LC-MS-Guided Isolation of Cyanogripeptides A-C, Cyclolipopeptides with β-Methyl-Leucine Residues, from an LHW52806.

Cyanogripeptides A-C (-), three new cyclolipopeptides with unusual β-methyl-leucine residues, were identified from an LHW52806 using an LC-MS-guided strategy. The structures of compounds - were elucidated by 1D/2D NMR, HR-MS/MS, and the advanced Marfey's method. The absolute configuration of the β-methyl-leucine residue was determined by a combination of stereoselective biosynthesis of (2,3)-β-methyl-leucine, racemization to its epimer (2,3)-β-methyl-leucine, and the advanced Marfey's method. The biosynthetic pathway of cyanogripeptides was deduced by analyzing the genome of . LHW52806. Compound exhibited antibacterial activity against G27, 26695, and ATCC607 with MIC values of 32 μg/mL.