Download - Study on selected trace elements and heavy metals in some popular medicinal plants from Sudan
NATURAL RESOURCE LETTER
Study on selected trace elements and heavy metals in somepopular medicinal plants from Sudan
Ammar Mubark Ebrahim • Mohamed Hassan Eltayeb •
Hassan Khalid • Haidar Mohamed •
Wail Abdalla • Peter Grill • Bernhard Michalke
Received: 15 September 2010 / Accepted: 17 January 2012 / Published online: 12 February 2012
� The Japanese Society of Pharmacognosy and Springer 2012
Abstract This study reports on the determination of 11
elements in 33 medicinal plants from Sudan and discusses
a possible correlation between their curative effects and
their trace elements content. Further, a possible accumu-
lation of adverse heavy metals could be excluded. A total
of 11 elements (cadmium, lead, mercury, tin, copper, iron,
manganese, zinc, chromium, selenium and magnesium)
were determined using inductively coupled plasma (ICP)-
optical emission spectrometry (ICP-OES), ICP-sector field-
mass spectrometry (ICP-sf-MS) and hydride generation
(HG)-ICP-OES techniques. The results of the present study
showed no heavy metal accumulation in any of the plants.
Cd, Pb, Hg and Sn were found only in trace concentrations
significantly below the global limits. This indicates the
possibility of a safe use of these medicinal plants. Elevated
chromium concentrations were found in those phytophar-
maca which are employed for the treatment of diabetes
mellitus in Sudanese traditional medicine. Cr was detected
in the same range as in other plants reported to be applied
for diabetes mellitus treatment. Aside from these medicinal
plants, some others were identified which could be poten-
tial sources for providing reasonable amounts of Cr, Zn,
Mn, Se and Mg for the treatment of diabetes mellitus,
smooth muscle relaxation and/or against gastro-intestinal
cramps.
Keywords Trace elements � Heavy metals �Medicinal plants
Introduction
Importance of trace elements and minerals
In recent years, research on the role of trace elements and
minerals in various metabolic processes and their impact
on human health has become an area of particular concern
and high priority in environmental research and protection.
The functional role of trace elements is described in terms
of their nutritionally essential role or their potential toxicity
[1, 2].
Minerals are of critical importance in the diet.
Throughout the world, there is increasing interest in the
importance of dietary minerals in the prevention of several
diseases. An essential element is that required for the
maintenance of life when a deficient intake consistently
results in an impairment of a function from optimal to
suboptimal and, in turn, supplementation with this element
(but not of others) prevents or cures this impairment [3].
Trace elements play an important role as catalysts or parts
of prosthetic groups for enzymes, and, consequently,
insufficient supply leads to element-specific deficiency
symptoms. However, when present in enormous excess, all
of them can exert toxicity. In tissues and fluids, metals are
mostly present as complexes with organic compounds like
amino acids, proteins and peptides, organic acids or
glutathione [4, 5].
A. M. Ebrahim (&) � M. H. Eltayeb
Sudan Atomic Energy Commission, Khartoum, Sudan
e-mail: [email protected]
H. Khalid � H. Mohamed � W. Abdalla
Medicinal and Aromatic Plants Research Institute,
National Center for Research, Khartoum, Sudan
P. Grill � B. Michalke
Research Unit Analytical BioGeoChemistry, Helmholtz Center
Munich, German Research Center for Environmental Health,
Neuherberg, Germany
123
J Nat Med (2012) 66:671–679
DOI 10.1007/s11418-012-0630-6
Medicinal plants
According to the World Health Organization (WHO), the
use of traditional herbal medicine has spread not only in the
developing countries, but also in the industrialised regions,
as a complementary way to treat and to prevent diseases.
The pharmacological properties of the medicinal plants
have been attributed to the presence of active constituents
which are responsible for important physiological functions
in living organisms [3, 6]. Consequently, medical practi-
tioners are also prescribing herbal medicine teas and herbal
extracts as a supplementary type of treatment in everyday
problems caused by our modern civilisation [7].
Sudan has an immense diversity and variation in vege-
tation and is one of the richest countries with regard to
phytopharmaca. Although herbal remedies are often per-
ceived as being natural and, therefore, safe, they are not
principally free from adverse effects. While many inves-
tigations of the quality values of medicinal plants are being
reported in the current literature, less emphasis has been
made on the metal content of herbal products [7].
Sudanese phytopharmaca and trace elements
The WHO estimates that 80% of the developing world’s
people rely on herbs for their primary health care needs [8].
This is also the case in Sudan (personal communications).
Sudanese medicinal plants in dried form have been
exported to different African, Asian, European, North and
South American countries since 1952. Variation in mar-
keted species and the quantity of plant material exported is
subjected to international demands. It was recently
observed that the demand for Hibiscus sabdariffa, Cassia
acutifolia and Boswellia papyrifera has increased, with an
annual revenue of about 42.2 billion USD. Sudan imports a
variety of plant species for use in traditional medicine in
their crude form or as herbal teas. Plant materials are
mainly imported from Egypt, Syria, India, China, Niger,
Guatemala, Saudi Arabia and Tanzania, as well as other
nearby African countries. This cost the country about
900,000 USD annually [9].
It is generally accepted that trace elements play an
important role in the maintenance of human health. How-
ever, a correlation between the elemental composition of
the Sudanese medicinal plants investigated here and their
probably curative properties have not been established yet.
Besides, element concentrations present in medicinal plants
are, aside from other organic plant compounds, of great
importance in order to understand their pharmacological
actions [3, 6, 10]. And, on the contrary, in some cases,
plants may be contaminated with toxic concentrations of
metals which may cause serious health hazard sequences,
such as renal failure, symptoms of chronic toxicity and
liver damage [7].
One very important feature when considering the health
effects of trace elements is their slow accumulation in
tissues, even at low doses. Hence, acute effects are reported
very rarely, whereas chronic exposure can lead to the
build-up of higher concentrations and onset of disease.
Trace element toxicity can manifest with non-specific
symptoms and, often, epidemiology is the only possible
approach to ascertain their role [5].
The present study was conducted to establish baseline
information for trace elements and the levels of heavy
metals in various Sudanese plants, which may help
upcoming research to focus on the site of nutrition, phar-
macology and toxicology. The results are compared to the
trace element concentrations of other medicinal plants from
the literature and discussed with respect to the known
actions of some trace elements. For our investigations, we
have selected the most popular items used in traditional
medicine in Sudan.
