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BIOMEDICAL AND ENVIRONMENTAL SCIENCES 21, 319-324 (2008) www.besjournal.com

Heavy Metal Accumulation in Medicinal Plants Collected fromEnvironmentally Different Sites

JYOTI BARTHWAL, SMITHANAIR,AND POONAM KAKKAR1

Herbal Research Section, Industrial Toxicology Research Centre, P. O Box-80, MG Marg, Lucknow, India

Objective To estimate the heavy metal content in soil and selected medicinal plants procured from environmentally

different sites of the same city. Methods Soil and plant samples ofAbutilon indicum, Calotropis procera, Euphorbia hirta,

Peristrophe bycaliculata, and Tinospora cordifolia were collected from 3 environmentally different sites of the city: heavy

traffic area (HTA), industrial area (IA), and residential area (RA). Pb, Cd, Cr, and Ni were estimated in soil and plant samples

by inductively coupled plasma emission spectrometry and compared. Results The level of heavy metal was higher in soil

than in plant parts studied. Accumulation of heavy metals varied from plant to plant. Pb was the highest in Calotropis procera

root from HTA site and the lowest inPeristrophe bycaliculata whole plant from IA site. It was also lower in residential area

than in heavy traffic area. Conclusion The level of heavy metal content differed in the same medicinal plant collected from

environmentally different sites of the same city. Thus, it reiterates our belief that every medicinal plant sample should be tested

for contaminant load before processing it further for medication.

Key words: Heavy metals; Medicinal plants; Lead; Cadmium; Chromium; Herbal raw material

INTRODUCTION

In the last quarter of the century, there has been agrowing interest in the use of substances of natural

origin especially herbs for therapeutic purposes. It has

also been observed that our natural resources have

been contaminated due to excessive use and disposalof chemicals. These chemical residues have the

capacity not only to affect adversely the potency ofherbs but also to cause abiotic and biotic changes at

different levels of the ecosystem. A well-documented

incidence is that of Itai-Itai disease due to residue built

up of Cd2+ in rice[1]. The geoclimatic/environmental

conditions of the region and the agricultural practicesdecide the level of heavy metals that couldaccumulate in herbal raw materials. Studies in our

laboratory have shown that Cd contamination causes

not only its residue built up in wheat seedlings but

also affects the uptake of other micronutrients andlevels of macromolecules affecting the quality of

crop[2-3]. Heavy metal contamination of soil andgroundwater is not at all uncommon today. They

interact with soil matrix and may persist for a long

period of time creating long-term hazards. Their

bioavailability in soil is increasingly used as a key

indicator of potential risks that contaminant pose toboth the environment and human health. Our researchgroup has been involved in evaluating levels of heavy

metals in therapeutically important medicinal plants[4],herbal tea[5], and its ingredients[6]. This study was taken

up to find the bioaccumulation of heavy metals in

selected Indian medicinal plants and its correlation to

the heavy metal load in soil. Efforts were also made tostudy any variation in heavy metal content of medicinal

plants collected from residential area, industrial areaand traffic congested area of the same city.

MATERIALS AND METHODS

Experts from National Botanical Research

Institute, Lucknow, ensured the identity of selected

five medicinal plants for the study. The selection of

plants was based on their therapeutic importance intraditional system of medicine. Samples were

collected from the residential, traffic congested and

industrial sites of Lucknow city along with soil from

the same place. The three areas identified were: a)heavy traffic area (HTA) situated in the center of the

city, b) residential area (RA) with large open fieldsand construction activities, c) industrial area (IA)

1Correspondence should be addressed to: Dr. (Mrs.) P. Kakkar, Head, Herbal Research, Industrial Toxicology Research Centre, Post Box No. 80,

M.G. Marg, Lucknow-226 001, India. Tel: (+91)-0522-2213786, 2627586*269. Fax: (+91)-0522-2628227. E-mail: poonam_kakkar@yahoo.com

Biographical note of the first author: Ms. Jyoti BARTHWAL is M. Sc, Environmental Science. She has been involved in estimation of

heavy metals in therapeutically important medicinal plants.

0895-3988/2008

CN 11-2816/Q

Copyright 2008 by China CDC

319

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320 BARTHWAL, NAIR, AND KAKKAR

near highway where small and medium sizeindustries operate. Soil samples were also collected

from the place of collection of plants.Plant and soil samples were dried, powdered, and

weighed before processing them for analysis. All the

chemicals used like HNO3,perchloric acid, and metal

standard etc., were of analytical (AR) grade (E. Merck,Germany). Deionised water was used throughout the

study and the glassware was of Borosil A grade.

