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This study is concerned with establishing a uniform experimental protocol for the determination of phenolic extractives, which play an essential role in the durability of the wood of selected species included in the field tests. European larch (Larix decidua), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), European oak (Quercus sp.), sweet chestnut (Castanea sativa), and black locust (Robinia pseudoacacia) were included in the study. Extraction yield data were collected for extraction in a Soxhlet apparatus using common polar extraction solvents (ethanol, acetone, methanol, water) and for single static extraction cycles in accelerated solvent extraction (ASE). The suitability of the solvents and the appropriate extraction conditions were evaluated based on the results of gravimetric analysis of hydrophilic extractives, spectrophotometric analysis of total phenols, and chromatographic analysis using high-performance liquid chromatography. Extraction in the ASE system with methanol proved to be a quick and accurate way to prepare samples for chemical analysis of extractives of selected wood species. With the chemical monitoring of targeted phenolic extractives in wood subjected to leaching, we propose a novel protocol suitable also for for measuring the effects of weathering on the natural durability of wood in future studies.

The main goal of the investigation was to measure and estimate the thermal stability of pinosylvin, pinosylvin monomethyl ether, robinetin, and dihydrorobinetin, i.e., characteristic compounds of wood of Scots pine and black locust, respectively. The pure compounds were analyzed with chromatography before and after they were steam-sterilized and oven-dried. Detailed thermogravimetric analysis was followed to check the thermal decomposition of the stilbenes and flavonoids of wood. The tested phenolic compounds were susceptible to thermal degradation. After the steam-sterilization and oven drying, the amount of investigated phenolic extractives decreased by more than a half. The thermogravimetric analysis showed that stilbenes decompose differently than flavonoids, which can be attributed to the different chemical structures. Twenty minutes of steam sterilization followed by 24 h of oven drying decreased the amount of phenolic compounds in the vials; however, after the applied thermal treatments, the stilbenes and robinetins stayed available in such quantities that they can still provide sufficient bioactivity. Nasl. z nasl. zaslona. Opis vira z dne 28. 9. 2022. Bibliografija: str. 9-12. Abstract.

Purpose Norway spruce log soaking water (SLSW) is considered a waste in the plywood and veneer industry but has not been characterised, and its possible uses remain unexplored. The purpose of this study is to characterise and test the possibility of using SLSW in wood preservative formulations. Methods First, the SLSW was characterised, and the presence of carbohydrates in the log soaking water was reduced with a hydrophobic adsorbent to reduce the nutrient availability for fungi in the liquids. Then, the feasibility of using SLSW and the sugar free SLSW (denoted later as EHC solution) as wood preservatives was studied by testing their antifungal and antioxidant activities and performing a mini-block test against Schizophyllum commune, Trametes versicolor, Fibroporia vaillantii and Gloeophyllum trabeum. Results Several phenolic compounds were found in the SLSW. This water also had high antioxidant activity at 1000 mg/L before and after carbohydrate removal but no antifungal activity. Its impregnation in wood caused a slight reduction in mass loss of the Pinus sylvestris specimens but had no effect on the Fagus sylvatica specimens when exposed against Schizophyllum commune, Trametes versicolor, Fibroporia vaillantii and Gloeophyllum trabeum. Conclusion The SLSW as a wood preservative is invalid, even after partial carbohydrate removal. However, due to the presence of wood constituents, SLSW could be a resource for other uses requiring high antioxidant activity but specific applications need further investigation. Graphical Abstract

The main goal of the study was to examine and compare the inhibition effect of knotwood extractives of Scots (Pinus sylvestris) and black pine (Pinus nigra) against the two white-rot fungi and two brown-rot fungi. Knotwood was extracted in a Soxhlet apparatus. Extracts were chemically analyzed, and the inhibitory effect of purified pinosylvins and crude hydrophilic extracts was tested against growth of the white-rot fungi Schizophyllum commune and Trametes versicolor and the brown-rot fungi Fibroporia vaillantii and Gloeophyllum trabeum with the in vitro antifungal assay. Knotwood of Scots pine and black pine contained comparable amounts of total extractives. Pinosylvin, pinosylvin monomethyl ether and nortrachelogenin were characteristic compounds in knotwood extracts of both pines. Scots pine knotwood contained larger amounts of pinosylvin than black pine. The ratio between pinosylvin monomethyl ether and pinosylvin was higher in black pine knotwood. Purified pinosylvins and crude hydrophilic extracts inhibited the growth of all the white-rot and brown-rot fungi tested. Pure pinosylvins better inhibited fungal growth than crude knotwood extracts, whereas the efficiency was not unambiguous and relates to fungi species. Crude hydrophilic extracts of Scots pine more efficiently inhibited fungal growth than extracts of black pine. With the present investigation, hydrophilic extracts of pine knotwood were demonstrated as formulations of natural compounds with good antifungal properties. Broken tops of Scots pine, which can lie on forest grounds for a month or even more, still contain high amounts of phenolic extractives and are therefore a potential raw material for recovery of bioactive compounds.