Materials and methods
Sample collection
Thirty-three different medicinal plants were collected from
a local market in Sudan. Botanical identification and
authentication of the collected species with depositions of
herbarium specimens have been done by the Medicinal and
Aromatic Plants Research Institute (MAPRI)—National
Center for Research, Sudan. A brief review on the use of
these plants in alternative phytopharmaca-based (tradi-
tional) medicine with their common and scientific names is
given in Table 1.
Chemicals and reagents
Chemicals and reagents used throughout this work were
of suprapure grade. Certified stock standards (1000 mg/L,
each) for Cd, Hg, Pb and Se were purchased from CPI
(Santa Rosa, CA, USA), whilst the customised certified
multi-element standard containing Cr, Zn, Cu, Mg and
Mn was bought from Horiba Jobin Yvon, Pullach, Ger-
many. Dilutions of standards and samples were done
using deionised water (18.2 MX cm) prepared by a
Milli-Q system (Millipore, Bedford, MA, USA). HNO3
was purchased from Merck (Darmstadt, Germany) and
sub-boiling distilled before use. Arliq and oxygen
(99.999% purity) were purchased from Air Liquide,
Grobenzell, Germany.
672 J Nat Med (2012) 66:671–679
123
Ta
ble
1A
bri
efre
vie
wo
fth
est
ud
ied
pla
nts
and
thei
ru
sein
trad
itio
nal
med
icin
e
Bo
tan
ical
nam
eL
oca
ln
ame
Fam
ily
Fo
rm,
med
icin
alu
ses
and
do
sag
e/d
ayC
oll
ecti
on
area
Aca
cia
nil
oti
ca(L
.)W
illd
.E
xD
el.
El-
gar
adM
imo
sace
aeM
acer
atio
no
f2
go
ffr
uit
sis
use
dfo
rp
neu
mo
nia
and
mal
aria
,
and
asa
gar
gle
for
ton
sill
itis
.P
ow
der
of
fru
its
isu
sed
totr
eat
dia
rrh
oea
and
dy
sen
tery
.F
um
igat
ion
for
cold
san
dfe
ver
Nil
eB
ank
Aca
cia
sen
ega
l(L
.)W
illd
.A
l-h
ash
abF
abac
eae–
Mim
oso
idae
Mac
erat
ion
of
10
go
fg
um
isu
sed
asa
dem
ulc
ent,
for
the
trea
tmen
to
fd
iab
etes
and
chro
nic
ren
alfa
ilu
re
Al
Ob
eid
Ad
an
son
iad
igit
ata
L.
Tab
ald
iB
om
bac
acea
eM
acer
atio
no
f1
0g
of
fru
itp
ulp
sis
use
dto
trea
td
iarr
ho
ea,
gia
rdia
sis,
mal
dig
esti
on
and
skin
ton
ics
Al
Ob
eid
All
ium
sati
vum
L.
Th
oo
mL
ilia
ceae
/All
iace
aeB
ulb
sar
eu
sed
asa
con
dim
ent,
anti
sep
tic,
anti
-hy
per
ten
siv
e,
red
uce
cho
lest
ero
lan
db
loo
dp
ress
ure
Do
ng
ola
Am
mi
visn
ag
aL
.K
hel
laB
alad
iya
Ap
iace
aeD
eco
ctio
no
f3
go
ffr
uit
sis
use
dfo
rre
nal
ure
thra
sto
nes
,
smo
oth
mu
scle
rela
xan
t
Kh
arto
um
Sta
te
Ba
lan
ites
aeg
ypti
aca
(L.)
Del
.L
alo
ub
Bal
anit
acea
eM
eso
carp
of
fru
its
isea
ten
or
mac
erat
edan
du
sed
asa
lax
ativ
ean
dan
thel
min
tic.
Oil
of
the
seed
sis
top
ical
ly
use
dfo
rw
ou
nd
hea
lin
g
Ged
arif
Ca
jan
us
caja
n(L
.)M
ills
p.
Ala
dsi
aF
abac
eae–
Pap
ilio
no
idea
eT
he
bo
iled
seed
sar
eea
ten
asa
hae
mat
inic
agen
to
red
ible
foo
dA
lF
aw
Ca
psi
cum
fru
tesc
ens
L.
Sh
atta
So
lan
acea
eT
wo
gra
ms
of
fru
its
use
das
ast
imu
lan
tan
dst
om
ach
ic.
Inm
od
ern
med
icin
e,ap
pli
edex
tern
ally
inth
efo
rmo
f
extr
acts
,ti
nct
ure
s,o
intm
ents
and
pla
ster
sto
trea
trh
eum
atis
m
and
scia
tica
Kh
arto
um
Nil
eB
ank
Cit
rull
us
colo
cyn
this
(L.)
Sch
rad
.A
l-h
and
alC
ucu
rbit
acea
eA
gra
mo
ffr
uit
su
sed
asa
gas
tro
-in
test
inal
stim
ula
nt
or
irri
tan
t,an
ti-r
heu
mat
ic,
for
trea
tmen
tja
un
dic
e,v
ario
us
typ
eso
fca
nce
ran
dsn
ake
bit
esin
folk
med
icin
e
Wes
tO
md
urm
an
Co
ria
nd
rum
sati
vum
L.
Kas
bar
aA
pia
ceae
Th
ree
gra
ms
of
the
po
wd
ero
fth
efr
uit
sis
use
das
a
carm
inat
ive,
sed
ativ
e,d
iure
tic
and
stim
ula
nt
Cu
curb
ita
ma
xim
aL
.A
lG
ara
Ase
liC
ucu
rbit
acea
eT
hre
eg
ram
so
fth
ese
eds
are
use
das
ad
iure
tic,
dem
ulc
ent
and
totr
eat
skin
dis
ease
s
Sin
nar
Cym
bo
po
go
nn
erva
tus
(Ho
chst
.)C
hio
v.
Aln
alP
oac
eae
Ess
enti
alo
ils
are
use
das
mo
llu
scic
idal
agen
ts.
As
an
anti
-bac
teri
al.