Mixed working standard (1 and 10 g/mL) solutionswere freshly prepared by diluting the stock solutions

of 1000 g/mL. One gram of each powdered plant

sample and soil sample was accurately weighed on anelectronic balance (Shimadzu LEBROR AEX 200G,

Japan). These were put separately into 100 mLdigestion flasks. A digestion mixture comprising of

conc. HNO3and perchloric acid in the ratio of 6:1 was

used for wet digestion of the samples and 10 mL of

this was added to each of the flasks. Blank and spiked

samples were also processed and analyzed

simultaneously. The flasks were first heated on a hot

plate in a fume chamber slowly and then vigorously till1 mL remained at the bottom. If the solution turned

brownish, another 10 mL of digestion mixture was

added and the process repeated till a white residue was

obtained. The residue was dissolved and made up to 10

mL with 0.1 N HNO3 in a volumetric flask[7]. The

solutions were then analyzed with an inductivelycoupled plasma emission spectrometer (8440 Plasma

Labtam). All necessary precautions were adopted toavoid any possible contamination of the sample as per

the AOAC guidelines, 1998[8]. The detection limit of

the instrument for each metal was Cr 0.006 g/g, Ni

0.010 g/g, Pb 0.042 g/g, and Cd 0.0025 g/g.

Statistical Analysis

All the samples were analyzed in triplicate and

mean values along with standard deviation () are

shown in bars in the figures. Percent accumulation by

plants as compared with their respective soil sample

for each metal was also calculated.

RESULTS

Medicinal plant samples collected from identified

sites of Lucknow city along with the soil samples were

subjected to heavy metal estimation, i.e Cd, Ni, Cr, andPb. Table 1 summarizes[10] botanical as well as the

common name of the plant, its part used, major

chemical constituents and medicinal uses. Differentplant parts were taken depending on their therapeutic

usage to get an idea regarding pattern of bioaccumulation

of heavy metal due to environmental pollution.

TABLE 1

Medicinal Plants Analyzed in the Study

Plant Species Common Name Plant Part Therapeutic Uses

Abutilon indicum Linn Country Mallow SeedsUsed in Piles, Laxative, Aphrodisiac, Expectorant, in Chronic

Cystitis, Gonorrhea

Calotropis procera R Br Madar Tree RootUseful for Treating Chronic Cases of Dyspepsia, Flatulence,

Constipation, Loss of Appetite, Indigestion and Mucus in Stool

Euphorbia hirta Linn Spurge Whole PlantPost Natal Complaints, Breast Pain, Skin Eruptions, Antiprotozoal,

Antiviral, and AntidysentricPeristrophe bycaliculataNees Marble Leaf Whole Plant Is Said to Be an Antidote to Snake Poison

Tinospora cordifolia Miers Gulancha Stems Stomachic, Antiperiodic, Antipyretic, Alterative, and Aphrodisiac

Note. Cited from Chopra et al.[10]

.

Abutilon indicum

Figs. 1(a-c) shows accumulation of Pb, Cd, Cr,

and Ni in Abutilon indicum seeds and soil. Pb was

found to be 3-4 g/g in soil samples from all sites

whereas in plants it ranged 0.5-1 g/g, which is below

the permissible limit of 10 g/g recommended byWHO[9]. Cd was the lowest in both soil and plant from

HTA site (Fig. 1a). Cr ranged 0.1-1.21 g/g whereas

Ni ranged 0.45-1.7 g/g. Both Cr and Ni were thelowest in the plant sample from the RA site (Fig. 1b).

Calotropis procera

Pb content in soil collected with Calotropis

procera was 3.8-4.8 g/g where as roots of

Calotropis procerafrom HTA site (Fig. 1d) showed 2

g/g. Samples from HTA site contained 0.25 g/g Cd,

which is below permissible limit of 0.3 g/g

recommended by WHO. The soil sample here

showed Cd content of 1.15 g/g. No Cd was detectedin root samples from RA site (Fig. 1e). Cr was the

highest in the soil as well as plant sample of RA site

(Fig. 1e) whereas Ni was the highest in soil sample of

HTA site. A clear correlation between metal contents

in the soil and plant could not be seen.

Euphorbia hirta

Euphorbia hirtaused extensively to treat postnatal

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HEAVY METAL ACCUMULATION IN MEDICINAL PLANTS 321

FIG. 1. Heavy metal content in plant part and soil ofAbutilon indicum(a-c) and Calotropis procera(d-f)collected from environmentally different sites.

complaints contained 1-1.9 g/g Pb (Figs. 2a-c). Soil

collected from RA and IA sites contained an equallevel of Pb. However, the plants collected from the

same site showed a difference in the Pb content (Figs.2b and 2c). Cr and Ni were the lowest in the soil as

well as plant sample from IA site, whereas Cd was

0.12 g/g and 0.17 g/g respectively, in plant and soil

samples of RA site (Fig. 2b).

Peristrophe bycaliculata

This plant used as an antidote for snake poison

showed 2.5-3.0 g/g of Pb in soil samples whereas inwhole plant the level ranged 0.38 -1.25 g/g (Figs. 2d-f).

Cd present in the plants from HTA site was 0.28 g/g,

which was marginally below the permissible limit of 0.3

g/g. The level of Cd in the plants was 0.07 g/g in the

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322 BARTHWAL, NAIR, AND KAKKAR

sample from RA site and 0.06 g/g in the sample fromIA site (Figs. 2e and 2f). Here the level of heavy metals in

the soil of these sites was also low, ranging 0.1-0.5 g/g.Cr and Ni were the lowest in the sample from IA site.

