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Three stilbenes, pinosylvin (PS), pinosylvin monomethyl ether (PSM) and pinosylvin dimethyl ether (PSD), were extracted from white spruce (Picea glauca), jack pine (Pinus banksiana), and red pine (Pinus resinosa) pine cones, and their structures were confirmed by spectroscopic and chromatographic (HPLC, GC/MS, NMR and FTIR) analysis. PS, PSM, PSD or a 1:1:1 mixture of these stilbenes at concentrations of 0.1 % and 1.0 % were examined for their fungal inhibitory activity by two bioassay methods. Growth of white-rot fungi (Trametes versicolor and Phanerochaete chrysosporium), and brown-rot fungi (Neolentinus lepideus, Gloeophyllum trabeum and Postia placenta) on agar media in the presence of each of the stilbenes or a 1:1:1 mixture inhibited growth of white-rot fungi, but slightly stimulated growth of brown-rot fungi. Soil-block assays, conditions more representative of those found in nature, did not correlate with those from the screening on agar media. PS, PSM, PSD or a 1:1:1 mixture of the three compounds at concentrations of 0.1 % and 1.0 % did not impart any significant decay resistance to white-rot fungi inoculated on a hardwood (Red maple). However under the same conditions, decay resistance was observed against brown-rot fungi on a softwood (Southern yellow pine). It appears that stilbenes at least partially contribute to wood decay resistance against brown-rot fungi. KeywordsExtractives Conifer seed cones Stilbenes Fungitoxicity White-rot fungi Brown-rot fungi Phytoalexins Brought to you by | University of Glasgow Library Authenticated Download Date | 7/1/15 8:17 AM

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Resin acids in the diethyl ether extracts of Picea glauca, Pinus ponderosa and Pinus banksiana seed cones were identified by gas-liquid chromatography of their methyl-ester derivatives. For these seed cones, abietic, dehydroabietic and isopimaric acids comprised 63.7-80.5% of the total resin acids identified. In P. banksiana, the resin acid composition of the seed cones was shown to be significantly different from that in either the leaves, bark or wood. Investigation of the role of resin acids in the apparent decay resistance of woody conifer tissues to white-rot fungi involved the incorporation of abietic, dehydroabietic and isopimaric acids individually, or äs a l: l: l mixture, into decay susceptible sweetgum (Liquidambar styraciflua) wood lest blocks which were subsequently exposed to cultures of Irpex lacteus and Trametes versicolor. Inhibition of decay by /. lacteus was observed for test blocks treated with abietic and dehydroabietic acids, but not isopimaric acid. With T. versicolor, only those test blocks treated with abietic acid showed less decay when compared with controls. Comparisons of the decay levels with the moisture contents of resin acid treated test blocks, and the analyses of residual resin acid contents of decayed blocks, indicate that resin acids provide decay resistance by their water repellency and inherent decay resistance rather than general toxicity.Holzforschung / Vol. 48 / 1994 / No. 4

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