J. Samuel Godber

Comparison of isopropanol and hexane for extraction of vitamin E and oryzanols from stabilized rice bran

The effects of solvent-to-bran ratio (2∶1 and 3∶1, w/w), extraction temperature (40 and 60°C), and time (5, 10, 15, 20, and 30 min) were studied for hexane and isopropanol extraction. Increasing the solvent-to-bran ratios and extraction temperature increased the amounts of crude oil, vitamin E and oryzanol recovered for both solvents. An extraction time of 15 min was sufficient for optimum crude oil, vitamin E, and oryzanol extraction. Preheated isopropanol (3∶1 solvent/bran ratio and 60°C) extracted less crude oil (P<.05) but more vitamin E (P<.05) and similar amounts of oryzanol (P>.05) relative to preheated hexane. The data suggest that isopropanol is a promising alternative solvent to hexane for extraction of oil from stabilized rice bran.

Tocopherols, Tocotrienols, and γ-Oryzanol Contents in Japonica and Indica Subspecies of Rice (Oryza sativa L.) Cultivated in Brazil

ABSTRACT Whole rice contains several fat-soluble phytochemicals such as tocopherols, tocotrienols, and γ-oryzanol which have been reported to possess beneficial health properties. This study was conducted to determine whether brown rice belonging to indica and japonica subspecies were distinguishable from each other regarding the concentration of these compounds by analyzing 32 genotypes. The fat-soluble compounds were analyzed by normal-phase HPLC in a single run. The variability of the compounds analyzed was high, but the mean content of γ-oryzanol across all samples was significantly higher (P < 0.01) in japonica (246.3 mg/kg) than in indica rice (190.1 mg/kg). Similar differences were found for total vitamin E contents which were 24.2 mg/kg in japonica and 17.1 mg/kg in indica rice, respectively. In japonica rice, α-tocopherol, α-tocotrienol, and γ-tocotrienol were the most abundant homologs, while in indica rice the most abundant were γ-tocotrienol, α-tocopherol, and α-tocotrienol. A significant Pear...

Isolation of four tocopherols and four tocotrienols from a variety of natural sources by semi-preparative high- performance liquid chromatography*

Abstract Quantitative measurements of tocopherols and tocotrienols required isolation of four tocopherols from a mixture of soybean oil and wheat germ and four tocotrienols from a mixture of wheat bran and rubber latex. Semi-preparative HPLC was accomplished using a 250 mm × 10 mm I.D. column packed with 10-μm silica gel in hexane containing 2–15% tetrahydrofuran. Identification of isolated and purified tocopherols and tocotrienols was confirmed from mass spectra, and concentrations of identified vitamers were determined by absorption coefficients. Recovery of tocopherols and tocotrienols ranged from 54 to 83%. Isomer purities were found to be above 99% by capillary GC and HPLC.

Extraction of Antioxidants from Wheat Bran Using Conventional Solvent and Microwave-Assisted Methods

ABSTRACT Total phenolic and tocopherol contents and free radical scavenging capability of wheat bran extracted using conventional and microwave-assisted solvent extraction methods were studied. Three different solvents (methanol, acetone, and hexane) were used in the conventional solvent extraction. Methanol was the most effective solvent, producing higher extraction yield (4.86%), total phenolic compound content (241.3 μg of catechin equivalent/g of wheat bran), and free radical scavenging capability (0.042 μmol of trolox equivalent/g of wheat bran) than either acetone or hexane. However, there was no significant difference in the total tocopherol contents (13.6–14.8 μg/g of wheat bran) among the three different solvent extraction methods. Microwave-assisted solvent extraction using methanol significantly increased the total phenolic compound content to 467.5 and 489.5 μg of catechin equivalent; total tocopherol content to 18.7 and 19.5 μg; and free radical scavenging capability to 0.064 and 0.072 μmol o...

Improved high-performance liquid chromatography of vitamin E vitamers on normal-phase columns

A method is described for improving column stability and reproducibility for analysis of vitamin E vitamers on normal-phase high-performance liquid chromatography columns with isooctane/ethyl acetate/acetic acid/2,2-dimethoxypropane (98.5:0.9:0.85:0.1) mobile phase. Acetic acid in the mobile phase reduced retention times of vitamin E vitamer and increased column stability. A small concentration of 2,2-dimethoxypropane, which reacts with water to form acetone and methanol, reduced the need for column regeneration and stabilized retention times.

Potential Antioxidant Activity of γ-Oryzanol in Rice Bran as Determined Using an In Vitro Mouse Lymph Axillary Endothelial Cell Model

ABSTRACT A mouse lymphatic endothelial cell (SVEC4-10) in vitro model was developed and found to be effective in the study of antioxidant activity of γ-oryzanol in rice bran. The critical and vital parameters in developing these cell models included the emulsion preparation of hydrophobic compounds, the consistent management of cell culture, and the selection of cell viability detection methods compatible with the cell lines and the test substances. The SVEC4-10 cell line had a fast metabolism and consequently could be used to determine antioxidant activity of a test substance in a relatively rapid manner. Results showed that γ-oryzanol, ferulic acid, and α-tocopherol could interact with cells such that oxidative damage induced by tert-butyl hydroperoxide on cellular mitochondrial activity lessened, and in some situations, γ-oryzanol was a more effective antioxidant than α-tocopherol. The results also suggested different antioxidant mechanisms among γ-oryzanol, ferulic acid, and α-tocopherol. The three ma...