Lea
ves
and
stal
ks
use
dto
flav
ou
rw
ater
Bu
tan
a
Cym
bo
po
go
np
roxi
mu
sS
tap
f.M
ahar
aib
Po
acea
eD
eco
ctio
no
f5
go
fae
rial
par
tsis
use
das
ad
iure
tic,
anti
sep
tic,
toal
lay
coel
icp
ain
and
asan
anti
-py
reti
cin
fev
er
Bu
tan
a
Fo
enic
ulu
mvu
lga
reP
.M
ill.
Als
ham
arA
pia
ceae
Infu
sio
no
f5
go
fd
ried
fru
its
isu
sed
asa
carm
inat
ive,
flat
ule
nce
and
dig
esti
ve.
Itis
use
din
vet
erin
ary
med
icin
e
Do
ng
ola
Gre
wia
ten
ax
(Fo
rssk
.)F
iori
Gu
dei
mT
ilia
ceae
Mac
erat
ion
of
10
go
fth
efr
uit
sis
use
dfo
rth
etr
eatm
ent
of
gen
eral
fati
gu
ean
dir
on
defi
cien
cyam
mo
nia
anae
mia
Al
Ob
eid
Gu
iera
sen
ega
len
sis
J.F
.G
mel
.G
ub
eish
Co
mb
reta
ceae
Infu
sio
no
f1
0g
of
the
leav
esis
use
dfo
rth
etr
eatm
ent
of
bro
nch
itis
,fe
ver
,co
ug
han
dst
om
ach
com
pla
ints
,
imp
rov
eth
eh
ealt
ho
fh
yp
er-t
ensi
on
and
dia
bet
icp
atie
nts
Tan
dal
ti
Ha
plo
ph
yllu
mtu
ber
cula
tum
Haz
aR
uta
ceae
Infu
sio
no
f5
go
fth
ele
aves
isu
sed
asan
anti
-sp
asm
od
ic,
anti
-dia
rrh
oea
and
also
use
dfo
rth
etr
eatm
ent
of
the
pro
stat
e
Ab
uH
amed
J Nat Med (2012) 66:671–679 673
123
Ta
ble
1co
nti
nu
ed
Bo
tan
ical
nam
eL
oca
ln
ame
Fam
ily
Fo
rm,
med
icin
alu
ses
and
do
sag
e/d
ayC
oll
ecti
on
area
Hib
iscu
ssa
bd
ari
ffa
L.
Kar
kad
ehM
alv
acea
eM
acer
atio
no
rin
fusi
on
of
5g
of
the
fru
its
epic
aly
ces
isu
sed
anan
ti-h
yp
erte
nsi
ve,
diu
reti
c,an
ti-m
icro
bia
l,an
ti-s
pas
mo
dic
and
for
rela
xat
ion
Kh
arto
um
Sta
te
Hyp
ha
ene
theb
aic
aD
om
Are
cace
aeT
eng
ram
so
fa
po
wd
ero
ffr
uit
epic
arp
sis
use
dfo
rth
e
trea
tmen
to
fg
astr
oin
test
inal
ailm
ents
,w
ou
nd
s
anti
-in
flam
mat
ory
and
anti
-hy
per
ten
siv
e
Dam
azin
La
wso
nia
iner
mis
L.
Hen
na
Ly
thra
ceae
Mac
erat
ion
of
leav
esis
use
das
anan
ti-b
acte
rial
and
anti
-fu
ng
alK
har
tou
mlo
cal
mar
ket
Lep
idiu
msa
tivu
mL
.H
abel
Ras
had
Bra
ssic
acea
e1
.5g
ram
so
fth
ep
ou
ltic
eo
fse
eds
for
the
trea
tmen
to
fM
adu
rafo
ot
Kh
arto
um
loca
lm
ark
et
Lu
pin
us
term
isL
.T
urm
us
Fab
acea
e–P
apil
ion
oid
eae
Th
eb
oil
edse
eds
are
eate
nfo
rth
eh
eali
ng
of
bo
ne
frac
ture
s,b
elie
ved
tore
du
ceb
loo
dsu
gar
Do
ng
ola
Nig
ella
sati
vaL
.A
lkam
oo
nA
laso
dR
anu
ncu
lace
aeT
wo
gra
ms
of
the
seed
sar
eu
sed
totr
eat
man
yd
isea
ses,
such
asd
iab
etes
,h
yp
erte
nsi
on
,ab
do
min
alu
lcer
s,p
rost
ate
gla
nd
infl
amm
atio
ns
and
asan
thel
min
tics
Kh
arto
um
loca
lm
ark
et
Peg
an
um
ha
rma
laH
arm
alZ
yg
op
hy
llac
eae
1.5
gra
ms
of
ap
ow
der
of
the
seed
sis
use
das
anan
thel
min
tic
and
wit
ho
ther
her
bs
for
dem
enti
a
Kh
arto
um
loca
lm
ark
et
Pen
nis
etu
mg
lau
cum
(L.)
R.
Br.
Du
kh
nP
oac
eae
Th
ep
ow
der
of
fru
its
isu
sed
asan
anti
-rh
eum
atic
Ny
alla
Sa
lva
do
rap
ersi
caL
.A
rak
Sal
vad
ora
ceae
Th
eb
ran
ches
and
roo
tsar
eu
sed
for
bru
shin
gte
eth
Kas
sala
Sen
na
ale
xan
dri
na
Mil
l.S
enn
aM
ekk
aF
abac
eae-
Cae
salp
inio
idea
eM
acer
atio
no
f5
go
fth
efr
uit
sis
use
das
ala
xat
ive
Wes
tO
md
urm
an
Ses
am
um
ind
icu
mL
.S
imsi
mP
edal
iace
aeO
ilfr
om
seed
sis
use
dto
pic
ally
asa
bo
dy
mas
sag
ean
dfa
tig
ue
trea
tmen
t,fo
rco
ug
han
dco
ld.
