Quantification of tocopherols, tocotrienols, and γ-oryzanol contents and their distribution in some commercial rice varieties in Taiwan

The eight vitamin E isomers [α-, β-, γ-, and δ-tocopherols (T) and α-, β-, γ-, and δ-tocotrienols (T3)] and γ-oryzanol are known to possess diverse biological activities. This study examined the contents of these compounds and their distribution in 16 commercial rice varieties in Taiwan. Results showed that the order of vitamin E, total T, total T3, and γ-oryzanol contents was rice bran > brown rice > rice husk > polished rice. γ-T3 was the highest vitamin E isomer present in all rice samples, while β-T, β-T3, δ-T, and δ-T3 were present in trace amounts. The Japonica varieties contained a higher total T, total T3, and γ-oryzanol than the Indica varieties. They also have a higher level of α-T and α-T3 but a lower level of γ-T and γ-T3 than the Indica varieties. However, no obvious difference in total T, total T3, and γ-oryzanol content was noted between black- and red-colored rice varieties.     

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.     

Antioxidants and antioxidant activity of several pigmented rice brans

This study investigated the antioxidant content and activity of phenolic acids, anthocyanins, α-tocopherol and γ-oryzanol in pigmented rice (black and red rice) brans. After methanolic extraction, the DPPH free radical scavenging activity and antioxidant activity were measured. The pigmented rice bran extract had a greater reducing power than a normal rice bran extract from a long grain white rice. All bran extracts were highly effective in inhibiting linoleic acid peroxidation (60-85%). High-performance liquid chromatography (HPLC) analysis of antioxidants in rice bran found that γ-oryzanol (39-63%) and phenolic acids (33-43%) were the major antioxidants in all bran samples, and black rice bran also contained anthocyanins 18-26%. HPLC analysis of anthocyanins showed that pigmented bran was rich in cyanidin-3-glucoside (58-95%). Ferulic acid was the dominant phenolic acid in the rice bran samples. Black rice bran contained gallic, hydroxybenzoic, and protocatechuic acids in higher contents than red rice bran and normal rice bran. Furthermore, the addition of 5% black rice bran to wheat flour used for making bread produced a marked increase in the free radical scavenging and antioxidant activity compared to a control bread.     

Cholesterol Response and Foam Cell Formation in Hamsters Fed Rice Bran,Oat Bran,and Cellulose + Soy Protein Diets With or Without Added Vitamin E

Four-week-old male golden Syrian hamsters were fed diets containing cellulose (control, CC), cellulose + soy protein (CS), CS + vitamin E, (CSE), rice bran (RB), RB + vitamin E (RBE), oat bran (OB), and OB + vitamin E (OBE) for six weeks (n = 10/treatment). Diets contained (by weight) 10% total dietary fiber, 3% N, 20% fat, 0.5% cholesterol, and some diets had an additional 0.1% vitamin E. After six weeks, RB and OB diets resulted in significantly higher weight gain than the CC diet. Plasma low-density lipoprotein cholesterol (LDL-C) values and the LDL-C/high-density lipoprotein cholesterol ratio in hamsters fed CSE, RBE, OB, and OBE diets were significantly lower than in those fed CC diet. There were no significant differences in total plasma cholesterol values among the hamsters fed any of the diets. Liver cholesterol in animals fed OB and OBE diets was significantly lower than in all other groups. Foam cell areas in the inner bend of the aortic arch in animals fed all treatment diets were significantly reduced when compared with that in animals fed CC diet. The level of additional dietary vitamin E did not result in further significant reductions in foam cell area. The results of this study suggest that diets containing rice bran, oat bran, or soy protein significantly reduced the development of atherosclerosis in hypercholesterolemic hamsters.     

