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At least 109 records · Page 6Linked to original sources

Gas-chromatographic resolution of enantiomeric secondary alcohols. Stereoselective reductive metabolism of ketones in rabbit-liver cytosol.

Chiral secondary alcohols were treated with (S)-(-)-1-phenylethyl isocyanate. For each racemic alcohol, the resulting diastereomeric urethane derivatives were resolved on flexible fused-silica capillary GLC columns with retention times of 15 min or less. Derivatization of individual enantiomers showed that the urethane derivatives of (R)-(-)-2-octanol, (R)-(+)-1-phenylethyl alcohol, and (S)-(+)-2,2,2-trifluoro-1-phenylethanol are eluted before the corresponding diastereomers. The procedure is simple and rapid, and is suitable for the determination of the enantiomeric composition of chiral alcohols extracted from biological media. A series of aliphatic alcohols, aryl alkyl carbinols, and arylalkyl alkyl carbinols were resolved with the procedure, and the degree of resolution varied from good to excellent. Eight achiral ketones were incubated, individually, with rabbit-liver 90,000 g supernatant fractions, and the enantiomeric composition of the alcohol metabolites was determined with the GLC procedure. The reductions proceeded with high stereoselectivity to give alcohol products of 90% or greater enantiomeric purity. The reduction of 2-octanone and acetophenone gave predominant alcohols of (S)-configuration, in agreement with the Baumann-Prelog rule. The configuration of the predominant alcohols arising in the reduction of the remainder of the ketones could not be firmly established, but the evidence suggests that they are also of the (S)-configuration. Fluorine or methyl substitution in the ortho position of acetophenone produced an increase in the stereoselectivity, and the alcohol produced from ortho-methylacetophenone was enantiomerically greater than 99% pure.

Alcohols↗

Attraction of Culex pipiens pipiens (Diptera: Culicidae) to flower volatiles.

Methylene chloride extracts of flowers from 4 plants (common milkweed, Asclepias syriaca L; ox-eye daisy, Leucanthemum vulgare Lamarck; Canada goldenrod, Solidago canadensis L.; and yarrow, Achillea millefolium L.) were tested in a dual-port olfactometer for attractiveness to female northern house mosquitoes, Culex pipiens pipiens L. Fifty milligrams of extract was used for each test, which was equivalent to the amount of extract from flowers of 0.58 common milkweed inflorescences, 1.75 ox-eye daisy flower heads, 0.33 Canada goldenrod plants, or 3.14 yarrow plants. Significantly more Cx. pipiens responded to the common milkweed flower extract than to a control. Ox-eye daisy, Canada goldenrod and yarrow flower extracts were not significantly attractive to this species. A headspace sample of the common milkweed extract was collected by solid phase microextraction and analyzed by gas chromatography-mass spectrometry. The most abundant compounds in the headspace sample were 2-phenylethanol and benzyl alcohol. Analysis of the common milkweed extract and standards of 2-phenylethanol and benzyl alcohol by gas chromatography-flame ionization detection confirmed that these compounds were present in the extract. Cx. pipiens did not respond to synthetic blends of these 2 compounds when tested in a dual-port olfactometer.

Animals↗

Heat activation of Phycomyces blakesleeanus spores: theromdynamics and effect of alcohols, furfural, and high pressure.

