Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
BMC Complement Altern Med. 2010 Jan 28;10:4. doi: 10.1186/1472-6882-10-4.
Free radical-induced oxidative stress is the root cause for many human diseases. Naturally occurring antioxidant supplements from plants are vital to counter the oxidative damage in cells. The main objective of the present study was to characterize the antioxidant and antiproliferative potential of rice bran extracted from an important Indian rice variety, Njavara and to compare the same with two commercially available basmati rice varieties: Vasumathi, Yamini and a non medicinal variety, Jyothi.
Methanolic extracts of rice bran from four varieties; Vasumathi, Yamini, Jyothi and Njavara were used to study their total phenolic and flavonoid contents, in vitro antioxidant activities including total antioxidant activity, scavenging of nitric oxide and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical, reducing power and cytotoxic activity in C6 glioma cells. Correlation coefficient and regression analysis were done by using Sigmastat version 3.1 and Stata statistical package respectively.
Rice bran methanolic extract from Njavara showed the highest antioxidant and cell cytotoxic properties compared to the other three rice varieties. IC50 values for scavenging DPPH and nitric oxide were in the range of 30.85-87.72 microg/ml and 52.25-107.18 microg/ml respectively. Total antioxidant activity and reducing power were increased with increasing amounts of the extract. Total phenolic and flavonoid contents were in the range of 3.2-12.4 mg gallic acid-equivalent (GAE)/g bran and 1.68-8.5 mg quercetin-equivalent (QEE)/g bran respectively. IC50 values of cytotoxic assay (MTT assay) were 17.53-57.78 microg/ml. Correlation coefficient and regression analysis of phenolic content with DPPH and NO scavenging, MTT (-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay, total antioxidant assay and reducing power showed a highly significant correlation coefficient values (96-99%) and regression values (91-98%).
The results of the present study show that the crude methanolic extract from Njavara rice bran contains significantly high polyphenolic compounds with superior antioxidant activity as evidenced by scavenging of free radicals including DPPH and NO. Njavara extracts also showed highest reducing power activity, anti-proliferative property in C6 glioma cells. In conclusion, it is conceivable that the Njavara rice variety could be exploited as one of the potential sources for plant--based pharmaceutical products.
自由基诱导的氧化应激是许多人类疾病的根本原因。植物中天然存在的抗氧化补充剂对于抵抗细胞中的氧化损伤至关重要。本研究的主要目的是表征来自印度重要水稻品种 Njavara 的米糠的抗氧化和抗增殖潜力，并将其与两种市售的巴斯马蒂水稻品种（Vasumathi、Yamini）和一种非药用品种（Jyothi）进行比较。
使用来自四种品种（Vasumathi、Yamini、Jyothi 和 Njavara）的米糠的甲醇提取物来研究它们的总酚和类黄酮含量、体外抗氧化活性，包括总抗氧化活性、清除一氧化氮和 1,1-二苯基-2-苦基肼（DPPH）自由基、还原能力和 C6 神经胶质瘤细胞的细胞毒性。使用 Sigmastat 版本 3.1 和 Stata 统计软件包分别进行相关系数和回归分析。
与其他三种水稻品种相比，Njavara 的米糠甲醇提取物表现出最高的抗氧化和细胞毒性特性。清除 DPPH 和一氧化氮的 IC50 值分别在 30.85-87.72μg/ml 和 52.25-107.18μg/ml 范围内。随着提取物用量的增加，总抗氧化活性和还原能力增加。总酚和类黄酮含量分别在 3.2-12.4mg 没食子酸当量（GAE）/g 糠和 1.68-8.5mg 槲皮素当量（QEE）/g 糠范围内。细胞毒性测定（MTT 测定）的 IC50 值为 17.53-57.78μg/ml。酚含量与 DPPH 和 NO 清除、MTT（噻唑蓝）测定、总抗氧化测定和还原能力的相关系数和回归分析显示出高度显著的相关系数值（96-99%）和回归值（91-98%）。
本研究结果表明，Njavara 米糠的粗甲醇提取物含有显著高含量的多酚化合物，具有优越的抗氧化活性，可清除自由基，包括 DPPH 和 NO。Njavara 提取物还表现出最高的还原能力活性和 C6 神经胶质瘤细胞的抗增殖特性。总之，可以想象 Njavara 水稻品种可以作为植物源药物产品的潜在来源之一。
