Ravidomycin Analogs from Streptomyces sp. Exhibit Altered Antimicrobial and Cytotoxic Selectivity.

Six new ravidomycin analogs (-, , and ) were isolated from sp. Am59 using UV- and LCMS-guided separation based on Global Natural Products Social (GNPS) molecular networking analysis. Furthermore, we isolated fucomycin V (), which possesses the same chromophore as ravidomycin but features a d-fucopyranose instead of d-ravidosamine. This is the first report of as a natural product. Four new analogs (-) of were also isolated. The structures were elucidated by combined spectroscopic and computational methods. We also found an inconsistency with the published [α] of deacetylravidomycin, which is reported to have a (-) sign. Instead, we observed a (+) specific rotation for the reported absolute configuration of deacetylravidomycin (containing d-ravidosamine). We confirmed the positive sign by reisolating deacetylravidomycin from and by deacetylating ravidomycin. Finally, antibacterial, antifungal, and cytotoxicity activities were determined for the compounds. Compared to deacetylravidomycin, the compounds -, , , and exhibited greater antibacterial selectivity.