Synthesis and PKC isozyme surrogate binding of indothiolactam-V, a new thioamide analogue of tumor promoting indolactam-V

To investigate the role of the amide group of (−)-indolactam-V (1) on PKC binding, we synthesized (−)-indothiolactam-V (2), a new thioamide analogue of 1, by microbial conversion using Streptomyces blastmyceticum. Compounds 2 and 1 showed similar binding affinities to conventional PKCs but 2 had lower affinities to novel PKCs, suggesting that novel PKCs recognize amide modifications more effectively than conventional PKCs.