trans-2-Hexen-1-ol

A comparative study of the volatile profile of wine vinegars with protected designation of origin by headspace stir bar sorptive extraction.[Pubmed:31284980]

Food Res Int. 2019 Sep;123:298-310.

The characteristic volatile profile of the Spanish Vinagre de Jerez (VJ), Vinagre de Condado de Huelva (VC) and Vinagre de Montilla-Moriles (VMM) protected designation of origin (PDO) wine vinegars has been studied and compared for the first time by headspace stir bar sorptive extraction-gas chromatography-mass spectrometry (HSSE-GC-MS). The possible markers of each category and PDO were assessed. Acetates were the majority group in all vinegars, while ketones, C13-norisoprenoids and volatile phenols showed significant differences between the three PDOs. Analysis of variance (ANOVA), heatmap and partial least squares-discriminant analysis (PLS-DA) were performed. According to these results, 1-heptanol, methyl nonanoate, 2-methylbutanoic acid, 2,2,6-trimethyl-cyclohexanone, trans-2-decenal, eucalyptol and alpha-terpineol, were the most significant compounds for differentiating of VC, diacetyl and acetoin, ethyl 3-ethoxypropanoate, 2- and 3-heptanone, 2-methyl-1-hexadecanol, 1-octen-3-ol, p-Cresol and camphene for VMM; and beta-damascenone, 5-hydroxymethylfurfural, 3-heptanol, trans-2-Hexen-1-ol and trans-2-hexen-1-yl acetate for VJ. Classification results showed that 100% of PDO samples were correctly classified, reaffirming the utility of the volatile profiles for classifying and authenticating wine vinegar PDOs.

Identification of volatile markers for the detection of adulterants in red ginseng (Panax ginseng) juice using headspace stir-bar sorptive extraction coupled with gas chromatography and mass spectrometry.[Pubmed:29797772]

J Sep Sci. 2018 May 24.

Red ginseng (Panax ginseng) products are frequently adulterated by manufacturers with cheaper medicinal plant products including deodeok (Codonopsis lanceolata) and doraji (Platycodon grandiflorum) to increase profits. To identify possible volatile markers for the adulteration of red ginseng juices with deodeok or doraji, a headspace stir-bar sorptive extraction method was developed. Gas chromatography with mass spectrometry and untargeted metabolomics analysis revealed that 1-hexanol, cis-3-hexen-1-ol, and trans-2-Hexen-1-ol are abundantly present in deodeok and doraji but not red ginseng. The peak area ratios in gas chromatograms of these compounds in red ginseng juices mixed with deodeok or doraji indicate that these volatile chemicals can be used as markers to detect the adulteration of red ginseng juice.

Rational Design of a Polyoxometalate Intercalated Layered Double Hydroxide: Highly Efficient Catalytic Epoxidation of Allylic Alcohols under Mild and Solvent-Free Conditions.[Pubmed:27748545]

Chemistry. 2017 Jan 23;23(5):1069-1077.

Intercalation catalysts, owing to their modular and accessible gallery and unique interlamellar chemical environment, have shown wide application in various catalytic reactions. However, the poor mass transfer between the active components of the intercalated catalysts and organic substrates is one of the challenges that limit their further application. Herein, we have developed a novel heterogeneous catalyst by intercalating the polyoxometalate (POM) of Na9 LaW10 O36 32 H2 O (LaW10 ) into layered double hydroxides (LDHs), which have been covalently modified with ionic liquids (ILs). The intercalation catalyst demonstrates high activity and selectivity for the epoxidation of various allylic alcohols in the presence of H2 O2 . For example, trans-2-Hexen-1-ol undergoes up to 96 % conversion and 99 % epoxide selectivity at 25 degrees C in 2.5 h. To the best of our knowledge, the Mg3 Al-ILs-C8 -LaW10 composite material constitutes one of the most efficient heterogeneous catalysts for the epoxidation of allylic alcohols (including the hydrophobic allylic alcohols with long alkyl chains) reported so far.

