Synthesis, antioxidant activity and SAR study of novel spiro-isatin-based Schiff bases

A new series of 21 Schiff bases of spiro-isatin was synthesized, and their DPPH, CUPRAC and ABTS cation radical scavenging abilities were investigated for antioxidant activity. The results showed that all the synthesized compounds exhibited antioxidant activity for each assay. 5-(2,3-Dihydroxybenzylideneamino)spiro[[1,3] dioxolane-2,3-indoline]-2-on (5c) (IC50 = 4.49 µM, for DPPH; IC50 = 0.39 µM, for ABTS.+; and A0.50 = 0.42 µM, for CUPRAC)...