Quantifying compounds in heartwood extractives of durable eucalypts
By Niklas Schroettke, Meike Holzenkämpfer and Clemens Altaner , August 2017.
Download SWP-T037 (pdf)
It is known that the relative amounts of heartwood compounds differ between trees of the same species (Fries et al., 2000; Haupt et al., 2003; Partanen et al., 2011). This within species variation implies different wood quality, i.e. durability, colour or processing parameters. The nature of the chemicals, the variation in their abundance within a species, the genetic control of their abundance as well as their biological or chemical properties are unknown for the durable eucalypts in the SWP programme. Being able to quantify the individual extractive compounds in the heartwood of these trees can be useful in several aspects:
- It will be possible to determine the variation in the chemical composition of the heartwood extracts within a species. In conjunction with our breeding trials this will allow us to quantify genetic parameters and get an idea on the variability of the product.
- It will be possible to identify the most fungicidal compounds in conjunction with bioactivity tests.
- Currently the breeding programmes for heartwood quality focuses on high extractive content (Li and Altaner, 2016). Knowledge of the chemical composition and the bioactivity of the compounds will allow to select those individuals with not only a high but also the most potent extractives in the heartwood – a second generation improvement of heartwood quality.
- Separating the individual compounds is a first step towards identifying their chemical structure.
- Some difficulties in the processing of durable heartwood, e.g. gluing, has been contributed to heartwood extractives. Processing can be optimised with the knowledge of the nature of the heartwood compounds.
- Individual heartwood compounds might have some value themselves. Consequently they could provide an additional revenue stream for growers of durable eucalypts.
- Understanding the nature of key heartwood components will give deeper insight into the biochemical processes of heartwood formation.
Gas chromatography (GC) of silylated ethanol extracts was found to be able to quantify 30 compounds in the heartwood of E. bosistoana and E. globoidea. A suitable internal standard was betulin. The variation in the composition of heartwood extracts can be investigated with this method.
Reverse-phase liquid chromatography (RP-HPLC) has potential to analyse the chemical composition of ethanol heartwood extracts without derivatisation. However, fewer compounds can be separated with RP-HPLC compared to GC.
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