**5. Health benefit potentials of pigmented rice**

Phenolic compounds have many biological activities, for instance, antioxidant [40, 41] and anti-inflammatory properties [42]. Several epidemiological studies suggested that high dietary consumption of polyphenols is associated with decreased risk of a range of diseases including antidiabetic [43, 44], cardiovascular disease (CVD) [45], and neurodegenerative diseases [46].

#### **5.1 Antioxidant activity**

Phenolic acids and flavonoids function as reducing agents, free radical scavengers, and quenchers of singlet oxygen formation. The antioxidant property of the phenolic ring depends on the number and location of the hydroxy groups [47]. Pigmented rice varieties showed high antioxidant capacity along with the highest flavonoid and polyphenol content [42]. Flavonoids and phenolic acids components play important roles in the control of oxidative stress, which is considered to be substantial in an initiation and development of many current conditions and diseases including inflammation, hyperglycemia, hypertension, heart diseases, neurodegenerative diseases, cancer and in the aging process. However, antioxidants are substances that significantly delay or prevent the oxidation of an oxidisable substrate when present in low concentrations compared to the substrate.

#### **5.2 Antidiabetic activity**

Hyperglycaemia, or high blood sugar, is one of the most common disorders. Antidiabetic activity of phenolic acids and flavonoids has been reported by several studies. It has been reported that these anthocyanins have various beneficial effects, including inhibitory effects against carbohydrate hydrolysing enzymes, including in α-amylase and α-glucosidase. Our study on α-amylose inhibitory action of cyanidin-3-glucoside, ranged from 0.1 mg/100 g DM in the red rice sample to 138.8 mg/100 g DM in the black rice sample, showed that the IC50 value for potential inhibition against α-amylase activity of crude extract of colored rice samples ranged from 2.5 μg/mL to 14.4 μg/mL. The potential inhibition against α-amylase activity in black rice samples were higher than those in red and purple rice samples, respectively [13]. In addition, the percentage inhibition on α-glucosidase and α-amylase of fragrant black rice fractions had higher potential than acarbose, a synthetic antidiabetic drug [48]. However, variation in the structure of anthocyanins makes it difficult to determine their effects on Type II diabetes. Understanding the absorption and metabolism of anthocyanins is important for understanding their role in the improvement of this disease. Previous literature suggested that anthocyanins may lower blood glucose by improving insulin resistance, protecting β cells, increasing secretion of insulin and reducing digestion of sugars in the small intestine. The mechanisms of action are primarily related to their antioxidant properties, but enzymatic inhibition and other pathways may also be relevant [49].

#### **5.3 Anti-inflammatory potential**

Overproduction of free radicals and/or oxidants can cause oxidative stress and oxidative damage to biological macromolecules including lipid, protein and nucleic

**77**

*Phenolic Compounds and Potential Health Benefits of Pigmented Rice*

**5.4 Cardiovascular disease risk inhibition potential**

**5.5 Anti-neurodegenerative potential**

induced oxidative damage in SH-SY5Y cells [46].

acids, which are associated with chronic diseases such as cancer, cardiovascular disease and neurological disease [42]. In addition, free radicals including superoxide anion, (NO) and peroxynitrite play important roles in the inflammatory process. According to the study carried out by Chalermpong et al. (2012) on the anti-inflammatory activities of bioactive rich extracts from Thai glutinous purple rice bran [50], the extracts of five purple rice bran sample showed a strong antiinflammatory activity through inhibitory effect on nitric/oxide (NO) production in combined LPS-IFN-γ-activated RAW 264.7 murine macrophage cells. Moreover, the results also indicated that γ-oryzanol rich extracts from Thai glutinous purple rice bran were acting as a lipophilic radical scavenger better than a hydrophilic radical scavenger. Moreover, these extracts exert a potent anti-inflammatory activity.