Forests are under great pressure due to climate changes. It is forecast that the importance of Mediterranean type forests will significantly increase. Among various types of oak species, pubescent oak (Quercus pubescens) will likely gain ecological and economic importance in the region south of Alps. Although this wood species is well known, there are not much data available about chemical properties and durability. A comprehensive analysis of extractives and durability against wood decay fungi was therefore performed. The results of the chemical analysis revealed that heartwood contains up to 20% of the extractives, with considerable amounts of phenols, including a fairly high concentration of Gallic acid (GAc). Anatomical structure, with high frequency of tylosis, resulted in good water exclusion efficacy. The presence of biologically active extractives and superior water exclusion efficacy resulted in good durability, as shown by basidiomycetes tests. Based on the laboratory data, factors that determine the service life of wood were calculated. Data indicate superior performance in above-ground applications.

Drug release profiles of novel alkane-crosslinked nanocellulose hydrogels were investigated. The common antiseptic compound chlorhexidine digluconate (CHX-DG) was loaded into the nanocellulose hydrogels, and the release kinetics were studied under two different release regimes. The hydrogels were effective at absorbing more than their dry weights of the antiseptic and retaining it during diffusion testing, with more than 60% of the drug retained in the hydrogels. Antimicrobial tests showed sustained antimicrobial activity of the CHX-DG-loaded hydrogels even after the two diffusion tests, which was attributable to non-ionic retention of the CHX-DG within the hydrogel structure.

The main goal of this study was to investigate the amounts of hydrophilic extractives in bark and wood samples of black locust stem (Robinia pseudoacacia L.). Six adult trees were included in the present investigation. Samples were taken from each felled trunk at four different heights. Material was extracted with a mixture of acetone and water, and the hydrophilic extractives were, then, qualitatively and quantitatively analysed. The highest contents of hydrophilic extractives, total phenols, dihydrorobinetin and robinetin were measured in wound-wood and heartwood. The concentrations of extractives were highest in the outermost samples of heartwood. Knotwood of black locust contained less dihydrorobinetin than heartwood. Significantly less hydrophilic compounds were extracted from bark and sapwood samples. This study shows that heartwood of black locust can be considered a source of value-adding compounds. The investigation showed significant variability in the content of extractives in radial direction and less pronounced axial variability within the black locust stems.

Research Highlights: The antifungal assay confirmed that knotwood extractives of Scots pine inhibit the growth of wood decay fungi. Heartwood extracts of black locust were found to be much stronger free radical scavengers than the extracts of Scots pine. The extracts were deposited in the lumina and on the wall surface of cells in the impregnated sapwood. Impregnation of the sapwood blocks with Scots pine and black locust extracts reduced the fungal decay of wood. Objectives: Hydrophilic extracts of Scots pine knotwood and black locust heartwood were chemically analyzed, tested for antifungal and antioxidant properties and used for impregnation of beech and Scots pine sapwood. Materials and Methods: Scots pine knotwood and black locust heartwood were extracted, and obtained hydrophilic extractives were chemically analyzed. Extracts were analyzed for antifungal properties with the in vitro well-diffusion method. The free radical scavenging activity of wood extracts was measured colorimetrically. The retention of the extracts in the impregnated sapwood blocks was evaluated with microscopy and gravimetry. A decay test was performed with the mini block test. Results: Almost half of both Scots pine knotwood and black locust heartwood hydrophilic extracts obtained were described by phenolic compounds. The extracts were deposited in the lumina of cells and on the cell wall surface. Extractives of Scots pine knotwood had good inhibitory properties against white- and brown-rot fungi. On the other hand, extractives of black locust heartwood were found to be good radical scavengers, better than knotwood extractives of Scots pine. The extracts of Scots pine knotwood and black locust reduced the fungal decay of the tested sapwood blocks. Conclusions: The results of this research show that the less-valued knotwood of Scots pine and heartwood of black locust are a potential source of antifungal and antioxidant agents for bio-based wood preservatives.

