Rearranged and enantiomeric alkaloids from Cephalotaxus sinensis

Abstract

Three undescribed alkaloids (1–3) along with 30 known ones were isolated from the twigs and leaves of Cephalotaxus sinensis. The structures of the new alkaloids were determined through comprehensive spectroscopic analysis and ECD calculations. Cephalosinine A (1) with 6/6/6/5 ring system represents a new type of Cephalotaxus alkaloid, which might be formed through a rearrangement from simultaneously isolated cephalotaxinone. Cephalolancine B (2) was the second cephalolancine skeleton alkaloid. (+)-Acetylcephalotaxine β-N-oxide (3) was an enantiomeric Cephalotaxus alkaloid. The isolated homoerythrina-type alkaloids were evaluated for their in vitro hearing protective effects against neomycin-induced cell death in HEI-OC-1 cells.