Influence of dietary fat and vitamin E supplementation on free radical production and on lipid and protein oxidation in turkey muscle extracts

The objectives of this study were to investigate the effects of dietary fat (6% soy oil or rapeseed oil or tallow) and alpha-tocopheryl acetate supplementation at two levels (30 or 200 ppm) on radical production, measured by ESR spectroscopy, and on lipid and protein oxidation in turkey muscle extracts oxidized by an enzymic system (NADPH, ADP, FeSO(4)/cytochrome P450 reductase). Two muscles were tested: pectoralis major (glycolytic) and sartorius (oxidative) muscles. Radical production measured by ESR was higher in pectoralis major muscle than in sartorius muscle, whereas lipid and protein oxidation was more important in sartorius muscle, showing the importance of the pro-/antioxidant ratio in oxidative processes in muscular cells and of the measurement methodology to appreciate the free radical production. Dietary fat had no effect on the level of ESR signals, whereas feeding of animals with soy oil induced higher oxidation of lipids. Protein oxidation was less sensitive to the nature of the dietary fat than lipid oxidation. Vitamin E supplementation significantly decreased radical production, as measured by ESR spectroscopy. Vitamin E also decreased lipid and protein oxidation, but the effect of vitamin E on protein oxidation was less pronounced than on lipid oxidation.     

Effect of beta-carotene and vitamin E on oxidative stability in leg meat of broilers fed different supplemental fats

The objectives of this study were to investigate the effects of dietary fat (6% lard and sunflower and olive oil) and supplementation of alpha-tocopheryl acetate or beta-carotene on vitamin E content and lipid oxidation in raw, cooked, and chilled-stored broiler leg meat. Vitamin E increased its tissue level, reducing lipid oxidation. The oxidative stability of leg meat tended to decrease with dietary sunflower oil. Effects of beta-carotene on vitamin E levels and oxidation depended on dietary fat and its concentration in feed, decreasing vitamin E, mainly at 50 ppm. beta-Carotene at 15 ppm acted as antioxidant in fresh and cooked meat in the sunflower and olive oil diets. However, in stored meat, beta-carotene at 50 ppm increased TBARS, probably due to a decrease in vitamin E content and direct prooxidant effects per se. It is suggested that the antioxidant effect of beta-carotene requires the presence of vitamin E in tissues.     

Glutathione peroxidase activity, TBARS, and alpha-tocopherol in meat from chickens fed different diets.

This study investigated the effect of feeding broilers with diets differing in dietary fat source (lard, sunflower oil, olive oil) and vitamin E (basal vs supplemented with 200 mg of alpha-tocopheryl acetate/kg) on meat lipid oxidative stability. The diets differed by their degree of unsaturation and included the natural antioxidant alpha-tocopherol (vitamin E). Glutathione peroxidase (GSHPx) activity was measured in raw meat and ranged from 3.62 to 8.06 nmol NADPH/min/mg protein. The enzyme activity was influenced by the degree of unsaturation of the diet. Capillary gas chromatography analyses showed that dietary alpha-tocopherol accumulated in the muscle tissue and contributed to a better oxidative stability of the raw and cooked meat. Thigh meat alpha-tocopherol levels ranged from 2.73 to 3.62 microg/g in unsupplemented chickens whereas levels from 8.69 to 13.37 microg/g were observed in the thigh meat from alpha-tocopherol supplemented animals. The inclusion of olive oil and alpha-tocopherol in the animal diet gave lower thiobarbituric acid reactive substance (TBARS) values and lower GSHPx activity. High correlations were found between the parameters studied. The results suggest that the glutathione peroxidase activity could be used as an indicator of the meat oxidative stability. A negative relationship was observed between GSHPx activity and tissue alpha-tocopherol levels, and a positive relationship was evidenced between TBARS and antioxidant enzyme activity.     

