O -Alkylazoxymycins A-F, Naturally Occurring Azoxy-Aromatic Compounds from Streptomyces sp. Py50.

Six new azoxy-aromatic compounds ( o -alkylazoxymycins A-F, 1 - 6 ) and two new nitrogen-bearing phenylvaleric/phenylheptanoic acid derivatives ( o -alkylphemycins A and B, 7 and 8 ) were isolated from Streptomyces sp. Py50. Their structures were elucidated based on HRESIMS, NMR, UV spectroscopic analyses, and X-ray crystallographic data. O -Alkylazoxymycins A-F ( 1 - 6 ) are the first natural examples of azoxy compounds with the azoxy bond attached to the ortho -position of the phenylheptanoic acid or phenylvaleric acid moiety. Compounds 1 , 5 , and 6 were active against Epidermophyton floccosum with MIC 50 values ranging from 10.1 to 51.2 μM. A plausible biosynthetic pathway of 2 and 3 was proposed.