The implication of quinones in decay resistance of teak wood is controversial. To better understand the role of individual quinone in this property, we studied the correlations between this latter and the content of 2-(hydroxymethyl)anthraquinone, tectoquinone, anthraquinone-2-carboxylic acid, 1,4-naphthoquinone, lapachol and the new compound 4’,5’-dihydroxy-epiisocatalponol found in teak wood. Then, we studied the fungicidal activities of these quinones in comparison to acetone/water extracts from teak heartwood and sapwood and also with the commercial biocide tebuconazole. Broth dilution technique was used to assess the toxicity of these compounds against Trametes versicolor and Poria placenta. Decay resistance was measured according to current standards and individual quinones content were quantified by high performance liquid chromatography. High positive correlations were found between teak decay resistance and the content of 4’,5’-dihydroxy-epiisocatalponol, tectoquinone, 2-(hydroxymethyl)anthraquinone. Whereas no correlation was found with anthraquinone-2-carboxylic acid, lapachol and 1,4-naphthoquinone. Concerning the fungicidal activities of teak wood extractives, acetone/water heartwood extract was toxic against the two fungi while that of acetone/water sapwood was only fungistatic. 1,4-naphthoquinone and 4’,5’-dihydroxy-epiisocatalponol from the naphthoquinones family were fungicide. However, lapachol and all studied anthraquinones (2-(hydroxymethyl)anthraquinone, anthraquinone-2-carboxylic acid and tectoquinone) were fungistatic or not toxic. In the present study, 1,4-naphthoquinone was found the more toxic with a fungicidal activity 1000-times lower than that of the commercial biocide and over 2000-times lower than that of acetone/water heartwood extracts. These results show that decay resistance of teak wood could be mostly due to the content of naphthoquinone, particularly to that of 1,4-naphthoquinone indicating that it could be used as a potential wood preservative for lesser durable species.

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