Phloroglucinol Derivatives with Unusual Skeletons from Cleistocalyx operculatus and Their in Vitro Antiviral Activity

Four
novel phloroglucinol derivatives (1–4) featuring a 2,4-dimethyl-cinnamyl-phloroglucinol moiety,
along with their putative biosynthetic precursors 5 and 6, were isolated from the leaves of Cleistocalyx operculatus. Compounds 1 and 2 are two pairs of new
enantiomeric phloroglucinol dimers possessing an unprecedented polycyclic
skeleton with a highly functionalized dihydropyrano­[3,2-d]­xanthene tetracyclic core. Compounds 3 and 4 are two new phloroglucinol-terpene adducts (PTAs) with a novel carbon
skeleton. The structures of 1–4 including
their absolute configurations were unambiguously accomplished by combination
of extensive spectroscopic analyses, X-ray crystallography, and quantum
chemical ECD calculations. A hypothetical biosynthetic pathway for 1–4 was also proposed. Compound 1 exhibited a promising in vitro antiherpes
simplex virus type-1 (HSV-1) effect.

从 Cleistocalyx operculatus 的叶中分离出四种新型的香豆素葡萄糖衍生物（1-4），它们含有2,4-二甲基桂皮基香豆素基团，以及其假定的生物合成前体5和6。化合物1和2是一对新的对映异构体香豆素二聚体，具有前所未有的多环骨架，并含有高度官能化的二氢吡喃[3,2-d]香豆素四环核心。化合物3和4是两种新的香豆素-萜类加成物（PTAs），具有新颖的碳骨架。通过结合广泛的光谱分析、X射线晶体学和量子化学ECD计算，明确地确定了1-4的结构及其绝对构型。同时，还提出了1-4的假想生物合成途径。化合物1在体外表现出对单纯疱疹病毒1型（HSV-1）的潜在抗病毒作用。