Y-Oryzanols

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. 

Tocotrienols present in rice bran inhibit the liver microsomal enzyme HMGCoA reductase (Qureshi and Qureshi, 1992), the key enzyme involved in the endogenous synthesis of cholesterol, and this helps to lower the circulating cholesterol. Inhibition of another enzyme, ACAT (Acyl coenzyme A acyl transferase), by y-oryzanol results in lowered LDL-C synthesis and enrichment... 

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. 

NAKAZAWA s, iMAi K, YAMAMOTO Y (1977) Clinical studies on y-oryzanol in the treatment of autonomic instability with abdominal symptoms. Japanese J. Psychosom Med, 17(4) 101-108. 

Carcinogenecity study of y-oryzanol in F 344 rats. Foot/ Chemical Toxicology, 30(1) 41-8. 

DNA damaging mutagenic, elastogenic and cell-cell communication inhibitory properties of y-oryzanoL . 1 Toxicol Sci. 16 191-202. 

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. 

Cycloartenol ferulate 67 Rice bran. y-Oryzanol 0.2 Skin 1 [48]... 

Bergman, C.J. Xu, Z. 2003. Genotype and environment effects on tocopherol, tocotrienol, and y-oryzanol contents of southern U.S. rice. Cereal Chem. 80 446-449. 

Figure 10.3 Structural formulas of selected steryl ferulates identified in y-oryzanol.

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. 

DHCF = dihydrocholesteryl ferulate ORY = y-oryzanol, SSta= sitostanyl ferulate, SSte = sitosteryl femlate... 

RP-HPLC The most commonly used methods for the analysis of SFs are reverse-phase liquid chromatography with UV-detection, which allow the separation of SFs with different sterol moieties. The number of components separated is naturally dependent on the type of column used, but most reverse-phase columns provide a full separation of at least five to six components of y-oryzanol. Cl 8-columns are most abundantly applied for the separation of SFs, but other reverse-phase... 

Aguilar-Garcia, C. Gavino, G. Baragano-Mosqueda, M. Hevia, P. Gavino, V.C. 2007. Correlation of tocopherol, tocotrienol, y-oryzanol and total polyphenol content in rice hran with different antioxidant capacity assays. Food Chem. 102 1228-1232. Awad, A.B. Fink, C.S. 2000. Phytosterols as anticancer dietary components evidence and mechanism of action. J. Nutr. 130 2127-2130. 

Diack, M. Saska M. 1994. Separation of vitamin E and y-oryzanols from rice bran by normal-phase chromatography. J. Am. Oil Chem. Soc. 71 1211-1217. 

Kumar, R.R. Tiku, P.K. Prakash, V. 2009. Preferential extractability of y-oryzanol from dried soapstock using different solvents. J. Sci. Food Agric. 89 195-200. 

Lerma-Garcia, M.J. Hemero-Martinez, J.M. Simo-Alfonso, E.F. Mendonca, C.R.B. Ramis-Ramos, G. 2009. Composition, industrial processing and applications of rice bran y-oryzanol. Food Chem. 115 389 04. 

Lilitchan, S. Tangprawat, C. Aryusuk, K. Krisnangkura, S. Chokmoh, S. Krisnangkura, K. 2008. Partial extraction method for the rapid analysis of total lipid and y-oryzanol contents in rice hran. Food Chem. 106 752-759. 

Miller, A. Engel, K.H. 2006. Content of y-oryzanol and composition of steryl ferulates in brown rice (Oryza sativa L.) of European origin. J. Agric. Food Chem. 54 8127-8133. 

Nagasaka, R. Shinoda, A. Ushio, H. Ohshima, T. 2008. y-Oryzanol in laminarian seaweeds (Abstract in English). Nippon Suisan Gakkaishi 74 61-65. 

Stdggl, W. Huck, C. Wongyai, S. Scherz, H. Bonn, G. 2005. Simultaneous determination of carotenoids, tocopherols and, y-oryzanol in crude rice bran oil by liquid ehromatography eoupled to a diode array and mass spectrometric detection employing silica C30 stationary phases. J. Sep. Sci. 28 1712-1718. 

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