We analysed the chemical composition of extracts in the sapwood, heartwood, knots and branches of silver fir (Abies alba Mill.) and examined their fungistatic, antimicrobial and antioxidative properties. We investigated the variability in extract content in the centripetal direction, that is, from the periphery of the trunk towards the pith, and in the longitudinal direction. We isolated wood samples from the trunk, knots and branches. The wood was extracted at an elevated temperature and pressure. Cyclohexane and acetone were used as solvents. Extract and total phenol content were determined by the gravimetric and spectrophotometric methods. Phenolic extracts were identified using thin-layer chromotography and high-resolution liquid chromatography. Fungistatic, antimicrobial and antioxidative properties of the extracts were assessed with a diffusion test and the diphenylpicrylhydrazyl radical scavenging method. We found that knot and branch wood contains the highest amount of hydrophilic extracts, heartwood less so and sapwood the least. Among the identified compounds are lignans, phenolic acids and flavonoids. Secoisolariciresinol was predominent in live knots and branches, while matairesinol was prevalent in heartwood. The largest amount of phenolic compounds was extraced from sections of knots included in the sapwood and from parts of branches closest to the trunk. Heartwood contained more lignans in its older sections. A characteristic variability in extract content in the longitudinal direction of the trunk was not found. Hydrophilic extracts from knots and branches inhibited the growth of wood-decay fungi and molds, but the inhibition was not strong. Knot and branch extracts exhibited good antioxidative properties. We found that knot and branch extracts are better free radical scavengers than heartwood extracts. The results of this study describe knot and branch wood as the richest sources of phenolic extracts and lignans in a silver fir tree. Results of biological activity tests indicate that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties.
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