20
go
fth
ese
eds
isal
so
use
das
nu
trit
ive,
lax
ativ
e,d
emu
lcen
tan
dem
oll
ien
tp
rop
erti
es
Ged
arif
So
len
ost
emm
aa
rgel
(Del
.)H
ayn
eH
arg
hel
Asc
lep
iad
acea
eM
acer
atio
no
f2
go
fth
ed
ried
aeri
alp
arts
isu
sed
for
cou
gh
,
gas
tro
-in
test
inal
cram
ps
and
uri
nar
ytr
act
pro
ble
ms
Riv
erN
ile
Sta
te
So
rgh
um
bic
olo
ur
Mo
ench
Zu
raP
oac
eae
Po
wd
ero
ffr
uit
sis
use
das
po
rrid
ge,
then
use
das
an
anti
-ab
ort
ive,
cyan
og
enet
ic,
dem
ulc
ent,
diu
reti
c,em
oll
ien
t,
into
xic
ant
also
use
das
ah
aem
atin
icag
ent
(an
ti-a
nae
mic
)
Ged
arif
-Rah
ad
Ta
ma
rin
du
sin
dic
aL
.A
red
eib
Fab
acea
e–C
aesa
lpin
ioid
eae
Mac
erat
ion
of
10
go
fth
efr
uit
sis
use
das
anti
-mal
aria
trea
tmen
tan
da
lax
ativ
e
Al
Ob
eid
Tri
ticu
ma
esti
vum
L.
sub
sp.
aes
tivu
mG
amih
Po
acea
eT
he
fru
its
are
use
das
pil
lsto
trea
tco
nst
ipat
ion
,as
an
erv
es
rela
xan
t.T
he
fru
its
wit
hm
ilk
and
gh
eear
eu
sed
tofe
ed
pu
erp
eral
wo
man
Gez
ira
Ziz
iph
us
spin
a-c
hri
sti
(L.)
Des
f.A
lsid
rR
ham
nac
eae
Th
ree
gra
ms
of
the
leav
esar
ecr
ush
edan
du
sed
asa
po
ult
ice
for
hai
rto
nic
(sh
amp
oo
san
do
ther
cosm
etic
pre
par
atio
ns)
Al
Ob
eid
674 J Nat Med (2012) 66:671–679
123
Sample preparation
Drying and homogenisation
Samples had already been dried at room temperature before
transportation to the laboratory. There, freeze-drying was
applied at 10�C sample temperature (Christ-Heraeus Beta
freeze dryer, Osterode, Germany) for 4 days until weight
constancy was reached. Aliquots of the plant material were
cut into small pieces using a ceramic knife and subse-
quently grinded and homogenised using an agate ball mill.
The resulting fine powder was used for digestion.
Pressure digestion
The dried and homogenised samples were properly
weighed into quartz vessels. Subsequently, 1 mL HNO3,
suprapure, sub-boiling distilled (Merck, Darmstadt), was
added. The vessels were closed and introduced into a
pressure digestion system (Seif, Unterschleissheim) for
10 h at 170�C. The resulting clear solutions were filled up
exactly to the mark at 10 mL with Milli-Q H2O and were
then ready for element determination.
Sample analysis
Cd, Hg and Pb were analysed with inductively coupled
plasma (ICP)-sector field-mass spectrometry (ICP-sf-MS),
Cr, Zn, Cu, Mg and Mn were measured using ICP atomic
emission spectrometry (ICP-AES), whilst Se was deter-
mined with hydride generation ICP-AES (HG-ICP-AES).
These methods were each best suited for measurement of
the respective elements at the given concentrations in these
samples.
ICP-optical emission spectrometry (OES) measurement
An ICP-AES ‘‘Spectro Ciros Vision’’ system (SPECTRO
Analytical Instruments GmbH & Co. KG, Kleve, Germany)
was used for the Cr, Zn, Cu, Mg and Mn determination in
digested samples. Sample introduction was carried out using
a peristaltic pump equipped with an ‘‘anti-pulse-head’’
(SPETEC, Erding, Germany), connected to a Meinhard
nebuliser with a cyclone spray chamber. The measured
spectral element lines were Cr 267.716 nm, Zn 213.956 nm,
Cu 324.754 nm, Mg 279.079 nm and Mn 257.611 nm. The
RF power was set to 1400 W, the plasma gas was 13 L Ar/min
and the nebuliser gas was 0.6 L Ar/min.
ICP-sf-MS measurement
An ELEMENT 1, Thermo-Finnigan (Bremen, Germany)
ICP-sf-MS instrument was employed for the 114Cd, 202Hg
and 208Pb determination in low-resolution mode. 103Rh was
administered to each sample at a concentration of 1 lg/L as
the internal standard. Sample introduction was carried out
using a peristaltic pump equipped with an ‘‘anti-pulse-
head’’ (SPETEC, Erding, Germany), connected to a
Meinhard nebuliser with a cyclone spray chamber. The RF
power was set to 1200 W, the plasma gas was 15 L Ar/min
and the nebuliser gas was 0.9 L Ar/min.
HG-ICP-OES
An ICP-AES ‘‘Optima 7300’’ system (Perkin Elmer,
Rodgau-Jugesheim, Germany) was used for the Se deter-
mination in digested samples. Sample introduction was
carried out using on-line hydride generation by mixing the
sample with NaBH4 (prepared in 100 mM NaOH) and 5%
HCl at a ratio of 1:2:1. A glass gas–liquid separator was
employed as the sample introduction part to the ICP torch.
The measured spectral element line was Se 196.090 nm.
The RF power was set to 1200 W, the plasma gas was
15 L Ar/min and the nebuliser gas was 0.6 L Ar/min.
Quality control for element determinations
Each of the determination methods had been validated
previously by regular laboratory inter-comparison studies
and by regular analysis of adequate certified reference
materials, the latest directly before this study.
Routinely, ten measurements, three blank determina-
tions and a control determination of a certified standard for
all the mentioned elements were performed. Calculation of
the results was carried out on a computerised laboratory
data management system, relating the sample measure-
ments to calibration curves, blank determinations, control
standards and the weight of the digested sample.
Results and discussion
In the present work, trace element analysis was carried out
among some popular Sudanese medicinal plants in order to
determine their trace elements content or to monitor a
possible accumulation of adverse heavy metals. A total of
11 elements were analysed: cadmium, lead, mercury, tin,
copper, iron, manganese, zinc, chromium, selenium and
magnesium were determined in all the plants listed in
Table 1.
Table 2 gives the concentrations of Cd, Pb, Hg and Sn.
