Chemical composition, aroma evaluation, and inhibitory activity towards acetylcholinesterase of essential oils from Gynura bicolor DC.

The compositions of the essential oils obtained from leaves and stems of Gynura bicolor DC. were analyzed by GC-MS. One hundred eight components of these oils were identified. (E)-ß-caryophyllene (31.42 %), α-pinene (17.11 %), and bicyclogermacrene (8.09 %) were found to be the main components of the leaf oil, while α-pinene (61.42 %), ß-pinene (14.39 %), and myrcene (5.10 %) were the major constituents of the stem oil. We found 73 previously unidentified components in these oils from G. bicolor. The oils were also subjected to odor evaluation. Eleven and 12 aroma-active compounds were detected in the leaf and stem oils, respectively. The abilities of these oils to inhibit acetylcholinesterase (AChE) activity were determined. The sesquiterpenoids in the oils were found to inhibit AChE activity more strongly than the monoterpenoids in the oils did. It was suggested that the three main components in each essential oil act synergistically against AChE activity. These results show that the essential oils obtained from G. bicolor are a good dietary source of AChE activity inhibition.

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%), ß-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) ß-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).

Chemical Composition and Character Impact Odorants in Volatile Oils from Edible Mushrooms.

The aim of this study was to investigate the chemical composition and the odor-active components of volatile oils from three edible mushrooms, Pleurotus ostreatus, Pleurotus eryngii, and Pleurotus abalonus, which are well-known edible mushrooms. The volatile components in these oils were extracted by hydrodistillation and identified by GC/MS, GC-olfactometry (GC-O), and aroma extract dilution analysis (AEDA). The oils contained 40, 20, and 53 components, representing 83.4, 86.0, and 90.8% of the total oils in P. ostreatus, P. eryngii, and P. abalonus, respectively. Odor evaluation of the volatile oils from the three edible mushrooms was also carried out using GC-O, AEDA, and odor activity values, by which 13, eight, and ten aroma-active components were identified in P. ostreatus, P. eryngii, and P. abalonus, respectively. The most aroma-active compounds were C8 -aliphatic compounds (oct-1-en-3-ol, octan-3-one, and octanal) and/or C9 -aliphatic aldehydes (nonanal and (2E)-non-2-enal).

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)-ß-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)-ß-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)-ß-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.

Metabolism of (-)-cis- and (-)-trans-rose oxide by cytochrome P450 enzymes in human liver microsomes.

The in vitro metabolism of (-)-cis- and (-)-trans-rose oxide was investigated using human liver microsomes and recombinant cytochrome P450 (P450 or CYP) enzymes for the first time. Both isomers of rose oxide were incubated with human liver microsomes, and the formation of the respective 9-oxidized metabolite were determined using gas chromatography-mass spectrometry (GC-MS). Of 11 different recombinant human P450 enzymes used, CYP2B6 and CYP2C19 were the primary enzymes catalysing the metabolism of (-)-cis- and (-)-trans-rose oxide. CYP1A2 also efficiently oxidized (-)-cis-rose oxide at the 9-position but not (-)-trans-rose oxide. α-Naphthoflavone (a selective CYP1A2 inhibitor), thioTEPA (a CYP2B6 inhibitor) and anti-CYP2B6 antibody inhibited (-)-cis-rose oxide 9-hydroxylation catalysed by human liver microsomes. On the other hand, the metabolism of (-)-trans-rose oxide was suppressed by thioTEPA and anti-CYP2B6 at a significant level in human liver microsomes. However, omeprazole (a CYP2C19 inhibitor) had no significant effects on the metabolism of both isomers of rose oxide. Using microsomal preparations from nine different human liver samples, (-)-9-hydroxy-cis- and (-)-9-hydroxy-trans-rose oxide formations correlated with (S)-mephenytoin N-demethylase activity (CYP2B6 marker activity). These results suggest that CYP2B6 plays important roles in the metabolism of (-)-cis- and (-)-trans-rose oxide in human liver microsomes.

Characteristic odor components of essential oils from Eurya japonica.

