In the course of searching for potent chitin synthase 1 inhibitors from natural resources, Streptomyces sp. A6705 was found to exhibit potent inhibitory activity against the chitin synthase 1 from C. albicans (CaCHS1p). As a result, the inhibitor was isolated and identified using a series of chromatographies. Through chemical analyses with UV spectrophotometry, MS spectrometry, and various NMR techniques, the inhibitor was identified as N,N-bis(2- phenylethyl)urea. The compound exhibited strong inhibitory activity against the chitin synthase 1 from C. albicans with an IC50 of 14 ¥ìg/ml, representing a similar inhibitory activity to that of the well-known chitin synthase inhibitor, polyoxin D (IC50; 15 ¥ìg/ml). However, the compound showed no inhibitory activity against the chitin synthase 2 of Saccharomyces cerevisiae up to 280 ¥ìg/ml, which is structurally and functionally analogous to CaCHS1p. In addition, the compound exhibited weak antifungal activities against Cryptococcus neoformans and Rhizoctonis solani.
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