香稻品种2-乙酰-1-吡咯啉多样性及籽粒分布特征的研究

采用田间试验方法研究同一地点和时间种植、同一栽培条件下2-乙酰-1-吡咯啉在11个香稻品种间差异性及籽粒分布特征.结果表明,桂香丝糯、中健2号、清香米、泰国香稻1号R207和Texmati等5个品种含有2-乙酰-1-吡咯啉,精米与糠中的2-乙酰-1-吡咯啉含量在上述5个品种间存在显著差异(P<0.05),其中Texma...     

Antioxidant activity of tocopherols, tocotrienols, and gamma-oryzanol components from rice bran against cholesterol oxidation accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride

The antioxidant activities of vitamin E (alpha-tocopherol, alpha-tocotrienol, gamma-tocopherol, and gamma-tocotrienol) and gamma-oryzanol components (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, and campesteryl ferulate) purified from rice bran were investigated in a cholesterol oxidation system accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride. All components exhibited significant antioxidant activity in the inhibition of cholesterol oxidation. The highest antioxidant activity was found for 24-methylenecycloartanyl ferulate, and all three gamma-oryzanol components had activities higher than that of any of the four vitamin E components. Because the quantity of gamma-oryzanol is up to 10 times higher than that of vitamin E in rice bran, gamma-oryzanol may be a more important antioxidant of rice bran in the reduction of cholesterol oxidation than vitamin E, which has been considered to be the major antioxidant in rice bran. The antioxidant function of these components against cholesterol oxidation may contribute to the potential hypocholesterolemic property of rice bran.     

Phytochemicals and antioxidant activity of milled fractions of different wheat varieties

The health-promoting effects of whole-grain consumption have been attributed in part to their unique phytochemical contents and profiles that complement those found in fruits and vegetables. Wheat is an important component of the human diet; however, little is known about the phytochemical profiles and total antioxidant activities of milled fractions of different wheat varieties. The objectives of this study were to investigate the distribution of phytochemicals (total phenolics, flavonoids, ferulic acid, and carotenoids) and to determine hydrophilic and lipophilic antioxidant activity in milled fractions (endosperm and bran/germ) of three different wheat varieties, two of which were grown in two environments. Grain samples of each of the wheat varieties were milled into endosperm and bran/germ fractions. Each fraction was extracted and analyzed for total phenolics, ferulic acid, flavonoids, carotenoid contents, and hydrophilic and lipophilic antioxidant activities. Total phenolic content of bran/germ fractions (2867-3120 micromol of gallic acid equiv/100 g) was 15-18-fold higher (p < 0.01) than that of respective endosperm fractions. Ferulic acid content ranged from 1005 to 1130 micromol/100 g in bran/germ fractions and from 15 to 21 micromol/100 g in the endosperm fractions. The bran/germ fraction flavonoid content was 740-940 micromol of catechin equiv/100 g. On average, bran/germ fractions of wheat had 4-fold more lutein, 12-fold more zeaxanthin, and 2-fold more beta-cryptoxanthin than the endosperm fractions. Hydrophilic antioxidant activity of bran/germ samples (7.1-16.4 micromol of vitamin C equiv/g) was 13-27-fold higher than that of the respective endosperm samples. Similarly, lipophilic antioxidant activity was 28-89-fold higher in the bran/germ fractions (1785-4669 nmol of vitamin E equiv/g). Hydrophilic antioxidant activity contribution to the total antioxidant activity (hydrophilic + lipophilic) was >80%. In whole-wheat flour, the bran/germ fraction contributed 83% of the total phenolic content, 79% of the total flavonoid content, 51% of the total lutein, 78% of the total zeaxanthin, 42% of the total beta-cryptoxanthin, 85% of the total hydrophilic antioxidant activity, and 94% of the total lipophilic antioxidant activity. Our results showed that different milled fractions of wheat have different profiles of both hydrophilic and lipophilic phytochemicals. These findings provide information necessary for evaluating contributions to good health and disease prevention from whole-wheat consumption.     