The chemical compositions of essential oils from the flower and aerial parts (i.e., leaf and branch) of Eurya japonica were determined and quantified using gas chromatography-mass spectrometry (GC-MS). A total of 87 and 50 compounds were detected in the oils from the flower and aerial parts, respectively. The main compounds of the flower oil were linalool (14.0%), (9Z)-tricosene (12.0%), and nonanal (7.4%). In the oil from the aerial parts, linalool (37.7%), α-terpineol (13.5%), and geraniol (9.6%) were detected. In the oils from the flower and aerial parts, 13 and 8 aroma-active compounds were identified by GC-olfactometry (GC-O) analysis, respectively. The key aroma-active compounds of the flower oil were heptanal [fatty, green, flavor dilution (FD) = 128, odor activity value (OAV) = 346], nonanal (sweet, citrus, FD = 128, OAV = 491), and eugenol (sweet, spicy, FD = 64, OAV = 62): in the oil from the aerial parts, the key aroma-active compounds were linalool (sweet, citrus, FD = 64, OAV = 95), (E)-ß-damascenone (sweet, FD = 256, OAV = 4000), and (E)-ß-ionone (floral, violet, FD = 128, OAV = 120). This study revealed that nonanal and eugenol impart the sweet, citrus, and spicy odor of the flower oil, while (E)-ß-damascenone and (E)-ß-ionone contribute the floral and sweet odor of the oil from the aerial parts.

Isolation and biological activity of a novel cadinane-type sesquiterpenoid from the essential oil of Alangium salviifolium.

The components of the essential oil from the roots of Alangium salviifolium were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Ninety compounds, representing 74.5% of the total oil, were identified; the main components of the oil were epi-α-cadinol, followed by trans-2-hydroxycalamenene, cadalene, and cadina-4,10(15)-dien-3-one. A further unknown component comprised 5.5% of the oil. Therefore, the essential oil was purified by flash column chromatography to isolate this component. Its structure was established using extensive spectroscopic data analyses, including NMR, HR-EI-MS, and IR. The results showed that this isolated compound was (-)-7, 8-dihydroxycalamenal, which is a novel cadinane-type sesquiterpenoid. This compound was tested for its antioxidant activity and inhibition of tyrosinase, and showed particularly strong inhibition effects.

Chemical composition and aroma evaluation of volatile oils from edible mushrooms (Pleurotus salmoneostramineus and Pleurotus sajor-caju).

This study is focused on the volatile oils from the fruiting bodies of Pleurotus salmoneostramineus (PS) and P. sajor-caju (PSC), which was extracted by hydrodistillation (HD) and solvent-assisted flavor evaporation (SAFE) methods. The oils are analyzed by gas chromatography-mass spectrometry (GC-MS), GC-olfactometry (GC-O), and aroma extract dilution analysis (AEDA). A total of 31, 31, 45, and 15 components were identified in PS (HD and SAFE) and PSC (HD and SAFE), representing about 80.3%, 92.2%, 88.9%, and 83.0% of the oils, respectively. Regarding the aroma-active components, 13, 12, 13, and 5 components were identified in PS (HD and SAFE) and PSC (HD and SAFE), respectively, by the GC-O analyses. The results of the sniffing test, odor activity value (OAV) and flavor dilution (FD) factor indicate that 1-octen-3-ol and 3-octanone are the main aroma-active components of PS oils. On the other hands, methional and 1-octen-3-ol were estimated as the main aroma-active components of PSC oils.

New compounds, 6-hydroxykarahanaenone and 10-hydroxykarahanaenone, from biotransformation of karahanaenone by CYP2A6.

The in vitro biotransformation of karahanaenone was examined in cytochrome P450 (CYP) 2A6. The biotransformation of karahanaenone by CYP2A6 was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Karahanaenone was found to be oxidized to two metabolites by CYP2A6. In order to produce large quantity of metabolites by CYP2A6, the biotransformation of karahanaenone by Salmonella typhimurium OY1002/2A6 was investigated. Similarly, two metabolites were confirmed by GC and GC-MS. The structure of metabolites was determined by 1D NMR, 2D NMR, and infrared, as a result there were new compounds, (6R)-hydroxykarahanaenone and 10-hydroxykarahanaenone.

Aroma evaluation of setonojigiku (Chrysanthemum japonense var. debile) by hydrodistillation and solvent-assisted flavour evaporation.

