Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
Guangxi Key Laboratory of Functional Phytochemicals Research and Utilization, Guangxi Institute of Botany, Guilin 541006, China.
Molecules. 2021 Jul 7;26(14):4134. doi: 10.3390/molecules26144134.
Ellagitannins (ETs) are plant polyphenols with various health benefits. Recent studies have indicated that the biological activities of ETs are attributable to their degradation products, including ellagic acid and its gut microflora metabolites, such as urolithins. Insect tea produced in the Guangxi region, China, is made from the frass of moth larvae that feed on the ET-rich leaves of . Chromatographic separation of the Guangxi insect tea showed that the major phenolic constituents are ellagic acid, brevifolin carboxylic acid, gallic acid, brevifolin, and polymeric polyphenols. Chemical investigation of the feed of the larvae, the fresh leaves of , showed that the major polyphenols are ETs including pedunculagin, casuarictin, strictinin, and a new ET named platycaryanin E. The new ET was confirmed as a dimer of strictinin having a tergalloyl group. The insect tea and the leaves of contained polymeric polyphenols, both of which were shown to be composed of ETs and proanthocyanidins by acid hydrolysis and thiol degradation. This study clarified that Guangxi insect tea contains ET metabolites produced in the digestive tract of moth larvae, and the metabolites probably have higher bioavailabilities than the original large-molecular ETs of the leaves of .
鞣花单宁（ETs）是具有多种健康益处的植物多酚。最近的研究表明，ETs 的生物活性归因于其降解产物，包括鞣酸及其肠道微生物代谢物，如尿石素。中国广西地区生产的虫茶是由以富含 ET 的叶子为食的蛾幼虫的粪便制成的。广西虫茶的色谱分离表明，主要的酚类成分是鞣酸、短叶苏木酚羧酸、没食子酸、短叶苏木酚和聚合多酚。对幼虫的饲料，即新鲜的叶子的化学研究表明，主要的多酚是 ETs，包括鞣花单宁、卡苏卡丁、斯特里蒂宁和一种名为 platycaryanin E 的新 ET。新的 ET 被确认为斯特里蒂宁的二聚体，具有三没食子酰基。虫茶和叶子都含有聚合多酚，酸水解和巯基降解表明它们均由 ETs 和原花青素组成。本研究阐明了广西虫茶含有在蛾幼虫消化道中产生的 ET 代谢物，并且这些代谢物可能比叶子中原有的大分子 ETs 具有更高的生物利用度。
