Polyphenols of Eucalyptus sideroxylon wood

Twenty-three major components were detected in the methanol extractives of the heartwood of Eucalyptus sideroxylon. The components identified include resveratrol, resveratrol-β-glucoside, 3,3′-di- and 3,3′,4-tri-o-methylellagic acids and their glucosides. The 3,3′-di-o-methylellagic acid 4′-glucoside isolated had properties significantly different from those previously reported for this compound. Also present were gailic acid, catechin, ellagic acid, an unidentified stilbene, the ellagitannins D-6 and D-13, polymerized leucocyanidin and an oily material. The sapwood contained gailic acid, small amounts of ellagitannins and ellagic acids and traces of other components. The heartwood extractives of related eucalypt species were also examined.     

Xanthones and triterpenes of Calophyllum tomentosum

The bark, branch timber, sapwood and heartwood extractives of Calophyllum tomentosum contain friedelin, friedelan-3β-ol, betulinic acid, taraxero     

Immunohistochemical localization of agatharesinol,a heartwood norlignan,in Cryptomeria japonica

Localization of a heartwood norlignan, agatharesinol, in Sugi (Japanese cedar, Cryptomeria japonica D. Don, Taxodiaceae) was investigated by immunohistochemistry. Immuno light microscopy showed that the contents of ray parenchyma cells were immunostained in heartwood but not in sapwood. The staining of the heartwood tissue was competitively inhibited by agatharesinol but not by other Sugi heartwood extractives, and was, furthermore, markedly reduced by pre-extraction of the tissue with MeOH. These results indicated that the staining can be ascribed to the immunolabeling of agatharesinol in situ. The accumulations over the inner surface of some tracheid cell walls adjacent to the ray parenchyma cells were also immunolabeled, while the contents in axial parenchyma cells were not. In conclusion, agatharesinol was localized in the ray parenchyma cells in Sugi heartwood, and differences between the chemical structure of the contents of ray and axial parenchyma cells were also suggested.     

Natural durability of selected larch and Scots pine heartwoods in laboratory and field tests

The aim of this study was to compare natural durability of Siberian larch heartwood grown in Siberia and Sweden as well as European larch and Scots pine heartwood grown in Sweden. The study was based on standard in- and above ground tests lasting 12 years but laboratory decay tests with white and brown rot fungi was also included. Field test results showed that Siberian larch heartwood from Siberia was the most durable among the studied heartwoods with a decay index of 60 after 12 years in Simlångsdalen (Sweden), while European larch heartwood grown in Sweden, was decayed to failure before the end of the test. Scots pine heartwood was found to perform similarly to Siberian larch from Siberia. No relationship could be established between natural durability of examined heartwoods and their water absorption behavior; however, strong correlation to the total amount of extractives was observed. Scots pine and Siberian larch heartwood from Siberia had 12.7 and 19.6% total extractives content respectively but the extractives composition differs. The study revealed also that lignin and monosaccharide content could not explain the variations in decay resistance of the studied heartwoods. No similarities in the natural durability revealed by laboratory and field tests were observed.     

Isoflavanoids of dalbergia Oliveri

The heartwood of Dalbergia oliveri has yielded 11 natural products of which two are new 3-phenylcoumarins. The structures of the extractives have been examined by physical methods and in addition the assigned structures have been confirmed by synthesis. The oxygenation pattern relating the structures of chalcone, isoflavone, pterocarpans, 3-arylcoumarins, coumestones and the isoflavan and isoflavanone suggests a common biosynthetic origin.     

Preparation of antibody against agatharesinol, a norlignan, using a hapten-carrier conjugate.

In order to immunolabel heartwood extractives in Japanese cedar (Sugi, Cryptomeria japonica), we attempted to prepare antibodies against agatharesinol, a major norlignan of these heartwood extractives. Agatharesinol by itself is not antigenic due to its low-M(r), and thus was covalently bound to bovine serum albumin in order to synthesize an antigenic hapten-carrier conjugate (artificial antigen). The number of agatharesinol molecules per artificial antigen molecule was estimated as 27-28 by quantifying Lys in an acid hydrolysate of the artificial antigen by HPLC. Reaction between the artificial antigen and serum obtained from a rabbit immunized with the artificial antigen was competitively inhibited by agatharesinol, indicating the successful production of anti-agatharesinol antibodies. Inhibition by sequirin C, another major norlignan in Sugi, was weaker than that by agatharesinol. Furthermore, an EtOAc soluble fraction, which contains mainly norlignans, inhibited the reaction more strongly than any of the other fractions of Sugi heartwood extractives. Thus, the antiserum we have produced reacts most strongly with agatharesinol and recognizes norlignans almost selectively among Sugi heartwood extractives.     

