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).

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.

Characteristic odor components of volatile oil from the cultivation medium of Lactobacillus acidophilus.

Volatile oils obtained from both the liquid medium after incubation (MAI) and liquid medium before incubation (MBI) in the cultivation process of Lactobacillus acidophilus were isolated by hydrodistillation (HD) and analyzed to investigate the utility of the liquid waste. The composition of the volatile oils was analyzed by capillary gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). In total, 46 and 19 compounds were detected in the volatile oils from MAI (MAI oil) and MBI (MBI oil), respectively. The principle components of MAI oil were fatty acids, including pentanoic acid (12.75%), heptanoic acid (14.05%), and nonanoic acid (14.04%). The important aroma-active compounds in the oils were detected by GC-MS/Olfactometry (GC-O), and their intensity of aroma were measured by aroma extraction dilution analysis (AEDA). Pyrazines were determined as key aroma components; in particular, 2-ethyl-5-methylpyrazine was the most primary aroma-active compound in MAI oil. In addition, as the characteristic aroma-active compounds, 3-(methylthio)-propanal, trimethylpyrazine, and pentanoic acid were also detected in MAI oil. These results imply that the waste medium after incubation of L. acidophilus may be utilized as a source of volatile oils.

Chemical composition and aroma evaluation of essential oils from Evolvulus alsinoides L.

The aim of this study was to investigate the chemical composition and the odor-active compounds of the essential oils from Evolvulus alsinoides, which is a well-known edible and medicinal plant. The volatile compounds in the oils were identified by hydrodistillation (HD) and solvent-assisted flavor evaporation (SAFE) in combination with GC, GC/MS, GC/O (=olfactometry), aroma extract dilution analysis (AEDA), and relative flavor activities (RFA values). The most abundant compound in the HD oil was cis-α-necrodol (12.62%), an irregular monoterpene with a cyclopentane skeleton, which is very unusual in the plant kingdom. In the SAFE oil, the main components included 2-butoxyethanol (9.01%), benzyl alcohol (8.01%), and γ-butyrolactone (7.37%). Through sensory analysis, 21 aroma-active compounds were identified by GC/O. The most intense aroma-active compounds in the HD oil were hexan-1-ol and γ-nonalactone, both of which showed high RFA values. α-Methyl-γ-butyrolactone and dimethyl sulfone contributed more strongly to the aroma of the SAFE oil. These results imply that the essential oils of E. alsinoides deserve further investigation in the food industry.

Volatile composition and sensory properties of Indian herbal medicine-Pavonia odorata-used in Ayurveda.

The chemical composition of volatile oil obtained from aerial parts of Pavonia odorata were investigated using gas chromatography-mass spectrometry (GC-MS). Its aroma-active compounds were identified using gas chromatography-olfactometry (GC-O) and aroma extraction dilution analysis (AEDA). In order to determine the relative contribution of each compound to the aroma of P. odorata, relative flavour activity (RFA) was calculated. The hydrodistillation of P. odorata afforded yellowish oil and the yield was 0.009% (w/w) with a spicy, sweet, and green odour. Eighty-five compounds were identified in the oil by GC-MS; the major constituents of the volatile oil were ageratochromene (11.95%), palmitic acid (9.95%), hexahydrofarnesyl acetone (5.96%), ß-eudesmol (4.53%) and ß-caryophyllene oxide (3.08%). The most characteristic aroma compounds in the volatile oil were identified for ß-caryophyllene oxide (FD-factor = 128, spicy), (E)-pinocarveol (FD-factor = 64, sweet), 3-butylpyridine (FD-factor = 64, spicy), and 2-nonanone (FD-factor = 32, green) by GC-MS, GC-O and AEDA. It seems that these compounds are responsible for the spicy, sweet and green odour of the aerial parts of P. odorata. The antioxidant activity of the volatile oil was also investigated by the oxygen radical absorbance capacity (ORAC) assay using fluorescein (FL) as the fluorescent probe. The ORAC value of the oil was 594.2 ± 25.9 µM TE/g. The results indicated that the volatile oil from the aerial parts of P. odorata could be considered as a natural antioxidant effect agent.

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.

Synthesis, antioxidant capacity, and structure-activity relationships of tri-O-methylnorbergenin analogues on tyrosinase inhibition.

A series of tri-O-methylnorbergenin analogues 1-9 were synthesized and their antioxidant activities and inhibitory effects on tyrosinase were evaluated. Among tested analogues, compound 4 bearing cathechol moiety exhibited greater antioxidant activity and excellent inhibition on tyrosinase with IC50 value of 9.1 µM, comparable to that of corresponding positive controls. The inhibition mechanism analysis of compound 4 demonstrated that it was a mixed-type inhibitor on tyrosinase. These results suggest that these compounds may serve as a useful clue for further designing and development of novel potential tyrosinase inhibitors.

Characterization of aroma-active compounds in dry flower of Malva sylvestris L. by GC-MS-O analysis and OAV calculations.

