IV.Resist Oxidation and Aging by Pu’er Tea
Fig.6-8 Anti-aging effect of Pu’er tea
The emergence of free radicals and the decline of immune function are the two important factors that cause the aging of human body.Tea polyphenol, theanine, tea pigment and other effective components in Pu’er tea are antioxidants, free radical scavengers and immune function regulators with obvious anti-aging effects.The free radicals formed in continuous consumption of oxygen in the metabolic process of human body will cause the peroxidation of fatty acids in the body,thus destroy the cell structure and function, and cause the aging of human body.Tea polyphenols,vitamin C and vitamin E in Pu’er tea can form stable substances with free radicals, inhibit the production of free radicals such as nitric oxide and reactive oxygen, scavenge free radicals such as NO,ROS and H2O2, inhibit the oxidation of low-density lipoprotein cholesterol, reduce the production of malondialdehyde, prevent cell damage caused by free radicals, improve survival rate of cell and prevent peroxidation of fatty acid.Polyphenols in Pu’er tea can increase the number and activity of WBCs and lymphocytes in human body.Tea pigment in Pu’er tea contains a large number of active genes such as active phenolic hydroxyl groups with strong free radical scavenging and antioxidant effects.In addition,amino acids and trace elements in Pu’er tea also have certain anti-aging effects.Therefore, Pu’er tea can enhance immune function and delay the aging process of human body.
王绍梅通过蒸馏萃取法对普洱茶进行外物提取，采用DPPH和FRAP方法分析普洱茶提取物的抗氧化活性，研究结果表明，普洱茶的外物提取溶液的抗氧化活性总体显著上升，经过发酵后的普洱茶中具有较多的挥发性物质，具有较强的DPPH自由基清除活性和总体的抗氧化活性。
有研究表明普洱茶多酚能增加小鼠血清中SOD活性和GSH含量，同时减少MDA的含量，进而保护胃黏膜不受氧自由引起的氧化损伤，具有很好的体内和体外抗氧化作用。儿茶素是茶多酚的主体物质，也是茶叶抗衰老功能的主要成分。目前已发现的儿茶素有20多种，其中含量最高的是EGCG，许多研究表明，EGCG抗氧化活性最强，具有清除自由基、抗自由基DNA损害、抗辐射和紫外线、防止皮肤老化和起皱等功效，普洱茶以云南大叶种毛茶为原料加工制成，其所含的儿茶素总量要高于其他茶树品种，因而抗衰老作用更显著。
王媛等对建立的人衰老成纤维细胞（HDF）模型添加低水平的普洱茶提取物及中高水平的普洱茶多糖，研究发现普洱茶多糖能显著提高衰老HDF细胞的增殖，并能显著提高SOD1、GPx和D-loop基因的表达，说明普洱茶多糖具有延缓HDF细胞衰老的功效。