Mitsuyoshi Yatagai

Termiticidal activity of wood vinegar, its components and their homologues

The termiticidal activity of wood vinegar, its components, and their homologues have been studied. Three kinds of wood vinegar made from the mixed chips ofCryptomeria japonlca andPseudotsga menziesii (wood vinegar A),Quercus serrata (wood vinegar B), andPinus densiflora (wood vinegar C) exhibited high termiticidal activities againstReticulitermes speratus. Acetic acid, which is the largest content of wood vinegar, exhibited high termiticidal acitivity. The contents of organic fraction of wood vinegars and acetic acid might be responsible for the differences in termiticidal activities among these wood vinegars. The structure and termiticidal activity relations of phenols were studied. Phenol with some substituents revealed higher termiticidal activity than benzene derivatives, which have no hydroxyl group; an ortho substituent of phenol plays an important role in termiticidal activity. It has become apparent that high termiticidal activity cannot be obtained by a phenolic hydroxyl group alone; it can be obtained, however, by some substituents, especially an ortho substituent in addition to a phenolic hydroxyl group. The bulkiness of the substituent at the ortho position participates in termiticidal activity; activity decreases as the size of an ortho substituent increases. It is thought that the interaction at the receptor site of termites is affected by the increased size of the ortho substituent.

Composition and antitermite activities of essential oils from Melaleuca species

Abstract The composition and antitermite activities of nine essential oils from two Melaleuca species, gelam and cajuputi, were compared using gas chromatography–mass spectrometry analysis and bioassays. Gelam oils were rich in compounds whose boiling points were high, and they were separated into the elemene-rich type and the γ-terpinene- and terpinolene-rich type. Cajuputi oils in this experiment were categorized into three chemotypes according to their 1,8-cineole content: high, low, none. In the termiticidal activity test, gelam oils were stronger than most cajuputi oils in the contact condition. The elemene-rich gelam lost its activity in the noncontact condition, whereas another type of gelam kept its termiticidal activity. The authentic sample of elemene showed the same result as the elemene-rich gelam, indicating that the termiticidal activity of gelam was caused by at least two types of compound: elemene and “others.” 1,8-Cineole exhibited the same tendency as elemene, but it was weak. Hence the 1,8-cineole content of cajuputi was irrelevant to termiticidal activity of samples that exhibited strong activity under both conditions despite their high content. The appearances of gelam and cajuputi leaves are easily confused, a problem that has not yet been solved. Other scientific methods, such as genetic analysis, are required to identify gelam. The difference in the compositions and antitermite activities, however, were charified in this experiment.

Saccharification of cellulose by dry pyrolysis

Pyrolysis of cellulose was studied for the purpose of practical production of 1,6-anhydro-β-D-glucopyranoside (levoglucosan, LG). To minimize secondary degradation of levoglucosan, two methods were examined: (1) conductive heating by glass bottle, and (2) radiation heating from the surface by CO2 laser beam, both under vacuum and in a nitrogen atmosphere. Glass-bottle pyrolysis under vacuum gave levoglucosan yield of 50%–55% in the optimum temperature range of 350°–410°C, where placing the cold trap in the vicinity of heated area was effective in improving the yield. In contrast, glass-bottle pyrolysis under nitrogen gave low yields of 17%–20%, probably due to slower diffusion of pyrolysis product from hot region. The CO2 laser pyrolysis under vacuum gave the product as aerosol (white smoke), causing difficulty in recovery of the product, and the maximum yield was 5%–17%. In this case the treatment under nitrogen flow was effective for recovery of aerosol, and the maximum yield reached approximately 25%.

Volatile components of Japanese cedar cultivars as repellents related to resistance to Cryptomeria bark borer

The response of the essential oils and their components toCryptomeria bark borer has been studied. The oils of inner bark and sapwood of resistant cultivars acted as a repellent toCryptomeria bark borer rather than as an attractant, whereas those of susceptible cultivars acted as an attractant.α-Terpineol, nerolidol,δ-cadinene,β-eudesmol, terpinolene, and cedrol showed high repellent activity. The relative contents of the former four compounds were larger in resistant cultivars than in sensitive cultivars. It suggests that these four compounds might be one of the causes of resistance toCryptomeria bark borer. The contents of terpinolene and cedrol were small, and these two compounds may have no or a small influence on resistance. Although some of compounds acted as attractants forCryptomeria bark borer, it was not attributable to the difference in the bark borer response of Japanese cedar because of the relatively low ratio of these compounds in each essential oil and the small differences in the ratios between resistant and susceptible cultivars.

