Appearance of a methoxy mycolate-like component by the acid methanolysis of Mycobacterium leprae.

It has been reported that Mycobacterium leprae contains two types of mycolic acid, namely, alpha- and keto-mycolic acids, thus it is taxonomically similar to M. bovis BCG. However, there was some controversy about the presence of methoxy mycolic acid which was observed in small amounts only in the case of experimentally infected (W45) armadillo-derived M. leprae. To investigate this fact, mycolic acids were extracted from the cell-wall structure of M. leprae and characterized using chromatographic techniques. The results showed the appearance of a methoxy mycolate-like component for both purified bacilli and infected human skin tissue materials. However, this appearance occurred only when the acid methanolysis procedure was followed for the release of mycolic acids from these bacilli. No such component appeared on the chromatogram when the alkaline methanolysis procedure was followed. Nevertheless, the consistent presence of this methoxy mycolate-like component by acid methanolysis is an important finding which has to be kept in mind while identifying this pathogen when using chromatographic techniques.