Relationships between biochemical attributes (non-structural carbohydrates and phenolics) and natural durability against fungi in dry teak wood (Tectona grandis L. f.)

Abstract

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. Non-structural carbohydrates were analyzed by spectrophotometry after enzymatic assays and phenolics compounds using HPLC. 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. 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 non-structural carbohydrates which were weakly correlated to natural durability.