In this study, the aroma-active compounds in the dried flower of Malva sylvestris L. were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), and gas chromatography-olfactometry (GC-O) and aroma extraction dilution analysis (AEDA). A light yellow oil with a sweet odor was obtained with a percentage yield of 0.039% (w/w), and 143 volatile compounds (89.86%) were identified by GC-MS. The main compounds were hexadecanoic acid (10.1%), pentacosane (4.8%) and 6,10,14-trimethyl-2-pentadecanone (4.1%). The essential oil consisted mainly of hydrocarbons (25.40%) followed by, alcohols (18.78%), acids (16.66%), ethers (5.01%) ketones (7.28%), esters(12.43%), aldehydes (2.30%) and others (2.00%). Of these compounds, 20 were determined by GC-O and AEDA, to be odor-active (FD (flavor dilution) factor ≥ 1). ß-Damascenone (FD = 9, sweet), phenylacetaldehyde (FD = 8, floral, honey-like) and (E)-ß-ocimene (FD = 8, spicy) were the most intense aroma-active compounds in M. sylvestris. In order to determine the relative contribution of each of the compounds to the aroma of M. sylvestris, odor activity values (OAVs) were used. ß-Damascenone had the highest odor activity values (OAV) (50,700), followed by (E)-ß-ionone (15,444) and decanal (3,510). In particular, ß-damascenone had a high FD factors, and therefore, this compound was considered to be the main aroma-active components of the essential oil. On the basis of AEDA, OAVs, and sensory evaluation results, ß-damascenone is estimated to be the main aroma-active compound of the essential oil.

Structure-activity relationships for bergenin analogues as ß-secretase (BACE1) inhibitors.

Here we evaluated the inhibitory effects of bergenin analogues (2-10), prepared from naturally occurring bergenin, (1) on ß-secretase (BACE1) activity. All the bergenin analogues that were analyzed inhibited BACE1 in a dose-dependent manner. 11-O-protocatechuoylbergenin (5) was the most potent inhibitor, with an IC50 value of 0.6 ± 0.07 µM. The other bergenin analogues, in particular, 11-O-3',4'-dimethoxybenzoyl)-bergenin (6), 11-O-vanilloylbergenin (7), and 11-O-isovanilloylbergenin (8), inhibited BACE1 activity with IC50 values of <10.0 µM. BACE1 inhibitory activity was influenced by the substituents of the benzoic acid moiety. To the best of our knowledge, this is the first report on the structure-activity relationships (SAR) in the BACE1 inhibitory activities of bergenin analogues. These bergenin analogues may be useful in studying the mechanisms of Alzheimer's disease.

Structure-activity relationships of bergenin derivatives effect on α-glucosidase inhibition.

The α-glucosidase inhibitory activities of bergenin derivatives were evaluated. Bergenin derivatives were synthesized from bergenin which is a characteristic compound of B. ligulata. A new bergenin derivative, 11-O-(3',4'-dimethoxybenzoyl)-bergenin showed the highest potent inhibitory activity among those of bergenin derivatives. The presence of substituents at 3',4'-position in bergenin derivatives altered the α-glucosidase inhibitory activity. 11-O-(3',4'-dimethoxybenzoyl)-bergenin was noncompetitive inhibitor for α-glucosidase. The present study reveals that bergenin derivatives could be classified as a new group of α-glucosidase inhibitors.

Synthesis and biological evaluation of bergenin analogues as mushroom tyrosinase inhibitors.

In this manuscript, we synthesized a series of bergenin analogues, analyzed their structural importance for two biologic activities (anitioxidant activity (ORAC) and mushroom tyrosinase inhibitory activity). Among them, compound 5 which contains catechol moiety exhibited the most antioxidant activity (3.75 µmol of Trolox equiv. per µmol of 5). Furthermore, compound 5 was found to be the most potent (IC50 value = 17.5 ± 0.04 µM) when compared with the standard tyrosinase inhibitors of arbutin (IC50 value = 221.8 ± 1.9 µM) and kojic acid (IC50 value = 46.6 ± 3.8 µM). The bergenin moiety, the ester linkage, and benzoic acid moiety of bergenin derivatives affected two biologic activities. Tyrosinase inhibitory activity was affected by substituents of benzoic acid moiety. This manuscript provides a good foundation for the design and development of new tyrosinase inhibitors.

Insecticidal effect and chemical composition of the volatile oil from Bergenia ligulata.

The chemical composition of the volatile oil from roots of Bergenia ligulalta was analyzed by GC-MS. A total of 97 compounds were identified. (+)-(6S)-Parasorbic acid (1) (47.45%), isovaleric acid (6.25%), 1,8-cineole (4.24%), (Z)-asarone (3.50%), and terpinen-4-ol (2.96%) were the most prominent constituents. (+)-(6S)-Parasorbic acid (1) was isolated and characterized by spectroscopic data. This is the first report of the existence of (+)-(6S)-parasorbic acid in the saxifrage family. The volatile oil and the isolated compound were tested against Drosophila melanogaster . The results obtained showed that the volatile oil from roots could be considered as natural insecticidal effect agents.