Syntheses and biological activities of benzimidazolo[2,1-b] benzo[e]thiazepin-5(10H)-ones.

Substituted benzimidazolo[2,1-b]benzo[e]thiazepin-5(10H)-one derivatives were prepared in moderate to good yield by reaction of mercapto benzimidazole derivatives with 2-chloromethylbenzoyl chloride as a coupling component. Their structures were confirmed by elemental analysis, IR, NMR, and MS. Their antioxidant properties were evaluated by several methods: scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, reducing power assay, and inhibition of lipid peroxidation. In DPPH assay, 3h exhibited an activity stronger than trolox. In the reducing power assay and inhibition of lipid peroxidation, compound 3a was more active than 3h and similar to trolox. The antidiabetic effect was also determined, and the antidiabetic activities were correlated with their antioxidant properties, compound 3a was the most active compound in the in-vivo experiments.