Determination of Selected Heavy Metals in Some Medicinal ... · PDF fileMedicinal Plants...

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-10, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 866

Determination of Selected Heavy Metals in Some Medicinal Plants Marketed in Three Major Selling-

outlets within Sokoto Metropolis-Nigeria

A.Uba1, S.I.B. Baburo2 A.I. Tsafe 2, M. Achor 3, M. I. Abdullahi1, M.E. Halilu4, C. Mohammad2, M. Yahaya2 & A. J. Yusuf1

1Department of Pharmaceutical and Medicinal Chemistry 2Department of Pure and Applied Chemistry

3Department of Pharmaceutics and Pharmaceutical Microbiology 4Department of Pharmacognosy and Ethnopharmacy

Usmanu Danfodiyo University, Sokoto

Abstract: Herbal plants and their extracts deserve special attention because of the important role they play on human health. The majority of the world population depends on herbal plants for their primary health care. According to the World Health Organization (WHO), almost 80% of the people in marginal communities use medicinal plants for treatment of various diseases. Although, the effectiveness of herbal plants is mainly associated with their constituents (phytochemicals), prolonged intake of these plants contaminated by heavy metals can cause devastating health problems. Therefore, the safety, quality and efficacy of herbal medicines has become increasingly important, thus this study was aimed at determining the levels of heavy metals (Cr, Cd, Mn, Cu, Fe, Pb, Zn and Ni) concentration in some medicinal plants frequently used and marketed in three selling-outlets in Sokoto Metropolis using atomic absorption spectrophotometer (AAS). The results revealed maximum concentrations (mg/Kg) of the heavy metals in the analyzed samples as: 0.156±0.001, 0.103±0.005, 44.900±0.002, 0.275±0.003, 18.496±0.001, 1.715±0.001, 3.649±0.001 and 0.429±0.001 for Cr, Cd, Mn, Cu, Fe, Pb, Zn and Ni respectively. The levels of the heavy metals evaluated in the samples were found to be within the WHO limits, except for chromium (Cr) which the concentration was found to be above the WHO limits in Casia singueana and Anogeissus leiocarpus (Kara Market) and in Guiera senegalensis (Old Market). Also the concentration of manganese (Mn) in ten other samples from all the locations, representing 33.33 % of the total samples ware found to be above the WHO limits. On prolong intake the plant extract intake could be risk to health. It is therefore, suggested that pharmacovigilance is required to ensure improved quality, safety and efficacy of these medicinal plants. Key Words: Heavy Metals, Medicinal Plants, AAS, Sokoto

1. Introduction

The term medicinal plant or herb is any plant or plant part that possesses medicinal properties [1] and is important in the art of practicing the use of plant remedies (Herbalism) in the prevention and treatment of illness. Herbal medicines have been used for thousands of years in healing ailments and diseases, and are still used widely in many cultures around the world. For decades, traditional remedies were empirically practiced in Nigeria, and indeed Africa to treat various diseases. The use of herbal medicine has been on increase in many developing and industrialized countries [2]. It is known that between 65 and 80% of the world’s population use herbal medicines as their primary form of health care [2]. In developing nations, the sale, importation and manufacturing of herbal medicines is not properly regulated as there is no rigorous scrutiny in terms of their safety and efficacy when compare to the conventional western medicine. The presence of heavy metals in medicinal plants and medicinal plant preparations used as medicines were reported in a number research articles [2-3], therefore, the use of herbal and traditional medicines raises concerns in relation to their safety even with the wide spread misconception that ‘natural’ means ‘safe’ [4]. Heavy metals have been defined differently depending on the angle of interest; however, toxicity, high density and molecular weight are salient points that inevitably appear in all the definitions of heavy metals [2,5]. Heavy metal therefore refers to any metallic element that has a relatively high density and is toxic or poisonous at low concentrations. Heavy metals include but not restricted to mercury, cadmium, arsenic, chromium, thalium and lead [3,5]. Heavy metals are natural components of the Earth's crust [6,7]. They cannot be degraded or destroyed and could enter human body via food, drinking water, soft drinks, hot drinks, cigarettes and air.

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These heavy metals constitute serious health risk to humans and animals because they bioaccumulate in the body when ingested [3,5]. The aim of this research was to determine the level of some heavy metals in selected medicinal plants marketed at three major selling-outlets in Sokoto town and compare the values to ascertain their compliance with stated limits by World Health Organization.