FIG. 2. Heavy metal content in plant part and soil ofPeristrophe bycaliculata(a-c) andEuphorbiahirta(d-f) collected from environmentally different sites.

Tinospora cordifolia

Pb inTinospora cordifolia(Stem), one of the most

extensively used plants in Ayurveda and other

traditional systems of medicine having propertiesranging from antipyretic to health promoter, was lower

than 2.5 g/g, both in soil and plant samples. Cd wasbelow the permissible limits recommended by WHO in

all the three samples (Figs. 3a-c), whereas Cr and Ni

levels did not vary much with the trend found in other

plants studied. As is evident from the data, althoughthere is variation in the levels of heavy metal detected

from three selected sites, no significant difference was

found in the Cr and Ni content. Pb and Cd were more in

the soil of HTA and IA sites, possibly due to heavy

vehicular traffic or industrial activity.

Percent Accumulation

Attempts to correlate level of Cd and Pb in plantto that present in soil showed that 71% Cd and 33%

Pb were found in HTA site samples compared to that

of soil in case ofAbutilon indicum (Fig. 4a) whereas

in Calotropis procera (Fig. 4b), there was noaccumulation of Cd and the level of Pb was 25%

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HEAVY METAL ACCUMULATION IN MEDICINAL PLANTS 323

compared to that of soil of RA site. In IA site samples,Cd was 68% compared to that of soil. Similarly in

Euphorbia hirta (Fig. 4d), Pb was the highest (67%)in HTA site samples and Cd was the highest in RA

site samples (70%) compared to that of soil. InPeristrophe bycaliculata (Fig. 4c), Cd was 58% in

RA site and 31% in HTA site samples as compared tosoil. In Tinospora cordifolia (Fig. 4e), Pb was 32% in

FIG. 3. Heavy metal content in Tinospora cordifolia and soil from HTA site (a), RA site (b), and IA site (c).

FIG. 4. Percent accumulation of Pb and Cd in medicinal plant samples as compared to soil collected

from (A) HTA site (B) RA site and (C) IA site.

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324 BARTHWAL, NAIR, AND KAKKAR

RA site and 27% in IA site samples as compared to

the level of Pb in soil collected from these areas.

The highest Pb content, among the plant samplesfrom three sites was found in root of Calotropis

procera(2 g/g collected from HTA site of Lucknow

city with soil Pb content of 4.8 g/g). Cd content in

this sample was 0.25 g/g, which was also the

highest among the three plant samples, soil Cd

content in the sample from HTA site was 1.15 g/g.In contrast, maximum Cd was found in the soil for

Tinospora cardifoliacollected from RA site. Both Pb

and Cd detected in our study were below the

permissible limit recommended by WHO.

DISCUSSION

Plants are a good source for bioaccumulation of

heavy metals. On one hand, this property has been

used for phytoremediation[11], on the other hand, it

may prove to be hazardous when plants are consumed

as food or therapeutic agent in traditional medicine.

Although there is a great concern about heavy metalcontamination of herbal raw materials, information

regarding permissible limit is available only for Pb

and Cd[9].

It is clear from the data generated in this study

that there is variation in the bioaccumulation of heavymetals in samples collected from environmentally

different sites of Lucknow city. No clear correlation

was found in this limited study between the level of

heavy metals in plants/soil and collection site and

bioaccumulation of Pb and Cd in the medicinal plants.

Accumulation of Pb in plants in relation to soilcontent was higher in 4 out of 5 plant species tested

in HTA site area with a heavy vehicular traffic. All

the samples tested showed a low level of Pb and Cd,which is well within the permissible limit given by

WHO (1998). On comparison of the medicinal plants

tested, Cd content was the highest in Peristrophe

bycaliculata collected from heavy vehicular traffic

site and industrial area but well within WHO

permissible limit (0.3 g/g). The lowest Cd content

was detected in Calotropis procera sample from

industrial area site and below detection limit in

sample from RA site, indicating that accumulation ofCd in Calotropis procerais minimum as compared to

other plants studied. At the same time, the highest

content of Pb was found in C. procerafrom HTA site

followed byEuphorbia hirtafrom the same site. The

lowest level of Pb was detected in Pristrophebycaliculata, (less than 0.4 g/g) whereas the soil

from the same site had more than 3.0 g/g Pb content,

clearly showing that there is a different accumulation

of heavy metals in medicinal plants exposed to same

environmental conditions and soil is not the onlysource for bioaccumulation of heavy metals. Thus,

the findings emphasize on the need for checking

each medicinal plant sample for heavy metal load,

as there is a considerable difference in their level in

samples collected from the same city during thesame season.

ACKNOWLEDGEMENTS

The authors thank director, I. T. R. C., Lucknow,

India for his interest in this work, and the support

extended by Dr. R. C. MURTHY, Head, Metalanalysis laboratory, I. T. R. C. in carrying out this

work. The authors are grateful to I. T. R. C.

Publication Committee for reviewing this work.

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(Received June19, 2007 Accepted May2, 2008)