The chemical composition of extractives in the sapwood (SW), heartwood (HW), knotwood (KW), and branchwood (BW of silver fir (Abies alba Mill.) was analyzed, and their antifungal and antioxidant properties were studied. In addition, the variability of extractives content in a centripetal direction, i.e., from the periphery of the stem towards the pith, was investigated. The extracts were analyzed chemically with gravimetry, spectrophotometry, and chromatography. The antifungal and antioxidative properties of the extracts were evaluated by the agar well diffusion method and the diphenyl picrylhydrazyl radical scavenging method. Average amounts of hydrophilic extractives were higher in KW (up to 210.4 mg/g) and BW (148.6 mg/g) than in HW (34.1 mg/g) and SW (14.8 mg/g). Extractives identified included lignans (isolariciresinol, lariciresinol, secoisolariciresinol, pinoresinol, matairesinol) phenolic acids (homovanillic acid, coumaric acid, ferulic acid), and flavonoids epicatechin, taxifolin, quercetin). Secoisolariciresinol was confirmed to be the predominant compound in the KW (29.8 mg/g) and BW (37.6 mg/g) extracts. The largest amount of phenolic compounds was extracted from parts of knots (281.7 mg/g) embedded in the sapwood and from parts of branches (258.9 mg/g) adjacent to the stem. HW contained more lignans in its older sections. Hydrophilic extracts from knots and branches inhibited the growth of wood-decaying fungi and molds. KW and BW extracts were better free radical scavengers than HW extracts. The results of the biological activity tests suggest that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties. The results of this study describe BW as a potential source of phenolic extractives in silver fir.

Qualitative and quantitative analysis of wood plant extractives depend on the efficiency of the extraction method used. The aim of this study was the application of the accelerated solvent extraction system ASE 350 to obtain hydrophilic extracts form silver fir wood (Abies alba Mill.) and optimization of the extraction protocol. Silver fir trees originated from Kočevska Reka. Dissected and milled samples of sapwood, heartwood and knots were extracted with the ASE 350 with water, ethanol (95 % aq), acetone (95 % aq) and ethyl acetate. The number of extraction cycles was determined. Analysis of extracts was done by UV/Vis spectrophotometry and HPLC. The most effective solvent for the extraction of phenolic components from heartwood was ethanol (95 % aq), in the case of sapwood water and acetone (95 % aq) in the case of knotwood. Only two 5-minute extraction cycles were required for sufficient extraction yield when using ASE 350 at 100 °C and 103.42 bar.

The aim of the study was to examine the amounts of extractives in sapwood and heartwood of black locust recovered using three different conventional extraction techniques and three different solvent compositions. Heartwood contained larger amounts of total phenols, dihydrorobinetin and robinetin than sapwood, irrespective of the extraction technique and solvent used. Dihydrorobinetin and robinetin were the characteristic phenolic compounds of black locust wood, whereas the concentration of dihydrorobinetin was significantly higher. The highest concentrations of examined extractives were obtained by Soxhlet extraction. More than ninety percent of extractives were leached from wood in a Soxhlet apparatus in less than 2 hours. Maceration with stirring and ultrasonic extraction gave smaller yields of extractives. The amounts of total extractives, total phenols and robinetin leached with the three solvents were comparable. Extraction of heartwood with acetone yielded significantly larger amounts of dihydrorobinetin than extraction with methanol or ethanol. Four hours extraction of wood meal with aqueous acetone in a Soxhlet apparatus was found to be the optimal extraction procedure for the recovery of dihydrorobinetin.