Influence of different dietary doses of n-3- or n-6-rich vegetable fats and alpha-tocopheryl acetate supplementation on raw and cooked rabbit meat composition and oxidative stability

This study evaluates the effects of replacing beef tallow added to rabbit feeds (3% w/w) by different doses (0%, 1.5% and 3% w/w) of n-6- or n-3-rich vegetable fat sources (sunflower and linseed oil, respectively) and alpha-tocopheryl acetate supplementation (0 and 100 mg/kg) on the fatty acid composition, alpha-tocopherol content, and oxidation levels [assessed by analyzing thiobarbituric acid (TBA) and lipid hydroperoxide values] in rabbit meat. We also measured these parameters after cooking and refrigerated storage of cooked rabbit meat. Both dietary alpha-tocopheryl acetate supplementation and the dose and source of fat added to feeds influenced meat fatty acid composition, modifying the n-6/n-3 ratio, which was more nutritionally favorable when linseed oil was used. Furthermore, the addition of linseed oil and the supplementation with alpha-tocopheryl acetate enhanced long-chain PUFA biosynthesis. However, the addition of 3% linseed oil increased meat oxidation, and although it was reduced by dietary supplementation with alpha-tocopheryl acetate in raw meat, this reduction was not as effective after cooking. Therefore, dietary supplementation with 1.5% linseed oil plus 1.5% beef tallow and with alpha-tocopheryl acetate would be recommended to improve the nutritional quality of rabbit meat.     

Antioxidant activity of fermented soybean extract

Free radicals are considered to be important causative factors in the development of cancer and cardiovascular diseases. This relationship has led to interest in evaluating the antioxidant capacities of many dietary supplements. Fermented soybean extract is produced by symbiotic fermentation of organic soybean with 20 types of Lactobacillus and yeast. In vitro and in vivo models are used in this study to evaluate the antioxidant effect of fermented soybean extract. Several in vitro models are used to detect the antioxidant capacity of the fermented soybean extract, which is compared to vitamin C and Trolox. The results demonstrate that the fermented soybean extract has strong antioxidant activity against unsaturated fatty acid peroxidation compared to vitamin C and Trolox. By the means of the test system developed by Y. Toshiki et al., it is shown that the fermented soybean extract can function both as an antioxidant and as a free radical acceptor that can convert free radicals into harmless substances through an energy-decreasing procedure. An in vivo study examines the effects of fermented soybean extract on the activity of antioxidant enzymes. The activities of the antioxidant enzymes (AOE) including total superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) are measured in liver, kidney, and brain from male Sprague-Dawley rats. The activities of CAT, SOD, and GPX are increased in the liver. However, the SOD activity is decreased in the kidney. SOD and GPX activities are decreased in the brain. These results lead to the conclusion that fermented soybean extract not only has antioxidant activity but also has an effect on the activity of antioxidant enzymes in liver.     

Effects of oxidized dietary oil and vitamin E supplementation on lipid profile and oxidation of muscle and liver of juvenile atlantic cod (Gadus morhua)

The effects of oxidized dietary lipid and the role of vitamin E on lipid profile, retained tocopherol levels, and lipid oxidation of juvenile Atlantic cod (Gadus morhua) were evaluated following a 9-week feeding trial. Four isonitrogenous experimental diets containing fresh or oxidized (peroxide value of 94 mequiv/kg) fish oil with or without added vitamin E (alpha-tocopherol or mixed tocopherols) were fed to juvenile cod in duplicate tanks. There was no significant (P > 0.05) influence on major lipid classes of cod liver and muscle by diet with the exception of sterols. Sterols content was increased in liver but decreased in muscle by oxidized dietary oil in the absence of vitamin E. Dietary vitamin E supplementation decreased the sterols level in cod liver but with no significant (P > 0.05) effect on their level in the muscle. Fatty acid composition varied between lipid fractions in muscle tissue and was affected by the diet. Oxidized oil significantly (P < 0.05) decreased the deposition of alpha-tocopherol in liver but not in muscle. gamma- and delta-Tocopherols from dietary tocopherol mixtures were retained at very low levels in liver, but higher retention was observed in muscle tissue. The oxidative state of both liver and muscle, as measured by the 2-thiobarbituric acid reactive substances (TBARS) and headspace propanal, negatively correlated with tissue vitamin E levels. It is suggested that oxidized oil affected juvenile Atlantic cod by causing vitamin E deficiency in certain tissues and that these effects could be alleviated by supplementation of a sufficient amount of dietary vitamin E. The results also indicate that mixed tocopherols were good antioxidants for Atlantic cod, although less effective than alpha-tocopherol alone in many tissues with the exception of muscle, where gamma- and delta-tocopherols were deposited at relatively high levels.     

