**5. Role of bioactive components**

#### **5.1. Hypertensive aspects**

fractions are centrifuged to separate the insoluble fiber fraction—called rice bran fiber—from the aqueous dispersible fraction—called rice bran soluble. The mixture of both insoluble and soluble extracts is called rice bran balance. Using different technologies, the bran is fully stabilized and the oil is removed. The resultant food‐grade, defatted rice bran is temporarily stored in food grade silos until it can be used in edible applications. Bleaching of the edible oil typically leaves minor flavor and odor compounds that must be removed by steam distillation before the oil is used. Steam distillation is the final step in the processing of edible oil, whereby

We produced two types of rice bran fraction: Driselase® fraction (DF) and ethanol fraction (EF). To process the rice bran, 500 g bran was agitated in 1.0 L of 70% ethanol for 2 h; this yielded two fractions: the solid and filtered fractions. The DF was derived from the solid fraction. Driselase® is a commercial plant cell wall‐degrading enzyme mixture containing cellulase, xylanase and laminarinase; however, it is esterase free. The solid fraction of rice bran was dried at room temperature and then suspended in 10 mM acetate buffer (500 mL) containing Driselase (0.2 mg/L) from *Basidiomycetes* spp. The bran was treated in this manner overnight at 37°C; the suspension was then filtered and finally lyophilized. As a result, Driselase‐treated rice bran had increased quantities of bioactive components that improve glucose and lipid

metabolism in the SHRSPs—a genetic animal model of metabolic syndrome [33, 34].

**4. Extraction, isolation and identification of the active components in rice**

Different conventional methods are used to extract the bioactive compounds from plant materials. Of these, solvent, supercritical fluid, microwave‐assisted and ultrasonic‐assisted extraction are notable. Microwave‐assisted extraction and ultrasound‐assisted methods are used to detect antioxidant and anticancer bioactive components in the plant extracts [35, 36]. Imsanguan et al. described conventional solvent extraction, with different modifications at different temperatures (32–60°C), using 100 ml hexane at a rotating speed of 200 rpm for 24 h to extract γ‐oryzanol from rice bran [37]. However, this conventional technique does not fully remove toxic solvent residues from the final product; for this reason, Herrero et al. used the prominent technique of supercritical fluid extraction, which offers better extraction and purification of bioactive compounds [38]. Zigoneanu et al. described antioxidant extraction from rice bran oil using microwave‐assisted extraction, which uses electromagnetic radiation

We developed the DF method to identify active components in the rice bran. As already described, the DF was derived from the solid fraction and chromatographed onto a silica gel column. One fraction derived from the methanol eluate was further fractionated using an octadecylsilane (ODS) column. The active fraction was obtained from the methanol/water (20– 70%) eluate and separated by high‐performance liquid chromatography (HPLC) using an ODS column. The BP‐lowering activity of each fraction was examined using a single oral adminis‐ tration to male, 14‐week old SHRSPs; we found that gavage of a certain fraction at 40 mg/kg

any off‐flavor and residual free fatty acids left in the oil are removed.

294 Superfood and Functional Food - An Overview of Their Processing and Utilization

**bran**

in the range of 0.3–300 GHz [39].

The following factors increase the risk of diet‐related disorders such as obesity, cancer and cardiovascular disease (CVD): consumption of fewer plant‐based foods, changing dietary patterns, increased consumption of Westernized food and socioeconomic conditions. High BP, one manifestation of CVD, continues to be a major cause of morbidity and death and one public health strategy is dietary management of high BP. Studies have shown that a 5‐mm Hg decrease in BP is related to a 16% decrease in CVD [45]. The risk factors for CVD are higher plasma cholesterol levels, lower high‐density lipoprotein (HDL) levels and higher low‐density lipoprotein (LDL) levels. Several bioactive compounds from rice bran that have been identified and used may reduce the risk of CVD. For instance, angiotensin‐converting enzyme (ACE) inhibitors reduce BP via the renin‐angiotensin system and FA has plasma ACE‐inhibitory activity. In this regard, Ardiansyah et al. showed that food supplementation using FA reduces high BP by inhibiting plasma ACE activity [5]. Later, the novel compound adenosine, isolated from the DF fraction, was also found to have BP‐lowering activity. Specifically, single‐dose or long‐term orally administered adenosine may reduce BP in the spontaneous hypertension of the SHRSP model [4]. Administered adenosine increases plasma nitric oxide levels, which in turn increase vasodilation. Adenosine also causes potent vasodilation by activating adenosine receptors (A2) on vascular smooth muscle; moreover, it stimulates K+ATP channels, resulting in the hyperpolarization of smooth muscle [4].

The risk of CVD is elevated in conditions of oxidative stress. Urinary 8‐hydroxydeoxyguano‐ sine (8‐OHdG) serves as a sensitive biomarker of oxidative stress resulting in genetic damage. FA significantly reduces urinary 8‐OHdG levels; thus, it can reduce CVD risk factors [4, 5].