Analysis of phenolic compounds in white rice, brown rice, and germinated brown rice

Two hydroxycinnamate sucrose esters, 6'-O-(E)-feruloylsucrose and 6'-O-(E)-sinapoylsucrose, were isolated from methanol extracts of rice bran. Soluble and insoluble phenolic compounds as well as 6'-O-(E)-feruloylsucrose and 6'-O-(E)-sinapoylsucrose from white rice, brown rice, and germinated brown rice were analyzed using HPLC. The results demonstrated that the content of insoluble phenolic compounds was significantly higher than that of soluble phenolics in rice, whereas almost all compounds identified in germinated brown rice and brown rice were more abundant than those in white rice. 6'-O-(E)-Feruloylsucrose (1.09 mg/100 g of flour) and 6'-O-(E)-sinapoylsucrose (0.41 mg/100 g of flour) were found to be the major soluble phenolic compounds in brown rice. During germination, an approximately 70% decrease was observed in the content of the two hydroxycinnamate sucrose esters, whereas free phenolic acid content increased significantly; the ferulic acid content of brown rice (0.32 mg/100 g of flour) increased to 0.48 mg/100 g of flour and became the most abundant phenolic compound in germinated brown rice. The content of sinapinic acid increased to 0.21 mg/100 g of flour, which is nearly 10 times as much as that in brown rice (0.02 mg/100 g of flour). In addition, the total content of insoluble phenolic compounds increased from 18.47 mg/100 g of flour in brown rice to 24.78 mg/100 g of flour in germinated brown rice. These data suggest that appropriate germination of brown rice may be a method to improve health-related benefits.     

Variation in the content of dietary fiber and components thereof in wheats in the HEALTHGRAIN Diversity Screen

Within the HEALTHGRAIN diversity screening program, the variation in the content of dietary fiber and components thereof in different types of wheat was studied. The wheat types were winter (131 varieties) and spring (20 varieties) wheats (both Triticum aestivum L., also referred to as common wheats), durum wheat (Triticum durum Desf., 10 varieties), spelt wheat (Triticum spelta L., 5 varieties), einkorn wheat (T. monococcum L., 5 varieties), and emmer wheat (Triticum dicoccum Schubler, 5 varieties). Common wheats contained, on average, the highest level of dietary fiber [11.5-18.3% of dry matter (dm)], whereas einkorn and emmer wheats contained the lowest level (7.2-12.8% of dm). Intermediate levels were measured in durum and spelt wheats (10.7-15.5% of dm). Also, on the basis of the arabinoxylan levels in bran, the different wheat types could be divided this way, with ranges of 12.7-22.1% of dm for common wheats, 6.1-14.4% of dm for einkorn and emmer wheats, and 10.9-13.9% of dm for durum and spelt wheats. On average, bran arabinoxylan made up ca. 29% of the total dietary fiber content of wheat. In contrast to what was the case for bran, the arabinoxylan levels in flour were comparable between the different types of wheat. For wheat, in general, they varied between 1.35 and 2.75% of dm. Einkorn, emmer, and durum wheats contained about half the level of mixed-linkage beta-glucan (0.25-0.45% of dm) present in winter, spring, and spelt wheats (0.50-0.95% of dm). All wheat types had Klason lignin, the levels of which varied from 1.40 to 3.25% of dm. The arabinoxylan contents in bran and the dietary fiber contents in wholemeal were inversely and positively related with bran yield, respectively. Aqueous wholemeal extract viscosity, a measure for the level of soluble dietary fiber, was determined to large extent by the level of water-extractable arabinoxylan. In conclusion, the present study revealed substantial variation in the contents of dietary fiber and constituents thereof between different wheat types and varieties.     