GC-MS analyses of the volatiles of Houttuynia cordata Thunb.[Pubmed:27731817]

Pak J Pharm Sci. 2016 Sep;29(5):1591-1600.

GC-MS is the basis of analysis of plant volatiles. Several protocols employed for the assay have resulted in inconsistent results in the literature. We developed a GC-MS method, which were applied to analyze 25 volatiles (alpha-pinene, camphene, beta-pinene, 2-methyl-2-pentenal, myrcene, (+)-limonene, eucalyptol, trans-2-hexenal, gamma-terpinene, cis-3-hexeneyl-acetate, 1-hexanol, alpha-pinene oxide, cis-3-hexen-1-ol, trans-2-Hexen-1-ol, decanal, linalool, acetyl-borneol, beta-caryophyllene, 2-undecanone, 4-terpineol, borneol, decanol, eugenol, isophytol and phytol) of Houttuynia cordata Thunb. Linear behaviors for all analytes were observed with a linear regression relationship (r2>0.9991) at the concentrations tested. Recoveries of the 25 analytes were 98.56-103.77% with RSDs <3.0%. Solution extraction (SE), which involved addition of an internal standard, could avoid errors for factors in sample preparation by steam distillation (SD) and solidphase micro extraction (SPME). Less sample material ( asymptotically equal to0.05g fresh leaves of H. cordata) could be used to determine the contents of 25 analytes by our proposed method and, after collection, did not affect the normal physiological activity or growth of H. cordata. This method can be used to monitor the metabolic accumulation of H. cordata volatiles.

Bitter-sensitive gustatory receptor neuron responds to chemically diverse insect repellents in the common malaria mosquito Anopheles quadrimaculatus.[Pubmed:27108454]

Naturwissenschaften. 2016 Jun;103(5-6):39.

Female mosquitoes feed on blood from animal hosts to obtain nutritional resources used for egg production. These contacts facilitate the spread of harmful human diseases. Chemical repellents are used to disrupt mosquito host-seeking and blood-feeding behaviors; however, little is known about the gustatory sensitivity of mosquitoes to known repellents. Here, we recorded electrical responses from gustatory receptor neurons (GRNs) housed within the labellar sensilla of female Anopheles quadrimaculatus to N,N-diethyl-3-methylbenzamide (DEET), picaridin, IR3535, 2-undecanone, p-menthane-3,8-diol, geraniol, trans-2-Hexen-1-ol, quinine, and quinidine. A bitter-sensitive GRN responded to all tested repellents and quinine, a known feeding deterrent. Responses of the bitter-sensitive neuron to quinine and an isomer, quinidine, did not differ. Delayed bursts of electrical activity were observed in response to continuous stimulation with synthetic repellents at high concentrations. Electrophysiological recordings from bitter-sensitive GRNs associated with mosquito gustatory sensilla represent a convenient model to evaluate candidate repellents.

Behavioral and electrophysiological responses of Aedes albopictus to certain acids and alcohols present in human skin emanations.[Pubmed:25049052]

Parasitol Res. 2014 Oct;113(10):3781-7.

Human skin emanations attract hungry female mosquitoes toward their host for blood feeding. In this study, we report the flight orientation and electroantennogram response of Aedes albopictus females to certain unsaturated acids and alcohols found in human skin. In the Y-tube olfactometer, odors of lactic acid and 2-methyl-3-pentanol attracted 54-65% of Ae. albopictus females at all doses in a dose-dependent manner. However, at the highest dose (10(-2) g), the acids repelled 40-45% females. Attractancy (ca. 62-68%) at lower doses and repellency (ca. 30-45%) at higher doses were recorded for 3-methyl-3-pentanol and 1-octen-3-ol, while 5-hexen-1-ol, cis-2-hexen-1-ol, and trans 2-hexen-1-ol odor repelled ca. 55-65% of Ae. albopictus females at all doses. Antenna of female Ae. albopictus exhibited a dose-dependent EAG response up to 10(-3) g of L-lactic acid, trans-2-methyl-2-pentenoic acid, 2-octenoic acid, trans-2-Hexen-1-ol and 1-octen-3-ol stimulations; however, the highest dose (10(-2) g) caused a little decline in the EAG response. EAG response of 9-10-fold was elicited by lactic acid, 2-octenoic acid, trans-2-hexenoic acid, and 3-methyl-3-pentanol, while cis-2-hexen-1-ol and trans-2-methyl pentenoic acid elicited 1-5-fold responses compared to solvent control. A blend of attractive compounds could be utilized in odor-baited trap for surveillance and repellent molecules with suitable formulation could be used to reduce the biting menace of mosquitoes.

