Nobuyuki Hara

Chemical Composition and Characteristic Odor Compounds in Essential Oil from Alismatis Rhizoma (Tubers of Alisma orientale)

Chemical composition and potent odorants that contribute to the characteristic odor of essential oil from Alismatis Rhizoma (tubers of Alisma orientale) were investigated by gas chromatography-mass spectrometry (GC-MS), GC-olfactometry (GC-O), aroma extract dilution analysis (AEDA) and relative flavor activity (RFA) methods. Fifty components, representing 94.5% of the total oil, were identified. In this study, we newly identified thirty-nine compounds in the oil from tubers of A. orientale. The major constituents of the essential oil were khusinol (36.2%), δ-elemene (12.4%), germacron (4.1%), alismol (3.8%), β-elemene (3.1%), and α-bisabolol (1.9%). Through sensory analysis, sixteen aroma-active compounds were detected and the key contributing aroma-active compounds were δ-elemene (woody, flavor dilution (FD)-factor = 4, RFA = 0.3) β-elemene (spicy, FD = 5, RFA = 0.7), spathulenol (green, FD = 5, RFA = 1.0), γ-eudesmol (woody, FD = 6, RFA = 1.5), and γ-cadinol (woody, FD = 5, RFA = 1.0). These compounds are thought to contribute to the odor from tubers of A. orientale. These results imply that the essential oil from the tubers of A. orientale deserve further investigations in the phytochemical and medicinal fields.

Chemical Composition and Aroma Evaluation of Essential Oils from Skunk Cabbage ( Symplocarpus foetidus )

Two sample preparation methods, namely hydrodistillation (HD) and solvent-assisted flavor evaporation (SAFE), have been used to investigate the essential oils of the aerial parts (leaves and stems) of Symplocarpus foetidus, a plant with a characteristic odor, by gas chromatography mass spectrometry (GC-MS). Characteristic aroma-active compounds in the oils were detected by GC-Olfactometry (GC-O) and aroma extract dilution analysis (AEDA). From the HD method, the main compounds in the oil were found to be p-vinyl-guaiacol (15.5%), 2-pentyl-furan (13.4%), and (Z)-ligustilide (9.5%). From the SAFE method, the main compounds were 2-butoxy-ethanol (49.6%), ethyl-pentanoate (4.5%), and mesitylene (4.0%). In HD oil, the most intense aroma-active compounds were 2-pentyl-furan (flavor dilution factor (FD) = 32, odor activity value (OAV) = 57), p-vinyl-guaiacol (FD = 16, OAV = 41), and dimethyl disulfide (FD = 16, OAV = 41). In SAFE oil, the main aroma-active compounds were 2-butoxy ethanol (FD = 32, OAV = 16), and 2-methoxy thiazole (FD = 32, OAV = 25).

Evaluation of the Key Odorants in Volatile Oils from Tubers of Apios americana Medikus

This study was investigated the chemical composition of volatile oils and aroma evaluation from the tubers of Apios americana Medikus. Theses volatile oils were obtained by the hydrodistillation (HD) and the solvent-assisted flavor evaporation (SAFE) methods. These oils were analyzed by Gas chromatography (GC), GC-mass spectrometry (GC-MS), GC-olfactometry (GC-O), aroma extract dilution analysis (AEDA) and odor activity values (OAV) for the first time. The major compounds in the HD oil were palmitic acid (36.5%), linoleic acid (10.5%) and nonadecanol (5.7%). Meanwhile, in the SAFE oil, the major compounds were 4-hydroxy-4-methyl-2-pentanone (34.2%), hexanal (11.0%) and hexanol (7.9%). Through aroma evaluation, 20 (HD) and 14 (SAFE) aroma-active compounds were identified by GC-O. As a result, the most intense aroma-active compounds in both extraction methods were 1-octen-3-ol and hexanal, both of which showed high odor activity values (OAV).

Volatile Compounds with Characteristic Odor of Essential Oil from Magnolia obovata Leaves by Hydrodistillation and Solvent-assisted Flavor Evaporation

The present study focuses on the volatile compounds with characteristic odor of essential oil from the leaves of Magnolia obovata by hydrodistillation (HD) and solvent-assisted flavor evaporation (SAFE) method. Eighty-seven compounds, representing 98.0% of the total oil, were identified using HD. The major compounds of HD oil were (E)-β-caryophyllene (23.7%), α-humulene (11.6%), geraniol (9.1%), and borneol (7.0%). In SAFE oil, fifty-eight compounds, representing 99.7% of the total oil, were identified. The main compounds of SAFE oil were (E)-β-caryophyllene (48.9%), α-humulene (15.7%), and bicyclogermacrene (4.2%). In this study, we newly identified eighty-five compounds of the oils from M. obovata leaves. These oils were also subjected to aroma evaluation by gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). As a result, twenty-four (HD) and twenty-five (SAFE) aroma-active compounds were detected. (E)-β-Caryophyllene, α-humulene, linalool, geraniol, 1,8-cineole, and bicyclogermacrene were found to impart the characteristic odor of M. obovata leaves. These results imply that the oils of M. obovata leaves must be investigated further to clarify their potential application in the food and pharmaceutical industries.

π-Stacked and unstacked aggregate formation of 3,3′-diethylthiatricarbocyanine iodide, a near-infrared dye

The absorbance and fluorescence spectra of 3,3′-diethylthiatricarbocyanine iodide (DTCI), a near-infrared dye, were measured in methanol and water at different concentrations. DTCI exhibited distinctive monomer and excimer (dimer) fluorescence emission bands on photo excitation in the two solvents. The monomer emission band at around 600–700 nm is unprecedented, and the dimeric nature of the typical emission band at around 750–850 nm has not been recognized in solution. In the ground state, DTCI is proposed to form π-stacked and unstacked aggregates in methanol and water, respectively, at higher concentrations. The proposed unstacked aggregates in water may be of high molar mass leading to a short relaxation time in NMR analysis, which did not show clear signals.

Inhibition of Polymorphic Property of Naphthoquinonepigment Derived from Vitamin K

Organicpigment, 2-Methyl-3-(4-fluorophenylthio)-1,4-naphthalenedione (2), that is a new Vitamin K derivative bearing a fluorine group, did not show any polymorphism disregard of three different solvents. For comparison, its naphthoquinone analogue with a bromine group (1) showed clearly polymorphism susceptible to these solvents.