不同发酵程度茶叶的体内与体外抗氧化功能比较

Comparison of in Vivo and in Vitro Antioxidant Functions of Tea Leaves with Different Fermentation Level

比较了三种茶粉(水提物)中的多酚、黄酮组成及其含量;测定了体外清除二苯基苦基偕腙肼(DPPH)自由基的作用;采用灌胃方式饲喂昆明小鼠三种茶粉3周后,观察小鼠血液及肝组织中谷胱甘肽过氧化物酶(GSH-PX)活性、超氧化物歧化酶(SOD)活性和丙二醛(MDA)的含量。结果表明:绿茶中的多酚含量高于红茶与普洱茶,而黄酮含量则低于红茶与普洱茶;红茶与普洱茶具有相当量的没食子酸,且含量均高于绿茶。体外清除DPPH自由基能力的大小依次为绿茶>红茶>普洱茶。三类茶均能显著提高小鼠血清与肝组织中的GSH-PX活性(P<0.05);绿茶与红茶均能显著提高小鼠肝组织中的SOD活性(P<0.01),普洱茶能显著降低血清与肝组织中的MDA含量(P<0.05)。不同的发酵程度对茶叶中多酚组成、体外清除自由基作用及对小鼠的抗氧化功能具有显著影响;在发酵过程中产生的一些未知的高分子量多酚类物质如儿茶素衍生物或聚合物还有待于进一步的研究。

The contents and compositions of polyphenols and flavones in three tea powder （aqueous extracts） were compared. Their scavenging ability of DPPH （2,2-dipheny1-1-picrylhydrazyl） in vitro was determined. Glutathione peroxidase（GSH-PX） and superoxide dismutase （SOD） activities, and malondialdebyde （MDA） content in serum and liver were evaluated in the female Kunming mice fed with tea extracts for 3 weeks, The resuhs showed that the content of polyphenols （including catechins） in green tea was higher than that of black and pu-erh teas, but flavones in green tea was lower than that of black and pu-erh teas. Black and pu-erh teas had the equivalent amount of gallic acid, which was higher than that of green tea. The order of DPPH scavenging ability of these teas was green tea〉black tea〉pu-erh tea. The activity of GSH-PX was increased in all tea-treatment groups significantly （P〈0.05 or P〈0.01）. The activity of antioxidant enzyme SOD increased significantly in green and black tea groups as compared to the control group （P〈0.01）. The MDA content in pu-erh tea group decreased significantly （P〈0.05）. There were remarkable effects of different fermented processes on polyphenols and antioxidant ability of tea. It suggested that some unidentified new polyphenols such as catechins during the processes of fermentation need further researches.