Composition, miticidal activity and growth regulation effect on radish seeds of extracts from Melaleuca species

Abstract The leaf oil components of six Melaleuca species were analyzed. M. symphyocarpa had a higher content of 1,8-cineole and M. bracteata contained large amounts of phenyl propanoids, while the other species had oils which contained complex mixture of mono- and sesquiterpenes. The leaf oil of M. bracteata exhibited the strongest miticidal activity against European house-dust mites (Dermatophagoides pteronyssinus) . It also had the strongest germination and growth-inhibition activity against radish seeds.

Tropolones Extracted from the Wood of Western Red Cedar by Supercritical Carbon Dioxide

Tropolones were efficiently extracted using a Supercritical carbon dioxide extraction procedure from the wood of western red cedar (Thuja plicata D. DonJ. The yields and composition. of the extractives obtained by hol water distillation were compared with those of the extractives by Supercritical carbon dioxide obtained frora the same source. The extractive yield with Supercritical carbon dioxide was 7.8 fold higher than yield of extractives obtained by hot water distillation. The tropolones from the extractives obtained by Supercritical carbon dioxide was about 8 tbnes higher than that of the extractives obtained by hot water distillation. The most efficient condition for extracting tropolones from the wood of western red cedar was under 300kgf/cm at 40 °C for 180min. Thujic acid, nezukone and ß-thujaplicin were presented in large amounts in the extractives obtained by Supercritical carbon dioxide. Nearly ninety percent of the extractives obtained by the present method were composed of the above tropolones.

Identification of a germicidal compound against picornavirus in bamboo pyroligneous acid.

The germicidal activity of pyroligneous acid (PA) against a picornavirus, encephalomyocarditis virus (EMCV), was analyzed, and the component responsible for its disinfectant activity was identified. Bamboo PA (BPA) inactivated EMCV, but neutralization of BPA abolished this activity. Using liquid-liquid phase extraction and silica gel column chromatography, the hydrophobic active fraction of BPA was separated and its 12 major components were identified. The active fraction was reconstructed by mixing synthetic chemicals at the determined concentrations, and a subtraction series of one chemical from the complete mixture was prepared. An in vitro virus assay demonstrated that phenol was the sole germicidal component, and acetic acid augmented the phenols inactivating activity resulting in >5-log decrease in EMCV infectivity. Considering the low environmental risk of PA, these findings suggest that BPA is a potentially useful agent for preventing viral epidemics in agricultural and human environments.

Components of the essential oils of Azadirachta indica A. Juss, Azadirachta siamensis Velton, and Azadirachta excelsa (Jack) Jacobs and their comparison

The components of the essential oils from seeds of Azadirachta indica, Azadirachta siamensis, and Azadi-rachta excelsa were studied by gas chromatography and gas chromatography-mass spectrometry. The main components of A. indica oil were hexadecanoic acid (34.0%), oleic acid (15.7%), 5,6-dihydro-2,4,6-triethyl-(4H)-1,3,5-dithiazine (11.7%), methyl oleate (3.8%), and eudesm-7(11)-en-4-ol (2.7%). The major components of A. siamensis oil were hexadecanoic acid (52.2%), tricosane (10.5%), tetradecanoic acid (6.8%), oleic acid (4.9%), and pentacosane (4.9%). Azadirachta excelsa oil contained oleic acid (31.3%), hexadecanoic acid (14.2%), octadecanoic acid (13.0%), 4-octylphenol (9.7%), and O-methyloximedecanal (6.8%) as the main constituents. The essential oils from A. indica, A. siamensis, and A. excelsa were found to contain fatty acids (52.6%–72.3%) as major components. The minor components of the oils were n-alkanes, aromatics, esters, sulfur and nitrogen compounds, and terpenoids. Differences in oil composition were observed between the three species.

Phenolic constituents of Taxus cuspidata I: lignans from the roots

The phenolic constituents of the roots ofTaxus cuspidata (Japanese yew) were investigated. Four lignans, [(+)-taxiresinol (1), (+)-lariciresinol (2), (−)-secoisolariciresinol (3), and (+)-pinoresinol (4)] were isolated and identified. The assignment of proton and carbon atoms for the lignans were finally solved by one- and twodimensional-nuclear magnetic resonance spectra. The enantiomeric excess of these lignans were determined by chiral high-performance liquid Chromatographic analyses. (+)-Lariciresinol and (−)-secoisolariciresinol were optically pure; (+)-taxiresinol was also suggested to be optically pure, although (+)-pinoresinol was not (77% enantiomeric excess).

Lanostane triterpenes from the bark of Neolitsea sericea

Abstract Three new lanostane type triterpenes have been isolated from the bark of Neolitsea sericea . Their structures were established as 24 Z -ethylidene