薏米中酚类提取物测定及抗氧化能力指数分析

摘要

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）。%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.