Effects of Cobalt and Zinc Stress on Rehmannia glutinosa Growth, Bioactive Compounds, Antioxidant Activity, and Molecular Insights

This study aimed to investigate the effects of cobalt (Co) and zinc (Zn) on the growth, antioxidant activity, total phenolic and flavonoid contents (TPC and TFC), targeted polyphenolic compounds, and molecular dynamics simulations of Rehmannia glutinosa (R. glutinosa ) L. Plants were exposed to varying concentrations of Zn (0.01 to 1 ppm) and Co (0.01 to 1 ppm). Growth parameters, including plant height, number of leaves, and root length, were measured. The antioxidant activity, TPC, and TFC were evaluated using standard biochemical assays. liquid chromatography‐tandem mass spectrometry was used to quantify the target polyphenolic compounds. Catalase and ascorbate peroxidase activities were also assessed. A 100 ns molecular dynamics simulation was performed to analyze the stability of key phytochemicals with high binding affinities and docking scores. At lower concentrations, Zn significantly enhanced plant growth, whereas at higher concentrations, it inhibited it. Co at 0.01 and 0.1 ppm adversely affected growth, and 1 ppm led to necrosis and plant death. Maximum TPC and TFC were observed at 0.01 ppm Zn, while 0.1 ppm Co resulted in elevated TPC and TFC. Antioxidant activity increased at lower metal concentrations. The enzymatic activity varied significantly in response to exposure to Zn and Co. Molecular dynamics simulations confirmed the stability of major polyphenols, such as luteolin, pelargonidin chloride, and ferulic acid, under different metal stress conditions. Exposure to Zn and Co significantly affects the growth, metabolism, and antioxidant activity of R. glutinosa. Lower concentrations of these metals may promote the synthesis of phenolic compounds, whereas higher concentrations may cause oxidative stress and growth inhibition. Molecular dynamics analysis supported these biochemical findings, demonstrating that specific phytochemicals remain stable under metal stress conditions.