Abstract
BackgroundIn the recent years, the health benefits of the pigmented rice varieties have reported due to the presence of bioactive compounds. In this study, the phytochemical constituents (total phenolic, flavonoid and anthocyanin content) and individual phenolics and flavonoids of the extracts of sixteen genotypes of pigmented rice bran were evaluated using spectrophotometric and ultra-high performance liquid chromatography method. Antioxidative properties of the free and bound fractions were evaluated using nitric oxide and 1,1-diphenyl-2-picrylhydrazyl scavenging assays. Extracts were evaluated for antiproliferative activity against breast cancer cell lines (MCF-7 and MDA-MB-231) using the MTT assay.ResultsSignifficant diferences were observed in the concentrations of phytochemicals and biological activities among different pigmented rice brans. The highest phytochemical content was observed in black rice bran followed by red and brown rice bran. The concentration of free individual flavonoids and phenolic compounds were significantly higher than those of bound compounds except those of ferulic acid and p-coumaric acid. Highest antioxidant activities were observed in black rice bran, followed by red and brown rice bran extracts. Extracts of black rice bran exhibited potent antiproliferative activity, with half maximal inhibitory concentrations (IC50) of 148.6 and 119.2 mg/mL against MCF-7 and MDA-MB-231 cell lines, respectively, compared to the activity of the extracts of red rice bran (175.0 and 151.0 mg/mL, respectively) and brown rice bran (382.3 and 346.1 mg/mL, respectively).ConclusionsBlack rice bran contains high levels of phytochemicals, and thus has potent pharmaceutical activity. This highlights opportunities for researcher to breed new genotypes of rice with higher nutritional values, which the food industry can use to develop new products that will compete in expanding functional food markets.
Highlights
In the recent years, the health benefits of the pigmented rice varieties have reported due to the presence of bioactive compounds
The current results showed that the phenolic and flavonoid compounds in rice bran were mostly present in the free form, and this is an important issue for future studies
Oki et al [32] reported that in red pericarp grains, a strong correlation between antioxidant activity and the content of proanthocyanidins was observed; in the case of black pericarp grains, the correlation was dependent on the content of anthocyanins. These results suggest that phenolic compounds were primarily responsible for the antioxidant activity of rice grains [33]
Summary
The health benefits of the pigmented rice varieties have reported due to the presence of bioactive compounds. The phytochemical constituents (total phenolic, flavonoid and anthocyanin content) and individual phenolics and flavonoids of the extracts of sixteen genotypes of pigmented rice bran were evaluated using spectrophotometric and ultra-high performance liquid chromatography method. Antioxidative properties of the free and bound fractions were evaluated using nitric oxide and 1,1-diphenyl-2-picrylhydrazyl scavenging assays. Rice grains have a hard husk protecting the kernel inside. After the husk is removed, the remaining product is known as brown rice. After removal of the bran and embryo, the remaining endosperm is known as polished rice. The rice bran fraction contains high levels of fibre and bioactive phytochemicals including
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