Counteraction of adriamycin-induced oxidative damage in rat heart by selenium dietary supplementation

Many reports indicate that dietary selenium, potentially increasing the activity of glutathione peroxidase, could offer protection against free-radical-induced damage. The effects of diets moderately enriched in selenium, as sodium selenite or as a lyophilized selenium-rich food, were studied in rats. Adriamycin, an anticancer drug causing a free-radical-mediated cardiotoxicity, was administered intraperitoneally to some rats. The onset of an oxidative damage was indicated by the increase in the plasma level of reactive oxygen metabolites coupled to a decrease in the total antioxidant activity but without modification of glutathione peroxidase activity, which were observed in all rats, independent of the dietary treatment. On the contrary, in the heart, selenium supplementation caused an increase in the total antioxidant activity, glutathione concentration, and glutathione peroxidase and catalase activities leading to a decreased generation of reactive oxygen metabolites. These results clearly indicate that a moderate Se dietary supplementation counteracts adriamycin-induced cardiotoxicity by preservation of endogenous antioxidants.     

Fermented pigeon pea (Cajanus cajan) ingredients in pasta products

Pigeon pea (Cajanus cajan var. aroíto) seeds were fermented in order to remove antinutritional factors and to obtain functional legume flour to be used as pasta ingredients. Fermentation brought about a drastic reduction of alpha-galactosides (82%), phytic acid (48%), and trypsin inhibitor activity (39%). Fermented legume flours presented a notable increase of fat and total soluble available carbohydrates, a slight decrease of protein, dietary fiber, calcium, vitamin B2, vitamin E, and total antioxidant capacity, and a decrease of soluble dietary fiber, Na, K, Mg, and Zn contents. No changes were observed in the level of starch and tannins as a consequence of fermentation. The fermented flour was used as an ingredient to make pasta products in a proportion of 5, 10, and 12%. The supplemented pasta products obtained had longer cooking times, higher cooking water absorptions, higher cooking loss, and higher protein loss in water than control pasta (100% semolina). From sensory evaluations, fortified pasta with 5 and 10% fermented pigeon pea flour had an acceptability score similar to control pasta. Pasta supplemented with 10% fermented pigeon pea flour presented higher levels of protein, fat, dietary fiber, mineral, vitamin E, and Trolox equivalent antioxidant capacity than 100% semolina pasta and similar vitamins B1 and B2 contents. Protein efficiency ratios and true protein digestibility improved (73 and 6%, respectively) after supplementation with 10% fermented pigeon pea flour; therefore, the nutritional value was enhanced.     

Antioxidant properties of soybean isoflavone extract and tofu in vitro and in vivo

Isoflavones in soybean were extracted in the crude form using 80% food-grade ethanol at 80 degrees C for 6 h and followed by concentration and dehydration. The soy extract contained isoflavones primarily in the forms of glucosides. In vitro antioxidant activities of the soy extract containing 20-500 ppm isoflavones were conducted using a Rancimat method. The results showed that soy isoflavone extract had strong in vitro antioxidant activity. There was a dose-dependent response for the in vitro antioxidant activity at the lower concentrations but not at the higher concentrations. In vivo antioxidant property was determined by measuring the antioxidant enzymes, superoxide dismutase, and catalase in various organs of rats that were fed with diets containing partially oxidized oil and various levels of isoflavones for up to 24 weeks. Neither short-term (8 weeks) feeding nor low isoflavone content (50 ppm) induced changes in superoxide dismutase or catalase activities in rats. Only diets containing high isoflavone contents (150 and 250 ppm) showed obvious elevated enzymatic levels in various organs. In addition, a laboratory-prepared tofu containing approximately 50 ppm isoflavones had better effects than the soy extract with the 250 ppm isoflavone group, which indicated that molecules other than isoflavones may have a synergistic effect on in vivo antioxidant enzyme inductions of tofu.     

