Synthesis and biological evaluation of novel isoxazoles and triazoles linked 6-hydroxycoumarin as potent cytotoxic agents

A new series of diverse isoxazoles and triazoles linked 6-hydroxycoumarin (1) were synthesized using click chemistry approach. All the derivatives were subjected to 3-(4,5-dimethylthiazol-yl)-diphenyl tetrazoliumbromide (MTT) cytotoxicity screening against a panel of five different human cancer cell lines viz. prostate (PC-3), colon (HCT-116 and Colo-205), leukemia (HL-60) and lung (A-549) to check their cytotoxic potential. Interestingly, among the tested molecules, some of the analogs displayed better cytotoxic activity than the parent 6-hydroxycoumarin (1). Of the synthesized isoxazoles, compounds 10 and 13 showed the best activity with IC₅₀ of 8.2 and 13.6 μM against PC-3 cancer cell line, while as, among the triazoles, compounds 23 and 25 were the most active with the IC₅₀ of 10.2 and 12.6 μM against A-549 cancer cell line. The other derivatives showed almost comparable activity with that of the parent molecule. The present study resulted in identification of ortho substituted isoxazole and triazole derivatives of 6-hydroxycoumarin as effective cytotoxic agents against prostate (PC-3) and lung (A-549) cancer cell lines, respectively.