Isolation of two cassane-type diterpenoids from the bark of Erythrophleum suaveolens (Guill. & Perr.) Brenan (Fabaceae)

Erythrophleum suaveolens is a plant species used to treat Buruli ulcer in Côte d'Ivoire. This plant is rich in cassane-type diterpenoids, compounds known for their multiple biological activities. This study focuses on the isolation, purification, and structural identification of two cassane-type diterpenoids from the ethyl acetate extract of the bark of Erythrophleum suaveolens. Two molecules were isolated using conventional purification and isolation methods, namely column chromatography and preparative HPLC. The structural analysis of these compounds was carried out using one-dimensional (1D) and two-dimensional (2D) 1H and 13C Nuclear Magnetic Resonance (NMR), COSY, HMBC, and NOESY. The molecules were identified as 3β-acetoxyerythrosuamine and 3β-hydroxy-3-methylbutanoyloxy-6α-hydroxy-nor-cassamine. These compounds have already been isolated from the root bark of this plant, but this is the first time they have been isolated from the trunk bark. Both compounds belong to the cassane genus, and their discovery enriches the chemistry of E. suaveolens.