A new component of the crude phosphatides of Zea Mays Linn. has been identified as sitosteryl-t3-D-(6-O-fattyacyl)-glucopyranoside (I). Its gross structure, as a monoester of sitostery143-D-glucoside, was derived from a study of the products formed on methanolysis and on acid hydrolysis. The location of the fatty ester was established by comparison of the proton chemical shift for H:C-6 in its tribenzoyl derivative with the chemical shifts for the corresponding protons in model benzoyl, acetyl and mixed benzoyl-acetyl derivatives of sitosteryl-t3-D-glucopyranoside. The structure was confirmed by comparison, especially of optical rotation data, with a sample of sitosteryl-#-D-(6-O-stearoyl)-glucopyranoside prepared by synthesis. The [C~]D values for the natural (-45 ° ) and the synthetic sample (-46.5 ° ) are practically identical. Further there is good agreement between the molar rotation difference (ZXMD) between (I) and its parent sitosterylglucoside and between the synthetic pair of glucoside and its ester.
The approach to structure followed, in particular the use of &M D comparisons, and the optical rotation data recorded in this paper, provide simple and convenient means for establishing the structure of other natural esterified sterol glycosides.
* Author to whom communications should be addressed. ** The abbreviation ESG for natural esterified steryl glucoside was suggested by Lepage . We have adopted this abbreviation, but add a postscript to specify the source of the natural lipids (e.g. ESG-maize), and, in the case of a synthetic compound, the identity of the fattyacyl group (e.g