The aim of the study was to prepare a bionanocomposite based on polylactic acid (PLA) with the addition of nanofibrillated cellulose (NFC) as a reinforcement component. For the production of the composite we used unmodified and acetylated NFC (A_NFC). Freeze-dried NFC was acetylated in a heterogeneous system with acetic anhydride in di- methylformamide (DMF) in the presence of pyridine as a catalyst. The success of the acetylation was determined by FT-IR spectroscopy. PLA films were prepared with the addition of 2.5 %, 5 % and 10 % of unmodified and acetylated NFC. The focus of this research was the impact of the NFC additive on the transparency and on the resistance of the biona- nocomposite to scratching. The transparency of the bionanocomposite film was measured using UV-Vis spectrophoto- metry, and the resistance of the films to scratching was evaluated with a scratch test. The optimal amount of NFC and A_NFC added to the polymer PLA to achieve better resistance of the bionanocomposite to scratching was determined. The best resistance of the prepared bionanocomposite to scratching was achieved by the addition of a 2.5 % A_NFC to the PLA polymer, which also has minimal reduced transparency with respect to the PLA film. With the highest addition of A_NFC to the PLA polymer, bionanocomposite films with minimal reduction of transparency were obtained. Cilj študije je bil priprava bionanokompozita na osnovi polimlečne kisline (PLA) z dodatkom nanofibrilirane celuloze (NFC) kot ojačitvene komponente. Za izdelavo kompozita smo uporabili nemodificirano in acetilirano NFC (A_NFC). NFC, posušeno z zamrzovanjem, smo acetilirali v heterogenem sistemu z acetanhidridom v dimetilformamidu (DMF) ob prisotnosti piridina kot katalizatorja. Uspešnost acetiliranja smo ugotavljali z infrardečo (FT-IR) spektroskopijo. Pripravili smo PLA filme z 2,5 %, 5 % in 10 % dodatkom nemodificirane oziroma acetilirane NFC. Osredotočili smo se na proučevanje vpliva dodatka NFC na prosojnost bionanokompozita in na njegovo odpornost proti razenju. Prosojnost bionanokompozitnega filma smo merili z UV-Vis spektrofotometrijo, odpornost površine filmov proti razenju pa smo ovrednotili z vzmetnim svinčnikom. Določili smo optimalno količino dodane NFC in A_NFC polimeru PLA za doseganje boljše odpornosti proti razenju. Ugotovili smo, da z dodatkom 2,5 % A_NFC dosežemo najboljšo odpornost pripravljenega bionanokompozita proti razenju, ki ima tudi minimalno zmanjšano prosojnost glede na PLA film. Celo z najvišjim dodatkom A_NFC k PLA polimeru smo dobili bionanokompozitne folije z minimalnim zmanjšanjem prosojnosti

Raziskali smo vsebnost in sestavo ekstraktivov v lesnih tkivih in skorji robinije (Robinia pseudoacacia L.). Vzorce njenega lesa in skorje smo ekstrahirali v aparatu Soxhlet z acetonom. Acetonske ekstrakte smo preiskali gravimetrično in s tem izmerili vsebnost skupnih hidrofilnih ekstraktivov. Z UV-Vis spektrofotometrom smo kolorimetrično izmerili vsebnost skupnih fenolov. Ekstrakte lesa in skorje robinije smo nato detajlno preiskali s sistemom za tekočinsko kromatografijo visoke ločljivosti (HPLC). S to tehniko smo v ekstraktih identificirali in kvantitativno ovrednotili dihidrorobinetin. Največje vsebnosti skupnih hidrofilnih ekstraktivov, skupnih fenolov in dihidrorobinetina smo izmerili v vzorcih jedrovine. Značilno manj ekstraktivov je bilo v vzorcih beljave in skorje. Aksialne variabilnosti v vsebnosti topnih komponent za les in skorjo robinije nismo dognali. Ugotovili smo, da je jedrovina robinije bogat vir fenolnih ekstraktivov. The content and composition of extractives in the wood and bark tissue of black locust (Robinia pseudoacacia L.) were investigated. Wood and bark samples were extracted using a Soxhlet apparatus with acetone. The extracts were gravimetrically examined to measure total hydrophilic extractive content. Total phenolic content was measured colorimetrically with a UV-Vis spectrophotometer. The wood and bark extracts were further investigated using high-pressure liquid chromatography (HPLC) to identify and quantify dihydrorobinetin in the extracts. The contents of total hydrophilic extractives, total phenols and dihydrorobinetin were higher in heartwood than in the sapwood and bark. No relationship was found between the height at which the samples were taken from the stem and the content of soluble components in the wood and bark. The heartwood of black locust represents a rich potential source of phenolic extractives.

