Antioxidant activity and cytotoxicity against cholangiocarcinoma of carbazoles and coumarins from Clausena harmandiana

Nine carbazoles and three coumarins were isolated from C. harmandiana. Crude extracts and all isolates were evaluated for antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and lipid peroxidation assay and cytotoxicity against cholangiocarcinoma, KKU-OCA17 and KKU-214 cell lines. 7-Hydroxyheptaphylline and nordentatin showed strong antioxidant activity on lipid peroxidation with IC50 values of 2.95 and 2.90 µM respectively, while the activity on a DPPH assay showed IC50 values of 56.82 and 29.3 µM, respectively. The two compounds exhibited strong cytotoxicity against KKU-OCA17 (IC50=88.7 and 46.1 µM, respectively) and KKU-214 (IC50=43.7 and 39.1 µM, respectively) cell lines. The results show convincingly that these compounds may be the promising leads for the development of cytotoxic agents.