Chemical factors affecting the brown-rot decay resistance of Scots pine heartwood

The cell wall chemistry (amount of hemicellulose, f-cellulose, and total lignin) and the concentration of extractives (total acetone-soluble extractives, resin acids, pinosylvins and the total phenolics quantified as tannin acid equivalents) were studied in brown-rot resistant and susceptible juvenile heartwood of Scots pine (Pinus sylvestris L.). The study material consisted of a total of 18 trees from two 34-year-old progeny trials at Korpilahti and Kerimäki. The trees were selected from among 783 trees whose decay rate had previously been screened in a laboratory test using a brown-rot fungus, Coniophora puteana. Samples from neither location showed any significant difference in the concentration (mg/cm³) of hemicellulose, f-cellulose and total lignin between the decay resistant and susceptible trees. At both locations only the concentration of total phenolics was higher in the decay-resistant heartwood than in the decay-susceptible heartwood. At Korpilahti, the amount of acetone-soluble extractives and the concentration of pinosylvin and its derivatives were higher in the resistant than in the susceptible trees.     

Wood anatomy and heartwood formation in Neem (Axadirachta indica A. Juss.)

The wood of Azadirachta indica is diffuse porous. Axial parenchyma is paratracheal banded or vasicentric. Rays are uniseriate to multiseriate and heterocellular with procumbent and upright cells. There is a strong negative correlation between vessel member length and diameter. The vulnerability and mesomorphic values are different in two trees of almost the same age growing in the same locality. The vessel member wall has spiral thickenings on its inner surface. Axial and ray parenchyma cells and sometimes vessels and fibres of the heartwood show the presence of extractives. The necrobiosis of the parenchyma cells occurs at the heartwood boundary. Senescence and death of parenchyma cells are associated with depletion of starch grains and accumulation of extractives. There is a climacteric rise in succinate dehydrogenase and acid phosphatase activities at the sapwood-heartwood interface which may be associated with heartwood formation. Peroxidase activity is greater near the cambial zone, indicating its probable role in lignification.     

Dalnigrin, a neoflavonoid marker for the identification of Brazilian rosewood (Dalbergia nigra) in CITES enforcement

International trade in Brazilian rosewood, Dalbergia nigra (Vell.) Allemão ex Benth., is regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). One problem in enforcing these regulations is the difficulty in distinguishing the wood of D. nigra from that of a closely-related but unregulated species, Dalbergia spruceana Benth. Using LC-MS to analyse methanol extracts of xylaria specimens, we identified a chemical marker for D. nigra heartwood, and determined its structure as the neoflavonoid 6-hydroxy-7-methoxy-4-(4-methoxyphenyl)-2H-1-benzopyran-2-one (4′-O-methylmelanettin; dalnigrin), using spectroscopic techniques. Dalnigrin was present in all nine available heartwood specimens of D. nigra, but it was not detected in extracts of 59 other heartwood samples representing 15 species of Dalbergia, including D. spruceana. Five other phenolic compounds were also isolated from D. nigra heartwood and similarly identified as the neoflavonoids 3′-hydroxymelanettin, melanettin, melannein and dalbergin, and the isoflavone caviunin. In extracts of D. spruceana heartwood, pseudobaptigenin was identified by LC-MS to be a major phenolic component that was not detected in wood extracts of D. nigra. We conclude that chemical analysis, in combination with anatomical investigation, can provide persuasive evidence to support the positive identification of untreated heartwood of D. nigra.     

