Extractives of tree barks have long been considered as a rich source of novel bioactive secondary metabolites, which are by far not well-explored. In the current work, bark extracts of Catalpa bungei were investigated for the first time and five extractives were isolated and purified, including a new triterpene saponin derivative, namely 3- O - β - D -glucuronopyranosyl-6′-methyl-21- O - cis -caffeoyl machaerinic acid ( 4 ), two known flavonoids [(+)-gallocatechin ( 1 ) and isoquercitrin-6″-gallate ( 2 )], a known oleanane-type triterpene [machaerinic acid ( 3 )] and a known phytosterol [stigmasterol ( 5 )]. Chemical structural elucidation of extractives 1 – 5 was carried out mainly on the basis of their physicochemical and spectroscopic (IR, NMR, MS) evidences and analysis, as well as by detailed comparison of the analytical evidence with those in the literature. To the best of the authors' knowledge, this is the first time to find the occurrence of extractives 1 – 5 in the tree of C. bungei . It is noteworthy that the five constituents have never previously been reported in any species of Catalpa genus. Compound 4 , a previously undescribed triterpene saponin derivative, was isolated and elucidated in this work for the first time.

中文翻译：

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楸树皮提取物：三萜、植物甾醇和类黄酮衍生物的分离、纯化和结构解析

长期以来，树皮提取物一直被认为是新型生物活性次级代谢物的丰富来源，但目前尚未对其进行充分探索。在目前的工作中，首次研究了楸树的树皮提取物，分离纯化了五种提取物，包括一种新的三萜皂苷衍生物，即3-O-β-D-吡喃葡萄糖醛酸基-6'-甲基-21-O - 顺式咖啡酰 machaerinic acid ( 4 )，两种已知的黄酮类 [(+)-gallocatechin ( 1 ) 和 isoquercitrin-6″-gallate ( 2 )]，一种已知的齐墩果型三萜 [machaerinic acid ( 3 )] 和一种已知的植物甾醇 [豆甾醇 ( 5 )]。提取物 1-5 的化学结构解析主要基于其理化和光谱（IR、NMR、MS）证据和分析，以及通过将分析证据与文献中的证据进行详细比较。据作者所知，这是第一次在 C. bungei 树中发现提取物 1 – 5 的出现。值得注意的是，这五种成分以前从未在任何楸属物种中报道过。化合物4，一种先前未描述的三萜皂苷衍生物，在该工作中首次被分离和阐明。