Genetically modified rapeseed oil containing cis-9,trans-11,cis-13-octadecatrienoic acid affects body fat mass and lipid metabolism in mice

Punicic acid, one of the conjugated linolenic acid (CLN) isomers, exerts a body-fat reducing effect. Although punicic acid is found in pomegranate and Tricosanthes kirilowii seeds, the amount of this fatty acid is very low in nature. The goal of this study was to produce a transgenic oil containing punicic acid. A cDNA encoding conjugase that converts linoleic acid to punicic acid was isolated from T. kirilowii, and the plant expression vector, pKN-TkFac, was generated. The pKN-TkFac was introduced into Brassica napus by Agrobacterium-mediated transformation. As a result, a genetically modified rapeseed oil (GMRO) containing punicic acid was obtained, although its proportion to the total fatty acids was very low (approximately 2.5%). The effects of feeding GMRO in ICR CD-1 male mice were then examined. Wild-type rapeseed (B. napus) oil (RSO) containing no CLN was used as a control oil. For reference oils, RSO-based blended oils were prepared by mixing with different levels of pomegranate oil (PO), either 2.5% (RSO + PO) or 5.0% (RSO + 2PO) punicic acid. Mice were fed purified diets containing 10% of either RSO, RSO + PO, RSO + 2PO, or GMRO for 4 weeks, and dietary PO dose-dependently reduced perirenal adipose tissue weight with a significant difference between the RSO group and the RSO + 2PO group. GMRO, as compared to RSO, lowered the adipose tissue weight to the levels observed with RSO + 2PO. The liver triglyceride level of the RSO + 2PO and GMRO groups but not that of the RSO + PO group was lower than that of the RSO group. The RSO + 2PO and GMRO groups, but not the RSO + PO group, had increased carnitine-palmitoyltransferase activity in the liver and brown adipose tissue. These results showed that dietary GMRO, even at a dietary punicic acid level as low as 0.25 wt % of diet, reduced body fat mass and altered liver lipid metabolism in mice and was more effective than an equal amount of punicic acid from PO.     

冷榨芝麻饼粕木脂素提取及其抗氧化研究

为有效提高芝麻冷榨副产物的利用价值,以芝麻冷榨制油后的饼粕为原料,乙醇为溶剂,采用超声波辅助法提取芝麻饼粕木脂素,选取乙醇浓度、料液比、提取时间、提取功率4个考察因素,在单因素试验的基础上应用响应面法对芝麻饼粕木脂素提取工艺条件进行优化,并应用Schaal烘箱法,以过氧化值(PV)、茴香胺值(AV)及全氧化值(TV)为指标,对添加木脂素的食用油进行抗氧化活性评价。结果表明,优化后芝麻饼粕木脂素的提取条件为:乙醇浓度93%、料液比(m/v)1∶10、提取时间40 min、超声功率600 W,此条件下木脂素的提取率为563.81 μg·g^-1。随着木脂素添加量的增加,食用油抗氧化活性逐渐增强,且抗氧化效果强于维生素E(VE),接近二丁基羟基甲苯(BHT)。此外,添加木脂素的菜籽油体系中的抗氧化活性普遍强于猪油体系。综上所述,冷榨芝麻饼粕木脂素是一种优质的天然抗氧化剂,可应用于食用油脂中。     

Protection against oxidative stress in diabetic rats by wheat bran feruloyl oligosaccharides

