Evaluation of heavy metals in some selected medicinal plants growing within the University of Ibadan Campus

Abstract

Background: Medicinal plants are a potent source of therapeutic molecules that heal various diseases in the world.Aim: The aim of this study was to evaluate heavy metal concentrations in the leaves of some selected medicinal plants in selected locations.Setting: The leaves of Azadirachta indica, Magnifera indica and Newbouldia laevis were collected from the botanical garden, roadside and residential area in the University of Ibadan and were authenticated at the Forest Herbarium Ibadan. The samples were thoroughly washed with deionised water and air-dried at room temperature for about three weeks, then ground into powder with a mechanical grinder. The samples were subsequently stored in air-tight bottles for further work.Methods: The milled samples were subjected to wet digestion, and then lead (Pb), chromium (Cr), cadmium (Cd) and nickel (Ni) were analysed using standard methods.Results: The results obtained show that the highest concentrations of Pb, Cr and Cd in the medicinal plants studied were found in N. laevis (23.93 ppm; road side), N. laevis (4.79 ppm; road side) and M. indica (0.36 ppm; road side), respectively, while the lowest concentrations of Pb, Cr and Cd were found in A. indica (7.10 ppm; botanical garden), N. laevis (0.73 ppm; residential) and N. laevis (0.05 ppm; residential), respectively. Ni was totally undetected in all three medicinal plants studied in all the locations.Conclusion: The concentrations of heavy metals at the roadside and residential area were higher than permissible limits set for medicinal plants, but the botanical garden was the lowest and safest in terms of heavy metals accumulation in the medicinal plants studied in the three locations.

Concentrations and Health Risk Assessment of Potentially Toxic Elements in Medicinal Herbs from Northern Nigeria

“…The comparison of this permissible limit with the results obtained indicated that the concentration of chromium was above the permissible limit except in PL1, PL2, and YF3. However, the chromium concentrations of 0.57 to 2.04 ppm of herbs in similar studies from Kenya [29] and 0.73 to 4.79 ppm in some selected medicinal plants growing within the University of Ibadan Campus, Nigeria [58] were above the results obtained in this finding. The concentrations of zinc ranged from 26.65 to 48.61 ppm medicinal herbs.…”

Determination and heavy metals some Nigerian medical plants

“…The levels of Cd recorded in this study were lower compared to similar studies earlier reported, (1.66 ppm) in ten important folk therapeutic plants, Peshawar, Pakistan (Jabeen et al, 2010), (14.05 µg/g) in some selected medicinal plants, Kumasi, Ghana (Kofi et al, 2013) and (0.36 ppm)in some selected medicinal plants, Ibadan, Nigeria (Rufai et al, 2019), but in line with values reported by Kishan et al, (2014). Chromium is important in carbohydrate metabolism and also functions in cholesterol and protein synthesis (Kishan et al, 2014), but chronic exposure of chromium may result in nose irritations, skinrash, stomach upset, bleeds, kidney, liver and lung damage (Zayed and Terry, 2003;Baye and Hymete, 2013).…”

“…Similarly, it has been confirmed that the deficiency of nickel in the human body results in liver disorder (Khan et al, 2008). The levels of Ni in this present study were higher than (0.88 mg/kg) and (0.113 ppm) reported in medicinal plants from India (Kishan et al, 2014), Borno, Nigeria (Adamu et al, 2016), and below detectable limit from Ibadan, Nigeria (Rufai et al, 2019) respectively. Lead is a non-essential element, exposure of lead beyond the permissible limits or long term use of contaminated plants may result in chronic nephritis, headache, colic, anemia, convulsions, brain damage and central nervous system (CNS) disorders (Tong et al, 2000;Klaassen, 2001;Kishan et al, 2014).…”

“…Chromium is important in carbohydrate metabolism and also functions in cholesterol and protein synthesis (Kishan et al, 2014), but chronic exposure of chromium may result in nose irritations, skinrash, stomach upset, bleeds, kidney, liver and lung damage (Zayed and Terry, 2003;Baye and Hymete, 2013). The values of Cr obtained from this study were higher than values reported in earlier studies, (0.69 mg/kg) in some medicinal plants, Riyadh, Saudi Arabia (Hatem et al, 2019), but lower than the value of (4.79ppm) reported by (Rufai et al, 2019).…”

“…The levels of Mn obtained from this study were lower than the similar studies as earlier reported, (49.39 mg/kg) in medicinal plants and their extracts, Serbia (Danijela et al, 2011), (105.56 ppm) in Pakistan (Jabeen et al, 2010), but in line with values reported by (Adamu et al, 2016). Nickel is required in the body in small quantities as it is present in the pancreas where it plays an important role in insulin production (Rufai et al, 2019). Similarly, it has been confirmed that the deficiency of nickel in the human body results in liver disorder (Khan et al, 2008).…”