A METABOLIC PRODUCT OF ANTIFUNGAL LIGNAN FROM THE HEARTWOOD OF GMELINA ARBOREA WITH A WHITE-ROT FUNGUS, TRAMETES VERSICOLOR

摘要

The heartwood of Gmelina arborea Linn. (Verbenaceae) had been known to show high durability. The methanol extracts, n-hexane-Solubles, ethyl acetate (EtOAc)-Solubles and EtOAc-Inolubles from the heartwood of G. arborea were assayed against Trametes versicolor using a medium containing homogenized hyphae. The EtOAc-Solubles, which showed the highest activity, were separated by TLC. The active zones were specified by autobiography. The constituents were isolated from active zones by preparative TLC andHPLC, and structurally determined by instrumental analyses. Several lignans were identified, and antifungal assay of each lignan was carried out. It was elucidated that (+)-gmelinol was the major antifungal lignan in the heartwood of G. arborea. Then the metabolic products of (+)-gmelinol with T. versicolor were investigated. (+)-Gmelinol was put into a liquid medium consisting of a malt extract, and incubated. After incubation, hyphae and liquid medium were partitioned with EtOAc. The metabolic products were isolated from EtOAc-Solubles by preparative HPLC, and structurally determined by instrumental analyses. (+)-7'-0-Methyl gmelinol was determined as a metabolic product of (+)-gmelinol. Antifungal assay of three metabolized products was conducted.(+)-7'-0-Methyl gmelinol showed activity at 50 tig/disk of minimum inhibitory concentration (MIC), and it was higher than that of substrate, (+)-gmelinol (MIC, 100 J.g/disk). The metabolic product, (+)-7'-0-methyl gmelinol appear to play important role in the antifungal activity of (+)-gmelinol against T. versicolor.