Lycotetrastine A, a novel hexacyclic alkaloid from Huperzia tetrasticha

A novel C20N-type Lycopodium alkaloid with an unprecedented fused-hexacyclic ring system consisting of a γ-lactone, an aza-cycloheptene, an aza-cyclohexane, a cyclohexane, a cyclopentane, and tetrahydrofuran rings, lycotetrastine A (1) was isolated from the club moss of Huperzia tetrasticha. The structure and absolute stereochemistry were elucidated on the basis of 2D NMR correlations and X-ray analysis.