Trehalose from glycolipids

Fig. 15.—Sequence of One of the Oligosaccharides Obtained from the Trehalose-containing Glycolipids of Mycobacteria kansasii. [Cleavage positions in the positive-ion mode (Pathway C, Section IV,2) are shown above the sequence. Cleavage positions in the negative-ion mode (Pathway B, Section IV,2) are shown below the sequence.

The purification procedure of 6,6 -esters of OMf-trehalose from Coryne-bacterium diphtheria has been modified and the products were analysed by m.s. of the permethylated derivative.The constituent fatty acids have been extensively examined and the detailed structure of the major acids have been confirmed by a variety of techniques. Novel glycolipids in the cord factor fraction from C. diphtheria were a 6,6 -bis(3-oxo-acyl)-o a -D-trehalose and a 6, 6 -mixed ester of aa-trehalose with the 3-oxo-acyl group and a corynomycolic acid. The metabolic implications of these structural studies suggest that condensation of the common fatty acids by a Claisen-like process via the oxo-ester pathway may not be the only pathway for the synthesis of the cord factors. 

The newest glycolipids from Mycobacterium spp., and the most suiprising in terms of novel structural principles, are the trehalose-containing lipo-oligosaccha-rides (LOS). The structures of all of those described thus far are summarized in Table ID. 

In the permethylatlon analysis of trehalose glycolipids such as cord factor and 6- -mycolyl-a,a-trehalose, various standard reagents proved unsatisfactory due to ester cleavage, but the method of Ciucanu and Kerek (Vol.18, p.50 powdered NaOH-Mel-DMSO) gave excellent results, only lower acyl groups such as acetyl being cleaved. 6,6 -Di- -methyl-a,a-trehalose was obtained from the... 

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