Design, Synthesis and Bioactivity Evaluation of Novel β-carboline 1,3,4-oxadiazole Derivatives

A series of novel β-carboline 1,3,4-oxadiazole derivatives were designed and synthesized, and the in vitro cytotoxic activity against Sf9 cells and growth inhibitory activity against Spodoptera litura were evaluated. Bioassay results showed that most of these compounds exhibited excellent in vitro cytotoxic activity. Especially, compound 37 displayed the best efficacy in vitro (IC₅₀ = 3.93 μM), and was five-fold more potent than camptothecin (CPT) (IC₅₀ = 18.95 μM). Moreover, compounds 5 and 37 could induce cell apoptosis and cell cycle arrest and stimulate Sf-caspase-1 activation in Sf9 cells. In vivo bioassay also demonstrated that compounds 5 and 37 could significantly inhibit larvae growth of S. litura with decreasing the weight of larvae and pupae. Based on these bioassay results, compounds 5 and 37 emerged as lead compounds for the development of potential insect growth inhibitions.