薏米中酚类提取物测定及抗氧化能力指数分析

选取3种薏米样品，经提取获得游离型和结合型多酚类化合物，采用改进的Folin-Ciocalteu比色法及硼氢化钠/氯醌(SBC)比色法，用酶标仪测定其多酚和黄酮含量；采用抗氧化能力指数(ORAC)方法，于荧光酶标仪中测定提取物中的总抗氧化活性。研究表明，游离型多酚含量中龙薏1号薏米显著性高于贵州黑谷薏米和辽宁5号薏米，结合型多酚含量中龙薏1号薏米显著性高于贵州黑米薏米和辽宁5号薏米，所有样品中其平均结合型多酚含量占总多酚含量的45.28%；游离型黄酮含量中辽宁5号薏米显著高于贵州黑谷薏米和辽宁5号薏米，结合型黄酮含量中龙薏1号薏米高于辽宁5号薏米和贵州黑谷薏米，总黄酮含量最高的是辽宁5号薏米。总抗氧化能力指数(ORAC)最高的是龙薏1号薏米，其值是(668.0 ± 32.7)mg Trolox /100g样品(以干质量计)，其次是贵州黑谷薏米和辽宁5号薏米，所有样品中平均结合型ORAC值占总ORAC值的48.08%；3个品种的薏米其总多酚含量与总抗氧化能力指数之间相关系数为0.933，有显著相关性(P＜0.05)。

Analysis of Phenols,Flavonoids and Oxygen Radical Absorbance Capacity(ORAC) of Three Varieties of Adlay

In order to explore the phytochemical profile of three adlay varieties,the levels of total,free and bound phenols and flavonoids were determined using a microplate reader.Meanwhile,the oxygen radical absorbance capacity(ORAC) was measured as an indicator for total antioxidant capacity using a multifunctional fluorescence microplate reader.The contents of free((45.19 ± 0.91) mg of gallic acid equivalent/100 g of dried samples) and bound((30.86 ± 1.18) mg of gallic acid equivalent/100 g samples) phenols in Longyi I were significantly higher than those in Liaoning V and Guizhou Heigu(P < 0.05).For all these adlay varieties,bound phenols averagely accounted for 45.28% of total phenols.The content of free flavonoids in Liaoning V showed a significant increase as compared with Longyi I and Guizhou Heigu,and the content of bound flavonoids in Longyi I was higher than that of Liaoning V and Guizhou Heigu.The highest content of total flavonoids was found in Liaoning V.The adlay varieties were ranked in decreasing order of ORAC as follows: Longyi I((668.0 ± 32.7) mg of Trolox equivalent/100 g of dried samples),Liaoning V and Guizhou Heigu.The average percentage of bound ORAC in total ORAC was 48.08%.A correlation coefficient(r2) of 0.933 was observed for the significant correlation(P < 0.05) between the total phenol content and total antioxidant capacity of each adlay variety.