Chemical Indices, Antioxidant Activity and Anti-Inflammatory Effect of Extracts of the Medicinal Rice “Njavara” and Staple Varieties: A Comparative Study

Abstract

Chemical indices, antioxidant and anti‐inflammatory activity of extracts of bran of medicinal rice – Njavara “black glumed” type (NBb) and its rice (NBr), were studied in comparison with bran and rice of staple varieties: Sujatha and Palakkadan Matta. Total oryzanol, phenolic, flavonoid, proanthocyanidin and phytate contents of NBb (1.84 mg/g, 27.16 mg of gallic acid/g, 4.50 mg of quercetin/g, 0.98 mg of catechin/g and 8.77 mg/g dry weight of bran, respectively) were higher compared with NBr and staple varieties. NBb showed greater reducing power and significantly higher scavenging activity with 2, 2‐diphenyl‐1‐picryl hydrazyl radical, superoxide and hydrogen peroxide with values of concentration of NBb required to scavenge 50% of respective radicals (IC50): 84.66, 203.16 and 73.55 µg/mL, respectively. The anti‐inflammatory effect (in vivo) of NBb was 83.3%, whereas NBr and staple varieties showed activity in the range 16–66%. The higher oryzanol content, chemical indices, antioxidant and anti‐inflammatory activity for Njavara compared with staple varieties corroborates with its medicinal use in Ayurveda. PRACTICAL APPLICATIONS Medicinal plants are a source of antioxidants and bioactive compounds responsible for the prevention of oxidative stress that leads to many degenerative diseases and conditions. The present study indicates that the extracts of “Njavara” (black glumed), a medicinal rice variety, contains significant amounts of oryzanols, phenolic acids, flavonoids, proanthocyanidins and phytic acid compared with staple varieties. These extracts are potential free radical scavengers and have anti‐inflammatory effect compared with staple varieties. Njavara, identified as a source of bioactive compounds, can be consumed as a health food in addition to its medicinal uses; thus, benefiting consumers. Higher oryzanol content in Njavara is beneficial for lowering plasma cholesterol, reducing platelet aggregation, nerve imbalances and aortic fatty streak formation. Higher antioxidants in Njavara are also beneficial against the diseases initiated by free radicals. These promising results also open up newer areas of research for developing improved varieties of rice containing more bioactive compounds.

Rice antioxidants: phenolic acids, flavonoids, anthocyanins, proanthocyanidins, tocopherols, tocotrienols, γ‐oryzanol, and phytic acid

“…In the husk, a different ranking was observed, with p-coumaric acid being the dominant phenolic acid (71%), followed by ferulic acid (23%), vanillic acid (3%), and syringic acid (1%). This ranking is consistent with the values reported in most studies (Harukaze et al 1999;Tian et al 2004;Zhou et al 2004;Vichapong et al 2010;Sompong et al 2011;Tuncel and Yılmaz 2011;Chen et al 2012a;Deng et al 2012;Huang and Ng 2012;Irakli et al 2012;Jun et al 2012;Mohanlal et al 2012;Moongngarm et al 2012;Goufo et al 2014a). In KDML 105 rice, however, Butsat et al (2009) found p-hydroxybenzoic acid to be the major phenolic acid in the husk, accounting for 42% of the total phenolic acids, followed by ferulic acid (24%), and p-coumaric acid (12%).…”

“…; Mohanlal et al. ), and vortexing (Huang and Ng ; Gunaratne et al. ) have also been used to obtain vitamin E isomers from rice.…”

“…The degree of polymerization and galloylation affect the bioactivity of proanthocyanidins. On the basis of the observed molecular weights, the main proanthocyanidin compounds in rice are most likely oligomers of epicatechin linked by four to eight carbon-carbon bonds (B-types) (Finocchiaro et al 2007;Mohanlal et al 2012). Analyses of proanthocyanidins based on their degree of polymerization showed that monomers to trimers of lower molecular weight proanthocyanidins account for 38% of the total proanthocyanidin content (Chen et al 2012b).…”

Antioxidant Activity of Indian Medicinal Rice (Oryza Sativa L.) cv. Njavara

“…Ascorbic acid was used as reference compound and its IC50 value was 3.90 µg/ml. Similar findings were reported by Smitha (2012). c) Super oxide anion-radical scavenging activity Over-production of superoxide anion radical has long been known as the starting point of ROS/RNS accumulation in cells, contributing to redox imbalance and other associated deleterious physiological consequences (Pervaiz and Clement, 2007).…”

Antioxidant effect of Purple basil(Lamiaceae) Phenolics

“…Basil is also used for pharmaceutical and cosmetic preparations due to the high content of phenolic compounds that are well-known phytochemical molecules found in all plants 7 .These constituents act as antioxidants to prevent heart disease 7 , reduce inflammation 8,9 , lower the incidence of cancers 10,11 and diabetes 12,13 , as well as reduce rates of mutagenesis in human cells (14,15) . The antioxidant activity of phenolic compounds is mainly caused by their redox properties, which permit them to act as reducing agents, hydrogen donors and singlet oxygen quenchers (16) .…”