The concentration of heavy metals in collected, non-culti-
vated medicinal plants (non-controlled growth) beyond
permissible limits is a matter of great concern to public
safety all over the world. The problem is rather more
serious in Sudan, because medicinal plants are neither
J Nat Med (2012) 66:671–679 675
123
controlled nor properly regulated by quality assurance
parameters; however, medicinal herbs are easily contami-
nated during growth, development and processing. The
WHO recommends that medicinal plants may be checked
for the presence of heavy metals; further, it regulates the
maximum permissible limits of toxic metals like arsenic,
cadmium and lead, which amount to 1.0, 0.3 and 10 mg/kg,
respectively [11]. The analysis of the present data reveals
that heavy metals such as Cd, Pb, Hg and Sn are found only
in trace concentrations. Lead and cadmium were signifi-
cantly below the WHO limits. Mercury was found to be
much lower than the limit of 0.5 lg Hg/g recommended in
drugs derived from plants in Singapore [12]. This indicates
the possibility of the safe use of these medicinal plants, as
shown in Table 2.
Cadmium was found in the range 0.8–187 lg/kg, where
the highest concentration was detected in Guiera senegal-
ensis, while the lowest value was found in Acacia Senegal.
Lead was observed in the range between 2.6 and 481 lg/kg,
the highest value being associated with Senna alex-
andrina and the lowest with Acacia senegal. Mercury was
observed in very trace amounts in all the studied plants,
varying between 0.2 lg/kg (Grewia tenax) and 40 lg/kg
(Guiera senegalensis). Tin showed a range between 0.2 and
845 lg/kg in Lupinus termis and Cymbopogon nervatus,
respectively. The heavy metal concentrations in these
Table 2 Concentration of Cd,
Pb, Hg and Sn in the studied
Sudanese medicinal plants
Plant Cd
(mean ± SD,
lg/kg)
Pb
(mean ± SD,
lg/kg)
Hg
(mean ± SD,
lg/kg)
Sn
(mean ± SD,
lg/kg)
Acacia nilotica (L.) Willd. Ex Del. 16 ± 1.6 85 ± 3.4 0.23 ± 0.002 49.8 ± 4.3
Acacia senegal (L.) Willd. 0.8 ± 0.01 3 ± 0.1 0.21 ± 0.001 13.8 ± 0.1
Adansonia digitata L. 6.0 ± 0.3 16 ± 0.9 0.25 ± 0.002 13.6 ± 3.9
Allium sativum L. 13 ± 0.5 8 ± 1.0 0.33 ± 0.002 6.70 ± 1.0
Ammi visnaga L. 51 ± 1.4 334 ± 7.1 0.24 ± 0.001 23.1 ± 2.9
Balanites aegyptiaca (L.) Del. 7.0 ± 0.5 11 0.21 ± 0.001 17.1 ± 2.2
Cajanus cajan (L.) Millsp. 114 ± 0.7 7 ± 0.9 0.23 ± 0.004 53.0 ± 2.5
Capsicum frutescens L. 29 ± 0.8 63 ± 1.2 0.46 ± 0.001 92.6 ± 4.6
Citrullus colocynthis (L.) Schrad. 9 ± 0.2 326 ± 26 0.22 ± 0.002 9.4 ± 1.2
Coriandrum sativum L. 29 ± 0.7 23 ± 2.8 3 ± 0.001 9.6 ± 1.3
Cucurbita maxima L. 36 ± 3.7 95 ± 9.4 4 ± 0.001 14.9 ± 0.9
Cymbopogon nervatus (Hochst.) Chiov. 67 ± 3.5 206 ± 10 6 ± 0.01 845 ± 41
Cymbopogon proximus Stapf. 29 ± 1.2 61 ± 4.6 0.27 ± 0.001 10.2 ± 0.1
Foeniculum vulgare P. Mill. 63 ± 1.9 351 ± 4.9 8 ± 0.002 35.5 ± 2.9
Grewia tenax (Forssk.) Fiori 16 ± 0.3 15 ± 1.9 0.2 ± 0.001 18.2 ± 0.1
Guiera senegalensis J.F. Gmel. 187 ± 10.6 454 ± 74 40 ± 0.1 54.8 ± 3.9
Haplophyllum tuberculatum 91 ± 0.8 32 ± 7.5 0.22 ± 0.002 3.1 ± 0.3
Hibiscus sabdariffa L. 59 ± 0.4 167 ± 36 0.25 ± 0.001 81.0 ± 6.6
Hyphaene thebaica 5.0 ± 0.03 8 ± 1.4 0.21 ± 0.002 24.3 ± 2.8
Lawsonia inermis L. 15 ± 0.01 293 ± 68 25 ± 0.01 53.2 ± 4.9
Lepidium sativum L. 60 ± 2.5 16 ± 0.9 0.25 ± 0.001 4.9 ± 1.1
Lupinus termis L. 131 ± 7.7 8 ± 0.1 7 ± 0.02 0.2 ± 0.001
Nigella sativa L. 6.0 ± 0.4 106 ± 6.3 0.29 ± 0.001 83.0 ± 2.6
Peganum harmala 104 ± 1.4 252 ± 16 3. 0 ± 0.01 38.7 ± 3.8
Pennisetum glaucum (L.) R. Br. 25 ± 1.7 41 ± 3.6 0.21 ± 0.001 22.0 ± 2.9
Salvadora persica L. 13 ± 0.2 31 ± 1.9 0.23 ± 0.001 22.6 ± 2.6
Senna alexandrina Mill. 30 ± 0.9 481 ± 43 0.24 ± 0.001 17.4 ± 0.6
Sesamum indicum L. 10 ± 1.3 41 ± 5.4 0.26 ± 0.002 12.5 ± 1.0
Solenostemma argel (Del.) Hayne 16 ± 1.1 120 ± 0.1 20 ± 0.01 5.3 ± 0.8
Sorghum bicolour Moench 7.0 ± 0.2 18 ± 5.3 0.22 ± 0.001 41.4 ± 4.2
Tamarindus indica L. 4.0 ± 0.7 197 ± 43 0.24 ± 0.002 34.5 ± 2.6
Triticum aestivum L. subsp. aestivum 17 ± 0.1 23 ± 0.7 0.21 ± 0.002 11.9 ± 2.8
Ziziphus spina-christi (L.) Desf. 3.0 ± 0.1 22 ± 2.4 0.42 ± 0.01 27.1 ± 3.8
676 J Nat Med (2012) 66:671–679
123
Sudanese phytopharmaca were considerably lower than the
global recommendations (see above) for these metals and
may be as comparably low as the herbal preparations from
Europe. No heavy metal-based health risk emanates from
the use of these phytopharmaca [11].
