Quantification of vitamin E and gamma-oryzanol components in rice germ and bran.
Rice bran is a rich natural source of vitamin E and gamma-oryzanol, which have been extensively studied and reported to possess important health-promoting properties. However, commercial rice bran is a mixture of rice bran and germ, and profiles of vitamin E and gamma-oryzanol components in these two different materials are less well-studied. In the current study, vitamin E and gamma-oryzanol components in rice bran and germ were analyzed by liquid chromatography/mass spectrometry/mass spectrometry. The components were identified by electrospray ionization mass spectrometry (ESI-MS) with both positive- and negative-ion modes. Both deprotonated molecular ion [M - H](-) and protonated molecular ion [M + H](+) found as the base peaks in spectra of vitamin E components made ESI-MS a valuable analytic method in detecting vitamin E compounds, especially when they were at very low levels in samples. Ultraviolet absorption was used for quantification of vitamin E and gamma-oryzanol components. While the level of vitamin E in rice germ was 5 times greater than in rice bran, the level of gamma-oryzanol in rice germ was 5 times lower than in rice bran. Also, the major vitamin E component was alpha-tocopherol in rice germ and gamma-tocotrienol in rice bran. These data suggest that rice bran and germ have significantly different profiles of vitamin E and gamma-oryzanol components. The method enables rapid and direct on-line identification and quantification of the vitamin E and gamma-oryzanol components in rice bran and germ.
Yu
Shanggong
S
Hubei College of Chinese Traditional Medicine, Wuhan 430065, People's Republic of China.
Nehus
Zachary T
ZT
Badger
Thomas M
TM
Fang
Nianbai
N
D002853:Chromatography, Liquid; D012275:Oryza / Q000737:chemistry*; D010666:Phenylpropionates / Q000032:analysis*; D012639:Seeds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014810:Vitamin E / Q000032:analysis*
D010666:Phenylpropionates; D014810:Vitamin E; C013172:gamma-oryzanol