Rapid High‐Performance Liquid Chromatography Determination of Tocopherols and Tocotrienols in Cereals

A rapid normal‐phase high‐performance liquid chromatography (NP‐HPLC) method has been developed for rapid determination of the total content of tocopherols (T) and tocotrienols (T3) in cereals. The new method uses a one‐step extraction followed by NP‐HPLC coupled with a fluorescence detector. The new method provides a baseline separation of the critical peaks of beta‐tocotrienol (β‐T3) and gamma‐tocopherol (γ‐T) within a short time of analysis. The extraction step requires no saponification step or addition of antioxidant. Addition of butylated hydroxytoluene (BHT) had no effect on the stability of vitamin E during sampling. The recovery was 96–100%. The method is demonstrated by successful quantification of vitamin E in barley, wheat, and spelt grains, as well as wheat germ and flours from wheat, spelt, and rye.     

Identification of anthocyanins in the sprouts of buckwheat

The anthocyanin profiles and varieties/breeding line differences of anthocyanin concentrations in common/tartary buckwheat sprouts have been studied. Four anthocyanins, cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-galactoside, and cyanidin 3-O-galactopyranosyl-rhamnoside, were isolated from the sprouts of common buckwheat, were separated using high-performance liquid chromatography (HPLC), and were identified using reversed-phase liquid chromatography (LC)/electrospray ionization-mass spectrometry (ESI-MS)/MS techniques. In tartary buckwheat sprouts, two anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside) were identified. Among 19 common/tartary buckwheat varieties/breeding lines, Hokkai T10 contained the highest amounts of anthocyanins. Cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside concentrations in 6-10 days after seeding sprouts of Hokkai T10 ranged from 0.16 to 0.20 mg/g dry wt and from 5.55 to 6.57 mg/g dry wt, respectively. In addition, dark-grown sprouts of Hokkai T10 accumulated 0.091 and 2.77 mg/g dry wt of cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside whereas other varieties/breeding lines accumulated trace amounts of anthocyanins. Given its anthocyanin-rich red cotyledons, Hokkai T10 is a promising line for use as "Moyashi" type sprouts and is strongly recommended as a new functional food, rich in dietary anthocyanins.     

Tocopherol and Tocotrienol Content in Commercial Wheat Mill Streams

The content of tocopherols and tocotrienols, collectively known as vitamin E (tocols), was determined in fractions of roller‐milled wheat grains. The results showed that vitamin E components are present in all major flour fractions of wheat, but that the vitamin E content and composition differed significantly between fractions. The total content of vitamin E, calculated as alpha‐tocopherol equivalents, changed from 16.1 mg α‐TE/g in wheat grain to 12.2 mg α‐TE/g in roller‐milled wheat flour. The germ fraction had the highest content of tocopherols, and the content of α‐tocopherol (195.2 μg/g) was 16 times higher (on average) than in any other fraction. The content of tocotrienols was distributed more uniform in the wheat grain with the highest content in the bran fractions, and the content of β‐tocotrienol was higher than the content of α‐tocopherol in all milling fractions except the wheat germ. The content of β‐tocotrienol was 24.1 μg/g in wheat grain, 25.3–31.0 μg/g in the bran fractions, and 14.3–21.9 μg/g in the fractions of endosperm. Overall, germ and fine bran fractions represent good sources of vitamin E and might be used in breadmaking.     

Nutraceutical Concentrations within the Bran of Various Rice Kernel Thickness Fractions

Several important nutraceutical compounds, such as tocotrienols, tocopherols, and oryzanols, can be extracted from rice bran, a by-product of milling. This study was conducted to not only provide information regarding nutraceutical concentrations within the rice kernel based on bran collected from successive milling, but also to determine levels of nutraceutical concentrations across several different thickness fractions. Nutraceutical compounds were measured in the bran from two long-grain rice varieties, Cypress and Drew. Rough rice was separated into three thickness fractions (<1·84, 1·84–1·98, and >1·98 mm) and each fraction milled for three successive 10 s milling durations. Bran was collected from each milling duration of each thickness fraction to allow quantification of the nutraceutical content. Results showed that bran collected from rice milled for longer durations (30 s) had lower levels of tocotrienols and tocopherols compared to bran from shorter milling durations (10 s). The highest concentration of oryzanols was in the rice bran from the first 10 s milling duration. Overall, compared to bran from thinner kernels (<1·84 mm), the bran from thicker kernel fractions contained a higher content of nutraceuticals.     