Another important aspect is the possible content of
(probably) curative trace elements. Plant-based drugs have
been in use in the amelioration of various ailments, ranging
from common cold up to the support of even cancer
therapies [13, 14], and various trace elements were previ-
ously shown to have a positive impact on some diseases.
As an example, Cr, Mn, Cu and Zn were reported to be
involved in the secretion of insulin from beta cells of the
islets of Langerhans and to enhance insulin action [15].
Further, abnormal zinc metabolism has been suggested to
play a role in the pathogenesis of diabetes [16].
The element concentrations of Cu, Fe, Mn, Zn, Cr, Se
and Mg are listed in Table 3. The variation in the elemental
Table 3 Concentration of some essential trace elements in the studied medicinal plants
Plant Cu
(mean ± SD,
mg/kg)
Fe
(mean ± SD,
mg/kg)
Mn
(mean ± SD,
mg/kg)
Zn
(mean ± SD,
mg/kg)
Cr
(mean ± SD,
mg/kg)
Se
(mean ± SD,
mg/kg)
Mg
(mean ± SD,
mg/kg)
Acacia nilotica (L.) Willd. Ex
Del.
3.4 ± 0.2 250 ± 9.0 9.8 ± 0.6 11.1 ± 2.0 0.58 ± 0.05 0.11 ± 0.01 459 ± 29
Acacia senegal (L.) Willd. 1.0 ± 0.1 10 ± 1.0 2.4 ± 0.01 0.2 ± 0.1 0.57 ± 0.01 0.02 ± 0.01 1235 ± 36
Adansonia digitata L. 4.3 ± 0.4 32 ± 3.0 10.5 ± 0.9 12.8 ± 1.0 0.58 ± 0.05 0.06 ± 0.01 2610 ± 24
Allium sativum L. 0.8 ± 0.1 5 ± 0.3 2.3 ± 0.1 5.6 ± 0.3 0.45 ± 0.06 0.05 ± 0.01 176 ± 7.8
Ammi visnaga L. 9.6 ± 0.1 1715 ± 8.0 64.3 ± 1.3 44.3 ± 0.9 2.6 ± 0.20 0.04 ± 0.01 4450 ± 49
Balanites aegyptiaca (L.) Del. 1.1 ± 0.1 12 ± 0.9 1.3 ± 0.1 3.0 ± 0.1 0.53 ± 0.05 0.04 ± 0.01 519 ± 9.2
Cajanus cajan (L.) Millsp. 11.8 ± 0.4 35 ± 1.0 13.6 ± 0.1 33.1 ± 0.4 0.56 ± 0.04 55 ± 0.01 1040 ± 0.01
Capsicum frutescens L. 9.5 ± 0.1 174 ± 2.0 12.2 ± 0.2 16.6 ± 0.2 0.53 ± 0.05 124 ± 0.02 1485 ± 35
Citrullus colocynthis (L.)
Schrad.
6.6 ± 0.5 46 ± 5.0 14.9 ± 0.8 27.6 ± 4.6 0.58 ± 0.05 1.13 ± 0.06 2070 ± 28
Coriandrum sativum L. 11.3 ± 0.2 107 ± 10 22.8 ± 1.6 39.3 ± 0.4 0.52 ± 0.04 0.08 ± 0.01 3455 ± 7.3
Cucurbita maxima L. 11.6 ± 0.1 173 ± 13 31.8 ± 0.1 74.3 ± 1.3 0.56 ± 0.02 0.2 ± 0.06 3750 ± 42
Cymbopogon nervatus(Hochst.) Chiov.
3.7 ± 0.1 224 ± 5.0 30.2 ± 0.6 81.4 ± 5.9 0.66 ± 0.03 526 ± 0.04 2240 ± 11
Cymbopogon proximus Stapf. 1.3 ± 0.1 189 ± 10 208 ± 10.3 22 ± 5.0 0.58 ± 0.01 0.31 ± 0.01 880 ± 12
Foeniculum vulgare P. Mill. 10.7 ± 0.5 2105 ± 34 65.7 ± 3.4 25.0 ± 1.0 3.6 ± 0.03 40 ± 0.02 3750 ± 84
Grewia tenax (Forssk.) Fiori 3.6 ± 0.03 19 ± 2.0 7.3 ± 0.04 7.1 ± 0.2 0.56 ± 0.01 0.05 ± 0.01 1410 ± 14
Guiera senegalensis J.F. Gmel. 5.8 ± 0.5 534 ± 5.0 517.5 ± 32 26.5 ± 2.0 1.2 ± 0.09 0.08 ± 0.01 1995 ± 46
Haplophyllum tuberculatum 2.6 ± 0.1 82 ± 3.0 13.4 ± 0.4 11.1 ± 1.0 0.66 ± 0.01 0.08 ± 0.01 763 ± 33
Hibiscus sabdariffa L. 2.6 ± 0.1 260 ± 6.0 454 ± 4.3 18.0 ± 0.4 0.7 ± 0.02 0.02 ± 0.01 2695 ± 21
Hyphaene thebaica 2.2 ± 0.04 37 ± 0.6 4.0 ± 0.23 6.5 ± 0.1 0.61 ± 0.01 0.07 ± 0.01 984 ± 7
Lawsonia inermis L. 4.2 ± 0.2 259 ± 15 52.2 ± 2.0 12.5 ± 0.5 0.57 ± 0.01 0.19 ± 0.01 4070 ± 19
Lepidium sativum L. 4.4 ± 0.1 98 ± 3.0 23.1 ± 1.5 45.3 ± 3.5 0.53 ± 0.08 0.32 ± 0.01 3655 ± 16.2
Lupinus termis L. 8.9 ± 0.01 28 ± 0.1 23.1 ± 1.5 47.1 ± 1.7 0.63 ± 0.02 0.32 ± 0.01 1620 ± 57
Nigella sativa L. 7.8 ± 0.2 695 ± 41 33.9 ± 0.6 45.7 ± 1.8 1.8 ± 0.01 36 ± 0.04 3130 ± 56
Peganum harmala 5.6 ± 0.1 449 ± 11 44.1 ± 0.2 23.9 ± 0.07 0.8 ± 0.02 0.43 ± 0.01 2955 ± 35
Pennisetum glaucum (L.) R. Br. 6.4 ± 0.1 138 ± 14 13 ± 0.6 33.9 ± 0.35 0.55 ± 0.01 119 ± 0.03 1680 ± 28
Salvadora persica L. 3.9 ± 0.2 25 ± 0.6 3.8 ± 0.2 8.0 ± 0.62 0.61 ± 0.02 0.05 ± 0.01 614 ± 23
Senna alexandrina Mill. 4.6 ± 0.4 261 ± 13 13.2 ± 0.9 21.1 ± 1.2 0.67 ± 0.03 0.21 ± 0.01 2950 ± 45
Sesamum indicum L. 15.8 ± 0.9 663 ± 4.0 22.6 ± 2.4 51.9 ± 1.7 1.23 ± 0.20 0.03 ± 0.01 3780 ± 35
Solenostemma argel (Del.)
