Sitosteryl-β-D-(6-O-fattyacyl)-glucopyranosides from the crude phosphatides of maize [1]

A new component of the crude phosphatides of Zea Mays Linn. has been identified as sitosteryl-β-D-(6-O-fattyacyl)-glucopyranoside (I). Its gross structure, as a monoester of sitosteryl-β-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 H₂C-6 in its tribenzoyl derivative with the chemical shifts for the corresponding protons in model benzoyl, acetyl and mixed benzoyl-acetyl derivatives of sitosteryl-β-D-glucopyranoside. The structure was confirmed by comparison, especially of optical rotation data, with a sample of sitosteryl-β-D-(6-O-stearoyl)-glucopyranoside prepared by synthesis. The [α]_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 (ΔM_D) 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 ΔM_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.