Diets containing cholesterol‐lowering phytochemicals and antioxidants can prevent the progression of atherosclerotic lesions. Experiments have demonstrated that γ‐oryzanol possesses potent anti‐atherogenic and antioxidant activity. Furthermore, in a rat model of two‐ kidney, one‐clip renovascular hypertension, Boonla et al. described the vasorelaxant and antihypertensive effects of peptides derived from rice bran protein hydrolysates [46]. **Table 1** describes the anti‐hypertensive roles of various bioactive components of rice bran.

#### **5.2. Metabolic disorder aspects**

Metabolic disorders consist of metabolism‐related diseases, including hyperglycemia, hypercholesterolemia, hypertriglyceridemia and insulin resistance; they accompany type 2 diabetes mellitus, obesity and CVD. Rice bran and its various active components, prevents or ameliorates metabolic disorders. Specifically, a rice bran enzymatic extract‐supplemented diet can prevent the adipose and macrophage changes associated with diet‐induced obesity in mice [54]. In addition, the antihyperlipidemic effects (lower cholesterol and triglyceride levels) of α‐tocopherol have been investigated in F344 rats fed a Western diet [55]. Pigmented rice, which contains anthocyanins and proanthocyanidins concentrated in the bran layer, stimulates glucose uptake by 3T3‐L1 adipocytes—a key function in glucose homeostasis. Specifically, basal glucose uptake is increased two to three fold, while mRNA levels of both GLUT1 and GLUT4 are upregulated [56]. γ‐Oryzanol and FA ester with phytosterols—both of which are abundant in rice bran—prevent high‐fat and high‐fructose diet (HFFD)‐induced metabolic syndrome [57]. In addition, only γ‐oryzanol treatment is more effective than FA in significantly decreasing the liver index and hepatic triglyceride content. Decreased serum C‐reactive protein and IL‐6 levels and increased serum adiponectin concentration confirmed that FA and γ‐ oryzanol can be used as dietary supplements to alleviate the deleterious effects of HFFD [57]. Adenosine, in particular, effectively mitigates metabolic syndrome in SHRSP [50]. Specifically, single‐dose and long‐term oral administration of adenosine improves hyperlipidemia and hyperinsulinemia; it also regulates body weight gain and food intake. Studies have shown that enhanced plasma adiponectin levels alleviate hyperinsulinemia and that dietary adenosine can elevate plasma adiponectin and increase insulin sensitivity. Adenosine administration for 3 weeks downregulates mRNA levels of glucose‐6‐phosphatase, a gene encoding the rate‐ controlling enzyme of hepatic gluconeogenesis. Adenosine also plays an important role in regulating hepatic mRNA expression of genes involved in β‐oxidation, fatty acid synthesis and AMP‐activated protein kinase [4, 50]. In conclusion, various active components of rice bran ameliorate metabolic‐related diseases.


ACE, angiotensin‐converting enzyme; ApoB, apolipoprotein B; BW, body weight; FFA, non‐esterified fatty acid; HDL‐C, high density lipoprotein cholesterol; LDL‐C, low density lipoprotein cholesterol; PL, phospholipid; TC, total cholesterol; TG, triglycerides; VLDL‐C, very low density lipoprotein cholesterol; eNOS, endothelial nitric oxide synthase.

**Table 1.** Summary of bioactive components and their prospective effects on blood pressure and metabolic parameters in different species.

#### **5.3. Anti‐cancer aspects**

patterns, increased consumption of Westernized food and socioeconomic conditions. High BP, one manifestation of CVD, continues to be a major cause of morbidity and death and one public health strategy is dietary management of high BP. Studies have shown that a 5‐mm Hg decrease in BP is related to a 16% decrease in CVD [45]. The risk factors for CVD are higher plasma cholesterol levels, lower high‐density lipoprotein (HDL) levels and higher low‐density lipoprotein (LDL) levels. Several bioactive compounds from rice bran that have been identified and used may reduce the risk of CVD. For instance, angiotensin‐converting enzyme (ACE) inhibitors reduce BP via the renin‐angiotensin system and FA has plasma ACE‐inhibitory activity. In this regard, Ardiansyah et al. showed that food supplementation using FA reduces high BP by inhibiting plasma ACE activity [5]. Later, the novel compound adenosine, isolated from the DF fraction, was also found to have BP‐lowering activity. Specifically, single‐dose or long‐term orally administered adenosine may reduce BP in the spontaneous hypertension of the SHRSP model [4]. Administered adenosine increases plasma nitric oxide levels, which in turn increase vasodilation. Adenosine also causes potent vasodilation by activating adenosine receptors (A2) on vascular smooth muscle; moreover, it stimulates K+ATP channels, resulting

The risk of CVD is elevated in conditions of oxidative stress. Urinary 8‐hydroxydeoxyguano‐ sine (8‐OHdG) serves as a sensitive biomarker of oxidative stress resulting in genetic damage. FA significantly reduces urinary 8‐OHdG levels; thus, it can reduce CVD risk factors [4, 5].