2 Materials and Methods

2.1. Sample Procurement

The sampling was carried out in the month of May, 2015. The samples were collected from three different sale outlets: Kara Market, Marina Market and Old market. The respective sampling points are shown on the expanded map of Sokoto metropolis, (Figure 1). Ten (10) samples (5 leaves and 5 barks) were obtained from each location making a total number of thirty (30) samples (15 leaves and 15 barks). The same set of samples in identity and number were collected from each location. The samples were collected in polyethylene bags. The

plant parts (leaves, flowers and fruits) were collected for identification purpose. The plants were identified by a consultant Taxonomist in the Department of Pharmacognosy and Ethnopharmacy, Faculty of Pharmaceutical Sciences, Usmanu Danfodiyo University, Sokoto. Voucher specimens of the plant samples were prepared and voucher numbers were assigned and deposited at the Herbarium of the Department for future reference.

2.2. Sample Preparation

All the samples were collected in coarse and powdered forms and were all grounded and sieved separately to very fine particles from which representative samples were quantitatively taken for digestion. The plant scientific and local names, parts of the plant employed in the research and their identification codes as well as the reference voucher number are shown in Table 1.

Figure 1: Map showing Sokoto metropolis and sampling points





Table 1: Medicinal plants used

S/N Hausa Name

Code Scientific Name Plant Part used

Voucher No.

01 Runhu RH Casia singueana Leaves PCG/UDUS/Legu/0001 02 Sabara SB Guiera senegalensis Leaves PCG/UDUS/Comb/0002 03 Geza GZ Combretum micranthum Leaves PCG/UDUS/Legu/0002 04 Fulasko FK Senna italic Leaves PCG/UDUS/Caes/0002 05 Marke MK-L Anogeissus leiocarpus Leaves PCG/UDUS/Comb/0001 06 Hanu HN Boswellia dalzielli Bark PCG/UDUS/Burs/0001 07 Malga MG Cassia arereh Bark PCG/UDUS/Caes/0001 08 Ƙirya ƘY Prosopis Africana Bark PCG/UDUS/Legu/0003 09 Marke MK-B Anogeissus leiocarpus Bark PCG/UDUS/Comb/0001 10 Taura TR Detarium microcarpum; D.

Senegalense Bark PCG/UDUS/Legu/0004

2.3. Reagents and Standards Chemicals of analytical grade were used; nitric acid (HNO3), sulphuric acid (H2SO4) were from M&B while perchloric acid (HClO4), hydrochloric acid (HCl) from BDH. Standard solutions of the metals under investigation were from AAS machine’s manufacturer. 2.4. Digestion of Samples and Analysis Wet ashing technique was used for the digestion of the samples for the analysis of specific process minerals [8]. The process was carried out by taking 1.00 g of each of the prepared sample into separate digestion tubes. 20.00 cm3 of 69.5 % concentrated HNO3 acid was added and heated in a fume cupboard until about one third of each of the content is left. This was followed by the addition of another 10 cm3 of the concentrated HNO3 and 2.00 cm3 of 60 % HClO4 acids, heating continued until clear solutions were obtained. The digested samples were each diluted with about 20 cm3 of double distilled water and boiled for another 15 minutes. The contents were allowed to cool and further transferred into 50 cm3

volumetric

flasks. These were all made to their marks with double distilled water. The solutions were then filtered using Whatman No. 42 filter paper into separate screw capped polyethylene bottles [9]. Similarly, the blank sample solution was prepared in the same way. The concentrations of Cr, Cd, Mn, Cu, Fe, Pb, Zn and Ni in the digested samples was determined using the hollow cathode lamps for the respective elements at the proper wave length and slit width (0.5nm) atomic absorption spectrophotometer (Model No. AA240FS, Varian). The flame type used for all the elements was air-acetylene. 2.5. Statistical data analysis The heavy metal concentrations in the digested samples were presented as mean ± standard deviation (SD). Differences among the sampling areas were analyzed by two-way multivariate and one-way analysis of variance (ANOVA), taking probability factor of 0.05. The software used was Statistical Package for Social Sciences (SPSS) V.15.