Hayne
10.8 ± 0.01 501 ± 6.0 156.5 ± 9.2 24.7 ± 0.6 1.5 ± 0.05 0.46 ± 0.01 5825 ± 50
Sorghum bicolour Moench 3.8 ± 0.1 45 ± 3.0 16.3 ± 0.6 30.2 ± 1.3 0.58 ± 0.02 40 ± 0.07 1370 ± 42
Tamarindus indica L. 7.3 ± 0.2 96 ± 2.0 8.1 ± 1.2 8.8 ± 0.8 0.52 ± 0.03 0.02 ± 0.01 1035 ± 21
Triticum aestivum L. subsp.
aestivum5.2 ± 0.1 77 ± 0.3 20.0 ± 0.2 30.5 ± 0.6 0.58 ± 0.02 33 ± 0.05 1590 ± 28
Ziziphus spina-christi (L.) Desf. 2.8 ± 0.2 20 ± 3.0 13.3 ± 1.3 5.7 ± 0.2 0.53 ± 0.02 114 ± 0.06 722 ± 57
J Nat Med (2012) 66:671–679 677
123
concentrations of the analysed plants is mainly attributed to
the differences in botanical structure, as well as in the
mineral composition of the soil in which the plants are
cultivated. Other factors responsible for the variation in
the elemental content are preferential absorbability of the
plant, use of fertilisers, irrigation water and climatological
conditions [17].
The high concentrations of K, Ca, Cr, Mn, Cu and Zn in
several medicinal plants which are applied as anti-diabetic
agents in traditional Sudanese medicine fit well with the
attribution of these elements to stimulate insulin action
[15, 16, 18]. Chromium concentrations ranged from 0.45 mg/kg
(Allium sativum) to 3.6 mg/kg (Foeniculum vulgare).
Further medicinal plants with elevated Cr amounts
were Sesamum indicum (1.23 mg/kg), Solenostemma argel
(1.5 mg/kg), Ammi visnaga (2.6 mg/kg), Foeniculum vulgare
(3.6 mg/kg), Nigella sativa (1.8 mg/kg) and Guiera senegal-
ensis (1.2 mg/kg), the latter being used as anti-diabetic
medicinal plants in Sudan traditional medicine. These con-
centrations found in medicinal plants were up to 100-fold
higher compared to most food stuffs (\0.015 lg/kg) [19].
Nigella sativa also showed higher Zn values; this plant may also
be a candidate for future investigations about supplements.
Overall, zinc was found in all the analysed plants,
showing concentrations ranging from 0.2 to 81 mg/kg.
Elevated concentrations were monitored for Sesamum
indicum (51.9 mg/kg), Lepidium sativum (45.3 mg/kg),
Ammi visnaga (44.3 mg/kg), Lupinus termis (47.1 mg/kg),
Coriandrum sativum (39.3 mg/kg), Cucurbita maxima
(74.3 mg/kg), Cymbopogon nervatus (81.4 mg/kg) and
Nigella sativa (45.7 mg/kg). When examining Zn and the
biological roles of its forms, being an integral part of more
than 300 enzymes [20], it is not surprising that these plants
are frequently used in traditional Sudanese medicine.
As an example, Cucurbita maxima is used for treating
skin diseases. This agrees well with its high zinc content.
Zn is known to play an important role in wound healing or
prevention and the reduction of skin irritation [20, 21],
although there might be other, organic curative factors, too.
In the current literature, much attention is paid to Se due
to its protective health effects. In this study, a high quantity
of selenium was observed in Citrullus colocynthis
(1.13 mg/kg), a plant which is used for supporting cancer
treatment and against inflammation (e.g. after snake bites).
These uses could be referred to the anti-oxidant properties
of this plant, which may be—aside others—a result of its
high selenium content. Selenium is known for its protective
action against oxidative stress [22] and is discussed in the
prevention of cancer [13, 23]. The Se values determined for
Citrullus colocynthis agree with Ip and Lisk [24], who
studied the anti-cancer effect of Brazil nuts on mammary
cancer in rats. A dose-dependent inhibitory response was
observed at dietary selenium concentrations of 1–3 mg/kg.
Finally, a high content of magnesium was observed
in Ammi visnaga (4450 mg/kg), Solenostemma argel
(5825 mg/kg) and Sesamum indicum (3780 mg/kg). These
plants are traditionally used as smooth muscle relaxant and
against gastro-intestinal cramps, which is in accordance
with the accepted rectification of Mg deficiency. The latter
is known to cause muscle cramps, gastro-intestinal cramps
and tremor up to heart spasm. The results also agree with
the findings of Ohira et al. and Tong et al., who have
proved that magnesium has affected smooth muscle vaso-
constriction [25, 26].
In conclusion, medicinal herbs appear to demonstrate
significant success in the traditional treatment of many
diseases. Their pharmacological modes of action may be
multifactorial. This paper sheds light on their trace ele-
ments content. The data presented in this study showed that
many Sudanese medicinal plants can be considered as
potential sources for providing a reasonable amount of the
required elements to patients of different health disorders.
