Antioxidants rice bran

Other natural antioxidants - rice bran oil, sesame oil, rosemary extract, flavonoids... 

Several other naturally occurring antioxidants have been identified in oils. Sesamol [533-31-3] (6) occurs as sesamoline [526-07-8], a glycoside, in sesame seed oil. FemUc acid [1135-24-6] (7) is found esterified to cycloartenol [469-38-5] in rice bran oil and to 3-sitosterol in com oil. Although it does not occur in oils, rosemary extract has also been found to contain powerful phenoHc antioxidants (12). 

SRB contains high-quality protein, oil, dietary fiber, polysaccharides, fat-soluble phytochemicals (plant derived bioactive compounds) and other bran nutrients. Rice bran and germ are the richest natural sources of B complex vitamins as well as E vitamins, polyphenols, several antioxidants and minerals. It is now available in the commercial food ingredient market as a safe and effective functional food and dietary supplement. 

Nutrient analysis of stabilized rice bran and its derivatives indicates that it is a good source of protein, dietary fiber and carbohydrates, in addition to several valuable phytonutrients, antioxidants, vitamins and minerals (Table 17.1). SRB and its water-soluble and water-insoluble derivatives contain all the nutrients at different levels. They are gluten and lactose free and do not give rise to any food allergy. 

The rice bran phytochemicals and antioxidants have a profound influence on the induction of antioxidant enzymes at the cellular level and control hpid peroxidation at the cellular level. 

Other papers in the Symposium deal with the antioxidant and hypolipidemic effects of IP6, its chelating effects in heavy metal toxicity, inhibition of renal stones and other beneficial effects such as inhibition of platelet aggregation, inhibition of inflammatory responses (Shamsuddin, 1998). The lipid lowering effect and anti-neoplastic effect of 1P6 were extensively reviewed (Jariwalla, 1999). Hence, 1P6 is a valuable component of rice bran in preventing disease and maintaining health. 1P6 is present at 1.8-2% in rice bran. 

Recent scientific investigations of natural polyphenols have demonstrated their powerful antioxidant property (Niki et al, 1995). Several classes of polyphenols have been chemically identified. Some of these are grape polyphenols, tea polyphenols, soy polyphenols, oligomeric proanthocyanidines (OPA) and other natural polyphenols of the flavone class. Rice bran polyphenols are different from the above in that they are p-hydroxy cinnamic acid derivatives such as p-coumaric acid, ferulic acid and p-sinapic acid. Tricin, a flavone derivative, has also been isolated from rice bran. 

The antioxidant property of ferulic acid and related compounds from rice bran was reported by Kikuzaki et al, (2002). Their results indicated that these compounds elicit their antioxidant function through radical scavenging activity and their affinity with lipid substrates. Another recent study reported by Butterfield et al, (2002) demonstrated that ferulic acid offers antioxidant protection against hydroxyl and peroxyl radical oxidation in synaptosomal and neuronal cell culture systems in vitro. The effect of ferulic acid on blood pressure (BP) was investigated in spontaneously hypertensive rats (SHR). After oral administration of ferulic acid the systolic blood pressure (SBP) decreased in a dose-dependent manner. There was a significant correlation between plasma ferulic acid and changes in the SBP of the tail artery, suggesting... 

Squalene is an isoprenoid compound that is found in large quantities in shark liver and in smaller quantities in olives, rice bran and wheat germ. It is a bactericidal compound and an antioxidant and it aids in skin nutrition. Several cosmetic applications of rice bran and rice bran oil arise from the biological effects of their squalene, vitamin E and y-oryzanol content. Since these compounds are fat-soluble, rice bran oil is used for all these preparations. 

The above scientific information on rice bran phytochemicals indicates that a multitude of mechanisms are operating at the cellular level to bring about specific health effects. Several health benefits of rice bran appear to be the result of the synergistic function of the many phytochemicals, antioxidants, vitamins and minerals which operates through a specific immune response. Their role in the biochemical mechanisms at the cellular level which result in major health effects is shown in Fig. 17.1. A short overview summarizing the effect of the various phytochemicals on major health issues such as cancer, immune function, cardiovascular disease, diabetes, altered liver function and gastrointestinal and colon disease will be given below. 