3. Results Table 2: Concentration of heavy metals in samples collected from Kara Market

Samples Heavy Metal Concentration (mg/Kg) Cr Cd Mn Cu Fe Pb Zn Ni

Runhu (leaves) 0.156± 0.001

0.103± 0.005

4.600± 0.001

0.275± 0.003

4.433± 0.003

1.133± 0.001

1.881± 0.001

0.340± 0.003

Sabara (leaves) 0.028± 0.001

0.027± 0.001

10.673± 0.001

0.223± 0.001

9.826± 0.001

0.644± 0.001

2.055± 0.001

0.170± 0.001

Geza (leaves) ND 0.016± 0.001

19.808± 0.001

0.165± 0.001

7.371± 0.002

0.395± 0.001

0.753± 0.001

0.146± 0.001

Fulasko (leaves) 0.055± 0.007

0.015± 0.001

5.190± 0.001

0.123± 0.001

18.496± 0.001

0.372± 0.001

0.698± 0.001

0.085± 0.001

Marke (leaves) 0.061± 0.001

0.016± 0.001

4.780± 0.001

0.119± 0.001

3.498± 0.002

0.386± 0.001

1.179± 0.001

0.070± 0.001

Hanu (bark) ND 0.016± 0.001

8.703± 0.001

0.047± 0.001

3.401± 0.002

0.492± 0.001

3.649± 0.001

0.054± 0.001

Malga (bark) ND 0.017± 0.001

5.382± 0.001

0.041± 0.001

4.214± 0.001

0.548± 0.001

0.611± 0.001

0.037± 0.001

Ƙirya (bark) ND 0.017± 0.001

5.453± 0.001

0.036± 0.001

2.173± 0.002

0.623± 0.001

1.659± 0.001

0.079± 0.001

Marke (bark) ND 0.019± 0.001

3.090± 0.001

0.034± 0.001

2.819± 0.001

0.651± 0.001

0.432± 0.001

0.048± 0.001

Taura (bark) ND 0.023± 0.001

44.900± 0.002

0.084± 0.001

5.881± 0.003

0.544± 0.001

0.640± 0.001

0.070± 0.001

Mean±SD.ND=Not Detected

Table 3: Concentration of heavy metals in samples collected from Old Market Samples Heavy Metals Concentration (mg/Kg)

Cr Cd Mn Cu Fe Pb Zn Ni Runhu (leaves) ND 0.038±

0.001 18.136±

0.001 0.127± 0.001

5.519± 0.001

0.576± 0.001

0.480± 0.001

0.212± 0.001

Sabara (leaves) 0.112±0.002

0.030±0.001

10.648±0.001

0.218± 0.001

15.010± 0.001

0.624± 0.001

0.535± 0.001

0.197± 0.001

Geza (leaves) ND 0.028±0.001

10.122±0.001

0.110± 0.001

4.580± 0.001

0.659± 0.001

0.447± 0.001

0.201± 0.001

Fulasko (leaves) ND 0.027±0.001

4.598± 0.001

0.136± 0.001

7.100± 0.001

0.707± 0.001

0.500± 0.001

0.062± 0.001

Marke (leaves) ND 0.026±0.001

8.097± 0.001

0.099± 0.001

4.443± 0.001

0.685± 0.001

0.577± 0.001

0.237± 0.001

Hanu (bark) ND 0.023±0.001

4.417± 0.001

0.062± 0.001

4.939± 0.001

0.766± 0.001

0.318± 0.001

0.083± 0.001

Malga (bark) 0.039±0.001

0.029±0.001

8.871± 0.001

0.042± 0.001

4.328± 0.001

0.736± 0.001

0.385± 0.001

0.157± 0.001

Ƙirya (bark) ND 0.028±0.001

5.076± 0.001

0.070± 0.001

6.928± 0.002

0.676± 0.001

0.151± 0.001

0.096± 0.001

Marke (bark) ND 0.027±0.001

10.775±0.001

0.066± 0.001

15.138± 0.001

0.943± 0.001

0.164± 0.002

0.107± 0.001

Taura (bark) ND 0.030±0.001

11.401±0.001

0.060± 0.001

4.740± 0.001

0.794± 0.001

0.111± 0.001

0.147± 0.001

Mean±SD. ND=Not Detected

Table 4: Concentration of heavy metals in samples collected from ‘Marina Market Samples Heavy Metals Concentration (mg/Kg)

