Hydrophobic and Hydrophilic Extractives in Norway Spruce and Kurile Larch and Their Role in Brown-Rot Degradation

Abstract

Extractives found in the heartwood of a moderately durable conifer (Larix gmelinii var. japonica) were compared with those found in a non-durable one (Picea abies). We identified and quantified heartwood extractives by extraction with solvents of different polarities and gas chromatography with mass spectral detection (GC-MS). Among the extracted compounds, there was a much higher amount of hydrophilic phenolics in larch (flavonoids) than in spruce (lignans). Both species had similar resin acid and fatty acid contents. The hydrophobic resin components are considered fungitoxic and the more hydrophilic components are known for their antioxidant activity. To ascertain the importance of the different classes of extractives, samples were partially extracted prior to subjection to the brown-rot fungus Rhodonia placenta for 2-8 weeks. Results indicated that the most important (but rather inefficient) defense in spruce came from the fungitoxic resin, while large amounts of flavonoids played a key role in larch defense. Possible moisture exclusion effects of larch extractives were quantified via the equilibrium moisture content of partially extracted samples, but were found to be too small to play any significant role in the defense against incipient brow-rot attack.

The Effects of Adding Heartwood Extractives from Acacia confusa on the Lightfastness Improvement of Refined Oriental Lacquer

“…The result exhibited that the polar solvent acetone has higher efficiency for A. confusa heartwood extraction. Previous studies [ 54 , 55 , 56 , 57 , 58 ] also indicate that polar solvents are more efficient in heartwood extraction than non-polar solvents. In addition, the extracts obtained from polar solvents extraction are mostly composed of polar compounds.…”

Natural Compounds for Wood Protection against Fungi—A Review

“…The extractives of paulownia wood had no or marginal inhibitory effect on T. palustris and G. trabeum and honey mesquite extractives were not effective against I. lacteus . Füchtner et al [ 104 ] showed that the resistance of non-durable Norway spruce heartwood to brown-rot fungus R. placenta results from the presence of fungitoxic hydrophobic resin, while in the case of moderately durable Kurile larch heartwood, the resistance is due to large amounts of different antioxidant flavonoids.…”

Removal of wood extractives as pulp (pre-)treatment: a technological review

“…Wood extractives play an essential role in protecting living trees against fungal attacks and other pests like insects [19]. Especially phenolic extractives and resin acids act as natural fungicides of trees [12,194]. The extract of Delonix regia (also known as flame tree or flamboyant) in the study of Salem et al [195] showed inhibition of fungal growth and antioxidant activity.…”