栓皮栎橡子壳色素理化性质和抗氧化活性

摘要

以秦巴山区栓皮栎橡子壳为原料,采用定性实验、紫外-可见光谱、傅里叶变换红外光谱及抗氧化实验研究了栓皮栎橡子壳色素的提取、分离、结构、理化性质及抗氧化特性.结果表明:栓皮栎橡子壳色素中含丰富的多酚类物质,其主要成分为缩合单宁,约占总酚含量的89％;光谱分析表明该色素分子中具有分子内氢键、多个苯环和酚羟基结构;易溶于乙醇、甲醇、碱液和水,微溶于乙酸乙酯,不溶于苯,在酸性条件下稳定,碱性条件下颜色加深,对温度、光照有较好耐受性,遇K+、Na+、Ca2+稳定,遇Mg2+、Zn2+、Al3+颜色基本不变,产生沉淀,遇氧化剂易褪色,遇还原剂较稳定;对1,1-二苯基-2-三硝基苯肼自由基清除能力和总还原能力均强于VC,而对超氧阴离子清除能力弱于VC,具有较强的抗氧化能力.%Pigment was extracted from Quercus variabilis acorn shell harvested from Qinba mountain area,China and it was qualitatively analyzed and structurally characterized by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy.Meanwhile,the antioxidant activity was evaluated.The results showed that the pigment contained abundant polyphenols,with condensed tannins being the predominant species,accounting for up to about 89％ of the total polyphenols.The UV-vis and FTIR analysis proved that the pigment molecule contained intramolecular hydrogen bonds as well as multiple benzene rings and phenolic hydroxyl groups.The pigment was easily soluble in ethanol,methanol,alkali solution and water,slightly soluble in ethyl acetate,and insoluble in benzene.The pigment exhibited good stability in acidic environments,but its color became darker with increasing pH in alkali environments.The pigment had good resistance to light and heat,and it was stable in K+,Ca2+ and Na+ solution and could basically retain its color although generating a precipitate in Al3+,Mg2+ and Zn2+ solution.The color of the pigment was obviously faded in antioxidant solution but was not changed in reducing agent solution.The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging capacity and reducing power of the pigment were stronger than those of VC,while the superoxide anion scavenging capacity was slightly weaker than that of VC.Therefore,the pigment has a good antioxidant effect in vitro.