Antioxidant & anticancer activities of isatin (1H-indole-2,3-dione), isolated from the flowers of Couroupita guianensis Aubl

BACKGROUND & OBJECTIVES Derivatives of isatin are known to have cytotoxicity against human carcinoma cell lines. This compound therefore, has a potential to be used as a chemotherapeutic agent against cancer. This study was done to investigate the antioxidant and anticancer activities of isatin, extracted from flower of a folklore medicinal plant Couroupita guianensis against human promylocytic leukemia (HL60) cells. METHODS Active fractions demonstrating anticancer and antioxidant activities were isolated from the extracts of shade-dried flowers of C. guianensis by bioassay guided fractionation. The free radical scavenging activity was determined using lipid peroxidation assay. Cytotoxicity against human promylocytic leukemia HL60 cells was determined by MTT assay. Apoptotic activity was analyzed by DNA fragmentation and flowcytometry. RESULTS Isatin isolated from the active fraction showed antioxidant activity with the EC(50) value of 72.80 μg/ml. It also exhibited cytotoxicity against human promylocytic leukemia HL60 cells in dose-dependant manner with the CC(50) value of 2.94 μg/ml. The isatin-treated cells underwent apoptosis and DNA fragmentation. Apoptosis was confirmed by the FACS analysis using FITC-annexin V markers. INTERPRETATION & CONCLUSIONS Isatin showed antioxidant activity and was cytotoxic to the HL60 cells due to induction of apoptosis. The isatin can be further evaluated to be used as a prophylactic agent to prevent the free radical-induced cancer and as a chemotherapeutic agent to kill the cancer cells.