Insecticidal and antifungal activities of aminorhodanine derivatives

Aminorhodanine (1) showed strong insecticidal activity against Culex pipiens pallens and Musca domestica, with respective LD50 values of 0.21 microgram/insect and 0.87 microgram/insect. Compound 1 had antifungal activity against Aspergillus niger ATCC-16404, Trichophyton mentagrophytes IFO-32412, Candida albicans ATCC-10231, Hansenula anomala OPS-308 and Penicillium expansum IFO-8800. In particular, 1 had potent antifungal activity against Aspergillus niger ATCC-16404, its minimal inhibitory concentration (MIC) being 6.25 micrograms/ml. Both activities of 1 were much higher than those of rhodanine (4), suggesting that the introduction of an amino group into N-3 of 4 plays an important role in the biological activity of rhodanine-related compounds. On the other hand, N-acetylaminorhodanine (2) and N-benzoylaminorhodanine (3) did not show either activity, suggesting that the free amino group at N-3 of 1 is closely related to the inhibitory activity of rhodanine derivatives.