A new β-class milbemycin derivative from a mutant of genetically engineered strain Streptomyces avermitilis AVE-H39.

A new β-class milbemycin, 13α-hydroxy milbemycin β6 (1), was isolated from the fermentation broth of a mutant of genetically engineered strain Streptomyces avermitilis AVE-H39. Its structure and absolute configuration were elucidated by extensive spectroscopic methods and confirmed by single crystal X-ray diffraction.