Isolation, structure elucidation, and antifungal activity of a manumycin-type antibiotic from Streptomyces flaveus

A manumycin-type antibiotic, SW-B, has been isolated from the solid agar culture of Streptomyces flaveus strain A-11. The structure was determined by mass spectrometry and one- and two-dimensional NMR spectroscopy. SW-B was detected at R(f) 0.5 on the TLC plate developed with chloroform-methanol (90:10 v/v). The UV spectrum of SW-B in methanol showed peaks at 208 and 260 nm. The antibiotic SW-B was confirmed to be a derivative of a manumycin-type antibiotic, 2,4,6-trimethyldeca-(2E,4E)-dienamide (C13H23NO, 209.1780). SW-B showed strong antifungal activity against Phytophthora capsici, Magnaporthe grisea, Cladosporium cucumerinum, and Alternaria mall. However, it lacked antimicrobial activity against yeast and bacteria.