Naoyuki Matsui

Effect of hinoki (Chamaecyparis obtusa) wood-wool in tatami mat on the activity of house dust mite Dermatophagoides pteronyssinus

To suppress the activity of house dust mites in tatami mats, where they tend to breed, a tatami mat consisting of hinoki (Chamaecyparis obtuse) wood-wool was prepared. The suppressive effect of hinoki wood-wool on house dust mites (Dermatophagoides pteronyssinus) was then measured. To investigate the effective period of the wood-wool on the mites, 5-day exposure tests were conducted every few weeks for a total of 52 weeks. In the tests of the first and sixth weeks, the activity of the mites was strongly suppressed, and no walking or moving mite was found after 5 days of exposure. The suppressive effect on mites was maintained for 52 weeks. It was concluded that using hinoki wood-wool to produce tatami mats is an effective method of suppressing the activity of mites for about 1 year.

The composition of volatiles from tatami mats containing hinoki (Chamaecyparis obtusa) wood-wool and its decline over the long term

Volatiles inside tatami mats containing hinoki (Chamaecyparis obtusa) wood-wool as padding were analyzed. Volatiles were collected with solid-phase microextraction (SPME) fibers in a small chamber prepared in tatami mats and assayed by gas chromatography. Most of the detected compounds are typically found in hinoki extractives. Monoterpenes rapidly decreased at the beginning of the experiment, while the dispersion of sesquiterpenes that contain hydroxyl groups was observed to last more than 1 year. These sesquiterpenes, T-cadinols, and α-cadinols may play a role in the suppression of house dust mites.

Extraction and decomposition of hiba wood into valuable chemicals using stepwise temperature supercritical carbon dioxide treatment

Hiba (Thujopsis dolabrata) wood was treated with supercritical carbon dioxide (scCO2) at stepwise temperature increments from 50° to 400°C continuously so that extractives (dichloromethane-soluble and -insoluble phases) and solid residues were obtained. The yield of extractives from hiba wood increased with increasing extraction temperature. The volatile compounds in the dichloromethane-soluble phase from scCO2 extraction at 50°C contained only terpenoids. However, the volatile compounds in the dichloromethane-soluble phase from scCO2 extraction at 300°C not only contained terpenoids but also phenols, furans, hydrocarbons, and organic acids. The yield of β-thujaplicin, which is a useful compound in hiba wood, increased with increasing extraction temperature from 50°C to 300°C; the optimal conditions for extracting β-thujaplicin were 300°C and 19.61 MPa. Further study of degradated compounds from the cellulosic and lignic materials of hiba wood after stepwise high-temperature scCO2 treatment above 300°C may provide clues to its efficient use.

Analysis of broad leaf lignin of Japanese angiospermous trees by DFRC (derivatization followed by reductive cleavage) method

The DFRC (Derivatization Followed by Reductive Cleavage) analysis of lignin gives phenylpropanoid (C6-C3 type) degradation products from arylether linkages and can be used to detect lignin specifically from plant tissues, excluding other (poly) phenolic substances. DFRC analysis was employed to investigate the lignin composition in broad-leaves of typical Japanese angiosperms. Many leaves gave both guaiacyl- (G, 3-methoxyphenyl-) and syringyl- (S, 3,5-dimethoxyphenyl-) type degradation products, which indicates the existence of lignin in angiospermous leaves, and the leaf lignin has common structural elements with xylem lignin of the same tree. However, the results sometimes differed among species. Persimmon and cherry leaves revealed only trace amounts of degradation products. These results show the heterogeneous distribution of leaf lignin in angiospermous tree species. The syringyl/guaiacyl ratio of leaf lignin DFRC products was apparently lower than that of xylem lignin, which suggests the role of leaf lignin as a material to reinforce leaf vascular tissue for water conduction, like the low S/G ratio in woody vessel element cells.