Growth and Secondary Metabolite Profiles of Vernonia amygdalina (Del.) Subjected to Cadmium and Drought Stress

Vernonia amygdalina is used for food and medicinal purposes because of its phytoconstituents. This study focused the effect of cadmium spiked and drought soil on GCMS-profiled secondary metabolite of Vernonia amygdalina leaf extracts. Soil samples were randomly divided into three treatment groups: the control group, cadmium group, and drought group, respectively. The cadmium-labelled soil was spiked with a solution of cadmium until a steady concentration of 400 mg/kg was attained. V. amygdalina planted on the control and spiked soils were grown under adequate water regimen while the third group was planted in soil deprived of daily water requirement. Leaves from the plants were harvested at the end of eight and nine weeks, respectively and then subjected to ethanolic and petroleum ether extraction. Vinyldimethyl (hydroxymethyl)silane, cyclononasiloxane, and octadecamethyl were the most abundantly present secondary metabolites in the petroleum ether leaf extracts of V. amygdalina planted under drought conditions, whereas phytol consistently dominated in the ethanolic leaf extracts of V. amygdalina after the same periods of exposure to drought conditions. Similarly, the ethanolic and petroleum leaf extracts of V. amygdalina cultivated in cadmium-contaminated soil had considerably varied secondary metabolite expressions with only diethyl phthalate appearing in both extracts. The expressed secondary metabolites varied with cadmium exposure, drought stress and the extraction media. V. amygdalina showed adaptive properties to stress due to changes in its secondary metabolites under varying conditions.