Study and prediction of the effect of cadmium and glycine on antioxidant enzyme activity and secondary metabolites production in Catharanthus roseus

The Catharanthus roseus is an important medicinal plant that has been widely used in medicine due to its compounds such as vinblastine and vincristine, and is used in the treatment of many diseases, including cancer. In this study, the effect of cadmium and glycine concentrations on the antioxidant enzyme activity and secondary metabolites synthesis was studied and predicted by response surface methodology, and the expression of the DAT and D4H genes was investigated. It was observed that the highest MDA, H 2 O 2 , and carotenoid (2.34 mg/g FW) were achieved by using 150 μM cadmium. The highest CAT activity was observed by using 8 mg/L glycine. The maximum POD activity, APX activity, and vinblastine accumulation were obtained by application of 150 μM cadmium and 4 mg/L glycine. The highest proline, total protein, total chlorophyll, and anthocyanin content (29.22 mg/g FW) were observed at 100 μM cadmium, 8 mg/L glycine, 8 mg/L glycine, and 2 mg/L glycine, respectively. Additionally, the maximum vincristine accumulation was 4.51 mg/g DW obtained with the application of 100 μM cadmium and 8 mg/L glycine. It was predicted that the optimum conditions for maximum anthocyanin and carotenoid content were 50 μM cadmium and 8 mg/L glycine (28.53 mg/g FW) and 117 μM cadmium and 2 mg/L glycine (2.06 mg/g FW). The optimum condition for maximum vinblastine and vincristine accumulation was predicted at 103 μM cadmium and 4.92 mg/L glycine (53.71 mg/g DW) and at 93.5 μM cadmium and 8 mg/L glycine (4.74 mg/g DW). The study of the expression of the DAT and D4H genes indicated that the expression of both genes increased in all selected treatments with the highest vinblastine accumulation.