Discovery of indole-3-acetic acid derivatives containing 1,3,4-thiadiazole thioether and amide moieties as novel antibacterial agents

A series of twenty one novel compounds derived from indole-3-acetic acid, the structure of which includes 1,3,4-thiadiazole, thioether, and amide moieties were designed, synthesized, and evaluated for their in vitro antibacterial activity against three bacterial strains. The bioassay results showed that among the synthesized compounds, N-{5-[(2-fluorobenzyl)sulfanyl]-1,3,4-thiadiazol-2-yl}-3-(1H-indol-3-yl)-propanamide demonstrated the best inhibition rate against Pseudomonas syringae pv. actinidiae and N-{5-[(4-chlorobenzyl)sulfanyl]-1,3,4-thiadiazol-2-yl}-3-(1H-indol-3-yl)propanamide possessed the best inhibition rate against Xanthomonas oryzae pv. oryzae and Xanthomonas axonopodis pv. citri, in all cases superior to that of bactericides thiodiazole copper and bismerthiazol.