Two new sixteen-membered macrolides from the genetically engineered strain Streptomyces avermitilis MHJ1011.

Two new sixteen-membered macrolides, Δ2,3-tenvermectin A (1) and 13α-hydroxy milbemycin ß11 (2), were isolated from the fermentation broth of the genetically engineered strain Streptomyces avermitilis MHJ1011. Their structures were determined based on extensive spectroscopic analysis and comparison with related known compounds. Compounds 1 and 2 exhibited potent acaricidal activity against Tetranychus cinnabarinus.