Structure of laurycolactone A and B,new C18 - quassinoids from Eurycoma longifolia and revised structured of Eurycomalactone (X - ray analysis)

Laurycolactone A $\text{2}$ and B $\text{3}$ are new quassinoids with a C₁₈ basic skeleton isolated from the Vietnamese Simaroubaceae, Eurycoma longifolia Jack. The structure of Eurycomalactone, a C₁₉ quassinoid isolated previously from the same plant, has been revised and shown to be $\text{4}$. The structures have been established by spectral means and those of $\text{2}$ and $\text{4}$ confirmed by X-ray diffraction analysis.