Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: 5/14/1997
Publication Date: N/A
Technical Abstract: Esters of sterols and the antioxidants ferulic, p-coumaric and caffeic acid are found, among others, in seeds of corn, wheat, rye, triticale, rice and canary grass. There is increasing interest in the steryl ferulate esters from rice bran oil as a result of studies showing these compounds to be involved in lowering blood cholesterol levels. Because these compounds can exist as both cis and trans isomers of the three cinnamic acid derivatives (CADs), and each of these can be esterified to a range of plant sterols, HPLC separation of the group is challenging. A DIOL-bonded phase column separates liquid extracts of corn fiber into lipid classes including steryl fatty-acyl esters, triacylglycerols, diacylglycerols, free fatty acids, free phytosterols, tocopherols, and steryl p-coumarates, steryl ferulates, and steryl caffeates. After purification of the latter three lipid classes (the steryl-CAD esters) on the DIOL column, each class can be further separated into molecular species using reverse-phase HPLC. Several combinations of stationary phase (three C18 and one C30 columns) and mobile phase (mixtures of acetonitrile, methanol, ethanol, tetrahydrofuran, methyl t-butyl ether, n-butanol, isopropanol, water and acetic acid) have been evaluated. Sitostanyl, campestanyl, campesteryl, delta7-sitosteryl, stigmasteryl, delta7-campesteryl, and sitosteryl ferulates (and p- coumarates of the first four) have been separated from corn bran (and fiber). Analysis of gamma oryzanol resolved five esters to baseline. Cis-isomers were separated from the corresponding trans forms but not from adjacent peaks.