Phytochemicals to suppress Fusarium head blight in wheat-chickpea rotation.[Pubmed:22520499]

Phytochemistry. 2012 Jun;78:72-80.

Fusarium diseases cause major economic losses in wheat-based crop rotations. Volatile organic compounds (VOC) in wheat and rotation crops, such as chickpea, may negatively impact pathogenic Fusarium. Using the headspace GC-MS method, 16 VOC were found in greenhouse-grown wheat leaves: dimethylamine, 2-methyl-1-propanol, octanoic acid-ethyl ester, acetic acid, 2-ethyl-1-hexanol, nonanoic acid-ethyl ester, nonanol, N-ethyl-benzenamine, naphthalene, butylated hydroxytoluene, dimethoxy methane, phenol, 3-methyl-phenol, 3,4-dimethoxy-phenol, 2,4-bis (1,1-dimethyethyl)-phenol, and 1,4,7,10,13,16-hexaoxacyclooctadecane; and 10 VOC in field-grown chickpea leaves: ethanol, 1-penten-3-ol, 1-hexanol, cis-3-hexen-1-ol, trans-2-Hexen-1-ol, trans-2-hexenal, 3-methyl-1-butanol, 3-hydroxy-2-butanone, 3-methyl-benzaldehyde and naphthalene. Also found was 1-penten-3-ol in chickpea roots and in the root nodules of two of the three cultivars tested. Chickpea VOC production pattern was related (P=0.023) to Ascochyta blight severity, suggesting that 1-penten-3-ol and cis-3-hexen-1-ol were induced by Ascochyta rabiei. Bioassays conducted in Petri plates established that chickpea-produced VOC used in isolation were generally more potent against Fusarium graminearum and Fusarium avenaceum than wheat-produced VOC, except for 2-ethyl-1-hexanol, which was rare in wheat and toxic to both Fusarium and tetraploid wheat. Whereas exposure to 1-penten-3-ol and 2-methyl-1-propanol could suppress radial growth by over 50% and octanoic acid-ethyl ester, nonanol, and nonanoic acid-ethyl ester had only weak effects, F. graminearum and F. avenaceum growth was completely inhibited by exposure to trans-2-hexenal, trans-2-Hexen-1-ol, cis-3-hexen-1-ol, and 1-hexanol. Among these VOC, trans-2-hexenal and 1-hexanol protected wheat seedlings against F. avenaceum and F. graminearum, respectively, in a controlled condition experiment. Genetic variation in the production of 2-ethyl-1-hexanol, a potent VOC produced in low amount by wheat, suggests the possibility of selecting Fusarium resistance in wheat on the basis of leaf VOC concentration. Results also suggests that the level of Fusarium inoculum in chickpea-wheat rotation systems may be reduced by growing chickpea genotypes with high root and shoot levels of trans-2-Hexen-1-ol and 1-hexanol.

Aroma composition of Vitis vinifera Cv. tannat: the typical red wine from Uruguay.[Pubmed:12926890]

J Agric Food Chem. 2003 Aug 27;51(18):5408-13.

