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Introduction
Rice (Oryza sativa L.) is a staple diet of Asia. Rice has potential health benefits. In India rice gruel is used in disorganized digestion, in bowel complaints in diarrhoea and dysentery. Rice water is demulcent, nourishing drink in febrile diseases and inflammatory states of intestine ([7] Chopra et al. , 1956). Epidemiological studies have shown that consumption of whole grains and grain-based products is associated with reduced risk of chronic diseases because of their unique phyto-chemical composition ([1] Adom and Liu, 2002). Apart from starch, rice grains contain several classes of compounds. Phenols, e.g. protochatechuic acid, p-coumaric acid (PCA), caffeic acid, ferulic acid, sinapic acid, vanillic acid, methoxy cinnamic acid, chlorogenic (3-caffeoylquinic) acid, hydroxybenzoic acid, syringic acid and tricin were identified in the extract of bran and intact brown rice ([11] Hudson et al. , 2000; [32] Tian et al. , 2005). Two hydroxycinnamate sucrose esters, 6'-O -(E )-feruloylsucrose and 6'-O -(E )-sinapoylsucrose, were isolated from the methanol extracts of rice bran. 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 ([31] Tian et al. , 2004). Vitamin E (α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, desmethyl tocotrienol, didesmethyl tocotrienol) and γ-oryzanol components (cycloartenyl ferulate, 24-methylene cycloartenyl ferulate and campesteryl ferulate) were purified from rice bran ([35] Xu et al. , 2001). [12] Ichikawa et al. (2001) reported that purple black rice extract contained almost exclusively a single anthocyanin, which was identified as cyanidin 3-O-beta-D-glucoside. Black rice is also reported to contain peonidin 3-glucoside in addition to cyanidin 3-glucoside ([10] Hu et al. , 2003).
In Asia, where rice is the staple diet, the incidence of colon and breast cancer is below that in the Western world. Rice contains phenols that interfere with the proliferation or colony forming ability of breast or colon cells ([11] Hudson et al. , 2000). Tocotrienol rich fraction of rice bran is effective in lowering serum total and LDL-cholesterol levels. Tocotrienols have superior efficacy compared with α-tocopherol ([22] Qureshi et al. , 2000). Red and black rices decrease atherosclerotic plaque formation and increase antioxidant status...