Evaluation of Heavy Metals, Phytochemical Constituents and Median Lethal Dose of Two Anti-diabetic Plants (Moringa oleifera and Carica papaya)
Keywords:Anti-diabetic, heavy metals, phytoconstituents, permissible limits, safe
Herbal medicine has been recognized as a major component of treatment for many diseases all over the world. Studies have shown that herbal specimens can be contaminated with heavy metals which can be detrimental to the health of the consumers if their concentrations exceed the allowable limits. The present study was aimed to determine the levels of heavy metals, phytoconstituents and median lethal dose of methanol extracts of two anti-diabetic plants; Moringa oleifera and Carica papaya. The heavy metals and phytoconstituents were evaluated using standard qualitative methods, while the median lethal dose was determined using Lorke’s method. The results showed that zinc, arsenic, copper, nickel, cobalt and manganese were detected in the leaves of all the plants, while lead was only detected in the leaves of C. papaya. However, none of the plants was found to contain cadmium. The preliminary phytochemical analysis revealed the presence of saponins, carbohydrates, flavonoids, tannins, cardiac glycosides and steroids in both extracts, while alkaloids were only detected in the methanol extract of C. papaya leaves. The acute toxicity study showed that the median lethal dose (LD50) of the two extracts was estimated to be above 5000 mg/kg body weight. The findings in this study showed that both extracts are practically non-toxic, and also, the levels of heavy metals detected didn’t exceed the permissible limits approved by the World Health Organization (WHO), thus, the leaves of these anti-antidiabetic plants are safe for human consumption.