The free volatiles, as well as those released from the glycosidically bound forms by enzyme hydrolysis, have been analyzed to chracterize young Tannat wines from two successive vintages. The Tannat wine showed some aroma profile peculiarities detected in the free forms but, above all, in the bound fraction for the level and profile of the norisoprenoidic fraction. Among the free volatile compunds, a rather low content of C(6) alcohols with a prevalence of cis-3-hexen-1-ol on the trans form and sometimes a remarkable level of trans-2-Hexen-1-ol seem to be typical for the variety. C(13)-norisoprenoidic and monoterpenic volatiles made up approximately 42% of the total level of the volatiles observed in the glycosidase enzyme-released fraction. The other volatiles were C(6) alcohols (6%) and benzenoid compounds (51%). The dominating monoterpene alcohols were the cis and trans isomers of 3,7-dimethyl-1,6-octadiene-3,8-diol (8-hydroxylinalool). The C(13)-norisoprenoid pattern was composed by 3-hydroxy-beta-damascone, 3-oxo-alpha-ionol, vomifoliol, 4-oxo-beta-ionol, 3-oxo-7,8-dihydro-alpha-ionol, 4-oxo-7,8-dihydro-beta-ionol, grasshopper ketone, and 7,8-dihydrovomifoliol.

In vitro differentiation of haustorial mother cells of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, triggered by the synergistic action of chemical and physical signals.[Pubmed:12684021]

Fungal Genet Biol. 2003 Apr;38(3):320-6.

Biotrophic plant pathogenic fungi often develop a sophisticated series of infection structures for non-destructive host tissue penetration. In vitro, early infection structures of rust fungi-germ tube, appressorium, substomatal vesicle, infection hyphae-can easily be induced, but in vitro differentiation rates of late infection structures-haustorial mother cells (hmc), haustoria-are low at best. Under appropriate conditions (humid atmosphere), a combination of physical (mild heat shock) and chemical signals (trans-2-Hexen-1-ol) induced the in vitro differentiation of hmc in the wheat stem rust fungus, Puccinia graminis f. sp. tritici. Around two thirds of the in vitro differentiated germlings developed up to three hmc which were cytologically identical to hmc formed in planta. Efficient in vitro differentiation of hmc will allow us to analyse in molecular detail the processes involved in the induction and differentiation of this critically important developmental stage of the economically important plant pathogenic rust fungi.

Olfactory discrimination of structurally similar alcohols by cockroaches.[Pubmed:12466954]

J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 Nov;188(10):787-97.

The capability of the cockroach Periplaneta americana to discriminate odors of structurally similar aliphatic alcohols was studied by using an operant conditioning paradigm. Cockroaches were trained to discriminate three odors: one odor associated with sucrose solution (reward) and two odors associated with NaCl solution (non-reward). After training, their odor preferences were tested by counting the number of visits to each odor source. We tested the capability of cockroaches to discriminate (1) three normal aliphatic alcohols with different numbers of carbon (1-pentanol, 1-hexanol and 1-octanol), (2) three C6 aliphatic alcohols (1-hexanol, 2-hexanol and trans-2-Hexen-1-ol), (3) binary mixtures of two of these three alcohols and their components, and (4) 1-hexanol solution of three different concentrations (1, 10 and 100 micro g micro l(-1)). Cockroaches exhibited higher preferences for the odors associated with reward in these tests, and we therefore conclude that cockroaches can discriminate these odors. However, discrimination of 1-hexanol and trans-2-Hexen-1-ol and their binary mixture was imperfect, in that some statistical tests suggested significant level of discrimination but other tests did not. In addition, the cockroaches learned to associate a 1-hexanol solution of the highest or lowest concentration with sucrose reward but failed to learn to associate 1-hexanol of an intermediate concentration with reward.

Silica-Supported Tantalum Catalysts for Asymmetric Epoxidations of Allyl Alcohols.[Pubmed:10602235]

Angew Chem Int Ed Engl. 1999 Dec 3;38(23):3540-3542.