Table 17.5 Comparison of phytonutrients and antioxidants of rice bran with com bran, oat bran and wheat bran...

Natural products have been noted for their potential health benefits from time immemorial and are the basis of Ayurveda, an ancient Indian medical practice (Bushkin and Bushkin, 2002). However, the potential benefits of several natural products reside in one or two active ingredients. For example green tea stands for polyphenols, soy for soy estrogens, broccoli for isothiocyanates and grape seed for polyphenols. The beauty of rice bran is that there are more than 100 antioxidants, several categories of bioactive phytonutrients, such as IP6, polyphenols, phytosterols, tocotrienols, y-oryzanol, B vitamins, minerals and trace minerals in addition to fat, protein, fiber, polysaccharides and other nutrients. These phytonutrients and antioxidants of rice bran are believed to act at the cellular level, and their synergestic function is responsible for the positive health benefits. 

FUKUSHIJ (1996) Edible rice bran oil III antioxidant effects of gamma oryzanol. /fokfanWo-ritus Elsei Kenkyushoho, 16 111. 

XU z, HUA N, GODBER s (2001) Antioxidant activity of tocopherols, tocotrienols, and y-oryzanol components from rice bran against cholesterol oxidation accelerated by 2, 2 -azobis(2-methylpropionamidine) dihydrochloride. J Agri Food Chem, 49 2077-81. 

Yamasaki, S., Manh, L.H., Takada, R., Men, L.T., Dung, N.N.X., Khoa, D.V.A. and Taniguchi, T. (2003) Admixing synthetic antioxidants and sesame to rice bran for increasing pig performance in Mekong Delta, Vietnam. Japan International Research Center for Agricultural Science, Research Highlights 38-39. 

Jang, S. Xu. Z. 2009. Hydrophilie and lipophilic antioxidants in purple rice bran. J. Agric. Food Chem. 57 858-862. 

Zigoneanu, I.G. Williams, L. Xu, Z. Sabliov, C.M. 2008. Determination of antioxidant components in rice bran oil extracted by microwave-assisted method. Biores. Tech. 99 4910-4918. 

Most of the studies on the antioxidant activity of SF have been performed using y-oryzanol or the addition of rice bran oil (containing also other components with antioxidant activity), and from those studies it is not possible to evaluate the activities of single compounds. Further, the information obtained on the relative antioxidant activities of the different FSs varies from one study to another (Table 10.2). One reason for this may be that the range of antioxidant tests used in these studies is wide and the results, therefore, are not necessarily comparable. More studies are definitely needed to fully understand the possible differences in the antioxidant activity of different SFs in different oxidation systems. 

Huang, C.J. Xu, Z. Godber, J.S. 2009. Potential antioxidant activity of gamma-oryzanol in rice bran as determined using an in vitro-mouse lymph axilliary endothelial model. Cereal Chem. 86 679-684. 

Limonene has recently been used in rice bran oil extraction as an alternative to hexane, which is commonly used in such processes.The yield and quality of crude rice bran oil obtained from the limonene extraction were almost equivalent to those obtained using hexane. Interestingly, although antioxidants were not present in the limonene, only a very small amount (<1 wt%) of oxidation product was found in the recovered limonene, and therefore the solvent is potentially recyclable in such a process. This also suggests that... 

Tocopherols and tocotrienols, collectively known as tocols, are monophenolic and lipophilic compounds that are widely distributed in plant tissues (7). The main commercial source of natural tocopherols is the soybean oil. Tocotrienols, less common than tocopherols, are present in palm oil, rice bran oil, as well as cereals and legumes (11). Tocopherols and tocotrienols are classified into a-, (3-, y-, and 5-, depending on their chemical structures (Figure 7). In general, tocotrienols have a stronger antioxidant effect on lipid oxidation than tocopherols. The antioxidant activity of tocopherols is dependent on temperature and is in the order of 5- > y->P-> oc-tocopherol (7). Tocopherols (mixed natural concentrate) are a golden... 

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