Synthesis and Structure-Activity Relationships of Novel Neocryptolepine Derivatives

Herein we reported the synthesis of a novel series of neocryptolepine(5-methyl-5H-indolo[2,3-b]quinoline) derivatives containing different substituents at C11 using methyl 1H-indole-3-carboxylate and N-methylaniline as starting material. The target 21 compounds were evaluated for their antibacterial activity in vitro against gram- positive bacteria(B. subtilis and S. aureus) and gram- negative bacteria(E. coli and S. typhi). Almost all the tested compounds showed moderate to high activities against the four bacterial strains at the minimum inhibitory concentrations(MICs) of 1- 10 mu g/ mL. The obtained results suggest that part of the novel synthetic neocryptolepine derivatives exhibit significant antibacterial effect against all the tested organisms.