The values of some Sudanese medicinal plants support
their integration in modern therapy and may also be of
importance for the development of new medical supple-
ments. Adequate and necessary precautions should be
taken while supplementing the trace elements through such
medicinal plants in order to avoid other complications of
metal toxicity.
Acknowledgements The practical work was done with the help and
understanding of the staff of the Institute of Ecological Chemistry and
the financial support of Helmholtz Center Munich—German Research
Center for Environmental Health, Neuherberg, Germany, and Deut-
scher Akademischer Austausch Dienst (DAAD; German Academic
Exchange Service).
References
1. Naidu GRK, Denschlag HO, Mauerhofer E, Porte N, Balaji T
(1999) Determination of macro, micro nutrient and trace element
concentrations in Indian medicinal and vegetable leaves using
instrumental neutron activation analysis. Appl Radiat Isot
50:947–953
2. Rahmatollah R, Mahbobeh R (2010) Mineral contents of some
plants used in Iran. Pharmacognosy Res 2:267–270
3. Ozcan M (2004) Mineral contents of some plants used as con-
diments in Turkey. Food Chem 84:437–440
4. Schumann K (2006) Dietary reference intakes for trace elements
revisited. J Trace Elem Med Biol 20:59–61
5. Prasad MNV (2008) Trace elements as contaminants and nutri-
ents: consequences in ecosystems and human health. Wiley, New
York
6. Yamashita CI, Saiki M, Vasconcellos MB, Sertie JA (2005)
Characterization of trace elements in Casearia medicinal plant by
neutron activation analysis. Appl Radiat Isot 63:841–846
7. Gomez MR, Cerutti S, Sombra LL, Silva MF, Martınez LD
(2007) Determination of heavy metals for the quality control in
Argentinian herbal medicines by ETAAS and ICP-OES. Food
Chem Toxicol 45:1060–1064
678 J Nat Med (2012) 66:671–679
123
8. International Union of Pure and Applied Chemistry (IUPAC)
(2007) Development of methodologies and protocols for docu-
mentation, evaluation of safety and efficacy and standardization
of herbal medicine. In: Mosihuzzaman M, Choudhary MI (eds)
Protocols on safety efficacy standardization, and documentation
of herbal medicine. IUPAC project: 2005-034-1-300. Available
online at: http://www.iupac.org/web/ins/2005-034-1-300
9. Khalid HS, El-Kamali HH, Atta Elmanan AM (2007) Trade of
Sudanese natural medicinals and their role in human and wildlife
health care. Cropwatch Newsletter 10. Available online at: http://
www.cropwatch.org/Trade%20of%20Sudanese%20Natural%20
Medicinals%20%282%29.pdf
10. Basgel S, Erdemoglu SB (2006) Determination of mineral and
trace elements in some medicinal herbs and their infusions con-
sumed in Turkey. Sci Total Environ 359:82–89
11. Kahn SA, Khan L, Hussain I, Marwat KB, Akhtar N (2008)
Profile of heavy metals in selected medicinal plants. Pak J Weed
Sci Res 14(1–2):101–110
12. Caldas ED, Machado LL (2004) Cadmium, mercury and lead in
medicinal herbs in Brazil. Food Chem Toxicol 42:599–603
13. Whanger PD (1992) Selenium in the treatment of heavy metal
poisoning and chemical carcinogenesis. J Trace Elem Electro-
lytes Health Dis 6:209–221
14. Quijano MA, Moreno P, Gutierrez AM, Perez-Conde MC,
Camara C (2000) Selenium speciation in animal tissues after
enzymatic digestion by high-performance liquid chromatography
coupled to inductively coupled plasma mass spectrometry. J Mass
Spectrom 35:878–884
15. Lokhande R, Singare P, Andhale M (2010) Study on mineral
content of some Ayurvedic Indian medicinal plants by instru-
mental neutron activation analysis and AAS techniques. Health
Sci J 4:157–168
16. Narendhirakannan RT, Subramanian S, Kandaswamy M (2005)
Mineral content of some medicinal plants used in the treatment of
diabetes mellitus. Biol Trace Elem Res 103(2):109–115
17. Naga Raju GJ, Sarita P, Ramana Murty GA, Ravi Kumar M, Reddy
BS, Charles MJ, Lakshminarayana S, Reddy TS, Reddy SB, Vijayan
V (2006) Estimation of trace elements in some anti-diabetic medicinal
plants using PIXE technique. Appl Radiat Isot 64:893–900
18. Castro VR (1998) Chromium in a series of Portuguese plants used
in the herbal treatment of diabetes. Biol Trace Elem Res
62:101–106
19. Thor M, Harnack L, King D, Jasthi B, Pettit J (2011) Critical
review: evaluation of the comprehensiveness and reliability of the
chromium composition of foods in the literature. J Food Comp
Anal 24:1147–1152
20. Al-Sayer H, Al-Bader A, Khoursheed M, Asfar S, Hussain T,
Behbehani A, Mathew A, Dashti H (2000) Serum values of
copper, zinc and selenium in adults resident in Kuwait. Med
Principles Pract 9:139–146
21. Rudolf E, Cervinka M (2008) External zinc stimulates prolifer-
ation of tumor Hep-2 cells by active modulation of key signaling
pathways. J Trace Elem Med Biol 22:149–161
22. Patching SG, Gardiner PH (1999) Recent developments in sele-
nium metabolism and chemical speciation: a review. J Trace
Elem Med Biol 13(4):193–214
23. Cobo-Fernandez MG, Palacios MA, Chakraborti D, Quevauviller
P, Camara C (1995) On line speciation of Se(VI), Se(IV), and
trimethylselenium by HPLC-microwave oven-hydride genera-
tion-atomic absorption spectrometry. Fresenius J Anal Chem
351:438–442
24. Ip C, Lisk DJ (1994) Bioactivity of selenium from Brazil nut for
cancer prevention and selenoenzyme maintenance. Nutr Cancer
21:203–212
25. Ohira T, Peacock JM, Iso H, Chambless LE, Rosamond WD,
Folsom AR (2009) Serum and dietary magnesium and risk of
ischemic stroke: the atherosclerosis risk in communities study.
Am J Epidemiol 169(12):1437–1444
26. Tong G, Rude R (2005) Magnesium deficiency in critical illness.
J Intensive Care Med 20:3–17
J Nat Med (2012) 66:671–679 679
123