Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2019, Article ID 8623909, 26 pages https://doi.org/10.1155/2019/8623909 Review Article A Comprehensive Review of the Structure Elucidation of Tannins from Terminalia Linn. Zihao Chang , Qiunan Zhang, Wenyi Liang , Kun Zhou, Ping Jian , Gaimei She , and Lanzhen Zhang School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China Correspondence should be addressed to Lanzhen Zhang; [email protected] Received 12 September 2019; Accepted 29 October 2019; Published 15 November 2019 Academic Editor: Luciana Dini Copyright © 2019 Zihao Chang et al. (is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. Tannins with complex structures are important plant resources, which are abundant in the genus Terminalia. Various Terminalia species have been playing an important role in traditional medicine system. A systematic scoping review of Terminalia Linn. research literature for tannins was conducted to summarize the structures of tannins and analysis fragmentation pathway characteristics, which could provide references for the structural analysis of tannins from Terminalia Linn. Methods. After an update of the literature search up to September 2018, the terms of Terminalia in all publications were analyzed. Electronic searches were conducted in scifinder and PubMed, and the information from 197 articles in all with regard to the tannin structure study was extracted. Results. (e compounds of 82 tannins from the genus Terminalia were reviewed. According to the structural differences, they can be divided into three categories, hydrolysable tannins, condensed tannins, and complex tannins, respectively. (e fragmentation pathways of 46 identified tannins were analyzed, and the fragmentation rules of tannins were speculated according to different types. Conclusion. (is review has attracted attention to the active substances in this species such as the tannins summarized in further study. How to improve the extraction and purification technology of tannins from genus Terminalia is an urgent problem to be solved. 1. Introduction condensed tannins, and complex tannins. Usually, their molecular weights are greater than 500 Da. Tannins are Plants of the genus Terminalia (family Combretaceae) are widely distributed in various plants, and they are considered widely used in traditional medicine all over the world [1]. defensive molecules to protect plant tissues from herbivo- (ere are about 250 Terminalia species, of which at least 50 rous attacks because of their astringent taste [10]. It has been are used as food [2]. Many species have biological activities reported that several natural tannins and related compounds including antitumor, anti-inflammatory, wound healing, have various biological activities, including antioxidant, antifungal, antibacterial, and antiviral activities [3–7]. In antitumor, hypolipidemic, hypoglycemic, and antibacterial particular, Terminalia chebula, an Indian species, is well activities [11–14]. Takashi Tananka isolated terflavin A and noted as the king of plants in Ayurveda for its extensive B, tercatain, and tergallagin from the leaves of Terminalia medicinal use [8]. (e plants mainly include tannins, catappa Linn. in 1986 [15]. Since then, more than 82 tannins polyphenols, triterpenoids, flavonoids, aliphatic com- have been isolated from the fruits, barks, leaves, and galls in pounds, and other active ingredients, among which tannins the plants of the genus Terminalia. (e mass spectrometric and polyphenols are the main constituents [9]. data of these tannins and the structure analysis of the Tannins are a kind of polyphenolic compounds with compounds are discussed. (is review aims to provide complex structures in plants. (ey are classified into three references for the structure identification of tannin con- groups on the basis of their structures: hydrolysable tannins, stituents in the plants of Terminalia Linn. In the further 2 Evidence-Based Complementary and Alternative Medicine OH OH HO OH HO OH O HO OH O OH OH HO O OH O OH HO HO OH O HO O O OH O O O OH O O HO OH H OH O O O OH O OH HO O O HO O HO O O H HO OH O O O OH