Cr Cd Mn Cu Fe Pb Zn Ni Runhu (leaves) ND 0.034±

0.001 14.977±

0.001 0.130± 0.001

7.438± 0.002

0.600± 0.001

0.286± 0.001

0.293±0.001

Sabara (leaves) ND 0.028± 0.001

5.569± 0.001

0.181±0.001

4.951± 0.002

0.638± 0.001

0.314± 0.001

0.249±0.001

Geza (leaves) ND 0.022± 0.001

11.886±0.001

0.132±0.001

7.711± 0.003

0.638± 0.001

0.281± 0.001

0.251±0.001

Fulasko (leaves) ND 0.021± 0.001

4.028± 0.001

0.160±0.001

15.160±0.002

0.725± 0.001

0.335± 0.001

0.178±0.001

Marke (leaves) ND 0.019± 0.001

4.461± 0.001

0.165±0.001

4.027± 0.001

0.775± 0.001

0.332± 0.001

0.429±0.001





Hanu (bark) ND 0.019± 0.001

3.457± 0.001

0.193±0.001

7.813± 0.001

1.715± 0.001

0.221± 0.001

0.128±0.001

Malga (bark) ND 0.021± 0.001

5.884± 0.001

0.054±0.001

4.182± 0.001

0.650± 0.001

0.307± 0.001

0.172±0.001

Ƙirya (bark) ND 0.029± 0.001

3.098± 0.001

0.065±0.001

4.540± 0.001

0.796± 0.001

0.099± 0.001

0.116±0.001

Marke (bark) ND 0.017± 0.001

2.848± 0.001

0.066±0.001

4.892± 0.003

0.935± 0.001

0.102± 0.001

0.087±0.001

Taura (bark) ND 0.019± 0.001

3.701± 0.001

0.087±0.001

3.636± 0.001

0.633± 0.001

0.203± 0.001

0.095±0.001

Mean±SD. ND=Not Detected

Figure 2: Comparison of chromium concentrations in (mg/Kg) for the 3 locations

Figure 3: Comparison of manganese concentrations in (mg/Kg) for the 3 locations





4. Discussion The results of the analyses are presented in Tables 2 to 4. The results in Table 2 shows the concentrations of Cr, Cd, Mn, Cu, Fe, Pb, Zn and Ni in samples collected from Kara Market with Mn having an overall concentration of 44.90±0.002 mg/Kg in Detarium microcarpum; D.Senegalense (bark) and Cd the least (0.015±0.001 mg/Kg) in Senna italica (leaves). Table 3 also shows the values of the above metals in samples collected from Old Market and Mn still maintaining the highest concentration of 18.136±0.001 mg/Kg and Cd lowest (0.023±0.001 mg/Kg) in Boswellia dalzielli. In Table 4, the concentration of these metals in samples from ‘Marina Market, Fe was the overall highest in concentration with 15.160±0.002 mg/Kg and Cd the lowest (0.017±0.001) mg/Kg in Anogeissus leiocarpus (bark). In a nutshell, the maximum mean concentrations of all the heavy metals in this study appeared in Kara Market except for Pb and Ni that were high in samples from Marina Market. In this study, the concentrations of Cr, Cd, Mn, Cu, Fe, Pb, Zn and Ni in almost all the samples collected from Kara Market, Old Market and Marina Market were within the permissible limits recommended by World Health Organization (WHO). The exceptions were concentrations in Casia singueana, Anogeissus leiocarpus (all leaves) from Kara Market, Guiera senegalensis (leaves) from Old Market were above the World Health Organization (WHO) standard for chromium (Cr) and ten samples from all the locations, representing 33.33 % of the total samples were not in conformity with the recommended limit of the World Health Organization (WHO) for manganese (Mn). In this study, the range of chromium across the three locations (0.028 – 0.156 mg/Kg) exceeded the 0.05mg/Kg of WHO limits in Casia singueana (0.156 mg/Kg) and Anogeissus leiocarpus (leaves) (0.061mg/Kg) from Kara Market and Guiera senegalensis (leaves) (0.112mg/Kg) from Old Market. The concentration of chromium in samples from Kara Market ranges from 0.028 – 0.156 mg/Kg with Casia singueana (leaves) containing the highest concentration of the metal. This was followed by Anogeissus leiocarpus (leaves), while the lowest concentration was in Guiera senegalensis and Senna italic leaves. Chromium was not detected in all the samples from Old Market and ‘Marina Market except for Guiera senegalensis and Cassia arereh with 0.112 mg/Kg and 0.039 mg/Kg respectively. Almost all the samples were within WHO prescribed limit (0.05 mg/Kg) except for Casia singueana and Anogeissus leiocarpus (leaves) in Kara Market and Guiera senegalensis (leaves) in Old Market. The concentrations for chromium were similar to result of [10] who reported 0.0506 mg/Kg of

