Content of γ-Oryzanol and Composition of Steryl Ferulates in Brown Rice (Oryza sativa L.) of European Origin

Abstract

The content of γ-oryzanol and the composition of steryl ferulates were determined in brown rice of European origin using on-line coupled liquid chromatography−gas chromatography (LC-GC). Analysis of 30 brown rice samples of various cultivars, grown at different sites and in different seasons, revealed the γ-oryzanol content to range from 26 to 63 mg/100 g. Cycloartenyl ferulate and 24-methylenecycloartanyl ferulate were the major components of γ-oryzanol followed by campesteryl ferulate, campestanyl ferulate, and β-sitosteryl ferulate. The proportions of individual steryl ferulates exhibited enormous variability. However, irrespectively of the great variations observed for single steryl ferulates, the proportions of the sum of 4,4‘-dimethylsteryl ferulates (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate) and the sum of 4-desmethylsteryl ferulates (campesteryl ferulate, campestanyl ferulate, and β-sitosteryl ferulate) were rather constant. The significant natural variability observed for γ-oryzanol content and composition of steryl ferulates were shown to be influenced by environmental conditions but not by the degree of maturity of rice grains. Keywords: γ-Oryzanol; steryl ferulate; brown rice; on-line LC-GC; natural variation; Oryza sativa