V pričujoči študiji smo preučevali anatomske, kemijske in izbrane fizikalne lastnosti beljave in jedrovine rdečega bora (Pinus sylvestris L.) in tudi morebitni vpliv ekstraktivov na sorpcijske lastnosti borovine. Študija je bil opravljena na 6 testnih drevesih. Anatomske preiskave so bile narejene s klasično svetlo-poljsko mikroskopijo. Preiskovanje vzorcev za določanje dimenzijske stabilnosti in sorpcijskih lastnosti je potekalo po uravnovešanju v steklenih klima komorah. Vzorce za kemijsko analizo smo ekstrahirali s cikloheksanom ter z zmesjo acetona in vode, delež celokupnih fenolov pa smo kolorimetrično določili z UV-Vis spektrofotometrijo. Razlike med beljavo in jedrovino so se pokazale v smolnih kanalih, v lumnih aksialnih traheid ob trakovih ter v trakovnih parenhimskih celicah in v obokanih piknjah. Delež ekstraktivnih snovi v jedrovini je bil večji kot v beljavi. Preiskave beljave in jedrovine niso pokazale statistično značilnih razlik v gostoti v absolutno suhem stanju, pri točki nasičenja celičnih sten, diferencialnem nabrekanju v radialni smeri in ne pri koeficientu nabrekanja v tangencialni smeri. Izkazalo se je, da se prečna krčitvena anizotropija, diferencialni nabrek v tangencialni smeri, koeficient nabrekanja v radialni smeri ter sorpcijski kvocient razlikujejo pri beljavi in jedrovini rdečega bora. Omenjene razlike lahko pripišemo vzajemnemu učinku anatomskih in kemičnih značilnosti obeh kategorij lesa, vsekakor In the case of Scots pine (Pinus sylvestris L.), anatomical differences between the sapwood and heartwood were researched, the content of extractives in the sapwood and heartwood defined, hygroscopicity of sapwood and heartwood studied, so as the relationship between the content of extractives and sorption properties. Research was carried out on 6 test trees. Anatomical investigations were performed using the classic light-field microscopy. Investigation of samples for determination of dimensional stability and sorption properties was held by conditioning in the glass-air condition chambers. Samples for chemical analysis were extracted with cyclohexane and a mixture of acetone and water, and the proportion of total phenols was determined by UV-Vis spectrophotometry. The differences between the sapwood and heartwood were in the resin canals, in the lumens of axial tracheids along the rays as well as differences in parenchymal cells and bordered pits. The content of extractives in the heartwood was higher than in the sapwood. Investigations of the sapwood and heartwood did not show statistically significant differences in the density in the absolutely dry state, at the point of saturation of cell walls, in the volume shrinkage, and not in the coefficient of swelling in the radial direction. We found differences between the sapwood and heartwood transverse anisotropy, differential swell in the tangential direction, in the coefficient of swelling in the radial direction and the sorption quotient. These differences can be attributed to mutual effect of the anatomical and chemical characteristics of both types of wood and when interpreting indicators

Qualitative and quantitative analysis of wood plant extractives depend on the efficiency of the extraction method used. The aim of this study was the application of the accelerated solvent extraction system ASE 350 to obtain hydrophilic extracts form silver fir wood (Abies alba Mill.) and optimization of the extraction protocol. Silver fir trees originated from Kočevska Reka. Dissected and milled samples of sapwood, heartwood and knots were extracted with the ASE 350 with water, ethanol (95 % aq), acetone (95 % aq) and ethyl acetate. The number of extraction cycles was determined. Analysis of extracts was done by UV/Vis spectrophotometry and HPLC. The most effective solvent for the extraction of phenolic components from heartwood was ethanol (95 % aq), in the case of sapwood water and acetone (95 % aq) in the case of knotwood. Only two 5-minute extraction cycles were required for sufficient extraction yield when using ASE 350 at 100 °C and 103.42 bar. Kvalitativna in kvantitativna analiza ekstraktivov iz lesa je v veliki meri odvisna od učinkovitosti uporabljene ekstrakcijske metode. Cilj te študije je bil uporabiti sistem za pospešeno ekstrakcijo ASE 350 za pridobivanje hidrofilnih ekstraktivov iz lesa bele jelke (Abies alba Mill.) ter optimizirati protokol ekstrakcije. Drevesa bele jelke so bila posekana v gozdovih Kočevske Reke. Izolirane in zmlete vzorce beljave, jedrovine in grč smo ekstrahirali z ASE 350 z vodo, etanolom (95 % aq), acetonom (95 % aq) in etil acetatom. Določili smo število ekstrakcijskih ciklov. Semi-kvantitativno analizo ekstraktov smo izvedli z UV/Vis spektrofotometrijo, kvalitativno analizo pa s HPLC. Najučinkovitejše topilo za ekstrakcijo fenolnih komponent iz jedrovine je bil etanol (95 % aq), v primeru beljave je bila to voda, pri grčah pa aceton (95 % aq). Za učinkovito ekstrakcijo z uporabo ASE 350 pri 100 °C in 103,42 bar sta bila potrebna le dva 5-minutna ekstrakcijska cikla.

The aim of the study was to find appropriate non-chlorinated solvent systems for the extraction and separation of pure pinosylvin (PS) and pinosylvin monomethylether (PSMME) from Scots pine/Norway spruce wood residues. The extraction was performed in a pressurized solvent extractor and the purification and isolation of pure substances was done by flash chromatography. More precisely, pure PS was isolated via sequential flash chromatography in two repetitions in the gradient mode of the mobile phase, with cylcohexane (CX) and ethylacetate (EtOAc), beginning with 100% CX and ending up with 100% EtOAc. The extractives were qualitatively and quantitatively analyzed in terms of PS and PSMME contents by gas chromatography-flame ionization detector (GC-FID), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC) and proton nuclear magnetic resonance (1H-NMR) spectroscopy.