Durability of five native Argentine wood species of the genera <Emphasis Type="Italic">Prosopis</Emphasis> and <Emphasis Type="Italic">Acacia</Emphasis> decayed by rot fungi and its relationship with extractive content

The natural durability of four Argentinean species of Prosopis and one of Acacia was evaluated in laboratory tests, according to European standards, using three brown rot and one white rot fungi. These tests were complemented by assessing the wood chemical composition. All the species were from moderately slightly durable to very durable (classes 4–1), and in all cases the heartwood was the most resistant to fungal attack. Chemical extractives content (organic, aqueous, tannic and phenolic) was higher in the heartwood. However, species durability was not related to extractive contents nor with wood density. Instead, it is possible that extractives could contribute to natural durability in different ways, including the effects related to the antioxidant properties of some of them.     

Neoflavanoids of Dalbergia melanoxylon

The heartwood of Dalbergia melanoxylon has yielded new examples of known neoflavanoid types. The isolates included 4-phenylcoumarins, (S)-4-methoxydalbergiones and benzophenones which have the corresponding oxygenation pattern. The structures of the extractives have been examined by physical methods, and confirmed by conversion to known compounds or by independent synthesis. A 2-cinnamylphenol (6) and 3-cinnamylflavan (7) were the only products in a condensation reaction in the attempted synthesis of the 4-methoxydalbergione (1b).     

Volatile constituents of Cupressus stephensonii heartwood

Nonpolar volatile extractives of Cupressus stephensonii heartwood amounting to 1·3% (drywood weight basis) were analyzed for their constituents and the main component was found to be carvacrol (78%). Tropolones (17%) were composed largely of β-thujaplicin and nootkatin with γ-thujaplicin in secondary quantities. Acids were low (1·7%). Neutral constituents (3·4%) contained α-pinene (8%), 4-terpinenol (27%), and methyl 4-trans-dehydrogeranate (45%).     

The effect of water soluble Scots pine (Pinus sylvestris L.) and Sitka spruce [Picea sitchensis (Bong.) carr.] heartwood and sapwood extracts on the growth of selected Trichoderma species

Extractable materials from some timber species have been identified which prevent wood decay; however, little has been reported on the effect(s) of such materials against mould species that colonize timber. With increasing interest in the use of Trichoderma species, both as agents of permeability enhancement and biological control, more information is required on how chemical components within fresh and processed timber influence growth of Trichoderma. Fresh and dried samples of Scots pine and Sitka spruce sapwood and heartwood were leached in a Soxhlet apparatus and the resulting extract was combined with malt extract agar and inoculated with Trichoderma. Trichoderma isolates were inhibited to varying degrees by extractives removed from fresh and dried heartwood of the two timbers. Growth on sapwood extractives, however, showed a lesser degree of inhibition. The implications of the results for applications of Trichoderma in timber are discussed.     

Biodeterioration of brazilwood Caesalpinia echinata Lam. (Leguminosae—Caesalpinioideae) by rot fungi and termites

The heartwood of Caesalpinia echinata Lam. (Leguminosae) (commonly called brazilwood) is used for violin bow manufacture due to the unique vibrational and physical properties found in the wood. In the present work, the effects of Pycnoporus sanguineus (white-rot fungus), Gloeophyllum trabeum (brown-rot fungus), Chaetomium globosum (soft-rot fungus), and Cryptotermes brevis (dry-wood termite) on weight losses and chemical composition of extractives and cell-wall polysaccharides of C. echinata wood were investigated under laboratory conditions and compared to those obtained for Anadenanthera macrocarpa, Eucalyptus grandis, and Pinus elliottii. The heartwood of C. echinata was found to be as resistant as A. macrocarpa to the decay fungi tested and to the attack of the dry-wood termite. Pinitol and galactopinitol A were the main sugar alcohols found in the extractives of wood of C. echinata, their presence, however, did not appear related to the resistance to fungal decay. Although only incipient stages of decay were found, the modifications in cell-wall polysaccharide composition of heartwood of C. echinata by rot fungi were related to decrease in polymers other than xylans. The high resistance of C. echinata to xylophages is probably due to the presence of toxic extractives in the wood.     

