Structure of the major triglycosyl phenol‐phthiocerol of Mycobacterium tuberculosis (strain Canetti)

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Abstract
Phenol-phthiocerol glycolipids have been found previously in Mycobacterium leprae, M. kansasii, M. bovis and M. marinum, but not in M. tuberculosis. A search for such glycolipids in this latter species showed that the Canetti strains of M. tuberculosis synthesize a major triglycosyl phenol-phthiocerol, accompanied by minor amounts of other glycolipids with a similar aglycone moiety. The triglycoside moiety has the following structure: 2,3,4-tri-O-methyl L-fucopyranosyl(α1→3)L-rhamno-pyranosyl(α1→3)2-O-methyl L-rhamnopyranosyl(α1 –. The aglycone moiety consists in phenol-phthiocerol (two homologs). Its two secondary alcohol functions are esterified by mycocerosic acids (homologs with 26–32 carbon atoms and with 2–4 methyl branches). The proposed structure differs on several points from the M. leprae glycolipids, but presents some analogy with the major glycolipid of M. kansasii. A minor monoglycosyl phenol-phthiocerol was also studied. Its overall structure is very similar to that of M. bovis, with 2-O-methyl rhamnose as sugar moiety.