INTRODUCTION: The Chrysanthemum genus consisting of about 200 species is mainly distributed over the Northern Hemisphere. Despite the pleasant odour of C. japonense var. debile (setonojigiku), no detailed analysis of the aroma-active compounds has been reported using sensory evaluation. OBJECTIVES: Using a hydrodistillation (HD) and a solvent-assisted flavour evaporation (SAFE) method to obtain the volatile oil from the leaf parts. METHODS: To clarify odorants contributing to the characteristic aroma-active compounds, the aroma-extract dilution analysis (AEDA) method was performed through gas chromatography olfactometry (GC/O) analysis. In addition, the odour activity value (OAV) was calculated in order to determine the relative contribution of each compound to the aroma-active compounds. RESULTS: A total of 42 components by HD oil were identified by GC-MS, whereas 34 components were identified in SAFE oil. Thirteen compounds were identified by GC/O analysis in HD and SAFE oils respectively. CONCLUSION: Each extraction method has its own advantages and disadvantages, and they are generally complementary to each other. On the basis of AEDA, OAV and sensory evaluations, [2.2.1] bicyclic monoterpenes (borneol, bornyl acetate and camphor) and ß-caryophyllene are considered to be the main aroma-active compounds of both extraction methods.

Characteristic odorants from bailingu oyster mushroom (Pleurotus eryngii var. tuoliensis) and summer oyster mushroom (Pleurotus cystidiosus).

In this study, the characteristic odorants of the volatile oils from Pleurotus species (P. eryngii var. tuoliensis and P. cystidiosus) were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and aroma extract dilution analysis (AEDA). A total of 52 and 54 components (P. eryngii var. tuoliensis and P. cystidiosus, respectively) were identified, representing about 98.8% and 85.1% of the volatile oils, respectively. The main components of the P. eryngii var. tuoliensis oil were palmitic acid (82, 38.0%), oleic acid (86, 25.0%) and linoleic acid (85, 9.7%). The main components of the P. cystidiosus oil, palmitic acid (82, 25.8%), indole (54, 9.1%) and myristic acid (77, 5.3%). Regarding the aroma components, 16 and 13 components were identified in the P. eryngii var. tuoliensis and P. cystidiosus oils respectively, by the GC-O analyses. The results of the sniffing test, odor activity value (OAV) and flavor dilution (FD) factor indicate that methional, 1-octen-3-ol and nonanal are the main aroma-active components of P. eryngii var. tuoliensis oil. On the other hands, dimethyl trisulfide and 1-octen-3-ol were estimated as the main aroma-active components of the P. cystidiosus oil.

Chemical composition, aroma evaluation, and oxygen radical absorbance capacity of volatile oil extracted from Brassica rapa cv. "yukina" used in Japanese traditional food.

The chemical composition of the volatile oil extracted from the aerial parts of Brassica rapa cv. "yukina" was analyzed using GC-MS, GC-PFPD, and GC-O. A total of 50 compounds were identified. The most prominent constituents were (E)-1,5-heptadiene (40.27%), 3-methyl-3-butenenitrile (25.97%) and 3-phenylpropanenitrile (12.41%). With regard to aroma compounds, 12 compounds were identified by GC-O analysis. The main aroma-active compounds were dimethyl tetrasulfide (sulphury-cabbage, FD = 64), 3-phenylpropanenitrile (nutty, FD = 64), 3-methylindole (pungent, FD = 64), and methional (potato, FD = 32). The antioxidant activity of the aroma-active compounds of the oil was determined using an oxygen radical absorbance capacity (ORAC) assay using fluorescein as the fluorescent probe. The ORAC values were found to be 785 ± 67 trolox equivalents (µmol TE/g) for B. rapa cv. "yukina" oil. The results obtained showed that the volatile oil extracted from the aerial parts is a good dietary source of antioxidants.

Comparison of agitake (Pleurotus eryngii var. ferulae) volatile components with characteristic odors extracted by hydrodistillation and solvent-assisted flavor evaporation.

