A series of isoquinoline-1, 3, 4-trione derivatives were identified as novel and potent inhibitors of caspase-3 through structural modification of the original compound from high- throughput screening. Various analogues (2, 6, 9, 13, and 14) were synthesized and identified as caspase inhibitors, and the introduction of a 6-N-acyl group (compound 13) greatly improved their activity. Some of them showed low nanomolar potency against ...