Relevant properties of stone pine (Pinus pinea) wood have been only fragmentarily addressed in the past, which has been recognized as a limiting factor for its potential applications. The sorption properties, permeability to water, extractives content and durability against fungi of Pinus pinea sapwood and heartwood were therefore determined in the present research. A SEM analysis was also performed. The Meyer-Veltrup model for material resistance was used to test relevant data. The results showed that sapwood of P. pinea fits into durability class 5 (very susceptible wood), while heartwood meets the requirements of durability class 2 (durable wood), if the mass loss after fungal exposure is considered as the sole criteria for classification. Heartwood contains up to 15% of lipophilic compounds, contributing to its hydrophobicity and influencing its sorption properties. In contrast, sapwood is very permeable and hence takes up a lot of water, while heartwood, with a higher resin content, exhibits better water performance. The higher durability of stone pine heartwood against wood decaying fungi can be linked to the presence of phenolic extractives and hydrophobic properties.

Common beech (Fagus sylvatica L.) is one of the most widespread and economically important tree species in Europe and, therefore, represents a potential source of high value added extractives. The aim of this paper was, therefore, to review the existing data regarding the composition of lipophilic and hydrophilic extractives of beech tissues, and the extraction systems and analytical techniques used for their examination. The lipophilic extractable fraction of beech is characterized mainly by saturated and unsaturated fatty acids, fatty alcohols and sterols while the hydrophilic extractives of beech consist of soluble sugars, i.e. monosaccharides, oligosaccharides, sugar alcohols and sugar acids, as well as of simple phenols and fl avonoids. Chromatography has been recognized as the convenient and most frequently used technique for the chemical analysis of extractives. This overview showed that the information about the composition of low-molecular extractives of beech is satisfactory, but the data on oligomeric extractives are still fragmentary.

Common beech (Fagus sylvatica) is one of the deciduous tree species characterized by the formation of a discolored red heart in the central part of the stem. The aim of this work was to review data in existing literature and to present original results on the extractives present in sapwood and the red heart of beech. Samples of sapwood and red heart were taken from freshly felled beech trees and extracted with a speed extractor. The content of lipophilic and hydrophilic extractives was determined gravimetrically and further evaluated by gas chromatography. The beech wood contained, on average, 1.04% lipophilic and 3.71% hydrophilic extractives. Even though the gravimetrically determined content of lipophilic extractives was comparable in the sapwood and the red heart, saturated fatty acids, fatty alcohols, and free sterols were dominant in the red heart. Sapwood contained a larger amount of total hydrophilic extractives. Mono- and oligosaccharides, sugar acids and alcohols, carboxylic acids, simple phenols, and flavonoids were identified as the prevailing hydrophilic solubles in sapwood, whereas the concentration of sugar alcohols was higher in the red heart. The composition and character of the extractives in the wood of red-hearted beech should be considered the relevant technological factor.

Various types of wound-associated wood, such as discoloured wood including knots of living and dead branches, were sampled from common beech trees (Fagus sylvatica L.), extracted, and the extracts have been analysed by GC and colourimetry assay. Sequential pressurised solvent extraction was applied with cyclohexane and aqueous methanol. The yield of hydrophilic compounds was three to five times higher than that of lipophilic extractives. The fractions differed mainly in their hydrophilic moieties. The lipophilic extractives consisted mainly of free fatty acids, fatty alcohols and free sterols. The yield of fatty acids was slightly higher in reaction zones and knots. The content of free sterols was highest in the reaction zones and in the discoloured wood. The hydrophilic extractives consisted of soluble sugars, various acids and phenolic compounds with catechin as the dominant one. Expectedly, the yield of phenolic extractives and catechin (proanthocyanidins) was highest in knots and wound-wood. Discoloured wood gave rise to lower amounts of catechin.

Extracts of wound-associated beech wood (Fagus sylvatica L.) were spectrophotometrically analyzed and a paper disc screening test was applied to estimate their fungicidal potential against selected brown (Gloeophyllum trabeum) and white (Trametes versicolor) rot fungi. Colorimetric analysis revealed that higher amounts of total phenols, flavonoids and proanthocyanidins were characteristic of the reaction zone, and especially of wound-wood, while the lowest contents were measured in red heart samples. Estimation of the fungicidal properties of wound-associated wood extracts revealed that the evident inhibitory effect on wood decaying fungi can be ascribed to methanolic extracts of wound-wood, as well as to healthy sapwood. Extracts of reaction zones did not exhibit a corresponding inhibitory effect toward the chosen fungi. These results indicate a potential defensive function of wound-wood and sapwood in living trees, whereas already formed reaction zones behave as physical barriers rather than chemically inhibiting fungal growth.

