|
|
Synthesis of Antifungal 2-Anilino-4-phenylthiazoles and Their Inhibitory Activities on Sterol Biosynthesis
Izumi KUMITA and Kaoru NODA
J. Pestic. Sci.
26, 136-142 (2001)
We previously reported that 1,2,4-thiadiazole derivatives such as 5-(4-chloroanilino)-3-(2,6-dichlorophenyl)-1,2,4-thiadiazole showed high antifungal activities in vitro against Trychophyton mentagrophytes and Botrytis cinerea, and accumulated squalene remarkably. In view of the Nussbaumer's model of squalene epoxidase inhibitors, we synthesized the corresponding thiazole derivatives in which 2-nitrogen atom of 1,2,4-thiadiazole was replaced by carbon in order to explore the structural requirement of the heteroaromatic moiety for fungicidal activity. We further synthesized the related thiazoles having various substituents to investigate the structure-activity relationships. Antifungal activities and squalene accumulation of the thiazole compounds were well correlated. Among the compounds synthesized, 2-(4-chlorophenylamino)-4-(2,6-dichlorophenyl)thiazole (5) showed the highest antifungal activity against T. mentagrophytes and B. cinerea, and was more active than tolnaftate, a clinically used thiocarbamate. The compound (5) inhibited squalene epoxidase remarkably in a cell free assay using S. cerevisiae. These experimental results indicate that the primary mode of action of the thiazole derivatives is the inhibition of squalene epoxidase in the sterol biosynthesis.
|
