Department of Food Science, Cornell University, Ithaca, New York 14853-7201, USA.
J Agric Food Chem. 2010 Jul 14;58(13):7580-7. doi: 10.1021/jf1007665.
Increased consumption of whole grains has been associated with reduced risk of developing major chronic diseases. These health benefits have been attributed in part to their unique phytochemicals. Previous studies on black rice mainly focused on anthocyanins. Little is known about the phytochemical profiles and antioxidant activities of different black rice varieties. The objective of this study was to determine the phytochemical profiles and antioxidant activity of rice bran samples from 12 diverse varieties of black rice. The free, bound, and total phenolic contents of black rice bran samples ranged from 2086 to 7043, from 221.2 to 382.7, and from 2365 to 7367 mg of gallic acid equiv/100 g of dry weight (DW), respectively. The percentage contribution of free phenolics to the total ranged from 88.2 to 95.6%. The average values of free, bound, and total phenolic contents of black rice bran were 8, 1.5, and 6 times higher than those of white rice bran, respectively (p < 0.05). The free, bound, and total flavonoid contents of black rice bran samples ranged from 3462 to 12061, from 126.7 to 386.9, and from 3596 to 12448 mg of catechin equiv/100 g of DW, respectively. The percentage contribution of free flavonoids to the total ranged from 96.3 to 97.6%. The average values of free, bound, and total flavonoid contents of black rice bran were 7.4, 1.9, and 6.7 times higher than those of white rice bran, respectively (p < 0.05). The free, bound, and total anthocyanin contents of black rice bran samples ranged from 1227 to 5096, from 4.89 to 8.23, and from 1231 to 5101 mg of cyanidin-3-glucoside equiv/100 g of DW, respectively. The percentage contribution of free anthocyanins to the total ranged from 99.5 to 99.9%. Cyanidin-3-glucoside, cyanidin-3-rutinoside, and peonidin-3-glucoside were detected in black rice bran samples and ranged from 736.6 to 2557, from 22.70 to 96.62, and from 100.7 to 534.2 mg/100 g of DW, respectively. The free, bound, and total antioxidant activities of black rice bran samples ranged from 476.9 to 180, from 47.91 to 79.48, and from 537.5 to 1876 mumol of Trolox equiv/g of DW, respectively. The percentage contribution of free antioxidant activity to the total ranged from 88.7 to 96.0%. The average values of free, bound, and total antioxidant activity of black rice bran were more than 8, 1.5, and 6 times higher than those of white rice bran, respectively (p < 0.05). The total antioxidant activity of black rice bran was correlated to the content of total phenolics, total flavonoids, and total anthocyanins and also was significantly correlated to the contents of cyanidin-3-glucoside, cyanidin-3-rutinoside, and peonidin-3-glucoside. These results indicate that there are significant differences in phytochemical content and antioxidant activity among the different black rice varieties. Black rice bran has higher content of phenolics, flavonoids, and anthocyanins and has higher antioxidant activity when compared to white rice bran. Interestingly, the phenolics, flavonoids, and anthocyanins of black rice bran are mainly present in free form. Knowing the phytochemical profile and antioxidant activity of black rice bran gives insights to its potential application to promote health.
增加全谷物的摄入量与降低发生主要慢性疾病的风险有关。这些健康益处部分归因于它们独特的植物化学成分。以前对黑米的研究主要集中在花青素上。关于不同黑米品种的植物化学成分谱和抗氧化活性知之甚少。本研究的目的是确定 12 种不同黑米品种的糙米糠样品的植物化学成分谱和抗氧化活性。黑米糠样品的游离、结合和总酚含量范围分别为 2086 至 7043、221.2 至 382.7 和 2365 至 7367 mg 没食子酸当量/100 g 干重(DW)。游离酚占总酚的百分比范围为 88.2%至 95.6%。黑米糠的游离、结合和总酚含量的平均值分别比白米糠高 8、1.5 和 6 倍(p<0.05)。黑米糠样品的游离、结合和总类黄酮含量范围分别为 3462 至 12061、126.7 至 386.9 和 3596 至 12448 mg 儿茶素当量/100 g DW。游离类黄酮占总类黄酮的百分比范围为 96.3%至 97.6%。黑米糠的游离、结合和总类黄酮含量的平均值分别比白米糠高 7.4、1.9 和 6.7 倍(p<0.05)。黑米糠样品的游离、结合和总花青素含量范围分别为 1227 至 5096、4.89 至 8.23 和 1231 至 5101 mg 矢车菊素-3-葡萄糖苷当量/100 g DW。游离花青素占总花青素的百分比范围为 99.5%至 99.9%。黑米糠样品中检测到矢车菊素-3-葡萄糖苷、矢车菊素-3-芸香糖苷和芍药素-3-葡萄糖苷,范围分别为 736.6 至 2557、22.70 至 96.62 和 100.7 至 534.2 mg/100 g DW。黑米糠样品的游离、结合和总抗氧化活性范围分别为 476.9 至 180、47.91 至 79.48 和 537.5 至 1876 mumol Trolox 当量/g DW。游离抗氧化活性占总抗氧化活性的百分比范围为 88.7%至 96.0%。黑米糠的游离、结合和总抗氧化活性的平均值分别比白米糠高 8、1.5 和 6 倍以上(p<0.05)。黑米糠的总抗氧化活性与总酚含量、总类黄酮含量和总花青素含量呈正相关,与矢车菊素-3-葡萄糖苷、矢车菊素-3-芸香糖苷和芍药素-3-葡萄糖苷的含量也呈显著正相关。这些结果表明,不同黑米品种之间的植物化学成分含量和抗氧化活性存在显著差异。黑米糠的酚类、类黄酮和花青素含量高于白米糠,抗氧化活性也高于白米糠。有趣的是,黑米糠中的酚类、类黄酮和花青素主要以游离形式存在。了解黑米糠的植物化学成分谱和抗氧化活性可以深入了解其在促进健康方面的潜在应用。