Sarcglabates A/B, Aromatized Pentanor Lindenane Sesquiterpenoid Dimers from Sarcandra glabra

Sarcglabates A-F (1-6), six lindenane sesquiterpenoid dimers possessing two unprecedented skeletons, were isolated from Sarcandra glabra. Their structures were thoroughly determined using HR-MS, NMR, and ECD and verified by single crystal X-ray diffraction. Structurally, compounds 1-2 represent the first examples of aromatized pentanor lindenane dimers featuring a critical 6/5/6 skeleton with a rare benzene ring, which formed via a plausible intramolecular nucleophilic reaction and aromatization assisted departure of a penta-carbon fragment. Lindenanes 3-5 were fused through rare tetrahydrofuran by nucleophilic addition. Compounds 1-6 were assessed through screening the inhibitory effect on the inflammatory factor IL-1β, with 6 further inhibiting the progression of inflammation by suppressing the activation of P65.