Prevention of Sugi (Cryptomeria Japonica D. Don) from Turning Black by Smoke Heating

Green sugi logs (tree A, normal heartwood color; tree B, heartwood color gradually turned to black after harvesting) were smoke-heated for 5, 10, 20, and 40 h to investigate the influence of smoke heating on the color change of heartwood. After the treatment, changes in color, pH, and content of norlignan were examined. The heartwood was also saturated with KHCO3 in order to examine the relationship between pH and changes in heartwood color. The results revealed that smoke heating the logs for at least 5 h prevented the heartwood from turning black; instead, the treated heartwoods turned yellowish-white. The pH value of the tree B decreased significantly from 7.4 to 6.5 after a 5-h smoke heating; from then on, the pH remained nearly constant with additional exposure. When smoke-heated, tree A- and tree B-heartwood specimens were saturated with a KHCO3 solution (pH 8.6), the brightness decreased, and the color turned black, suggesting that the blackening substances did not deteriorate when exposed to smoke heating. In the tree A heartwood, on the other hand, the contents of sequirin-C and agatharesinol barely changed before and after smoke heating. In the tree B heartwood, however, the amounts of agatharesinol and sequirin-C decreased significantly compared with those in the fresh heartwood before it turned black, whereas a large amount of norlignans, in particular, sequirin-C, was found in the smokeheated heartwood. The results obtained in the present study suggest that the chemical changes of norlignans accompanied with pH changes are closely involved in color changes in the sugi heartwood

Radial distribution of quinones in plantation teak (Tectona grandis L.f.)

• Quinones are primarily responsible for the natural durability of teak. • The previous paper in this series reported on the natural termite resistance of teak trees of different ages (8-, 30- and 51-year-old trees). In this study, the radial distribution of quinones (tectoquinone, lapachol, desoxylapachol and its isomer) and other components in the ethanol-benzene (1:2) extract were measured by means of gas chromatography. • Significant differences in desoxylapachol or its isomer content were found among the outer heartwood of 8-, 30- and 51-year old trees, as well as between the inner and outer parts of the heartwood. • All toxic quinone contents were positively correlated with the total extractive content. The highest correlation degree was measured in the isodesoxylapachol content. • Although linearly related, only modest correlations were observed between the natural termite resistance parameters and the content of tectoquinone and isodesoxylapachol.Distribution radiale des quinones dans du teak de plantation (Tectona grandis L.f.). • Les quinones sont à l'origine de la durabilité naturelle du teak. • Le précédant papier de la série traitait de la résistance naturelle contre les termites pour des arbres de 8,30 et 51 ans. Dans cette étude, la distribution radiale des quinones (tectoquinone, lapachol, deoxylapachol et son isomère) et des autres composés présents dans les extraits éthanol-benzène (1:2) est déterminée par chromatographie en phase gazeuse. • Le contenu en desoxylapachol ou ses isomères présente des différences significatives en périphérie du bois de cœur des arbres de 8, 30 et 51 ans de même qu'entre la partie interne et externe du bois de cœur. • Toutes les teneurs en quinones toxiques sont corrélées positivement avec le contenu total d'extractibles. Le degré de corrélation le plus élevé est mesuré pour la teneur en isodesoxylapachol. • Bien qu'il existe une relation linéaire entre les paramètres de résistance naturelle aux termites et la teneur en tectoquinone et isodesoxylapachol, les corrélations observées sont modestes

Variation in the natural termite resistance of teak (Tectona grandis Linn. fil.) wood as a function of tree age

$\bullet$ Tree age is one of the most important factors to affect the natural durability of wood. $\bullet$ The purpose of this study was to determine the natural termite resistance of heartwood and sapwood of teak (Tectona grandis Linn. fil.) for trees aged 8, 30 and 51 years. Reticulitermes speratus Kolbe was employed as a test termite using a no-choice feeding method. $\bullet$ The heartwood and sapwood of all of the trees tested exhibited antitermitic activity. Based on the mean mass loss due to termite activity, the sapwood and heartwood regions of 8-year-old trees are the most susceptible to termites while the heartwood regions of the 30-year-old trees showed termite resistance similar to the termite resistance of 51-year-old trees. $\bullet$ The mass loss is moderately correlated with $n$-hexane extractive content, total extractive content, brightness and redness of the wood.Effet de l'âge de l'arbre sur la résistance naturelle du bois de teck (Tectona grandis Linn. fil.) aux termites. $\bullet$ L'âge de l'arbre est un des facteurs les plus importants de la durabilité du bois. $\bullet$ Le propos de cette étude était  de déterminer la résistance naturelle du bois de cœur et de l'aubier de teck (Tectona grandis Linn. fil.) aux termites, pour des arbres âgés de 8, 30 et 51 ans. Reticulitermes speratus Kolbe a été utilisé comme termite test dans un essai d'alimentation sans choix. $\bullet$ Le bois de cœur et l'aubier de tous les arbres ont été testés pour leur activité anti-termite. En se basant sur la perte moyenne de masse de bois résultant des activités des termites, l'aubier et le bois de cœur des arbres de 8 ans se sont révélés les plus sensibles, alors que le bois de cœur des arbres de 30 ans a montré une résistance aux termites semblable à celle des arbres de 51 ans. $\bullet$ La perte de masse était modérément corrélée au contenu de l'extrait n-hexane, à celui de l'extrait total, ainsi qu'à la brillance et à la rougeur du bois

Growth-inhibitory components in Sugi (Cryptomeria japonica) extracts active against Microcystis aeruginosa

The growth-inhibitory activity of extracts obtained from Sugi (Cryptomeria japonica) effective against Microcystis aeruginosa, an alga that causes harmful algal blooms in freshwater environments, was examined. Each sample of the inner bark, outer bark, heartwood, and leaves of Sugi was extracted with hexane, ethyl acetate, and methanol successively. Inhibitory activities were observed in the inner bark ethyl acetate and methanol extracts, the heartwood hexane extract, the outer bark hexane extract, and the leaf ethyl acetate extract. The inner bark ethyl acetate and methanol extracts showed stronger activities than the other extracts. Catechin, epicatechin, and procyanidin B3 were identified as the active components in the inner bark ethyl acetate and methanol extracts. The terpenoids 1-epicubenol, 4-epicubebol, cubenol, δ-cadinol, sandaracopimarinal, and sandaracopimarinol were the active components of the heartwood hexane extract. Thus, it was indicated that not only the polyphenolic components but also non-phenolic terpenoids had growth inhibition activity against M. aeruginosa