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【目的】比较不同水稻品种谷壳中游离态和结合态酚类物质的含量、组成及其抗氧化活性差异。【方法】选用5个代表性的南方籼稻品种,分析其谷壳中的游离态和结合态总酚、总黄酮含量,采用高效液相色谱法分析其单体酚类的组成及含量,采用铁离子还原能力(FRAP,Ferric reducing ability of plasma)和ABTS(2,2’-联氨-二-3-乙基-苯并噻唑-6-磺酸,2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid)自由基清除能力两种方法评价其体外抗氧化能力差异。【结果】5个不同籼稻品种谷壳的游离酚、结合酚和总酚含量分别介于42.8—123.0、260.9—325.2和320.2—398.3 mg GAE/100 g DW,其结合态酚占总酚含量百分比平均为78.9%;游离态黄酮、结合态黄酮和总黄酮含量分别介于34.0—58.0、47.9—64.4和82.0—115.7 mg CE/100 g DW,其结合态黄酮占总黄酮含量的百分比平均为56.4%;稻壳中的酚类物质主要为没食子酸、原儿茶酸、绿原酸、香草酸、咖啡酸、丁香酸、香豆酸和阿魏酸,其中游离态酚类物质以丁香酸和香豆酸为主,平均含量分别为25.09μg.g-1DW和31.21μg.g-1DW;结合态酚类物质以香豆酸含量为主,平均含量为2141.61μg.g-1DW。稻壳游离态、结合态和两者合计FRAP抗氧化能力值分别介于37.7—106.0、217.9—281.0和269.3—370.3 mg TE/100 g DW,其结合态占总FRAP百分比平均为77.3%;稻壳游离态、结合态和两者合计ABTS抗氧化能力值分别介于26.3—85.8、67.2—111.9和93.4—155.2 mg TE/100 g DW,其结合态占总ABTS百分比平均为64.8%。【结论】稻壳中含有较丰富的酚类物质,具有较强的抗氧化活性。稻壳总酚、总黄酮含量、单体酚组成及其抗氧化活性均以结合态形式为主,且有显著的品种间差异。提示水稻谷壳可以作为一种潜在的天然抗氧化剂资源进行开发利用。
【Objective】 The content, composition and antioxidant activity of free and bound phenols in rice hulls of different rice varieties were compared. 【Method】 Five representative indica rice cultivars from southern China were selected to analyze free and bound total phenols and total flavonoids in chaff. The composition and content of single phenols were analyzed by high performance liquid chromatography (HPLC) FRAP (Ferric reducing ability of plasma) and ABTS (2,2’-azino-bis-3-ethylbenzothiazoline -6-sulphonic acid) free radical scavenging ability of two methods to evaluate its in vitro antioxidant capacity differences. 【Result】 The results showed that the contents of free phenol, bound phenolics and total phenols in chaff of five different indica rice varieties ranged from 42.8-123.0, 260.9-325.2 and 320.2-398.3 mg GAE / 100 g DW, respectively, With an average of 78.9%. The contents of free flavonoids, bound flavonoids and total flavonoids were 34.0-58.0,47.9-64.4 and 82.0-115.7 mg CE / 100 g DW, respectively. The percentages of bound flavonoids in total flavonoids were 56.4% The main phenolic compounds in rice hull were gallic acid, protocatechuic acid, chlorogenic acid, vanillic acid, caffeic acid, syringic acid, coumaric acid and ferulic acid. The free phenols were syringic acid and coumaric acid With the average content of 25.09μg.g-1DW and 31.21μg.g-1DW respectively. The content of phenolic compounds in coumarin was the highest with the average content of 2141.61μg.g-1DW. The values of free radical, bound state and total FRAP of rice husk were 37.7-106.0, 217.9-281.0 and 269.3-370.3 mg TE / 100 g DW, respectively, and their percentages of total FRAP were 77.3% The ABTS antioxidant capacity values of free, bound and both were 26.3-85.8, 67.2-111.9 and 93.4-155.2 mg TE / 100 g DW, respectively. The average percentage of bound ABTS in ABTS was 64.8%. 【Conclusion】 Rice husk contains abundant phenolic compounds and has strong antioxidant activity. The contents of total phenols, total flavonoids, monomer phenolics and antioxidant activities of rice husk were mainly in the form of bound state, and there were significant differences among cultivars. Suggesting that rice husk can be exploited as a potential natural antioxidant resource.