Antioxidative defense responses and activation of phenolic compounds in Brassica juncea plants exposed to cadmium stress

Abstract

Background: The present work has explored the effects of cadmium (Cd) on Brassica juncea plants. Materials and Methods: Malondialdehyde (MDA) content, hydrogen peroxide (H2O2) content, activities of antioxidative enzymes (superoxide dismutase, guaiacol peroxidase, and catalase), protein content, level of antioxidants (ascorbic acid, tocopherol, and glutathione), antioxidant assays (1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical scavenging assay, molybdate ion reduction assay and reducing power assay), total phenolic content, and polyphenols were analyzed in 90-day-old plants. Seeds of B. juncea were exposed to 0, 0.2, 0.4, and 0.6 mM Cd concentrations. Results: Significant increase in MDA and H2O2 content was observed in Cd-stressed plants as compared to untreated control. Cd toxicity positively influenced the activities of antioxidative enzymes and radical scavenging activities of the plant. Results revealed the enhancement in the level of antioxidants. Ultra performance liquid chromatography studies showed the variation in the level of polyphenols with respect to untreated plants. Conclusions: This investigation showed that defensive strategies of this plant activated under metal stress and overcame the adverse effects produced due to the generation of reactive oxygen species.