Tabernaesine J, a Novel Vincamine‐Type Indole Alkaloid with 6/5/6/6/6/5/5 Heptacyclic‐Ring System Scaffold from Tabernaemontana pachysiphon

Abstract

Comprehensive SummaryTabernaesine J (1), an unprecedented vincamine‐type indole alkaloid with 6/5/6/6/6/5/5 heptacyclic‐ring system, as well as one new biogenetically related vincamine‐type indole alkaloid (2), were isolated from leaves of Tabernaemontana pachysiphon. Their structures were established by a combination of HRESIMS, NMR, single crystal X‐ray diffraction, and ECD calculation. The unprecedented penta‐lactone ring in tabernaesine J (1) was postulated to be derived from acetyl‐CoA enolate anion. Alkaloid 2 combined with fluconazole has the potential to overcome fluconazole resistance in Candida albicans.