Antimycobacterial serratamolides and diacyl peptoglucosamine derivatives from Serratia sp.

The cyclodepsipeptide serratamolide A (1) and five closely related compounds together with three new glucosamine derivatives were isolated by bioactivity-guided chromatography from the XAD adsorber resin extract of a Serratia sp. The structures of the compounds were elucidated by 2D NMR and MS analyses. In addition to the known serratamolide A (1) with two C(10) alkyl chains, its derivatives always contained one C(10) chain combined with either C(12:1), C(12), C(11), C(9), or C(8) chains. The glucosamine derivatives contained a common core consisting of an N-butyl-alpha-glucopyranosylamide, which was acylated at the C-1 oxygen with valine. The differences between the derivatives arise from the nature of the acyl groups attached to the N-terminus of valine, which were identified as the linear fatty acid moieties C(16:1), C(15), or C(14). Each compound was present in two isomeric forms arising from racemization of the valine moiety. All compounds showed antibiotic activity against Mycobacterium diernhoferi and other rapidly growing mycobacteria.