Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study.

Six known indole alkaloid derivatives have been isolated for the first time from Bacillus thuringiensis and Bacillus velezensis strains, all of them as building blocks for the synthesis of larger natural products. Their structure was elucidated by a complete spectroscopy. Their biological activities were tested against some Gram-positive and Gram-negative bacteria and three phytopathogenic fungi which cause diseases in important crops, such as Moniliophthora roreri, the causal agent of cacao disease. The results indicated that some compounds had modest antibacterial activity; however, some of them had strong antifungal activity against the probed fungi. This antifungal activity of these compounds has not been reported.