Impact of heavy metals on growth and biosynthesis of important secondary metabolites from mucuna pruriens L DC and withania somnifera L DUNAL

Abstract

Herbal medicine has a long history of utilizing medicinal plants to treat various newlineailments for a long time. However, heavy metal toxicity in herbal medicines has been newlinedocumented. The occurrence of heavy metals in medicinal plants is a consequence of exposure to tainted agricultural sources. The consumption of medicinal plants newlinecontaminated with heavy metals has caused detrimental health implications. On the newlineother hand, plants when subjected to heavy metal stress exhibit changes in secondary newlinemetabolite production. Thus, the assessment of heavy metal stress on plant growth, newlinesecondary metabolite production, and its bioaccumulation must be worked on. The newlinepresent study investigates the effect of heavy metals such as lead, cadmium and newlinemercury on germination, growth, biochemical variations, heavy metal accumulation, newlineand biosynthesis of secondary metabolites in two of the most valuables ayurvedic newlinemedicinal plants Mucuna pruriens (L.) DC and Withania somnifera (L). Dunal. The M. pruriens seeds were exposed to 25 -250 ppm Cd and Hg and 200-2000 ppm Pb and the seeds of W. somnifera were exposed to 20-200 ppm Cd, 10-100 ppm Hg and 100-1000 ppm Pb for 21 days to evaluate the LD50 value. M. pruriens showed 50% germination at 150 ppm Cd, 175 ppm Hg, and 1200 ppm Pb. W. somnifera showed newline50% germination at 70 ppm of Hg, 140 ppm Cd and 400 ppm Pb. The LD50 value obtained was used to select the appropriate Cd concentrations for further studies to newlinebe carried out in the polyhouse. The seeds of M. pruriens were sown in soil pretreated newlinewith metals ranging from 50-200 ppm Cd, 25-225 ppm Hg and 400- 1600 ppm Pb, newlinewhereas the two months old W. somnifera were exposed to 40-200 ppm Cd, 20-100 ppm Hg and 200-1000 ppm Pb. The heavy metals impacted the growth of plants and significantly varied biochemical parameters, such as carbohydrate, chlorophyll, flavonoid, protein, proline, phenol, MDA content, metabolite content, and newlineantioxidant activity.