茶叶黑色素的理化性质及其清除DPPH自由基的研究

Physico-chemical Properties and DPPH Free Radical Scavening Potential of Melanin from Tea

以氨水溶液提取、酸水解、有机溶剂洗涤、酸沉淀等工艺从红茶中分离纯化茶叶黑色素,并对其理化性质、光谱特征和清除DPPH自由基能力进行研究。结果表明,该天然黑色素不溶于水、酸和有机溶剂,对光、热、碱和还原剂稳定,Cu2+、Ca2+、Zn2+等金属离子对该色素有护色、增色作用,Fe3+、Al3+有一定的减色作用;茶叶黑色素中总酚含量为82.8μg/mg(以没食子酸计);具有较强的清除DPPH自由基能力I,C50为58.4μg/mL,是一种非常有潜力的天然黑色素和抗氧化剂资源。

The melanin was isolated from black tea leaves by ammonia extraction,acid hydrolysis,and repeated precipitation.The total polyphenol contents and DPPH free radical scavenging potential have been studied,besides physico-chemical properties and spectral feature of melanin.The results showed that the natural melanin was indissolvable in water,acid and organic,which was light fastness and heat resistance.It was stable under alkaline conditions also on the reducing agent;Cu2＋,Ca2＋,Zn2＋ had color retention and hyperchromic effect on the pigment,but on the contrary,Fe3＋,Al3＋ had a certain role in subtractive.The total phenol content of the tea melanin was 82.8 μg/mg gallic acid.The 50 % inhibition concentration（IC50） values of the tea melanin was 58.4 μg/mL.Thus the tea melanim is a potential natural resources in melanoma and anti-oxidants.