Resistance of Scots pine wood to Brown-rot fungi after long-term forest fertilization

The susceptibility of Scots pine (Pinus sylvestris L.) sap- and heartwood against the wood decaying brown-rot fungus (Coniophora puteana) was investigated after long-term forest fertilization at three different sites in central Finland. Different wood properties: wood extractives, wood chemistry, and wood anatomy were used to explain sap- and heartwood decay. Scots pine sapwood was more susceptible to decay than its heartwood. In one site, sapwood seemed to be more resistant to wood decay after forest fertilization whereas the susceptibility of heartwood increased. Significant changes in the sapwood chemistry were found between treatment and sites, however, no relationship between wood chemistry and wood decay was observed in the factor analysis. The results of this study show that there was an inconsistent relationship between decay susceptibility and fertilization and the measured physical and chemical attributes of the wood were not consistently correlated with the decay rate.     

Naturally durable heartwood: evidence for a proposed dual defensive function of the extractives

We previously proposed that extractives in highly durable heartwood may protect wood against fungal colonization and subsequent degradation by dual mechanisms: the extractives have some fungicidal activity and are also free radical scavengers (antioxidants). In short-term laboratory decay tests using two different wood species and decay fungi, the antioxidant 2,6-dimethyl-di-tert-butyl-4-methylphenol (BHT) alone had little or no preservative effect. In contrast, the combination of BHT with different organic commercial biocides always showed an increase in efficacy compared to the organic biocide alone. Consequently, we conclude that the combination of a commercial antioxidant and biocide is synergistic. This implies that extractives may protect wood by more than simply being fungicidal.     

Argentinean native wood species: Physical and mechanical characterization of some Prosopis species and Acacia aroma (Leguminosae; Mimosoideae)

One of the problems in marketing the wood of Prosopis and Acacia is the lack of standardization of its qualities. The aim of this paper was to obtain a preliminary detection of some properties of the wood of four species of the genus Prosopis and one species from Acacia grown in Argentina. To accomplish this objective, the content of extractives and some physical and mechanical characteristics were analyzed.The density ρ₁₂ of all the species indicates that these woods range from heavy to very heavy (?0.69 g/cm³). The total volumetric shrinkage values are low, less than 10%, for all species. The parallel compression strength and the shear strength for all the species indicate a very resistant wood (?46.93 MPa and ?18.35 MPa, respectively). Brinell hardness was higher than 5 kg/mm² in all cases. The species with less content of extractives is P. ruscifolia (approximately 9% of anhydrous mass) whereas A. aroma was the one with the greatest content (approximately 25% of anhydrous mass in the heartwood).     

Natural wood colouring process in Juglans sp. (J. nigra, J. regia and hybrid J. nigra 23 ×J. regia) depends on native phenolic compounds accumulated in the transition zone between sapwood and heartwood

 Radial distribution of soluble phenolics was investigated at different heights in stems of Juglans nigra, J. regia and hybrids J. nigra 23 × J. regia. Four major phenolic compounds were studied: hydrojuglone glucoside (HJG), quercitrin (QUER) and two unknown compounds characterized as two ellagic acid derivatives E1 and E2. HJG and E1 content increased gradually in the sapwood, peaked in the sapwood-heartwood transition zone, and decreased drastically in the heartwood. QUER was accumulated preferentially around the transition zone, and its content was relatively low in the outer part of the sapwood and in the inner part of the heartwood. E2 content was low in the sapwood and increased in the heartwood. The heartwood formation was marked by the accumulation of new soluble compounds. The relationship between wood extractives and wood colour were evaluated and discussed. HJG was considered to be a major precursor of heartwood colour providing chromophores through hydrolysis (deglucosylation), oxidation and polymerization processes. Received: 2 September 1997 / Accepted: 23 November 1997     

The GSTome Reflects the Chemical Environment of White-Rot Fungi

White-rot fungi possess the unique ability to degrade and mineralize all the different components of wood. In other respects, wood durability, among other factors, is due to the presence of extractives that are potential antimicrobial molecules. To cope with these molecules, wood decay fungi have developed a complex detoxification network including glutathione transferases (GST). The interactions between GSTs from two white-rot fungi, Trametes versicolor and Phanerochaete chrysosporium, and an environmental library of wood extracts have been studied. The results demonstrate that the specificity of these interactions is closely related to the chemical composition of the extracts in accordance with the tree species and their localization inside the wood (sapwood vs heartwood vs knotwood). These data suggest that the fungal GSTome could reflect the chemical environment encountered by these fungi during wood degradation and could be a way to study their adaptation to their way of life.