Diabetes is one of the most costly of the chronic diseases and is increasing in epidemic proportions in developing countries. It has been found that some antioxidants play a role in protection against oxidative stress, which is associated with diabetes. In this study, enzyme-released feruloyl oligosaccharides from wheat bran were given intragastrically (ig) to test their effect on antioxidant capacity, body weight restoring capacity, and serum glucose level in alloxan-induced diabetic Sprague-Dawley (SD) rats, using sodium ferulate and vitamin C as positive control groups. The levels of blood glucose, total antioxidant capacity (TAOC), and malondiadehyde (MDA) and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and xanthine oxidase (XOD) were determined in rat serum, liver, and testes. Feruloyl oligosaccharides significantly increased TAOC level, GSH-Px, and SOD activities, but decreased blood glucose and MDA levels and XOD activity in serum, liver, and testes of diabetic rats compared to diabetic controls. Feruloyl oligosaccharides were, overall, more efficient in mitigating oxidative damage in diabetic rats than sodium ferulate and vitamin C. In this feruloyl oligosaccharide feeding study, the antioxidant restoring capacity varied across the tissues observed, and also the activity change of the various antioxidant enzymes varied within a single tissue. Feruloyl oligosaccharides showed greater antioxidant capacity in vivo than in vitro when compared with vitamin C.     

Effect of far-infrared irradiation on the antioxidant activity of defatted sesame meal extracts

To determine the effect of far-infrared (FIR) irradiation on the antioxidant activities of sesame meal, half of sesame seeds were FIR-irradiated and then oil was extracted from the seeds. The resulting defatted sesame meal (DSM) was extracted with methanol, and the antioxidant activities of methanolic extract were determined. FIR irradiation of sesame seeds for 30 min increased the total phenol content from 34.0 to 59.0 muM and radical scavenging activity of DSM extracts from 26.40 to 68.76%. The induction time of lipid oxidation of oil added to extracts was also retarded from 0.82 to 0.96 h. According to the gas chromatography-mass spectrometry analysis, several low molecular weight phenolic compounds, such as p-hydroxy benzoic acid, vanillic acid, p-coumaric acid, isoferulic acid, and o-coumaric acid, were frequently detected in FIR-irradiated DSM extracts as compared to unirradiated ones. These results indicated that FIR irradiation of sesame seeds increased the antioxidant activity of methanolic extracts of DSM.     

Susceptibility to hypoxia/reoxygenation of aged rat cardiomyocytes and its modulation by selenium supplementation

Since in the aged heart an increased basal production of reactive oxygen species (ROS) has been demonstrated, and the resistance to ROS attack could be ameliorated by antioxidant supplementation, we verified the protective effect of selenium, as sodium selenite (SS) or seleno methionine (SM), in cultured rat cardiomyocytes aged in vitro. In normoxia, glutathione peroxidase (GPx) activity and total antioxidant activity were higher in old than in young cardiomyocytes, suggesting the existence of a compensatory increase of antioxidant defenses. When aged cells were submitted to hypoxia/reoxygenation, GPx activity was not modified; while total antioxidant activity decreased, conjugated diene level increased. Selenium supplementation, particularly as SM, was able to increase GPx, and consequently total antioxidant activity, and to decrease conjugated diene production. The observed ability of selenium supplementation to protect aged cardiomyocytes from hypoxia/reoxygenation damage underlines the importance of an optimal selenium dietary intake, particularly in the elderly.     

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.     

Effect of processing on the antioxidant vitamins and antioxidant capacity of Vigna sinensis Var. Carilla

Cowpea (Vigna sinensis L. var. Carilla) flours obtained by fermentation with inoculum Lactobacillus plantarum (PF) or with the natural microorganisms present in the flour (NF) and subsequent heat treatment in an autoclave were prepared to study the effect of fermentation on the antioxidant vitamin content and on the antioxidant capacity. Bacterial counts and pH values, vitamins C and E, carotenoids, glutathione (GSH), superoxide dismutase-like activity (SOD-like activity), peroxyl radical-trapping capacity (PRTC), lipid peroxidation in unilamillar liposomes, and Trolox equivalent antioxidant capacity (TEAC) were evaluated in raw and processed cowpea flours. gamma-Tocopherol and delta-tocopherol were found in raw cowpea, whereas vitamin C and carotenoids were not detected. An increase in the vitamin E activity was observed in PF, whereas vitamin C and carotenoids were not detected in fermented cowpea flours. Fermentation or heat treatment in an autoclave after fermentation produced processed cowpea flours with lower PRTC, glutathione content, and SOD-like activity than those of the raw seeds. However, those processes increased the capacity to inhibit the lipid peroxidation in unilamellar lipoposomes and TEAC. According to the results obtained in this study, the fermentation of cowpeas (naturally or with L. plantarum) and fermentation and subsequent heat treatment in an autoclave are good processes to obtain functional cowpea flours having higher antioxidant capacity than the raw legume.     