OH OH OH O HO OH O O OH O OH OH OH OH HO OH OH 1 234 OH OH HO OH OH HO OH HO OH OH OH O HO OH OH HO OH OH HO O O HO O HO O O O O O HO OH OH O HO O H O OH O HO O O HO OO HO O O O O O OH O H O HO O O OO OH HO O O HO O OOH O HO OH O HO O OH O OH HO OH OH HO HO OH OH OH OH OH 5 678 OH OH OH HO OH HO OH HO OH OH OH OH HO HO HO O O OH O O OH O O OH O OH O OH O OH HO O HO O HO O O O O O O O O OH O OH O OH HO O O O HO OH O HO O O O OO HO HO HO O OH OH OH HO OH OH 91011 Figure 1: Structures of compounds 1–11. study of phytochemistry, the research field of medicinal 3. Results and Discussions activity of this important genus should be highlighted and guided. 3.1. Tannins. Tannins are widely distributed in plants. (ey can be classified into three types according to their structural 2. Methods differences. Hydrolysable tannins are a group of compounds formed by phenolic acids and their derivatives through 2.1. Data Sources and Searches. Electronic searches were glycoside bonds or ester bonds with glucose or polyols. (ey conducted in scifinder and PubMed for articles up to are further divided into gallotannins containing only galloyl September 2018, using terms related to tannins, Terminalia, groups, ellagitannins containing hexahydroxydiphenoyl and MS. Searches were conducted with no date or language group(s), and hydrolysable tannin oligomers divided into restrictions. dimers, trimers, and tetramers according to the number of glucose nuclei [16]. Condensed tannins are a class of compounds formed by the carbon-carbon bond polymeri- 2.2. Eligibility and Selection. (e titles and abstracts of 197 zation of flavane-3-ol such as catechins or their derivative articles were screened, respectively, and the full text of the gallocatechin. Complex tannins are a class of compounds article was reviewed to obtain sufficient information. Any composed of flavane-3-ol, the unit of condensed tannins, disagreements regarding the inclusion of articles were re- and hydrolyzed tannins, which are partially linked by car- solved through discussion and consensus. bon-carbon bonds. On the basis of the structural differences, they are di- 2.3. Data Extraction. (e final data extraction included the vided into different types. Compounds 1–74 are hydro- following five categories: (1) general characteristics (com- lysable tannins. Among them, compounds 1–11 (Figure 1) pound name, source, structure, and journal name); (2) MS having only galloyl groups are gallotannins and compounds data (compound name, ion Source, ion mode, fragments, 12–71 (Figure 2) having hexahydroxydiphenoyl group(s) are and journal name); and (3) MS fragmentation pattern ellagitannins. In addition, compounds 72 and 73 (Figure 3) (fragmentation rules and journal name). possess two glucose nuclei, and compound 74 (Figure 3) Evidence-Based Complementary and Alternative Medicine 3 OH OH O OH OH OH HH OH OH OH O O O OH O HO OH O H O O O O HO OH O HO OH O O O OH O HO O OH OH OH O O H O HO O O OH HO HO HO O O OH OH O O O OH OH O HO OO O O OH O OH OH 12 13 14 15 OH OH HO OH OH HO O OH OH OH O O OH HO HO OH OO O OH HO OH O O OH O O O OH HO O OH HO HO HO H HO O O O OH OH O O O O HO OO OH O OH O HO OH OH HO OO OH OH OH HO O O OH OH OH OH OH OH OH OH 16 17 18 19 O OH O HO H OH HO OH O O OH O OH OH HO O H HO OH OH O OH HO OH HO HO O O HO O OH HO H OH OH OH HO O O O HO O HO OH HO OH H O O O O O O O O OH HO O O OH HO O O OH O O O O OH HO OH O O HO HO OH HO OH OH 20 21 22 23 OH OH HO OH OH OH OH OH HO OH O OH O O OH OH OH OH OH OH HO O OH OH O OH O OH O O O O O O O O O H O O O O OH O HO OO O O O OH O OH OH O O O O HO HO O HO O O OH HO OO OH O HO O O OH OH OH O OH OH OH 24 25 26 27 O OH OH OH OH OH HO OH HO O HO O HO OH OH OH HO HO OH OH OH O OH OH O OH O HO O O OH OO HO OH HO O O O OH O OH O O HO O O O O O HO O OH O HO OH HO O OH O OH O O OH OH HO O OH O HO OH OH HO O O O OH O OH O OH O OH OH OH OH 28 29 30 31 OH HO OH OH HO OH O O OH HO OH OH OH HO OH O O OH OH HO O OH O OH O O HO O O OH OH H OO OH HO O O OH O O OH OH HO O O O H O OH O OH HO O OH O O HO O OH O OH H O O HO O HO O O OH O OH HO O OH O O O HO O HO O OH O HO OH OH HO OH HO OH 32 33 34 35 Figure 2: Continued.