Structure of a new antimicrobial unsaturated fatty acid from Sm. kitasatoenis NU-23-1.

Abstract

Antimicrobial compound LA-1 (I) has been isolated from the culture broth of the leucomycin (LM) producing strain, Sm. kitasatoensis NU-23-1 and its structure determined. It has been found that the new compound I is transiently accumulated preceding the production of LM during fermentation process. I is extracted with organic solvents under acidic conditions from the culture filtrate of its highly accumulative mutant NU-4-4-2 after 27-30 hours incubation. I is exceedingly unstable in its solid state. Its ultraviolet (UV) spectrum (UV λMeOHmax nm : 270) and infrared (IR) spectrum (IR νCCl4max cm-1 : 3000-, 1925, 1700-, 1630-1610, 985) have suggested that I is an oxo-unsaturated fatty acid having a conjugated allene segment. Its proton magnetic resonance (PMR) and 13Carbon-nuclear magnetic resonance (CMR) spectra and the spectroscopic data (IR, PMR, CMR, and mass spectrum) of its stable derivatives, octahydro LA-1 (II) and octahydro methyl LA-1 (III), have been fully compatible with the molecular formula, C10H10O3 and with the molecular weight, 178. Its structure has been elucidated on the basis of these spectroscopic properties.