chromium contamination on Nigerian herbs while [11] did not detect Cr on analysis of some selected toxic heavy metals in some branded Nigerian Herbal Products. Figure 1 above shows the chromium concentrations of the areas under study. Significant difference in chromium (Cr) content at p<0.006 were not observed for plants and plant parts, and also no significant interaction between Cr and the location. The (WHO) daily allowable limit for manganese is 2 – 9 mg/Kg. It was exceeded in 33 % of the samples (2.8 – 44.9 mg/Kg) from all the three locations in this study. The concentration level of manganese ranges from 3.090 – 44.9 mg/Kg in Kara Market with Detarium microcarpum; D.Senegalense (bark) having the highest concentration, followed by Combretum micranthum leaves (19.808 mg/Kg) and Guiera senegalensis (leaves) (10.673 mg/Kg). The lowest being the Anogeissus leiocarpus (bark) and Casia singueana (leaves) constitute 3.090 and 4.600 mg/Kg respectively. The range of manganese in Old Market is 4.417 – 18.136 mg/Kg in which Casia singueana (leaves) and Detarium microcarpum; D.Senegalense (bark) leading, while Boswellia dalzielli (bark) and Senna italic (leaves) were the lowest in concentration. In ‘Marina Market, the range is 2.848 – 14.977 mg/Kg where Casia singueana (leaves) still leads, followed by Combretum micranthum (leaves) and the least are Anogeissus leiocarpus (bark) and Ƙirya (bark). However, a similar manganese concentration of 52.95 mg/Kg was reported by [12]on the profile of heavy metals in selected medicinal plants in Peshawar, Pakistan and lower than 80.90 mg/Kg compared to the concentration reported by [13]. Figure 2 above shows the manganese concentrations of the areas under study. The result revealed a significant effect for plants with difference at p<0.006 in manganese (Mn) content, but no such difference for plant parts as well as no significant interaction between Mn and the location. Chromium was detected in only 20 % of the total samples, three samples representing 10 % slightly exceeded the WHO limit. This was possibly attributed to the fact that high Cr absorption and translocation have been shown to be modified by soil pH, organic matter content and chelating agents, among others [14]. Also, the pathway of Cr (VI) transport is thought to be an active mechanism involving carriers of essential anions such as sulphate [15]. Fe, S and P are known also to compete with Cr for carrier binding [16]. The manganese content which exceeded the WHO limit in 33.33 % may not be unconnected with the fact that the intake of manganese by plants increases in acidic soils (pH < 5.5) and plant requirements for manganese vary, but for the majority of the