Potential of rosemary (Rosemarinus officinalis L.) diterpenes in preventing lipid hydroperoxide-mediated oxidative stress in Caco-2 cells

The effects of 24 h supplementation of Caco-2 cells with carnosic acid and carnosol, and their activities against 5 microM oleic acid hydroperoxide (OAHPx)-mediated oxidative stress, were investigated. At 24 h of incubation, under nonstressed and stressed conditions, both compounds at 25, 50, and 100 microM supplement concentrations reduced catalase activity, whereas changes in glutathione peroxidase and superoxide dismutase activities varied depending upon the concentrations. Relative to control cultures, carnosic acid and carnosol reduced membrane damage by 40-50% when stressed by OAHPx. Carnosic acid and carnosol inhibited lipid peroxidation by 88-100% and 38-89%, respectively, under oxidative stress conditions. Both compounds significantly lowered DNA damage induced by OAHPx. Results of this study suggest that antioxidant activities of carnosic acid and carnosol could be partly due to their ability to increase or maintain glutathione peroxidase and superoxide dismutase activities.     

Effects of dietary vitamin B6 supplementation on fillet fatty acid composition and fatty acid metabolism of rainbow trout fed vegetable oil based diets

Fish oil replacement in aquaculture feeds results in major modifications to the fatty acid makeup of cultured fish. Therefore, in vivo fatty acid biosynthesis has been a topic of considerable research interest. Evidence suggests that pyridoxine (vitamin B(6)) plays a role in fatty acid metabolism, and in particular, the biosynthesis of LC-PUFA has been demonstrated in mammals. However, there is little information on the effects of dietary pyridoxine availability in fish fed diets lacking LC-PUFA. This study demonstrates a relationship between dietary pyridoxine supplementation and fatty acid metabolism in rainbow trout. In particular, the dietary pyridoxine level was shown to modulate and positively stimulate the activity of the fatty acid elongase and Δ-6 and Δ-5 desaturase enzymes, deduced by the whole-body fatty acid balance method. This activity was insufficient to compensate for a diet lacking in LC-PUFA but does highlight potential strategies to maximize this activity in cultured fish, especially when fish oil is replaced with vegetable oils.     

58个不同品种甘薯茎叶营养与功能成分的研究

为了明确不同品种甘薯茎叶的营养与功能成分组成,本试验系统比较了58个不同品种甘薯茎叶中的粗蛋白、粗脂肪、膳食纤维、维生素、多酚类物质、黄酮类物质含量及抗氧化活性。结果表明,甘薯茎叶富含粗蛋白(9.35~38.45 g·100 g^-1 DW)、粗脂肪(1.36~12.30 g·100 g^-1 DW)、总膳食纤维(35.30~45.0 g·100 g^-1 DW)、维生素C(1.47~131.64 mg·100 g^-1 DW)、β-胡萝卜素(6.75~59.35 mg·100 g^-1 DW)及维生素E(0.39~23.30 mg·100 g^-1 DW);湛薯01-2品种甘薯茎叶中总酚含量(21.39 g CAE·100 g^-1 DW)及抗氧化活性(40.28 g TE·100 g^-1 DW)最高。抗氧化活性与营养成分之间的相关性分析结果表明,甘薯茎叶中主要的抗氧化活性物质为多酚类物质(R²=0.748)。本研究为甘薯茎叶的合理开发利用提供了一定的指导。     

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.