**1. Introduction**

Although white rice is consumed as a major staple food worldwide, quite a few countries in Southeast Asia (SEA) also consume pigmented cultivars such as red, black, purple, and brown rice. Rice cultivars that originated in Southeast Asia (SEA) have been classified in the species of *Oryza sativa* L., which differs from the *Oryza glaberrima* Steud. species that is cultivated in West Africa. In Thailand, the total area of cultivation has been recorded at 56.3 million Rai (22.3 million acres) with the majority being comprised of white rice cultivars (90%), while pigmented rice is only 0.1% or makes up approximately 62,000 Rai (24,506 acres) [1]. The largest cultivated area is located in the northeast of Thailand (63.10%) followed by the northern region of Thailand (21.93%), the central area (14.5%), and the south (0.47%). India and Indonesia have more cultivated area of pigmented rice than any other SEA countries, although they report a smaller proportion than that of the white rice cultivar. The total cultivated area in India has been recorded at

43.77 million acers (29.4% of the global rice area) with a production of 90 million tons [2]. The world production of rice is estimated at around 680 million tons, which is equivalent to that of wheat [3]. The color intensities of pigmented rice are obtained from the value of lightness, redness, and yellowness and seem to be correlated to the indicators of its bioactive compounds [4–6].

Recently, pigmented rice varieties have received increased amounts of attention from consumers for their high bioactive compounds that present potential nutraceutical benefits to health. It is also well known that these compounds are primarily located in the outer layer of the rice grain, which is regarded as a rice by-product. The by-products of rice processing are rice germ and bran, along with the rice hulls which protect the rice seeds during growth. These account for 20% of the rice crop. These by-products are frequently used as animal feed in developing countries. However, recently, significant amounts of data have revealed the beneficial nutritional impacts of these by-products on human health. The major bioactive compounds that are found in red, black, purple, and brown rice include gallic, protocatechuic, hydroxybenzoic, and vanillic acid, cyanidin 3-O-glucoside, peonidin-3-O-glucoside, proanthocyanidin, flavanol, catechin and epicatechin, carotenoids, and γ-oryzanol content. Several research findings have reported on the biological modulating effects of pigmented rice seeds and bran phytochemicals, including anti-inflammatory activities [7, 8], anticancer activities that have suppressed tumor growth in mice and several human cancer cell lines [9–13], the anti-metastasis properties of cancer cell invasion [14–16], antiaging effects with the reduction of oxidative stress in both in vitro and in vivo models [17, 18], the modulation of serum lipid profiles and the enhancement of mRNA expression levels of fatty acid metabolism-related genes [19], a reduction of platelet hyperactivity and hypertriglyceridemia in dyslipidemic rats [20], and skin antiaging treatments [21–24].

In this current review, we have focused on the health benefits of pigmented rice and the relevant bioactive compounds. We have tried to present the information in this chapter in a way that is easy to understand, even for readers who are not experts in this field of research. The bioactive compounds found in pigmented rice display significant immersion potential with regard to a range of beneficial health effects and also provide significant informative data that could lead to the expansion in the growing of pigmented cultivated areas in Thailand and other Southeast Asian countries. There is also the prospect of additional practical implications, not only for agriculture expansion but in the food industry as well. Several pigmented rice varieties have been used to create new nutraceuticals, and these seem to hold a promise in terms of potential cosmeceutical utilization in the new global business era.

#### **2. Pigmented rice and bioactive compounds**

The rice processing industry is well-developed and produces a number of products from rice kernels or grains (70%) along with a large quantity of rice byproducts. These by-products include rice bran (8–9%), rice germ (1–2%), and rice husks (20%). Figures on rice paddy composition are presented in **Figure 1**. These by-products are frequently used as animal feed in developing countries [25], but the demand for these by-products in terms of their human nutritional impacts has increased due to their potential health benefits. Rice kernels are primarily a good source for the energy intake of carbohydrates and proteins in humans. Rice bran makes up the outer layer of the rice kernel and is mainly comprised of a pericarp,

**5**

the extraction efficiency [35].

*Anthocyanins and Proanthocyanidins in Natural Pigmented Rice and Their Bioactivities*

aleurone, sub-aleurone layer, and germ. Rice bran and germ contain appreciable quantities of fiber, vitamins, minerals, unsaturated fatty acids, tocopherols, γ-oryzanol, and tocotrienols, which offer potent antioxidant content along with a

Several common extraction techniques that are used in the process of rice extraction include the method of solvent extraction, which is a conventional technique used to extract bioactive compounds from pigmented rice, supercritical fluid extraction, and subcritical water extraction. With regard to the conventional technique, a number of organic solvents are commonly used such as acetone, methanol, ethanol, butanol, and water in certain proportions as the extraction solvent [28–30]. In our study, 50% ethanol was used as an extraction solvent at a proportion of 1:5 grain or bran liquid, and extraction was carried out at room temperature for 3–12 h. The extracts were then concentrated with a rotary evaporator until all ethanol residues were removed and then further partitioned against saturated butanol to obtain the medium polar bioactive compounds of the black rice extract [31] or red rice extract [7, 15, 16]. The bioactive compounds present in these fractions shall be described in a later section. In another study, 60% ethanol containing 0.1% HCL was used as an extraction solvent with a 1:10 feed to liquid proportion, and extraction was carried out for 3–12 h. The extracts were then concentrated and further partitioned against petroleum ether [8]. In another study, the rice bran was extracted with 70% ethanol for 30 min repeated three times and was then further partitioned with ethyl acetate at pH 2–3 [32]. The same method was used to extract soluble phenolic compounds in

**2.1 Extraction methods for bioactive compounds in pigmented rice**

*DOI: http://dx.doi.org/10.5772/intechopen.86962*

range of other potential health benefits [26, 27].

