**2. Constituents and biological activity of brown rice before and after**  *Aspergillus oryzae***-mediated fermentation**

#### **2.1 Nutrients and non-nutrient components in brown rice**

Brown rice generally contains many kinds of nutrients, carbohydrates, lipids, proteins, and micronutrients such as minerals and vitamins, which are essential for our life [1]. As compared to white rice, it contains higher amount of lipids, potassium, phosphorus, ferrous, manganese, alpha-tocopherol, vitamin B1, vitamin B2, niacin, Vitamin B6, folic acid, pantothenic acid, and dietary fiber. Non-nutrient components such as plant polyphenols and phytic acid are also important components in brown rice, especially rich in a part of rice bran [1, 2]. These phytochemicals carry antioxidative activity [1–4], protect plants themselves from environmental oxidative stress, and are distributed in free, solubleconjugated, and bound forms in the endosperm and bran/embryo fractions of the whole rice grain [4]. Beneficial biological functions of brown rice or rice bran have been shown in cultured cells and animal disease models by using whole rice, extracts with various solvents, or identified biologically active components as described in Section 2.2.

#### **2.2 Biological activity of components in brown rice**

Brown rice and rice bran, and several known constituents in brown rice have been reported to show beneficial functions against diseased conditions such as tumor and life style-related diseases. Rice bran extract from pigmented rice, containing phenolic compounds and antioxidant activity, showed antiproliferative properties against the human and mammalian cancer cell lines [4–6]. Antigenotoxic activity of rice bran was shown in *Salmonella* mutation assay and sister chromatid exchange assay [6–8]. Antitumor effects through a modification of immunity were also reported [9, 10]. Henderson et al. [11] reviewed chemopreventive properties of dietary rice bran in *in vivo* and *in vitro* studies, and highlighted the effective components and their mechanism of action from *in vitro* studies with various cancer cell lines. They classified chemopreventive components with literature-supported activity to two items: 1) components in rice bran oil including fatty acids, tocopherol, flavonoids, γ-oryzanol, and other phenolic compounds; 2) components in defatted rice bran including polysaccharide, phytic acid, and dietary fiber. These components in rice bran contributed to chemopreventive effects on various stages

#### *Fermented Brown Rice as a Functional Food DOI: http://dx.doi.org/10.5772/intechopen.98840*

of carcinogenesis through anti-oxidative action, anti-proliferative/pro-apoptotic action, mucosal protection, and immune modulation [11].

Obesity and obesity-related diseases is another worldwide problematic issue of human health. As well as chemopreventive effects on multistage carcinogenesis, brown rice could show multifactorial functions against these diseased state. Certain food components such as phenolic compounds and antioxidants have been reported to have anti-diabetic effects in cultured cells and in model mice [12–14]. Such polyphenols have often worked to improve viability of β cells or decreased the apoptosis through modification of gene expression in the pancreas [13–15]. Pre-germinated brown rice prevented high fat diet induced hyperlipidemia [16] and showed hypocholesterolemic action [17]. A rice bran oil diet was reported to improve lipid abnormalities and hyperinsulinemic responses in type 2 diabetes model animal [18]. Acylated steryl β-glucosides in pre-germinated brown rice diet reduced oxidative stress in streptozotocin-induced diabetes [19]. Among bran-specific phenolic compounds, γ-oryzanol has been well demonstrated to be protective against diabetes and obesity [20–22]. It protected pancreatic islet β cells by directly ameliorating ER stress-induced β cells dysfunction [20, 21], and also functioned as an epigenetic controller in the brain reward system [20, 22]. Moreover, it enhances adipocyte differentiation and glucose uptake in insulin-resistant cells through cell signaling pathway [23]. Stress-induced and animal fat ingestion-induced hypoadiponectinemia have been ameliorated by γ-oryzanol and γ-aminobutyric acid [24, 25]. Sakai et al. [26] reported the importance of Glutathione peroxidase 4 (GPx4) against oxidative stress in the pathologies of vascular diseases such as athelosclerosis and diabetes, and suggested that vitamin E rich food such as brown rice, can compensate for GPx4 loss by protecting cells against lipid peroxidation.
