长黑青稞中不同形态多酚的提取及体外抗氧化活性

Extraction and Antioxidant Activity of Different Polyphenols from ‘Changhei’ Hulless Barley

本实验以长黑青稞为材料,提取分离总可溶性、游离、酯化、醚化和不可溶键合多酚,测定其多酚含量、黄酮含量和体外抗氧化活性,并采用高效液相色谱法分析酚类化合物组成与含量。结果表明,长黑青稞总可溶性、游离、酯化、醚化和不可溶键合多酚含量范围为(1.97±0.06)^(16.97±0.25)μmol/g,黄酮含量范围为(0.14±0.04)^(1.08±0.11)μmol/g;总可溶性多酚和黄酮含量均显著高于其他4种多酚(P<0.05),不可溶键合多酚含量均显著高于游离、酯化和醚化多酚(P<0.05);总可溶性多酚的铁离子还原能力、1,1-二苯基-2-三硝基苯肼自由基清除能力和总抗氧化能力最高,不可溶键合多酚系列抗氧化能力显著高于游离、酯化和醚化多酚,在过氧化氢清除能力中,不可溶键合多酚显著高于其他4种多酚(P<0.05);长黑青稞中多酚含量与体外抗氧化能力间呈显著正相关(R^2=0.880~0.998);长黑青稞多酚中含有18种酚类化合物,包括羟基苯甲酸、羟基肉桂酸和类黄酮3类,主要酚类化合物为原儿茶酸、阿魏酸和儿茶素。说明长黑青稞中含有丰富的酚类化合物,可作为一种具有潜在抗氧化价值的功能性食品原料。

In this study, total soluble, free, esterified, etherified and insoluble bound polyphenols were extracted and separated from ‘Changhei’ hulless barley kernels. The contents of polyphenol and flavonoids and antioxidant activities in vitro were determined. Moreover, the composition of phenolic compounds was quantitatively and qualitatively analyzed by high performance liquid chromatography(HPLC). The results showed that the polyphenol contents of the total soluble, free, esterified, etherified and insoluble bound polyphenol-rich extracts ranged from(1.97 ± 0.06) to(16.97 ± 0.25) μmol/g and the flavonoids contents from(0.14 ± 0.04) to(1.08 ± 0.11) μmol/g. The contents of polyphenols and flavonoids in the total soluble polyphenol-rich extract were significantly higher than those in the other four polyphenol-rich extracts, and insoluble bound polyphenols were significantly more abundant than free, esterified and etherified polyphenols(P < 0.05). The ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and Trolox equivalent antioxidant capacity of the total soluble polyphenols were the highest among the 5 polyphenols, and the insoluble bound polyphenols were significantly stronger antioxidants than the free, esterified and etherified polyphenols. Similarly, the hydrogen peroxide scavenging activity of the insoluble bound polyphenols was significantly higher than that of the other four polyphenols(P < 0.05). There was a significantly positive correlation between the polyphenol contents and the antioxidant activity(R^2 = 0.880–0.998). A total of 18 phenolic compounds were identified including hydroxybenzoic acid, hydroxycinnamic acid and flavonoids, with protocatechuic acid, ferulic acid and catechin being the most abundant ones. It can be concluded that hulless barley, with abundant phenolic compounds, can be regarded as a potential antioxidant value-added functional food ingredient.