Synthesis, characterization and antibacterial activity evaluation of new Indole-based derivatives

Abstract

Indole is widely distributed heterocycle found in natural biologically active molecules, drugs, and other substances. Starting from Indole-3-propionic acid (IPA) a metabolite produced by gut's bacteria, new series of N-acyl hydrazones (4a-g) was synthesized. These N-acyl hydrazones were prepared by the reaction of 3-(1H-indol-3-yl) propane hydrazide and aldehyde in the presence of glacial acetic acid as a catalyst. 1HNMR and FT-IR analyses were used to identify the synthesized compounds. In vitro study was performed to evaluate the antibacterial activity of the synthesized compounds against six different types of microorganisms by using well diffusion method. All the tested N-acyl hydrazones (4a-g) displayed moderate activity against the Gram-negative E.coli which was comparable to Amoxicillin, except compound (4e), which showed high activity. Also, selective moderate activities against other Gram-negative bacteria were shown by compounds (4a, 4c, 4e, 4f and 4g), while, compounds (4b) and (4d) exhibited intermediate activity against Gram-positive B.subtilis. All the synthesized compounds exhibited selective lower antibacterial activity compared to Ciprofloxacin. Additionally, no activity was exhibited by any of the examined compounds against the Gram-positive S. aureus.