**Figure 1.**

*Rice paddy composition.*

white rice, brown rice, and germinated brown rice [33].

Supercritical fluid extraction has been widely used for the extraction of functional active compounds from medicinal plants including rice and cereals. This was in common with the use of supercritical carbon dioxide as an extraction solvent in other successful experiments. Kim et al. [34] used the method of supercritical fluid extraction of rice bran oil from pigmented rice, which provided higher yields of polyunsaturated fatty acids than the conventional use of organic solvent extraction. In yet another study, supercritical carbon dioxide extraction was used, and yields of 17.5% oil were achieved from powdered rice bran, and a yield of 37% of γ-oryzanols was also obtained, which was characterized as 85% of

*Anthocyanins and Proanthocyanidins in Natural Pigmented Rice and Their Bioactivities DOI: http://dx.doi.org/10.5772/intechopen.86962*

**Figure 1.** *Rice paddy composition.*

*Phytochemicals in Human Health*

43.77 million acers (29.4% of the global rice area) with a production of 90 million tons [2]. The world production of rice is estimated at around 680 million tons, which is equivalent to that of wheat [3]. The color intensities of pigmented rice are obtained from the value of lightness, redness, and yellowness and seem to be

Recently, pigmented rice varieties have received increased amounts of attention from consumers for their high bioactive compounds that present potential nutraceutical benefits to health. It is also well known that these compounds are primarily located in the outer layer of the rice grain, which is regarded as a rice by-product. The by-products of rice processing are rice germ and bran, along with the rice hulls which protect the rice seeds during growth. These account for 20% of the rice crop. These by-products are frequently used as animal feed in developing countries. However, recently, significant amounts of data have revealed the beneficial nutritional impacts of these by-products on human health. The major bioactive compounds that are found in red, black, purple, and brown rice include gallic, protocatechuic, hydroxybenzoic, and vanillic acid, cyanidin 3-O-glucoside, peonidin-3-O-glucoside, proanthocyanidin, flavanol, catechin and epicatechin, carotenoids, and γ-oryzanol content. Several research findings have reported on the biological modulating effects of pigmented rice seeds and bran phytochemicals, including anti-inflammatory activities [7, 8], anticancer activities that have suppressed tumor growth in mice and several human cancer cell lines [9–13], the anti-metastasis properties of cancer cell invasion [14–16], antiaging effects with the reduction of oxidative stress in both in vitro and in vivo models [17, 18], the modulation of serum lipid profiles and the enhancement of mRNA expression levels of fatty acid metabolism-related genes [19], a reduction of platelet hyperactivity and hypertriglyceridemia in dyslipidemic rats [20], and skin antiaging treatments

In this current review, we have focused on the health benefits of pigmented rice and the relevant bioactive compounds. We have tried to present the information in this chapter in a way that is easy to understand, even for readers who are not experts in this field of research. The bioactive compounds found in pigmented rice display significant immersion potential with regard to a range of beneficial health effects and also provide significant informative data that could lead to the expansion in the growing of pigmented cultivated areas in Thailand and other Southeast Asian countries. There is also the prospect of additional practical implications, not only for agriculture expansion but in the food industry as well. Several pigmented rice varieties have been used to create new nutraceuticals, and these seem to hold a promise in terms of potential cosmeceutical utilization in the

The rice processing industry is well-developed and produces a number of products from rice kernels or grains (70%) along with a large quantity of rice byproducts. These by-products include rice bran (8–9%), rice germ (1–2%), and rice husks (20%). Figures on rice paddy composition are presented in **Figure 1**. These by-products are frequently used as animal feed in developing countries [25], but the demand for these by-products in terms of their human nutritional impacts has increased due to their potential health benefits. Rice kernels are primarily a good source for the energy intake of carbohydrates and proteins in humans. Rice bran makes up the outer layer of the rice kernel and is mainly comprised of a pericarp,

correlated to the indicators of its bioactive compounds [4–6].

**4**

[21–24].

new global business era.

**2. Pigmented rice and bioactive compounds**

aleurone, sub-aleurone layer, and germ. Rice bran and germ contain appreciable quantities of fiber, vitamins, minerals, unsaturated fatty acids, tocopherols, γ-oryzanol, and tocotrienols, which offer potent antioxidant content along with a range of other potential health benefits [26, 27].
