Metabolite profiling of the three areas of Pseudotsuga menziesii wood

Pseudotsuga menziesii (Mirb) Franco, called Douglas fir or Oregon pine, is a species of Pinaceae family, native to North America. It was introduced in Europe in the nineteenth century from poorly documented genotypes. Its heartwood has the ability to resist to attacks caused by pathogens due to the presence of metabolites which display antioxidant, antifungal and insecticide activities [1, 2]. Chemical markers present in the three areas of its wood, namely sapwood, transition zone and heartwood were identified. In the meantime, their metabolic profiles were compared in order to establish a correlation between the presence of metabolites and genotype of trees. Wood sample was ground to a fine powder. The extraction was carried out by solvents of increasing polarity and the mixture acetone/H₂O (70/30) provides the best yield. Optimal conditions for liquid solid extraction with the same solvent were found using accelerated solvent extractor at 100 ° C. The composition of each extract was determined by LC-UV. Qualitative analysis of the metabolite profile of extracts obtained from the three areas of wood was performed using tandem mass spectrometry (LC/MS and LC/MS/MS). Mass spectra data were recorded using electrospray ionization in the negative mode. Compounds were identified using the m/z ratio and their fragmentation patterns. Phenolic compounds were predominant with flavonoids followed by terpenes. Taxifolin and quercetin were found to be the most abundant metabolites present in the three areas along with pinobanskin, myricetin and dihydrokaempferol. More than sixty-four compounds were identified in heartwood, forty in transition zone and sixty in sapwood. The developed method in LC/MS/MS allowed the separation of isomers for taxifolin and its derivatives which are aglycons or O-glycosylated. They showed the same fragmentations and m/z at different retention times.

Acknowledgements: SCRABL Platform (Yves Champavier).

Keywords: Sapwood, heartwood, transition zone, polyphenols, Pseudotsuga menziesii.

References:

[1] Schultz TP, Nicholas DD. Naturally durable heartwood: evidence for a proposed dual defensive function of the extractives. Phytochemistry 2000; 54: 47 – 52

[2] Dellus V, Mila I, Scalbert A, Menard C, Michon V, Herve du Penhoat CLM. Douglas-fir polyphenols and heartwood formation. Phytochemistry 1997; 45: 1573 – 1578

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