茶黄素类化合物的氧化制备方法及其生物活性研究进展

Research progress on oxidation preparation methods and biological activity of theaflavins

中文关键词:  茶黄素  氧化制备  酶法制备  生物活性

英文关键词:theaflavin  oxidation preparation  enzymatic preparation  biological activity

中文摘要:

      茶黄素类化合物(theaflavin, TF)是茶叶中的一种水溶性色素, 具有抗氧化、抗菌、缓解代谢综合征、抗炎、保护牙齿、保护神经、抗抑郁等丰富的生物活性, 具有广阔应用前景。基于TF结构复杂、化学性质不稳定、提取效率低难度大等问题, TF的氧化制备广受关注。TF氧化制备方法包括化学法和酶法, 化学法制备使用化学氧化剂, 氧化程度均匀、可控性强, 在酸性环境中会生成更多的酯型TF, 但化学氧化法专一性差, 需要保护儿茶素A环上的羟基以提高TF的产率, 且氧化剂用量大, 安全性差; 酶法制备使用多酚氧化酶和过氧化物酶, 条件温和、高效、专一, 酶法制备TF的效率受氧化酶来源和种类、底物组成和反应参数的影响, 优先氧化儿茶酚型儿茶素的氧化酶、提高联苯三酚型儿茶素比例、在弱酸低温环境下长时间反应均能提高TF的产率, 但目前的制备方法依旧存在提取率低、产品纯度低的问题。本文对两种氧化制备方法进行了讨论, 并对其生物活性进行总结和归纳, 旨在为TF的工业生产和应用研究提供参考。

英文摘要:

      Theaflavins (TF) are water-soluble pigments in tea. They possess rich biological activities such as antioxidant, antibacterial, alleviating metabolic syndrome, anti-inflammatory, tooth-protecting, neuroprotective, and antidepressant effects, and thus have broad application prospects. Given the complex structure, unstable chemical properties, low extraction efficiency, and the difficulty in obtaining TF, the oxidative preparation of TF has attracted significant attention. Oxidation preparation methods of TF include the chemical method and the enzymatic method. Chemical method utilizes a chemical oxidant. It features a uniform oxidation degree and strong controllability, and generates more ester TF in an acidic environment. However, the chemical oxidation method has poor specificity. Consequently, it is necessary to protect the hydroxyl group on the catechin A-ring to enhance the yield of TF. Moreover, the amount of oxidant required is large, and safety is a concern. In enzymatic preparation, polyphenol oxidase and peroxidase are employed. The conditions are mild, efficient, and specific. Efficiency of enzymatically preparing TF is influenced by the sources and types of oxidases, substrate composition, and reaction parameters. Yield of TF can be increased by preferentially oxidizing the oxidases of catechol catechins, increasing the proportion of biphenyl catechins, and reacting for an extended period in a weak-acid and low-temperature environment. Nevertheless, the current preparation methods still face problems such as a low extraction rate and low product purity. This paper discussed 2 kinds of oxidation preparation methods, and summarized their biological activities, in order to provide reference for the industrial production and application research of TF.