High-pressure liquid chromatographic determination of vitamin D3 in resins, oils, dry concentrates, and dry concentrates containing vitamin A.

A high-pressur liquid chromatographic (HPLC) procedure has been developed for the determination of vitamin D3 in resins, oils, dry concentrates, and dry concentrates containing vitamin A. Specificity of the method for vitamin D3 in the presence of isomers and other related constituents was shown by ultimate recovery of the vitamin D3 and the individual constituents and their characterization by other methods such as ultraviolet spectrophotometry. Precision and accuracy are within 2%, and as many as 20 determinations may be completed in a working day. Excellent agreement with the official AOAC biological assay was found. A comparison of the response of isomers of vitamin D3 by the HPLC method vs. other instrumental and chemical procedures shows HPLC to be the most specific method for determining the bioactive isomers.     

Evaluation of allelopathic potential and quantification of momilactone A,B from rice hull extracts and assessment of inhibitory bioactivity on paddy field weeds

Rice (Oryza sativa L.) hull extracts were used in a bioassay to evaluate the allelopathic potential of rice on the germination and growth of barnyard grass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi), to quantify momilactone A and B levels in rice hull germplasm and to assess the inhibitory bioactivity of momilactone A and B as a potential natural source of herbicide for weed control in paddy fields. Four varieties of weeds including E. crus-galli P. Beauv. var. oryzicola Ohwi, Monochoria vaginalis var. plantaginea, Scirpus juncoides, and Eleocharis kuroguwai were tested in the paddy field. Of 99 rice varieties, the top five including Noindari exhibited inhibition effects greater than 50% in average inhibition of dry weight (AIDW). Noindari among them exerted the strongest effect (55.6%). The next five in the ranking exhibited inhibition effects of greater than 40%. Also, 46 varieties had inhibition effects between 20 and 40%, and 29 varieties had inhibition effects greater than 10%. Fourteen varieties had very low inhibitory effects (less than 10%), the lowest of which was Heunbe (4.7%). These varieties showed a mean inhibition of 19.8% for germination rate (GR), 9.9% for germination percentage (GP), 16.6% for leaf dry weight (LDW), 38.9% for straw dry weight (SDW), and 26.8% for root dry weight (RDW). Rice varieties were classified into six categories based on their total momilactones (TMs) (momilactone A + momilactone B). The highest level of momilactone A was found in the Baekna rice variety (34.7 microg g(-1)), and Baekgwangok contained the highest level of momilactone B (37.8 microg g(-1)). In allelopathic potential with genetic properties and morphological characteristics, the total inhibition rate (TIR) was 18.3% for Korean rice varieties, 19.0% for middle maturing varieties, 17.8% for colorless hull varieties, 18.3% for awn varieties, and 19.0% for colorless awn varieties. In addition, Korean varieties showed higher TMs (4.5 microg g(-1)) as compared with varieties that were late maturing (4.4 microg g(-1)), had colorless hulls (4.1 microg g(-1)), awns (4.7 microg g(-1)), and colorless awns (4.8 microg g(-1)). Momilactone A levels were generally higher than momilactone B levels. Total inhibition rates on barnyard grass correlated with average inhibitions of germination (AIG) (r2 = 0.62***), AIDW (r2 = 0.92***), and were affected by the inhibition rate of GP (r2 = 0.57***). Regions of origin for rice varieties correlated with the AIG (r2 = -0.23***), and maturing time showed a positive correlation with SDW (r2 = 0.15**) and RDW (r2 = 0.19**). Levels of momilactones were also correlated with the region of origin (r2 = -0.32***), maturing time (r2 = 0.13***), and awns (momilactone A, r2 = 0.23***; momilactone B, r2 = 0.14**), suggesting that rice varieties with awns, Korean varieties, and varieties with later maturing times contain higher levels of momilactone. Also, the investigation of the momilactone A and B bioactivity (0, 250, 500, 1000, 2000, and 4000 g a.i./ha) for weed control in paddy fields indicated that momilactones A and B exhibited no toxicity (0 in all concentrations) against rice plants, and the inhibitory bioactivity on weeds with momilactone A was higher than that of momilactone B. When compared with no momilactone control, the highest inhibitory effect (50%) on E. crus-galli P. Beauv. var. oryzicola Ohwi was shown on the 14th day after the application of momiactone A. The inhibitory effect increased with the concentration of the compound from 250 to 4000 g a.i./ha. Furthermore, momilactone A showed greater suppression than momliactone B toward toward E. crus-galli P. Beauv. var. oryzicola Ohwi, M. vaginalis var. plantaginea, S. juncoides, and E. kuroguwai. In broad weed species, momilactone A showed the highest inhibitory effect (90% in 4000 g a.i./ha) on S. juncoides, 14 days after the application as compared with no momilactone control. Further studies on allelopathic effects and momilactones from the germplasm of rice varieties using genetic properties and morphological characteristics may facilitate the development of rice varieties with higher allelopathic potential. Momilactones A and B present in rice hulls may serve as a potential natural herbicide source for weed control in paddy fields reducing the dependence on synthetic herbicides.     