Common beech (Fagus sylvatica L.) is one of the most widespread and economically important tree species in Europe and, therefore, represents a potential source of high value added extractives. The aim of this paper was, therefore, to review the existing data regarding the composition of lipophilic and hydrophilic extractives of beech tissues, and the extraction systems and analytical techniques used for their examination. The lipophilic extractable fraction of beech is characterized mainly by saturated and unsaturated fatty acids, fatty alcohols and sterols while the hydrophilic extractives of beech consist of soluble sugars, i.e. monosaccharides, oligosaccharides, sugar alcohols and sugar acids, as well as of simple phenols and flavonoids. Chromatography has been recognized as the convenient and most frequently used technique for the chemical analysis of extractives. This overview showed that the information about the composition of low-molecular extractives of beech is satisfactory, but the data on oligomeric extractives are still fragmentary., Obična bukva (Fagus sylvatica L.) jedna je od najrasprostranjenijih i gospodarski najvažnijih vrsta drva u Europi i stoga je potencijalni izvor ekstraktivnih tvari visoke dodatne vrijednosti. Cilj rada bio je preispitati postojeće podatke koji se odnose na sastav lipofilnih i hidrofilnih ekstraktivnih tvari u tkivima bukve te sustave za ekstrakciju i analitičke tehnike koje se primjenjuju za njihovo istraživanje. Lipofilne frakcije koje se mogu ekstrahirati iz bukve uglavnom su zasićene i nezasićene masne kiseline, masni alkoholi i sterol, dok se hidrofilne ekstraktivne tvari iz bukve sastoje od topljivih šećera, tj. monosaharida, oligosaharida, šećernih alkohola i šećernih kiselina, kao i od jednostavnih fenola i flavonoida. Kromatografija je prepoznata kao prikladna i najčešće primjenjivana tehnika kemijske analize ekstraktivnih tvari. Ovaj je pregled pokazao da su podaci o sastavu niskomolekularnih ekstraktivnih tvari iz bukve zadovoljavajući, ali su podaci o oligomernim ekstraktivnim tvarima još uvijek fragmentarni.

The aim of this research was to examine the content of catechin in normal and traumatic structures of beechwood by high performance liquid chromatography (HPLC). Two discs were sawn from each of six harvested trees. The first disc was taken from the lower, wounded part and the second one from the upper part of each stem. Discs containing the bases of living and dead branches were taken from the crown. Samples of wound-wood, reaction zones, sapwood, as well as living and dead knots, were sampled from discs. Samples were milled and then extracted sequentially by cyclohexane and methanol/water in a Soxhlet apparatus. A method for the separation of catechins from extracts was developed for the present chromatographic investigation. Statistical analysis did not reveal significant differences in total or hydrophilic extractives, nor in the content of catechin among the investigated trees. The content of hydrophilic extractives and catechin were significantly different among the investigated categories of wood tissues. Wound-wood and knot extracts contained the highest amount of this flava-3-ol. Reaction zones contained higher amounts of catechin than discolored wood, but less than sapwood. The extracts of discolored wood showed the lowest amounts of catechin. Sapwood samples that originated from wounded discs exhibited significantly higher contents of catechin than normal sapwood from upper discs. Accumulation of bioactive compound catechin in wound-wood, sapwood and knots is considered to be an important part of the survival strategy of living trees., Cilj istraživanja bio je ispitati sadržaj katehina u normalnim i traumatskim strukturama bukovine primjenom tekućinske kromatografije (HPLC). Od šest bukovih stabala ispiljena su po dva diska. Prvi je disk uzet iz donjega, ranjenog dijela stable, a drugi od gornjeg dijela svakog stabla. Diskovi koji su sadržavali baze živih i mrtvih grana uzeti su od krošnje. Uzorci ranjenog dijela drva, reakcijskih zona, bjeljike, kao i živih i mrtvih kvrga, izrađeni su od pripremljenih diskova. Ispiljeni su uzorci sekvencijalno ekstrahirani cikloheksanom i smjesom metanola i vode u Soxhlet aparatu. Metoda za odvajanje katehina iz ekstrakata razvijena je za potrebe ovoga kromatografskog istraživanja. Statistička analiza dobivenih podataka nije pokazala značajne razlike između ukupnih i hidrofilnih ekstraktiva, niti u sadržaju katehina među istraživanim stablima. Sadržaj hidrofilnih ekstraktiva i katehina značajno se razlikuje u ispitivanim vrstama drvnog tkiva. Ekstraktivi iz ranjenog drva i kvrga sadržavali su najveću količinu flava-3-ola. Reakcijsko drvo sadržava veće količine katehina nego drvo s diskoloracijom, ali manje nego drvo bijeljike. Ekstraktivi drva s diskoloracijom imali su najmanje količine katehina. Uzorci od drva bjeljike izrađeni od diskova ranjenog drva imali su značajno veći sadržaj katehina nego uzorci normalnog drva bjeljike izrađeni od diskova od gornjeg dijela trupca. Akumulacija bioaktivnih spojeva katehina u ranjenom drvu, drvu bjeljike i kvrgama smatra se važnim dijelom strategije preživljavanja stabala.

