莓茶叶黄酮的抗氧化活性及其稳定性

Antioxidant Activity and Stability of Flavonoids from Mei-tea(Ampelopsis grossedentata)

该研究采用超声辅助水提法提取莓茶叶中黄酮类化合物,通过DPPH、ABTS^(+)自由基清除实验探究莓茶叶水提液中黄酮的抗氧化活性,并利用紫外分光光度法探究不同光照、pH值、金属离子、氧化剂还原剂、水溶性高分子物质等因素对莓茶叶水提液中黄酮稳定性的影响。结果表明,莓茶叶中黄酮具备很好的抗氧化性能,对DPPH、ABTS^(+)自由基均能起到很好的清除效果,其IC50分别为3.09、1.43μg/mL。同时,莓茶叶中黄酮在长时间保存时存在自氧化现象且光照在一定程度上能够促进莓茶叶黄酮的氧化。碱性条件和还原剂会破坏莓茶叶黄酮分子结构从而影响其稳定性。莓茶叶黄酮与Cu^(2+)、Fe^(3+)等金属离子易形成不溶性络合物,影响其稳定性。水溶性高分子物质能对莓茶叶黄酮起到一定保护作用,避免其与氧气接触发生氧化。

In this study,the flavonoids in Mei-tea(Ampelopsis grossedentata)were extracted by the ultrasoundassisted water extraction method,and the antioxidant activity of flavonoids in the aqueous extract of Mei-tea(Ampelopsis grossedentata)was investigated by the DPPH and ABTS radical scavenging assays,and the effects of different lighting,pH values,metal ions,oxidants,reducing agents and water-soluble macromolecules on the stability of flavonoids in the aqueous extract of Mei-tea(Ampelopsis grossedentata)were investigated by UV spectrophotometry.The results showed that the flavonoids had good antioxidant activity and could scavenge effectively DPPH and ABTS^(+)free radicals,with the IC50 values being 3.09μg/mL and 1.43μg/mL for DPPH and ABTS^(+)radicals,respectively.Meanwhile,the flavonoids in the Mei-tea(Ampelopsis grossedentata)underwent autoxidization during a long-term storage and light could promote the oxidation of the flavonoids in Mei-tea(Ampelopsis grossedentata)to a certain extent.Alkaline conditions and reducing agents could destroy the molecular structures of the flavonoids in the Mei-tea(Ampelopsis grossedentata).The flavonoids in the Mei-tea(Ampelopsis grossedentata)could easily form insoluble complexes with metal ions such as Cu^(2+)and Fe^(3+),thereby affecting the stability of flavonoids.Water-soluble macromolecules could protect the flavonoids in the Mei-tea(Ampelopsis grossedentata)to a certain extent,to prevent their oxidation through avoiding contact with oxygen.