Enhancing secondary metabolite production and antioxidants in Bacopa monnieri grown on tannery sludge contaminated soil

Abstract

The current study focuses on the stimulation of Bacoside A content of the Bacopa plant that played a potential role in the treatment of Alzheimer’s disease and epilepsy. The objective of the study was to explore the potential of the B. monnieri plant for metal tolerance when cultivated on tannery sludge-contaminated soil without compromising its phytochemical quality. Bacoside content of the plant gets 2 times higher than the control without any chemical additives. Bacosides are the alleged bioactive component and attribute to the neuroprotective function. Export-import bank of India acknowledged Bacopa monnieri as the second most crucial medicine as it has metabolites that can cure mental disorders and amnesia. The effect of tannery sludge on enzymatic and non-enzymatic antioxidant potential along with the effect on metabolite i.e. bacoside A content of the plant. The maximum transfer (known as translocation factor) from root to shoot for Cr, Cd, Co, Ni and Pb was 0.33, 0.28, 0.75, 0.69 and 0.43 respectively. This depicts that here in tannery sludge mixed soil, B. monnieri was not behaving like a hyperaccumulator plant. Although it sequestered a large portion of metal in the root region and showed high vegetative growth in a combination of 75:25 tannery sludge and soil. Superoxide dismutase, Catalase, peroxidase, malondialdehyde, proline & ascorbic acid scaled up with increasing tannery sludge in the treatment whereas in the case of chlorophyll a, b, and carotenoid content, a sharp decline trend was observed at 100% tannery sludge treatment. A similar trend was recorded in bacoside A content of the plant, and the highest was 2% that of control in a 75:25 ratio of tannery sludge and soil. Enzymatic antioxidant along with non-enzymatic antioxidants protects the plant from oxidative stress generated by tannery sludge. Principal components confirm our finding that the translocation factor plays a direct role in the activation of the photosynthetic machinery. Principal component-I contributes 59% of the total variance and Principal component-II contributes 33% of the total variance.