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Extractives can affect vibrational properties tan1 (damping coefficient) and E'/2 (specific Young's modulus) but this is highly dependent on species, compounds, and cellular locations. This paper investigates such effects for African Padauk (Pterocarpus soyauxii Taub.), a tropical hardwood with high extractives content and a preferred material for xylophones. 5 groups of 26 heartwood specimens with large, yet comparable, ranges in vibrational properties were extracted in different solvents. Changes in vibrational properties were set against yields of extracts and evaluation of their cellular location. Methanol (ME) reached most of compounds (13%), located about half in lumen and half in cell-wall. Water solubility was extremely low. tan1 and E'/2 were very strongly related (R 2 30.93), but native wood had abnormally low values of tan1, while extraction shifted this relation towards higher tan1 values. ME extracted heartwood became in agreement with the average of many species, and close to sapwood. Extractions increased tan1 as much as 60%, irrespective of minute moisture changes or of initial properties. Apparent E'/2 was barely changed (+2% to -4%) but, after correcting the mass contribution of extracts, was in fact slightly reduced (down to -10% for high E'/2), and increasingly so for specimens with low initial values of E'/2.

Introduction Non-structural carbohydrates and phenolic compounds are implicated in the natural durability of wood. In order to find the chemical traits of natural durability in teak wood, the radial distribution of phenolics compounds and non-structural carbohydrates were studied in trees ranked by contrasting natural durability class against Antrodia sp. • Methods Non-structural carbohydrates were analyzed by spectrophotometry after enzymatic assays and phenolics compounds using HPLC.• Results High concentrations of starch, sucrose, glucose, and fructose were found in the sapwood, whereas only trace amounts were found in the heartwood. In the sapwood, low concentrations of H1 (a hydroxycinnamic acid derivative) were specifically detected. Tectoquinone was also detected in the sapwood but its content increased dramatically in the heartwood. 2-(Hydroxymethyl)anthraquinone and P1, an unidentified compound, were only detected in the heartwood and at high concentrations (>3 mg equivalent 5-methoxyflavone g −1 dry weight. Lower concentrations of 1,4-naphthoquinone, anthraquinone-2-carboxylic acid, and lapachol were also only detected in the heartwood. H1 and tectoquinone present in the sapwood could be considered as phenolic precursors of the synthesis of heartwood toxic phenolics in the heartwood. • Conclusion Correlations between natural durability and chemical composition of heartwood (quinone derivatives, P1, and non-structural carbohydrates) suggest that P1, 2-(hydroxymethyl)anthraquinone and tectoquinone could be natural durability traits. Heartwood extractives, mainly quinone derivatives, were formed from nonstructural carbohydrates which were weakly correlated to natural durability.