Alscholarines A and B, two rearranged monoterpene indole alkaloids from Alstonia scholaris

• DOI: 10.1039/d3ob01424j
• Publication Date: 2023-09-28T15:01:13Z
• Authors: Guanqun Zhan; Fuxin Zhang; Kailing Yang; Tao Yang; Ruixi Zhou; Wenwen Chen; Jingwei Zhang; Xinxin Zhang; Zengjun Guo
• Keywords: Monoterpene; Indole alkaloid; Moiety; Imidazole; Quantum chemical; Apocynaceae

Alscholarines A and B (1 2), two unprecedented rearranged monoterpene indole alkaloids, were isolated from Alstonia scholaris. Alscholarine (1) features an imidazole ring fused with a vallesamine-type alkaloid possessing unparalleled 6/5/6/6 tetracyclic skeleton through C7-C-19 connectivity. (2), incorporating unusual 7-oxa-1-azabicyclo[3.2.1]octane moiety, represents unique 6/5/6/6/5 system via C-6-C-20 Their structures established by spectroscopic analysis, X-ray crystallography, quantum-chemical calculations. plausible biosynthetic pathways proposed. The vasorelaxant anti-inflammatory activities of them also evaluated. Compounds 1-3 showed moderate activities.