The chemical composition of volatile oil from agitake (Pleurotus eryngii var. ferulae) was established for the first time using gas chromatography (GC) and GC-mass spectrometry. Sixty-seven and 24 components were extracted by hydrodistillation (HD) using diethyl ether (DE) and dichloromethane (DM), respectively; these components accounted for 80.3% and 91.8% of the total oil, respectively. Thirteen and 48 components of were extracted by the solvent-assisted flavor evaporation method (SAFE), using DE and DM, respectively, and identified; these components accounted for 83.5% and 82.0% of the total oil, respectively. Methylsuccinimide and 2,3,7-trimethyl-2-octene were the most characteristic components by SAFE using DM.Odor evaluation of the volatile oil from agitake was also carried out using GC-olfactometry (GC-O), aroma extraction dilution analysis (AEDA), and the odor activity value (OAV). Sixteen, 8, 5 and 9 aroma-active components were identified using HD (DE and DM) and SAFE (DE and DM), respectively. The main aroma-active components extracted using HD and SAFE were 1-octen-3-ol (mushroom-like) and phenylacetaldehyde (floral), respectively. This study proved that HD and SAFE can be used as complementary extraction techniques for the complete characterization of volatile oil from agitake.

Biotransformation of (+)-fenchone by Salmonella typhimurium OY1002/2A6 expressing human CYP2A6 and NADPH-P450 reductase.

In this study, biotransformation of (+)-fenchone (compound 1) by Salmonella typhimurium OY1002/2A6 expressing human CYP2A6 and NADPH-P450 reductase yielded two oxidized metabolites, namely, (+)-(1S,6R)-6-endo-hydroxyfenchone (compound 2) and (+)-(1S,6S)-6-exo-hydroxyfenchone (compound 3). The conversion rate of compound 1 to compound 2 and 3 was 2.4% and 5.2%, respectively. This is the first study that succeeded in metabolizing compound 1 to obtain large amounts of metabolite 2 and 3 by using S. typhimurium OY1002/2A6 expressing human CYP2A6 and NADPH-P450 reductase.

Characteristic chemical components of the essential oil from white kwao krua (Pueraria mirifica).

The components of the essential oil from the roots of Pueraria mirifica were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Eighty-two components, representing 88.5% of the total oil, were identified by GC-MS. The main component of the oil was 2-pentylfuran, followed by hexanal and hexadecanol. With regard to the odor components from the essential oil of P. mirifica as determined by gas chromatography-olfactometry and aroma extract dilution analysis, it was revealed that phenylacetaldehyde and (2E)-nonenal imparted the green odor of the oil, and geraniol contributed to the sweet odor.

Biotransformation of (-)-camphor by Salmonella typhimurium OY1002/2A6 expressing human CYP2A6 and NADPH-P450 reductase.

In a previous in vitro study, (-)-camphor (1) was examined by incubation with human liver microsomes, and the oxidative metabolites thus formed were analyzed using gas chromatography-mass spectrometry. However, thus far, no large-scale biotransformation using recombinant human P450 has been performed. Here, the biotransformation of compound 1 has been investigated by using Salmonella typhimurium OY1002/2A6 expressing human CYP2A6 and human NADPH-P450 reductase as a biocatalyst. Compound 1 (400 mg) was converted to (1S,5S)-(-)-5-exo-hydroxycamphor (2) (30.4 mg) and (1S,7S)-(-)-8-hydroxycamphor (3) (2.4 mg) by S. typhimurium OY1002/2A6. This is the first report to show that large quantities of metabolites 2 and 3 can be produced by S. typhimurium OY1002/2A6 expressing human CYP2A6 and NADPH-P450 reductase.

Metabolism of (+)- and (-)-menthols by CYP2A6 in human liver microsomes.

The in vitro metabolism of (+)-(1S,3S,4R) and (-)-(1R,3R,4S)-menthol enantiomers was examined by incubation with human liver microsomes, and the oxidative metabolites thus formed were analyzed using gas chromatography-mass spectrometry (GC-MS). The (+)- and (-)-menthols were found to be oxidized to the respective (+)-(1S,3S,4S)- and (-)-(1R,3R,4R)-trans-p-menthane-3,8-diol derivatives by human liver microsomal P450 enzymes. Cytochrome P450 (CYP) 2A6 was determined to be the major enzyme involved in the hydroxylation of (+)- and (-)-menthols by human liver microsomes on the basis of the following lines of evidence. First, of 11 recombinant human P450 enzymes tested, CYP2A6 catalyzed the oxidation of (+)- and (-)-menthols. Second, oxidation of (+)- and (-)-menthols was inhibited by (+)-menthofuran and anti-CYP2A6 antibody. Finally, (+)- and (-)-menthol activities were found to correlate with contents of CYP2A6 in liver microsomes of 9 human samples.