Radial distribution of quinones in plantation teak (Tectona grandis L.f.)

Quinones are primarily responsible for the natural durability of teak. The previous paper in this series reported on the natural termite resistance of teak trees of different ages (8-, 30- and 51-year-old trees). In this study, the radial distribution of quinones (tectoquinone, lapachol, desoxylapachol and its isomer) and other components in the ethanol-benzene (1: 2) extract were measured by means of gas chromatography. Significant differences in desoxylapachol or its isomer content were found among the outer heartwood of 8-, 30- and 51-year old trees, as well as between the inner and outer parts of the heartwood. All toxic quinone contents were positively correlated with the total extractive content. The highest correlation degree was measured in the isodesoxylapachol content. Although linearly related, only modest correlations were observed between the natural termite resistance parameters and the content of tectoquinone and isodesoxylapachol.