cultivated plants, the levels of 10 – 25 mg/kg are sufficient [17]. Manganese plays important metabolic roles in plants including participation in redox processes [18]. Chromium, cadmium and lead are considered to be toxic and non essential elements. Even though, they were low (Cr, Cd and Pb) in concentrations compared to the World Health Organization (WHO) standards, their presence is worrisome as continuous exposure can be toxic. 5. Conclusion In this study it was found that the heavy metals in the samples from all the selling outlets are below WHO limits for heavy metals and therefore, the use of these herbal plants at the time of this research could be relatively harmless, but prolong intake could pose a threat to the health of their users, due to the fact that all elements (essential and non-essential) are toxic in certain forms and in sufficiently high doses. The toxicity of an element/compound is a function of their chemical properties, the biological properties of the organism at risk and also the doses. Even though, 90 % and 66.67 % of the total samples were within the WHO prescribed limits for chromium and manganese respectively, almost 100 % of all the samples were also below WHO limits for all the metals under study other than chromium and manganese. Traditional herbal practitioners need to be cautious on possible contamination of herbal medicines by heavy metals, and the stake holders involved in traditional herbal medicine should also be at alert on the potential risk these metals pose and ensure pharmacovigilance to improve the quality, safety, and efficacy of herbal and herbal products. 6. References [1] John, R.S. The role of Weeds as Sources of Pharmaceuticals, Journal of Ethnopharmacology, 2004, 92 (2-3), 163-166. [2] Barnes, J. Quality, Efficacy and Safety of Complementary Medicines: Fashions, Facts and the Future. Part1: Regulation and Quality, British Journal of. Clinical Pharmacology, 2003, 55, 226-233. [3] Zaleska, A. Heavy Metals: Health and Environmental Effects of Some Heavy Metals (concentration on RoHS Directive), Gdańsk: Chemical Faculty, Gdańsk University of Technology PG Press, 2008, pp. 1- 27. [4] WHO The Importance of Pharmacovigilance, Safety Monitoring of Medicinal products. The Uppsala Monitoring Centre, WHO Collaborating Centre for International Drug Monitoring. World Health Organization , 2002.

[5] Phillips, S., Balge, M. Heavy Metal Toxicity, Texas (SA): New Fields, pp. 1-30.Planning Commission Report (2000) Report of the Task Force on Conservation and Sustainable use of Medicinal Plants. Planning Commission, Government of India, 2007, pp 1–194. [6] WHO Hazardous Chemicals in Human and Environmental Health: A Resource Book for School, College and University Students 2000. [7] Alqosouimi, S. Complementary/Alternative Medicine. United Arab Emirate: Charity Press. 2006, pp. 1-20. [8] Miller-Ihli, J. N. and Baker, A. S. Food and Dairy Products, Applications of Atomic Spectroscopy. Encyclopedia of Spectroscopy and Spectrometry. Vol. 1, Academic Press (AP), London 2000, 583-588. [9] Audu, A. A. and Lawal, A. O. Variation in Contents of Plants in Vegetable Garden Sites in Kano Metropolis, Journal of Applied Science, Environmental and Management, 2006, 10 (2): 105 – 109. [10] Igweze, Z. N., Orisakwe, O. E. Obianime, A. W. Nigerian Herbal Remedies and Heavy Metals: Violation of Standard Recommended Guidelines, Asian Pacific Journal of Tropical Biomedicine, S, 2012, 1423-1430. [11] Ekeanyanwu, R. C., Njoku, J. O., Nwodu, P. O. and Njokuobi A. E. Analysis of Some Selected Toxic Heavy Metals in Some Branded Nigerian Herbal Products, Journal of Applied Pharmaceutical Science, 2013, 3 (04), 088-091. [12] Shad, A. K., Lajbar K., Iqbal H., Khan, B. M. and Naveed, A. Profile of Heavy Metals in Selected Medicinal Plants, Pakistan Journal of Weed Science Research, 2008, 14(1-2), 101-110. [13] Lasisi, A. A., Yusuf, A. A., Ejelonu, B. C., Nwosu, F. O. and Olayiwola, M. A. Heavy Metals and Macronutrients Content in Selected Herbal Plants of Nigeria, International Journal of Chemistry, 2005, 15: (3) 147-154. [14] Han, L., Mason, M., Risseeuw, E.P., Crosby, W.L. and Somers, D.E. Formation of an SCF Complex is Required for Proper Regulation of Circadian Timing. Plant Journal 2004, 40, 291–301. [15] Cervantes, C., Garcia, J. C., Devars, S., Corona, F. G., Tavera, H. L. and Torres-guzman, J. C. Interactions of Chromium with Micro-organisms and Plants. FEMS Microbiol 2001, 25: 335–47. [16] Wallace, A., Soufi, S. M., Cha, J. W. And Romney, E. M. Some Effects of Chromium Toxicity on Bush Bean Plants Grown in Soil. Plant SoiI 1976, 44: 471–3. [17] Kabata-pendias A. and Pendias H. Biogeochemia Pierwiastkow Sladowych, PWN, Warszawa, 1999, 75-88 pp. [18] Foy C. D. Plant Adaptation to Mineral Stress Problem in Soils. Iowa State Journal of Research 1983, 57, 339.



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