New Antiinflammatory Pseudopterosins from the Marine Octocoral Pseudopterogorgia elisabethae

Article abstract of DOI:10.1021/jo00303a030

Eight new diterpene glycosides, pseudopterosins E-L (1-8), along with the methylated aglycon from pseudopterosin E (9), have been isolated from the organic extracts of two individual collections of the tropical Atlantic sea whip Pseudopterogorgia elisabethae.The aglycon portions of pseudopterosins E and F (1, 2) are identical with that of pseudopterosin A, but both metabolites have sugar moieties (α-L-fucose for pseudopterosin E and α-D-arabinose for pseudopterosin F) attached at the C-10 hydroxyl.Pseudopterosin G and its monoacetates (pseudopterosins H-J) are C-9 α-L-fucose glycosides.The diterpene aglycon of these molecules is a methyl epimer at the C-7 chiral center, in relation to the aglycons derived from pseudopterosins E and F.Pseudopterosins K and L (7, 8) are α-fucosides with the same diterpene skeleton as pseudopterosins E and F, but with the sugar attached to the C-9 hydroxyl.However, the aglycons of pseudopterosins K and L were found to be enantiomeric to those from pseudopterosins E and F (1, 2).The structure of pseudopterosin F was confirmed by X-ray crystallographic analysis, and the other new pseudopterosins were chemically converted to the derivatives derived from pseudopterosin F.The new pseudopterosins are superior antiinflammatory agents in comparison to pseudopterosin A.Pseudopterosin E (1) shows very low acute toxicity in mice (LD₅₀ > 300 mg/kg) and appears to act by a novel mechanism of pharmacological action.