Tannins, polyphenols in medicinal plants, have been divided into two groups of hydrolysable and condensed tannins, including gallotannins, ellagitannins, and (–)‐epigallocatechin‐3‐gallate (EGCG). Potent anticancer activities have been observed in tannins (especially EGCG) with multiple mechanisms, such as apoptosis, cell cycle arrest, and inhibition of invasion and metastases. Furthermore, the combinational effects of tannins and anticancer drugs have been demonstrated in this review, including chemoprotective, chemosensitive, and antagonizing effects accompanying with anticancer effect. However, the applications of tannins have been hindered due to their poor liposolubility, low bioavailability, off‐taste, and shorter half‐life time in human body, such as EGCG, gallic acid, and ellagic acid. To tackle these obstacles, novel drug delivery systems have been employed to deliver tannins with the aim of improving their applications, such as gelatin nanoparticles, micelles, nanogold, liposomes, and so on. In this review, the chemical characteristics, anticancer properties, and drug delivery systems of tannins were discussed with an attempt to provide a systemic reference to promote the development of tannins as anticancer agents.

中文翻译：

---

单宁的抗癌活性和药物传递系统的最新进展

单宁，药用植物中的多酚，已分为两类可水解和缩合的单宁，包括没食子单宁，鞣花单宁和（-）-表没食子儿茶素-3-没食子酸酯（EGCG）。单宁（尤其是EGCG）具有多种机制，例如细胞凋亡，细胞周期停滞以及对侵袭和转移的抑制，均已观察到有效的抗癌活性。此外，本综述已证明了单宁酸和抗癌药的联合作用，包括化学保护，化学敏感性和拮抗作用以及抗癌作用。但是，由于单宁酸的脂溶性差，生物利用度低，异味且在人体中的半衰期较短，例如EGCG，没食子酸和鞣花酸，因此其应用受到了阻碍。为了克服这些障碍，为了改善单宁的应用，已经采用了新颖的药物输送系统来输送单宁，例如明胶纳米颗粒，胶束，纳米金，脂质体等。在这篇综述中，对单宁的化学特性，抗癌特性和药物传递系统进行了讨论，以期为促进单宁作为抗癌剂的发展提供系统参考。