Traditional medicinal plants of Thailand, IX. 10-Hydroxy-11-methoxydracaenone and 7,10-dihydroxy-11-methoxydracaenone from Dracaena loureiri.

Examination of Dracaena loureiri, a Thai medicinal plant possessing anti-bacterial activity, has led to the isolation of two new representatives, 1 and 2, of a rare skeleton of homoisoflavans. Proton assignments of the two isolates were aided by extensive 2D-homonuclear chemical shift correlation and nOe difference spectroscopy. Carbon assignments were completed through the utilization of simple and sensitive one-dimensional techniques such as selective population transfer via one-bond (CSCM 1D) and selective polarization transfer via long range coupling (selective INEPT) experiments. Conformational assignments were proposed through nOe difference spectroscopy and have been established by X-ray crystallography. The absolute configuration is proposed based on the octant rule and a biogenetic pathway for this type of homoisoflavan is briefly discussed.