Chemical Study of Cassane-type Diterpenoid Isomers from the Root Bark of Erythrophleum ivorense A. Chev. (Fabaceae)

Abstract

Cassane-type diterpenoid alkaloids are among the major secondary metabolites reported in the genus Erythrophleum and are known for their important biological activities. In the present study, the methanolic extract of the root bark of Erythrophleum ivorense was investigated in order to isolate and characterize cassane-type diterpenoid isomers. Successive chromatographic separations of the ethyl acetate extract led to the isolation of two diterpenoid alkaloid isomers. Their structures were elucidated by combining IR, HR-ESI-MS, 1D and 2D NMR analyses. The two compounds exhibited the same molecular formula, C25H39NO7, and were identified as N,N-dimethyl-3β,6α-dihydroxy-nor-cassane and N,N-dimethyl-3β,7α-dihydroxy-nor-cassane. These compounds had previously been reported in the genus Erythrophleum, but this work constitutes their first isolation from the root bark of Erythrophleum ivorense. This study contributes to the phytochemical knowledge of the species and confirms the richness of its root bark in cassane-type diterpenoid alkaloids.