Abstract
The heartwood of two European larch trees was examined for the content of lipophilic extractives. Hexane was used as a solvent for extractions, while gas chromatography with fl ame ionisation detection and gas chromatography coupled to mass spectrometry were applied for analyses. Different lipophilic groups of compounds, such as fatty acids, resin acids, diterpenoids, sterols, steryl esters and triglycerides were identifi ed and quantitatively evaluated as well as individual low molecular mass components. Distribution of heartwood lipophilics in relation to the trunk heights was also determined and their most likely biological function in wood tissues discussed. The content of hexane extract increased with stem height. Various fatty and resin acids as well as diterpenoid alcohols and sterols were characterized. The predominating lipophilic compounds identifi ed were isopimaric acid and diterpenoid alcohol larixyl acetate. Their average concentrations in examined samples was between 2.0 and 2.5 mg/g. Higher molecular mass lipophilics, e.g. steryl esters and triglycerides, were also present with concentrations between 0.5 and 2.2 mg/g.
Highlights
The content of hexane extract in the heartwood samples increased with stem height
A detailed chemical characterisation of the lipophilic fraction of larch heartwood was performed by means of modern chromatographic techniques, such as gas chromatography with flame ionization detector (GC-FID) and gas chromatography coupled to mass spectroscopy (GC-MS)
It was established that heartwood contained some characteristic compounds that could not be found in other conifer genera as for example pine (Pinus), spruce (Picea) and fir (Abies)
Summary
Different nonstructural wood components with relatively low molecular masses, which are well soluble in nonpolar organic solvents are classified as lipophilic extractives. Their content is much smaller than that of the main building elements, e. A function of lipophilic extractives in living trees is not yet fully understood, it is well known that some compounds, such as sterols and steryl esters are components of cell membranes and take an active part in different biochemical processes, while others, e.g. triglycerides and diglycerides represent food reserve. The most important function of extractives is most probably mechanical and chemical protection of wood tissues against microbial, fungal and insect attack.
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