Impact of Baking on Vitamin E Content of Pseudocereals Amaranth,Quinoa, and Buckwheat

The aim of this study was to analyze the vitamin E composition of amaranth, quinoa, and buckwheat pseudocereals. The method used consisted of a one‐step extraction with hexane followed by normal‐phase high‐performance liquid chromatography (NP‐HPLC) coupled with a fluorescence detector. This method afforded complete separation of all vitamin E compounds present. In addition, vitamin E stability following high‐temperature processing such as breadmaking was also studied. The vitamin E composition differed significantly from grain type to grain type, and highest vitamin E content (expressed as α‐tocopherol equivalents) was found in quinoa grains, followed by amaranth and buckwheat (24.7, 15.4, and 6.3 μg/g respectively). None of the pseudocereal grains contained tocotrienols, which were only detected in wheat grains in minor quantities. Vitamin E recovery following breadbaking was high (70–93%) and gluten‐free breads containing pseudocereal had significantly higher vitamin E content compared with the gluten‐free control. Amaranth, quinoa, and buckwheat grains proved to be good sources of vitamin E and may be used as ingredients in gluten‐free products for improving vitamin E content and thus overall nutritional quality.     

Preparation of ferulic acid from agricultural wastes: its improved extraction and purification

Ferulic acid (FA) is a phenolic antioxidant present in plants, which is widely used in the food and cosmetic industry. In the present study, various agricultural wastes such as maize bran, rice bran, wheat bran, wheat straw, sugar cane baggasse, pineapple peels, orange peels, and pomegranate peels were screened for the presence of esterified FA (EFA). Among the sources screened, maize bran was found to contain the highest amount of EFA. Pineapple peels, orange peels, and pomegranate peels were also found to contain traces of EFA. Alkaline extraction of EFA from maize bran was carried out using 2 M NaOH. Response surface methodology (RSM) was used for optimization of EFA extraction, which resulted in a 1.3-fold increase as compared to the unoptimized conventional extraction technique. FA was analyzed by means of high-performance liquid chromatography (HPLC). Purification was carried out by adsorption chromatography using Amberlite XAD-16 followed by preparative high-performance thin-layer chromatography (HPTLC). The recovery of Amberlite XAD-16 purified FA was up to 57.97% with HPLC purity 50.89%. The fold purity achieved was 1.35. After preparative HPTLC, the maximum HPLC purity obtained was 95.35% along with an increase in fold purity up to 2.53.