Diets containing cholesterol‐lowering phytochemicals and antioxidants can prevent the progression of atherosclerotic lesions. Experiments have demonstrated that γ‐oryzanol possesses potent anti‐atherogenic and antioxidant activity. Furthermore, in a rat model of two‐ kidney, one‐clip renovascular hypertension, Boonla et al. described the vasorelaxant and antihypertensive effects of peptides derived from rice bran protein hydrolysates [46]. **Table 1**

Metabolic disorders consist of metabolism‐related diseases, including hyperglycemia, hypercholesterolemia, hypertriglyceridemia and insulin resistance; they accompany type 2 diabetes mellitus, obesity and CVD. Rice bran and its various active components, prevents or ameliorates metabolic disorders. Specifically, a rice bran enzymatic extract‐supplemented diet can prevent the adipose and macrophage changes associated with diet‐induced obesity in mice [54]. In addition, the antihyperlipidemic effects (lower cholesterol and triglyceride levels) of α‐tocopherol have been investigated in F344 rats fed a Western diet [55]. Pigmented rice, which contains anthocyanins and proanthocyanidins concentrated in the bran layer, stimulates glucose uptake by 3T3‐L1 adipocytes—a key function in glucose homeostasis. Specifically, basal glucose uptake is increased two to three fold, while mRNA levels of both GLUT1 and GLUT4 are upregulated [56]. γ‐Oryzanol and FA ester with phytosterols—both of which are abundant in rice bran—prevent high‐fat and high‐fructose diet (HFFD)‐induced metabolic syndrome [57]. In addition, only γ‐oryzanol treatment is more effective than FA in significantly decreasing the liver index and hepatic triglyceride content. Decreased serum C‐reactive protein and IL‐6 levels and increased serum adiponectin concentration confirmed that FA and γ‐

describes the anti‐hypertensive roles of various bioactive components of rice bran.

in the hyperpolarization of smooth muscle [4].

296 Superfood and Functional Food - An Overview of Their Processing and Utilization

**5.2. Metabolic disorder aspects**

Dietary factors have a significant effect on the risk of cancer. Only 5–10% of all cancer is heredity; all other incidents are directly or indirectly correlated with lifestyle and dietary habits. If dietary supplements are used appropriately, they may reduce the incidence of cancers in humans by as much as 30% [58, 59]. Phytic acid extracted from rice bran has anticancer activity against hepatocellular carcinoma (HepG2) cells, wherein apoptotic activity was evaluated by expression analysis of apoptosis‐regulatory genes (i.e., p53, Bcl‐2, Bax, Caspase‐ 3 and ‐9) [60]. Similarly, δ‐tocotrienol (δ‐T3) is reportedly useful as an anticancer agent against human colorectal adenocarcinoma (DLD‐1) cells under both normoxic and hypoxic conditions. *In vivo*, oral administration of rice bran tocotrienol (mainly γ‐T3; 10 mg/mouse/day) signifi‐ cantly inhibited tumor growth in nude mice [61]. Tumor cells produce reactive oxygen species, which damage cellular integrity. Cycloartenyl ferulate, a major component of γ‐oryzanol, successfully inhibits proliferation in the colorectal adenocarcinoma SW480 cell line because of its antioxidant activity [62].

#### **5.4. General health‐promoting aspects**

Rice bran itself has health benefits, while rice bran oil and isolated active components have immune stimulatory effects. Rice bran that is rich in phytosterols, γ‐oryzanol and compounds with antioxidant properties may modulate the immune system. In addition, rice bran has several generalized health‐promoting characteristics. For example, rice bran supplementation enhances gut health by encouraging the growth and colonization of *Lactobacillus rhamnosus* and it provides effective protection against human rotavirus diarrhea in pigs by modulating gut permeability [63].

Long‐term supplementation has a positive impact on survival, cognition and brain mitochon‐ drial function, which may delay Alzheimer's disease [64]. Rice bran supplements can also be used as ergogenic supplements by body builders and athletes [65] and they may mitigate menopausal symptoms such as hot flashes, as well as bone loss in older women who suffer from osteoporosis [66]. Rice bran can be regarded as a source of plant‐derived active com‐ pounds and as an alternative to expensive vitamin sources from animals. For instance, different colored rice bran has micronutrients, including a rich reserve of β‐carotene, which can be converted to vitamin A [67]. **Table 2** describes the role of various bioactive components of rice bran for general health.


**Table 2.** Summary of bioactive components and their prospective effect on generalized health aspects.
