五对新的摩洛半萜对映体,命名为dau间苯二酚A-E(1-5),是从杜鹃花的叶子中分离出来的。通过全面的光谱数据分析阐明了它们的结构,量子化学计算,Rh2(OCOCF3)4诱导的ECD,和单晶X射线衍射分析。Dau间苯二酚A(1)和B(2)拥有两个新的甲半萜骨架,带有前所未有的2,6,7,10,14-五甲基-11-氧合四环[8.8.0.02,7.012,17]十八烷和笼状的15-异己基-1,5,15-三甲基-2,10-二氧杂环[7.4.1.111,14.03,8]十五烷分别。提出了1-5的合理生物合成途径,涉及关键的oxa电环化和Wagner-Meerwein重排反应。(+)/(-)-1和3-5显示出有效的α-葡萄糖苷酶抑制活性,比阿卡波糖强3到22倍,针对α-葡萄糖苷酶的抗糖尿病药物。对接结果为设计和开发作为有效的α-糖苷酶抑制剂的聚半萜类化合物提供了基础。
Five pairs of new merosesquiterpenoid enantiomers, named dauresorcinols A-E (1-5), were isolated from the leaves of Rhododendron dauricum. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum chemical calculations, Rh2(OCOCF3)4-induced ECD, and single-crystal X-ray diffraction analysis. Dauresorcinols A (1) and B (2) possess two new merosesquiterpene skeletons bearing an unprecedented 2,6,7,10,14-pentamethyl-11-oxatetracyclo[8.8.0.02,7.012,17]octadecane and a caged 15-isohexyl-1,5,15-trimethyl-2,10-dioxatetracyclo[7.4.1.111,14.03,8]pentadecane motif, respectively. Plausible biosynthetic pathways of 1-5 are proposed involving key oxa-electrocyclization and Wagner-Meerwein rearrangement reactions. (+)/(-)-1 and 3-5 showed potent α-glucosidase inhibitory activity, 3 to 22 times stronger than acarbose, an antidiabetic drug targeting α-glucosidase. Docking results provide a basis to design and develop merosesquiterpenoids as potent α-glycosidase inhibitors.