{"title":"[单宁的动态化学]。","authors":"Takashi Tanaka","doi":"10.1248/yakushi.23-00170","DOIUrl":null,"url":null,"abstract":"<p><p>Tannins are a group of polyphenols that possess the ability to precipitate proteins, causing an undesirable astringent taste by interacting with salivary peptides. This interaction deactivates the digestive enzymes; therefore, tannins are considered as plant defense substances. The health benefits of tannins and related polyphenols in foods and beverages have been demonstrated by biological and epidemiological studies; however, their metabolism in living plants and the chemical changes observed during processing of foods and medicinal herbs raises some questions. This review summarizes our studies concerning dynamic changes observed in tannins. Ellagitannins present in the young leaves of Camellia japonica and Quercus glauca undergo oxidative degradation as the leaves mature. Similar oxidative degradation is also observed in whiskey when it is kept for aging in oak barrels, and in decaying wood caused by fungi in natural forests. In contrast, ellagitannins have been observed to undergo reduction in the leaves of Carpinus, Castanopsis, and Triadica species as the leaves mature. This phenomenon of reductive metabolism in leaves enabled us to propose a new biosynthetic pathway for the most fundamental ellagitannin acyl groups, which was also supported by biomimetic synthetic studies. Polyphenols undergo dynamic changes during the process of food processing. Catechin in tea leaves undergo oxidation upon mechanical crushing to generate black tea polyphenols. Though detailed production mechanisms of catechin dimers have been elucidated, structures of thearubigins (TRs), which are complex mixtures of oligomers, remain ambiguous. Our recent studies suggested that catechin B-ring quinones couple with catechin A-rings during the process of oligomerization.</p>","PeriodicalId":23810,"journal":{"name":"Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.3000,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"[Dynamic Chemistry of Tannins].\",\"authors\":\"Takashi Tanaka\",\"doi\":\"10.1248/yakushi.23-00170\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Tannins are a group of polyphenols that possess the ability to precipitate proteins, causing an undesirable astringent taste by interacting with salivary peptides. This interaction deactivates the digestive enzymes; therefore, tannins are considered as plant defense substances. The health benefits of tannins and related polyphenols in foods and beverages have been demonstrated by biological and epidemiological studies; however, their metabolism in living plants and the chemical changes observed during processing of foods and medicinal herbs raises some questions. This review summarizes our studies concerning dynamic changes observed in tannins. Ellagitannins present in the young leaves of Camellia japonica and Quercus glauca undergo oxidative degradation as the leaves mature. Similar oxidative degradation is also observed in whiskey when it is kept for aging in oak barrels, and in decaying wood caused by fungi in natural forests. In contrast, ellagitannins have been observed to undergo reduction in the leaves of Carpinus, Castanopsis, and Triadica species as the leaves mature. This phenomenon of reductive metabolism in leaves enabled us to propose a new biosynthetic pathway for the most fundamental ellagitannin acyl groups, which was also supported by biomimetic synthetic studies. Polyphenols undergo dynamic changes during the process of food processing. Catechin in tea leaves undergo oxidation upon mechanical crushing to generate black tea polyphenols. Though detailed production mechanisms of catechin dimers have been elucidated, structures of thearubigins (TRs), which are complex mixtures of oligomers, remain ambiguous. Our recent studies suggested that catechin B-ring quinones couple with catechin A-rings during the process of oligomerization.</p>\",\"PeriodicalId\":23810,\"journal\":{\"name\":\"Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.3000,\"publicationDate\":\"2024-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1248/yakushi.23-00170\",\"RegionNum\":4,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"PHARMACOLOGY & PHARMACY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1248/yakushi.23-00170","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHARMACOLOGY & PHARMACY","Score":null,"Total":0}
引用次数: 0
摘要
单宁酸是一类多酚类物质,具有沉淀蛋白质的能力,通过与唾液肽相互作用,产生一种不良的涩味。这种相互作用会使消化酶失活,因此单宁酸被视为植物防御物质。生物学和流行病学研究证明,食品和饮料中的单宁酸和相关多酚对健康有益;然而,单宁酸在活体植物中的新陈代谢以及在食品和药材加工过程中观察到的化学变化提出了一些问题。本综述总结了我们对单宁酸动态变化的研究。山茶和柞树嫩叶中的鞣花丹宁会随着叶子的成熟而发生氧化降解。威士忌在橡木桶中陈酿时也会发生类似的氧化降解,天然森林中的真菌也会导致木材腐烂。与此相反,人们观察到鞣花丹宁会随着木犀属(Carpinus)、栲属(Castanopsis)和三叶草属(Triadica)物种叶子的成熟而减少。叶片中的这种还原代谢现象使我们能够为最基本的鞣花丹宁酰基提出一种新的生物合成途径,生物模拟合成研究也支持这一观点。多酚在食品加工过程中会发生动态变化。茶叶中的儿茶素在机械粉碎时会发生氧化,生成红茶多酚。虽然儿茶素二聚体的详细生成机制已被阐明,但由低聚物组成的复杂混合物大黄素(TRs)的结构仍然模糊不清。我们最近的研究表明,在低聚物形成过程中,儿茶素 B 环醌与儿茶素 A 环发生了耦合。
Tannins are a group of polyphenols that possess the ability to precipitate proteins, causing an undesirable astringent taste by interacting with salivary peptides. This interaction deactivates the digestive enzymes; therefore, tannins are considered as plant defense substances. The health benefits of tannins and related polyphenols in foods and beverages have been demonstrated by biological and epidemiological studies; however, their metabolism in living plants and the chemical changes observed during processing of foods and medicinal herbs raises some questions. This review summarizes our studies concerning dynamic changes observed in tannins. Ellagitannins present in the young leaves of Camellia japonica and Quercus glauca undergo oxidative degradation as the leaves mature. Similar oxidative degradation is also observed in whiskey when it is kept for aging in oak barrels, and in decaying wood caused by fungi in natural forests. In contrast, ellagitannins have been observed to undergo reduction in the leaves of Carpinus, Castanopsis, and Triadica species as the leaves mature. This phenomenon of reductive metabolism in leaves enabled us to propose a new biosynthetic pathway for the most fundamental ellagitannin acyl groups, which was also supported by biomimetic synthetic studies. Polyphenols undergo dynamic changes during the process of food processing. Catechin in tea leaves undergo oxidation upon mechanical crushing to generate black tea polyphenols. Though detailed production mechanisms of catechin dimers have been elucidated, structures of thearubigins (TRs), which are complex mixtures of oligomers, remain ambiguous. Our recent studies suggested that catechin B-ring quinones couple with catechin A-rings during the process of oligomerization.