is known to irre-mage the insulin secreting cells of the pan-Sweeney et al., 1995). This suggests that an intactpancreas and insulin are not essential for antidi-ity of Piper betle extracts. This ability of low-

lood glucose levels of STZ-induced diabetic ratsts that Piper betle extracts have insulinomimetic

imilar mode of action also reported with hotct of Piper sarmentosum whole plant (Peungvicha8) and 50% ethanolic extract of Piper longumd Daradka, 1999) fruit, which are close relatives of. However, repeated oral administration of Piperm extract was needed to lower the blood glucoseZ-induced diabetic rats. On the other hand, a sin-both Piper betle and Piper longum extracts had

lycaemic effects in diabetic rats. Although all theextracts possessed antidiabetic effects, the chem-uents present in their leaves or fruits are not com-eaves and fruits of Piper sarmentosum has showne of hydrocinnamic acid, -sitosterol, pellitorine,ine, sarmentine and sarmentosine (Niamsa andmma, 1983; Likhitwitayawuid et al., 1987; Strunz

insulposesome

Hfromaccu

Thisexhibsis mskeleMun(NaiksynthlipiddatioLipidoxidacan pBothity asIn adantiosuspelectivof Pi

PieffecovertALTatinieto inh1990appeFurthwhicclusiPipeshowsafe

Ackn

ThJayakfor afor th

Refe

Allen,Puetagogue and/or sensitize insulin receptors as pro-ome plant extracts (Ratnasooriya et al., 2004) andonylureas (Campbell, 2000).

ailed to significantly inhibit glucose absorptionmen of the intestine. However, HWE provoked

on of glycogen in the liver and the skeletal muscle.ther peripheral mechanism through which HWEantidiabetic activity. This increased glycogene-

ult from enhanced glucose uptake from liver andscle by sensitization of insulin receptors (Frati-l., 1988) and/or inducing the activity of enzymes, 1991; Perfumi et al., 1991) involved in glycogenarpen et al. (1982) observed an elevated level of

ides in the plasma of diabetes rats and lipid peroxi-e of the characteristic features of chronic diabetes.idation is a free radical induced process leading to

eterioration of polyunsaturated fatty acids and thisted by antioxidants (Allen and Hamilton, 1983).and CEE had profound in vitro antioxidant activ-d by TBARS assay and DPPH scavenging assay.

, Santhakumari et al. (2003) have observed a potenteffect in vivo, when 75 mg/kg of Piper betle

administered to STZ-induced diabetic rats. Col-ese observations suggest that antioxidant activitytle may contribute to its antidiabetic potential.etle extracts were devoid of unacceptable sidefollowing chronic administration. There were no

of toxicity, hepatotoxicity (in terms of serum AST,) or renotoxicity (as judged by serum urea and cre-s). However, Piper betle leaf extract are reportedale reproductive competence (Ratnasooriya et al.,asooriya and Premakumara, 1996, 1997), whichbe due to a direct action rather than a toxic effect.th extracts increased the weight of the spleen,ibly suggest lymphoproliferative activity. In con-r results demonstrate the antidiabetic activity ofleaves grown in Sri Lanka for the first time and

erapeutic potential to be used as a cost effectiveantidiabetic agent.

gements

thors express their gratitude to Mr. J.R.A.C.University of Colombo, Department of Zoology,g in this study and National Science Foundationearch grant (SIDA (1L) 2000/BT/03).

s

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Antidiabetic activities of aqueous and ethanolic extracts of Piper betle leaves in ratsIntroductionMaterials and methodsPlant materialAnimalsPreparation of plant extractsPreparation of hot water extract (HWE)Preparation of cold ethanolic extract (CEE)

Administration of extractsEvaluation of antidiabetic activityEffect of HWE and CEE on fasting blood glucose levelEffect of HWE and CEE on oral glucose toleranceEffect of the HWE and CEE on blood glucose level of STZ-induced diabetic ratsBlood sampling

Determination of the mode of hypoglycaemic activityEffect on liver and skeletal muscle glycogen contentEffect on glucose absorption from intestineEvaluation of antioxidant activity

Toxicological studiesStatistical analysis

ResultsEffect on fasting blood glucose levelsEffect on glucose tolerance testEffect of blood glucose level on STZ-induced diabetic ratsEffect of liver and skeletal muscle glycogen contentEffect on glucose absorption from intestineAntioxidant activityToxicological studies

DiscussionAcknowledgementsReferences