School of Chemical Technology Degree Programme of Forest Products Technology Tiina Belt WOOD PRESERVATIVE POTENTIAL OF SCOTS PINE BARK AND KNOT EXTRACTIVES Master’s thesis for the degree of Master of Science in Technology

The purpose of this investigation was to assess the potential of Scots pine (Pinus sylvestris L.) bark and knot extractives to function as preservative chemicals. Scots pine was chosen to due to its importance in Finland; bark and knots were chosen due to their high extractives content and lack of industrial applications. The bark and knots of Scots pine were extracted with acetone and the extraction yields calculated. The chemical composition of the extracts was determined using gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and UV Raman spectroscopy. Their antifungal activity was studied using a wood-free agar plate method. The bark and knots of Scots pine were found to contain large amounts of extractives, 16.8% and 24.6%, respectively. The bark extract consisted primarily of monosaccharides and resin acids; the knot extract of resin acids and pinosylvins. Both extracts also contained smaller amounts of fatty acids and other compounds. The bark extract was found to have no significant antifungal activity: at a low concentration the extract promoted the growth of fungi, while at a high concentration it had no statistically significant effect on growth. The lack of activity was concluded to be due to the chemical composition of the extract. None of the main compounds present in the bark extract are significantly antifungal, and the saccharides most likely acted as an additional food source, leading to increased growth at the lower concentration. The knot extract inhibited the growth of fungi at the higher concentration, and the activity of the extract was concluded to be due to the presence of large amounts of pinosylvins, which are known for their antifungal properties. The results of this investigation showed that Scots pine knot extractives may have potential as wood preservative chemicals. The knot extract showed significant antifungal character at a moderate concentration, and the extractives were obtainable in high yields. However, more study is needed before definitive conclusions can be drawn. Most importantly, the preservative potential of the extractives should be determined using tests that involve impregnation of wood. The use of extractives in wood impregnation is also subject to a number of general problems that should be studied before conclusions can be drawn.