Cardiovascular disease (CVD) is a chronic disease related to a range of genetic and environmental factors including smoking, high saturated fat diets and physical inactivity. Moreover, coronary heart disease and stroke are a major cause of mortality in developed countries Dyslipidemia is an abnormal high level of dietary lipids such as plasma cholesterol, triglycerides, or a low level of highdensity lipoproteins (HDL). In addition, dyslipidemia often increases the risk factor for atherosclerosis, which further increases the risk for developing coronary heart diseases that are the leading cause of death among the aged population [51]. Several studies indicated a correlation between the intake of flavonols, flavones and flavanols and a reduced risk of coronary artery disease and anthocyanin and flavanone intake and reduced CVD related mortality. Lo et al., (2016*)* demonstrated the effects of the newly bred Korean non-germinated and germinated pigmented rice cultivars on ovariectomized (OVX) rats in comparison with the nonpigmented normal brown rice [45]. All rat groups were fed with 20% rice per total diet and showed that the supplementation of germinated rice for some groups, particularly pigmented rice cultivars, resulted in better a lipid profile compared to the groups that consumed non-germinated rice cultivars. In addition, germination increased the quantities of the bioactive compounds that are responsible for the hypolipidemic activities of these rice grains. Showed a low total cholesterol levels, high levels of high-density lipoproteins-cholesterol, high fecal lipid output, low hepatic lipid values, and low hepatic adipocyte accumulation. There were also an increase in the rate of lipolysis and decrease in lipogenesis based on the lipid-regulating enzyme activity profiles obtained for the groups that fed on germinated rice. Also, results revealed that pigmented rice cultivars had superior effects in improving the lipid metabolism relative to the non-pigmented normal brown rice variety. The application of germinated rice, blackish-purple cultivars enhanced potential for the prevention and occurrence of dyslipidemias.

Neurodegenerative disorders including Parkinson's and Alzheimer's diseases have been increasing in our aging societies. Flavonoids may act to protect the brain in a number of ways, including by protection of vulnerable neurons, the enhancement of existing neuronal function or by stimulating neuronal regeneration. Vargas et al. (2018) reported the of studies using neuron-like cells, such as the SH-SY5Y cell line, allowed the evaluation of the antioxidant activity of compounds in human cells with biochemical characteristics similar to neurons, indicated the extract of bioactive compounds in red and black rice brans extracts was able to prevent H2O2-

*DOI: http://dx.doi.org/10.5772/intechopen.93876*

*Phenolic Compounds and Potential Health Benefits of Pigmented Rice DOI: http://dx.doi.org/10.5772/intechopen.93876*

*Recent Advances in Rice Research*

**5.1 Antioxidant activity**

**5.2 Antidiabetic activity**

**5.3 Anti-inflammatory potential**

polymers (DP > 10) accounted for 29% [12]. Moreover, total proanthocyanidins of the traditional Sri Lankan red-grained rice varieties ranged from 11.95 to 24.70 mg/g

Phenolic compounds have many biological activities, for instance, antioxidant [40, 41] and anti-inflammatory properties [42]. Several epidemiological studies suggested that high dietary consumption of polyphenols is associated with decreased risk of a range of diseases including antidiabetic [43, 44], cardiovascular disease

Phenolic acids and flavonoids function as reducing agents, free radical scavengers, and quenchers of singlet oxygen formation. The antioxidant property of the phenolic ring depends on the number and location of the hydroxy groups [47]. Pigmented rice varieties showed high antioxidant capacity along with the highest flavonoid and polyphenol content [42]. Flavonoids and phenolic acids components play important roles in the control of oxidative stress, which is considered to be substantial in an initiation and development of many current conditions and diseases including inflammation, hyperglycemia, hypertension, heart diseases, neurodegenerative diseases, cancer and in the aging process. However, antioxidants are substances that significantly delay or prevent the oxidation of an oxidisable substrate when present in low concentrations compared to the substrate.

Hyperglycaemia, or high blood sugar, is one of the most common disorders. Antidiabetic activity of phenolic acids and flavonoids has been reported by several studies. It has been reported that these anthocyanins have various beneficial effects, including inhibitory effects against carbohydrate hydrolysing enzymes, including in α-amylase and α-glucosidase. Our study on α-amylose inhibitory action of cyanidin-3-glucoside, ranged from 0.1 mg/100 g DM in the red rice sample to 138.8 mg/100 g DM in the black rice sample, showed that the IC50 value for potential inhibition against α-amylase activity of crude extract of colored rice samples ranged from 2.5 μg/mL to 14.4 μg/mL. The potential inhibition against α-amylase activity in black rice samples were higher than those in red and purple rice samples, respectively [13]. In addition, the percentage inhibition on α-glucosidase and α-amylase of fragrant black rice fractions had higher potential than acarbose, a synthetic antidiabetic drug [48]. However, variation in the structure of anthocyanins makes it difficult to determine their effects on Type II diabetes. Understanding the absorption and metabolism of anthocyanins is important for understanding their role in the improvement of this disease. Previous literature suggested that anthocyanins may lower blood glucose by improving insulin resistance, protecting β cells, increasing secretion of insulin and reducing digestion of sugars in the small intestine. The mechanisms of action are primarily related to their antioxidant properties, but enzymatic inhibition and other pathways may also be relevant [49].

