3-Indolepropionic acid (IPA)-related compounds having a benzo [b] thiophene or an indazole ring and derivatives having various substituents in the propionic acid moieties were tested for their antibacterial activity against Ralstonia solanacearum. Substitution of the indole ring for other aromatic rings resulted in lowered activity, whereas addition of a methyl or a trifluoromethyl group to the propionic acid moiety had little effect. Of the derivatives, 3- ...