Tantalum good, titanium bad: This appears to be the case for silica-supported catalysts for the asymmetric epoxidation of allyl alcohols. Complexes such as [SiO-Ta(OEt)(4)] were prepared from silica and [Ta(=CHCMe(3))(CH(2)CMe(3))(3)], and in the presence of a tartrate and an alkyl hydroperoxide, these surface tantalum compounds lead to efficient and convenient catalysts for the asymmetric epoxidation of 2-propen-1-ol (R=H) and trans-2-Hexen-1-ol (R=nPr; see reaction).

Specificity-related suppression of responses to binary mixtures in olfactory receptors of the Colorado potato beetle.[Pubmed:3382950]

Brain Res. 1988 Apr 26;447(1):18-24.

Responses of antennal olfactory receptors of the Colorado potato beetle (Leptinotarsa decemlineata Say) to stimulation with 5 general green odour components, i.e. cis-3-hexen-1-ol, trans-2-hexenal, cis-3-hexenyl acetate, trans-2-Hexen-1-ol and 1-hexanol, were recorded extracellularly. Response spectra derived from these recordings cannot be classified into distinct reaction types. The spectra overlap in their sensitivity to individual stimuli, but there are differences in their degree of specialization with a gradual conversion from generalist to specialist receptors. Moreover, specialization is found to different stimuli. Receptor reactions to stimulation with binary mixtures of 3 of these compounds indicated that suppression of the response to one chemical by another is very common in olfactory receptor cells. The more a receptor is specialized, the stronger is this suppression. Suppression in narrowly tuned olfactory receptor neurones, therefore, is expected to play a fundamental role in the recognition of natural odour blends.

Integration of olfactory information in the Colorado potato beetle brain.[Pubmed:3382944]

Brain Res. 1988 Apr 26;447(1):10-7.

The processing of olfactory information in the Colorado potato beetle, Leptinotarsa decemlineata Say, was studied by recording responses of olfactory neurones intracellularly in the deutocerebrum. Response characteristics of neurones in this first relay station of the olfactory pathway were measured when the antennae were stimulated with five general green leaf volatiles, i.e. cis-3-hexen-1-ol, trans-2-hexenal, cis-3-hexenyl acetate, trans-2-Hexen-1-ol and 1-hexanol. These compounds are part of the so-called green odour of potato, whose defined composition is essential for the beetle's host plant finding. The response spectra of deutocerebral neurones can be divided roughly into two classes: one class containing neurones which are not very specific for the tested compounds, and another class with highly specialized neurones. Their different responses to a potato leaf extract suggest two channels for the processing of olfactory information in the antennal lobe: one channel for the detection of the presence of green leaf odour components, and another one for an evaluation of the component ratios.

Strawberry foliage headspace vapor components at periods of susceptibility and resistance toTetranychus urticae Koch.[Pubmed:24276131]

J Chem Ecol. 1988 Mar;14(3):789-96.

Headspace components from strawberry foliage have been isolated by nitrogen entrainment and Tenax trapping. Traps were eluted with hexane, and components were analyzed by gas chromatography-mass spectrometry. Fifteen compounds were identified by comparison with authentic standards,trans-2-hexenal, 1-hexanol,trans-2-Hexen-1-ol,cis-3-hexen-1-ol, hexyl acetate,cis-3-hexenyl acetate, 6-methyl-5-hepten-2-ol, 1-octanol, 1-octen-3-ol, linalool, alpha-terpineol, methyl salicylate, ethyl saiicylate, benzyl alcohol, and 2-phenylethanol. The relative amounts of these components were compared at flowering and after fruit harvest when plants were more resistant to the two-spotted spider mite,Tetranychus urticae Koch. The predominant components,cis-3-hexen-1-ol and its acetate, did not change markedly between the sampling periods, but methyl salicylate increased approximately 10-fold after fruit harvest. Methyl salicylate at low concentrations under bioassay conditions did not affect mite behavior. The biosynthetic relationship of this compound to other phenols which have been implicated in plant resistance is discussed.