The thermodynamic parameters for the heat activation of the sporangiospores of Phycomyces blakesleeanus were determined. For the apparent activation enthalpy (DeltaH(#)) a value of 1,151 kJ/mol was found, whereas a value of 3,644 J./ degrees K.mol was calculated for the apparent activation entropy (DeltaS(#)). n-Alcohols (from methanol to octanol), phenethyl alcohol, and furfural lowered the activation temperature of P. blakesleeanus spores. The heat resistance of the spores was lowered concomitantly. The effect of the alcohols was a linear function of the concentration in the range that could be applied. When the log of the concentration needed to produce an equal shift of the activation temperature was plotted for each alochol against the log of the octanol/water partition coefficient, a straight line was obtained. The free energy of adsorption of the n-alcohols to their active sites was calculated to be -2,487 J/mol of CH(2) groups. Although still inconclusive, this points toward an involvement of protein in the activation process. The effect of phenethyl alcohol was similar to the effect of n-alcohols, but furfural produced a greater shift than would be expected from the value of its partition coefficient. When the heat activation of the spores was performed under high pressure, the activation temperature was raised by 2 to 4 degrees K/1,000 atm. However, with pressures higher than 1,000 atm (1.013 x 10(5) kPa) the activation temperature was lowered until the pressure became lethal (more than 2,500 atm). It is known that membrane phase transition temperatures are shifted upward by about 20 degrees K/1,000 atm and that protein conformational changes are shifted upward by 2 to 6 degrees K/1,000 atm. Consequently, heat activation of fungal spores seems to be triggered by a protein conformational change and not by a membrane phase transition. Activation volumes of -54.1 cm(3)/mol at 38 degrees C and -79.3 cm(2)/mol at 40 degrees C were found for the lowering effect of high pressure on the heat activation temperature.

Alcohols↗

Quorum sensing: alcohols in a social situation.

Many microbes use extracellular signals to transmit information about population density and environmental conditions. Recent evidence suggests that the budding yeast Saccharomyces cerevisiae exhibits this type of regulation and that the signals are aromatic alcohols.

Hyphae↗

Rhythmic emission of floral volatiles from Rosa damascena semperflorens cv. 'Quatre Saisons'.

The control of rhythmic emission of floral volatiles emitted from Rosa damascena semperflorens cv. 'Quatre Saisons' throughout floral development under various light regimes was studied. 2-Phenylethanol was the major volatile emitted in addition to monoterpenols, oxidised monoterpenols, monoterpenes and aromatic compounds. All detected volatiles were emitted rhythmically, with maximum peaks coinciding 8-10 h into a 12-h photoperiod. For some compounds a secondary, nocturnal peak was apparent. The primary and secondary maxima both occurred at approximately 24-h intervals. Rhythms appeared to be regulated endogenously: rhythmic emission continued upon exposure to continuous light or continuous darkness, and a phase shift in emission was induced upon inversion of the photoperiod. Additionally, emission continued after flower excision. A similar profile of free volatiles was stored within the floral tissue, together with glycosidic forms of 2-phenylethanol (>99% beta-D-glucoside), benzyl alcohol, citronellol and geraniol. Regression analysis indicated a significant decrease in glycosylated 2-phenylethanol through the photoperiod. These results suggest that glycosylated volatiles stored within petals may be a source of rhythmically emitted volatiles.

Alcohols↗

Chemoenzymatic synthesis of optically active, biodegradable polymers based on phenyl- and naphthyl-ethanols esterified with divinyladipate.

For the purpose of developing a new synthetic polymer containing an asymmetric molecule branch, three racemic alcohols, i.e. 1-phenylethanol, 1-(4-methylphenyl)ethanol and 1-(2-naphthyl)ethanol, were esterified enzymatically with divinyladipate using a lipase from Pseudomonas cepacia. The enzymatic acylation of alcohols produced monoacylated products. Optically active polymerizable monomers, (R)-vinyl adipic acid (phenyl-1-yl) ethyl ester, (R)-vinyl adipic acid (4-methylphenyl-1-yl) ethyl ester and (R)-vinyl adipic acid (2-naphthyl-1-yl) ethyl ester with enantiometric excesses over 99%, 96% and 99%, respectively, were obtained. Each optically active monomer was then subjected to free radical polymerization, to give polymers having a number average molecular weight of 2.9 x 10(3) - 2.2 x 10(4). These polymers are considered useful as optically active polymers having biodegradability.

Adipates↗

PHENETHYL ALCOHOL. II. EFFECT ON THYMINE-REQUIRING ESCHERICHIA COLI.

