Aldgamycins Q1 and Q2, two novel 16-membered macrolides from the rare actinomycete Saccharothrix sp. 16Sb2-4.

Two novel 16-membered macrolides, named aldgamycin Q1 (1) and Q2 (2), were isolated from the culture broth of the rare actinomycete Saccharothrix sp. 16Sb2-4. The structures of 1 and 2 were elucidated as new aldgamycin analogs with a demethylated mycinose residue by spectroscopic analyses and comparison with data of aldgamycin K. Compounds 1 and 2 showed moderate to weak antibacterial activities against Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus and Acinetobacter baumannii, with MIC values ranging from 16 to 64 μg mL-1.