Overproduction of free radicals and/or oxidants can cause oxidative stress and oxidative damage to biological macromolecules including lipid, protein and nucleic

in bran samples and from 1.07 to 2.27 mg/g in brown rice samples [39].

**5. Health benefit potentials of pigmented rice**

(CVD) [45], and neurodegenerative diseases [46].

**76**

acids, which are associated with chronic diseases such as cancer, cardiovascular disease and neurological disease [42]. In addition, free radicals including superoxide anion, (NO) and peroxynitrite play important roles in the inflammatory process. According to the study carried out by Chalermpong et al. (2012) on the anti-inflammatory activities of bioactive rich extracts from Thai glutinous purple rice bran [50], the extracts of five purple rice bran sample showed a strong antiinflammatory activity through inhibitory effect on nitric/oxide (NO) production in combined LPS-IFN-γ-activated RAW 264.7 murine macrophage cells. Moreover, the results also indicated that γ-oryzanol rich extracts from Thai glutinous purple rice bran were acting as a lipophilic radical scavenger better than a hydrophilic radical scavenger. Moreover, these extracts exert a potent anti-inflammatory activity.

#### **5.4 Cardiovascular disease risk inhibition potential**

Cardiovascular disease (CVD) is a chronic disease related to a range of genetic and environmental factors including smoking, high saturated fat diets and physical inactivity. Moreover, coronary heart disease and stroke are a major cause of mortality in developed countries Dyslipidemia is an abnormal high level of dietary lipids such as plasma cholesterol, triglycerides, or a low level of highdensity lipoproteins (HDL). In addition, dyslipidemia often increases the risk factor for atherosclerosis, which further increases the risk for developing coronary heart diseases that are the leading cause of death among the aged population [51]. Several studies indicated a correlation between the intake of flavonols, flavones and flavanols and a reduced risk of coronary artery disease and anthocyanin and flavanone intake and reduced CVD related mortality. Lo et al., (2016*)* demonstrated the effects of the newly bred Korean non-germinated and germinated pigmented rice cultivars on ovariectomized (OVX) rats in comparison with the nonpigmented normal brown rice [45]. All rat groups were fed with 20% rice per total diet and showed that the supplementation of germinated rice for some groups, particularly pigmented rice cultivars, resulted in better a lipid profile compared to the groups that consumed non-germinated rice cultivars. In addition, germination increased the quantities of the bioactive compounds that are responsible for the hypolipidemic activities of these rice grains. Showed a low total cholesterol levels, high levels of high-density lipoproteins-cholesterol, high fecal lipid output, low hepatic lipid values, and low hepatic adipocyte accumulation. There were also an increase in the rate of lipolysis and decrease in lipogenesis based on the lipid-regulating enzyme activity profiles obtained for the groups that fed on germinated rice. Also, results revealed that pigmented rice cultivars had superior effects in improving the lipid metabolism relative to the non-pigmented normal brown rice variety. The application of germinated rice, blackish-purple cultivars enhanced potential for the prevention and occurrence of dyslipidemias.

#### **5.5 Anti-neurodegenerative potential**

Neurodegenerative disorders including Parkinson's and Alzheimer's diseases have been increasing in our aging societies. Flavonoids may act to protect the brain in a number of ways, including by protection of vulnerable neurons, the enhancement of existing neuronal function or by stimulating neuronal regeneration. Vargas et al. (2018) reported the of studies using neuron-like cells, such as the SH-SY5Y cell line, allowed the evaluation of the antioxidant activity of compounds in human cells with biochemical characteristics similar to neurons, indicated the extract of bioactive compounds in red and black rice brans extracts was able to prevent H2O2 induced oxidative damage in SH-SY5Y cells [46].
