Three new 16-membered macrolide compounds from a genetically engineered strain S. avermitilis MHJ1011.

Abstract Three new 16-membered macrolide compounds, 13α- O -α- l -oleandrosyl milbemycin β 3 ( 1 ), 13α- O -α- l -oleandrosyl-25-ethyl milbemycin β 3 ( 2 ), 13α- O -α- l -oleandrosyl-25-isopropyl milbemycin β 3 ( 3 ), were isolated from the genetically engineered strains Streptomyces avermitilis MHJ1011. Their structures were determined on the basis of spectroscopic analysis, including 1D and 2D NMR techniques as well as ESI-MS and comparison with data from the literature. Both compounds 1 – 3 displayed impressive acaricidal activity against larval mites with the IC 50 values of 0.0327, 0.0276 and 0.0235 mg/L, respectively, which are higher than those of 13α-hydroxy milbemycin β 3 and 13α-hydroxy-25-ethyl milbemycin β 3 .