The structure of wound-associated wood has been relatively well studied in beech, but only a little information about the occurrence of extractives and particular classes of compounds in these tissues is available. We examined the content of total phenols and variability in their distribution in sapwood, wound-wood and the reaction zones walling-off typical red heart and xylem altered by wounding in two beech trees, using spectrophotometric method. Significant differences in total phenols in different types of beech wood, as well as differences between trees, were confi rmed. Concentrations of total phenols were markedly lower in red heart than in reaction zones and sapwood extracts. The content of total phenols was highest in extracts of the reaction zones formed as a direct response of sapwood to wounding. Differences in the content of total phenols in reaction zones walling-off typical red heart and directly wounded xylem indicate differences in their formation process, in alterations to surrounding tissues and in the characteristics of individual trees., Za drvo bukve relativno je dobro istražena struktura ranjenog drva, ali je dostupno malo informacija o pojavi određenih ekstraktiva i pojedinih klasa spojeva u tim tkivima. Primjenom spektrofotometrijske metode na dva smo bukova stabla istražili sadržaj ukupnih fenola i varijabilnost njihove raspodjele u drvu bijeljike, ranjenom drvu i reakcijskim zonama koje ograđuju tipična crvena srca i ksileme promijenjene zbog ranjavanja drva. Potvrđene su značajne razlike u ukupnim fenolima u različitim tipovima bukova drva, kao i razlike među stablima. Koncentracije ukupnih fenola znatno su niže u crvenom srcu nego u reakcijskim zonama i ekstraktima bjeljike. Sadržaj ukupnih fenola bio je najviši u ekstraktima reakcijskih zona formiranih kao izravan odgovor bjeljike na ranjavanje. Razlike u sadržaju ukupnih fenola u reakcijskim zonama koje ograđuju tipična crvena srca i izravno ranjen ksilem pokazuju razlike u procesu formiranja, u promjenama na okolnim tkivima i u obilježjima pojedinih stabala.

Discoloration of wood is frequently caused by blue-stain fungi. Among them Aureobasidium pullulans and Sclerophoma pithyophila are reported as the most important staining organism. In previous researches, it was generally considered that blue-stain fungi do not influence mechanical properties. However, there were some opposite results published as well. In order to elucidate this issue, specimens made of Scots pine (Pinus sylvestris) sapwood were exposed to two blue stain fungi A. pullulans and S. pithyophila for periods between two and eight weeks. FTIR, weight, colour and non-destructive modulus of elasticity measurements were performed before and after exposure. The results showed that blue stain fungi, besides considerable discoloration, do not cause any significant damage to wood. Surprisingly the non-destructive MoE analysis showed that modulus of elasticity even slightly increase after fungal exposure., Promjeni boje drva često uzrokuju gljive plavila. Među tim gljivama najpoznatije su Aureobasidium pullulans i Sclerophome pithyophila. U dosadašnjim radovima prevladavalo je mišljenje da gljive plavila ne mijenjaju mehanička svojstva zaraženog drva, iako su se pojavili i neki kontradiktorni rezultati. Radi razjašnjenja tih suprotnosti, 70 uzoraka bjeljike bijeloga bora (Pinus sylvestris) (veličine 0,5 × 1,0 × 20,0 cm3) bilo je izloženo djelovanju gljiva Aureobasidium pullulans i Sclerophoma pithyophila u trajanju od dva do osam tjedana, a prema europskoj normi EN 152-1 (1990). Prije i nakon izlaganja gljivama, na istim je uzorcima obavljeno mjerenje mase, boje, FTIR te nedestruktivno mjerenje modula elastičnosti (MoE). Rezultati su pokazali da, osim značajne promjene boje, gljive plavila ne uzrokuju znatnije razaranje drvne tvari. Nedestruktivna metoda mjerenja modula elastičnosti pokazala je slabo povećanje MoE uzoraka nakon izlaganja gljivama.