The major mycolic acids of Mycobacterium smegmatis

Abstract

Mycolic acids derived from the cell wall of Mycobacterium smegmatis have been fractionated as their phenacyl esters by high performance liquid chromatography. Chromatography on a lo-pm particle size silica gel column resulted in the isolation of two minor (A and D) and two major (B and C) components. When subjected to reverse phase partition chromatography, the major components (B and C) were further resolved into five and four components, respectively. Analysis of these components by 270-MHz ‘H nuclear magnetic resonance spectroscopy and ammonia chemical ionization and electron impact mass spectrometry demonstrated that each isolated component was a different mycolic acid. Mycolic acids of the C series were found to form an homologous series with the empirical formula CnH2n-203, where n = 60,62,64, and 66. Each member of the series was found to contain a linear CzzH4, branch at C-2, a C3 hydroxyl group, and a single isolated carbon-carbon double bond. The complete structures of members of this series are reported in the accompanying article (Wang, M. Y. H., and Gray, G. R. (1979) J. BioZ. Chem. 254, 5741-5744). Mycolic acids of the B series were found to form two homologous series with the same empirical formula (CnH2n-403), one series with n = 74, 76, 78, 80, and 82, and the other series with n = 75,77,79,81, and 83. Each member of both series was found to contain a linear C22H45 branch at C-2, a C-3 hydroxyl group, and two isolated carbon-carbon double bonds. Each member of the latter series (n = odd) was also found to contain a secondary C-methyl group, which was absent in the former series. The locations of the double bonds have not been established for members of these series.