O-BENZOYLATION AS A DERIVATIZATION PROCEDURE FOR ANALYSIS OF 1-MONOMYCOLOYLGLYCEROL BY MASS-SPECTROMETRY

Benzoyl groups were attached to hydroxyl groups of monomycoloylglycerol isolated from Rhodococcus rhodochrous and R. lentifragmentus. The resulting benzoyl monomycoloylglycerol displayed a characteristic infrared spectrum in the fingerprint region with two strong absorptions at 1110 cm-1 and 1267 cm-1, respectively. In addition, bands characteristic of the O-perbenzoyl derivative appeared at 1603 cm-1 and 1693 cm-1. Moreover, the mass spectrum of O-perbenzoylmonomycoloyglycerol using electron impact spectroscopy showed the following fragmentation peaks: (a) a peak representing the glycerol backbone; (b) a peak related to the glycerol backbone linked to a segment of the mycolic acid corresponding to the α-unit, which revealed the length of the side chain of that unit, finally (c) a series of peaks corresponding to the whole carbon chain length of the mycolic acid moiety, i.e., acylium ion minus benzoic acid. © 1990.