Cadmium content, metabolite profile, biological properties of Eclipta alba (L.) Hassk plant exposed to elevated cadmium in soil

Cadmium (Cd), a highly mobile and hazardous toxic heavy metal negatively affects plant’s yield by regulating synthesis of biomolecules, involved in both physiological and biochemical activities. The present study investigated the Cd content, metabolite profile, antioxidant and antibacterial activities of methanolic leaf extracts (MLEs) of Eclipta alba L., plant exposed to elevated soil Cd (eCdS). The tested plants were grown in earthen pot and were weekly treated with Cd as CdCl₂. H₂0 (20 mg/L) till 70 days after the plant transplantation. The results showed that eCdS significantly elevated Cd content in root and shoot tissue of E. alba plant (91 % and 94 %, respectively) as compared to the control. UHPLC-HRMS profile of MLEs revealed a significant decrease in the amino acids and its derivatives with an increased level of phenolic contents, fatty acids, and lipids. Metabolites in MLEs were also upregulated and downregulated (31 and 98, respectively) by an eCdS. An eCdS further increased both total phenolics and total flavonoids content in MLEs of E. alba by 71 % and 31 %, respectively over the control. In-vitro antioxidant activities in MLEs were also found to be significantly increased due to eCdS as DPPH > ABTS > FRAP (30 %, 26 % and 21 %, respectively) as compared to the control. Cd treated plant’s MLEs also revealed maximum reduction in an inhibition zone of Pseudomonas aeruginosa (ATCC 27853), among the tested bacterial strains. The present study concludes that eCdS led to the significant changes in the metabolite profile, phenolics content and biological activities of E. alba’s MLEs suggesting its ameliorating role in improving the medicinal value of E. alba plant. However, direct consumption of raw material of E. alba plant is not recommended due to high accumulation of Cd in its different parts.