Rosenkranz, Herbert S. (Columbia University, New York, N.Y.), Howard S. Carr, and Harry M. Rose. Phenethyl alcohol. II. Effect on thymine-requiring Escherichia coli. J. Bacteriol. 89:1370-1373. 1965.-Phenethyl alcohol (PEA) at levels (0.05%) presumed to interfere with messenger ribonucleic acid synthesis also inhibits thymineless death, when the agent is added prior to the exponential killing phase. The addition of more concentrated solutions of PEA (0.5%) during this initial starvation leads to an immediate killing. Identical results were obtained when 0.5% PEA was added to cells growing in the presence of thymine. The addition of this high level (0.5%) of PEA to bacteria undergoing thymineless death results in the rescue of the survivors.

Alcohols↗

Electrophysiological responses to non-electrolytes in lingual nerve of rat and in lingual epithelia of dog.

Epithelial and neural mechanisms underlying the trigeminal chemoreception of non-electrolytes were investigated in whole-nerve recordings from lingual nerve and in Ussing-chamber studies of isolated lingual epithelia. The non-electrolytes included menthol, amyl acetate, phenethyl alcohol, toluene, methanol, ethanol, propanol, butanol, hexanol and octanol. They produced different lingual nerve responses: methanol and ethanol only increased ongoing activity; longer-chain alcohols initially increased but then suppressed activity below baseline; phenethyl alcohol and toluene only suppressed activity. Their threshold concentrations for lingual nerve responses, with the exception of menthol, were proportional to the octanol:water partition coefficients of the stimuli. The threshold concentration for menthol was significantly lower than predicted by this coefficient. Calculation of the free energy of transfer from the threshold concentrations for the n-alcohols suggests that they undergo partition into a hydrophobic environment such as is found in lipid bilayers. Lanthanum chloride, which inhibited lingual nerve responses to hydrophilic compounds, presumably by blocking their diffusion across tight junctions, did not inhibit responses to these non-electrolytes. At high concentrations, hexanol acted as an anaesthetic in that the lingual nerve no longer responded to thermal and chemical stimuli whereas ethanol, which only increased lingual nerve activity, did not inhibit those responses. Epithelial transport, as indicated by the short-circuit current (Isc) measured across tongues bathed in symmetrical solutions of Krebs-Henseleit buffer, was reversibly inhibited by ethanol, hexanol, octanol, phenyl ethanol and menthol. The stimulus concentration necessary to inhibit 50% of the Isc decreased with increasing octanol:water partition coefficient.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

Use of apple seed meal as a new source of beta-glucosidase for enzymatic glucosylation of 4-substituted benzyl alcohols and tyrosol in monophasic aqueous-dioxane medium.

A facile method for enzymatic glycosylation of 4-substituted benzyl alcohols and tyrosol with glucose in a monophasic aqueous-dioxane medium was reported, using a crude meal of apple seed as a new catalyst. The corresponding beta-d-glucosides were synthesized in moderate yields (13.1-23.1%), among which the salidroside was obtained in 15.8% yield.

Benzyl Alcohol↗

Glycosidation with a disarmed glycosyl iodide: promotion and scope.

[reaction: see text] Glucuronyl iodide 1 has been studied in detail as a "disarmed" glycosyl donor. In a model reaction, using N-iodosuccinimide (NIS) as a promoter and 2-phenylethanol as acceptor, best results were obtained using NIS with I(2), followed by trimethylsilyltrifluoromethanesulfonate (TMSOTf). When a series of primary and secondary alcohols was glycosylated using these conditions, yields of 60-83% of beta-glucuronides were obtained. Various "nonheavy" metal salts also effectively catalyzed the model reaction but led to significant amounts of alpha-product with less reactive secondary alcohols.

Alcohols↗

Sensitivity of tryptophan, tyrosine and phenylalanine mutants of Saccharomyces cerevisiae to phenethyl alcohol.

Phenethyl alcohol inhibits the growth of many microorganisms. It is believed that the growth inhibition is mediated by its effect on the cell membrane. Differences between sensitive and resistant strains are suggested to be due to alterations in membrane structure. We report that, in some strains, an unexpected relationship exists between auxotrophy for tryptophan, tyrosine and phenylalanine and sensitivity to phenethyl alcohol.

Ethanol↗

Quantification of selected volatile constituents and anions in Mexican Agave spirits (Tequila, Mezcal, Sotol, Bacanora).

A large collection (n = 95) of Mexican Agave spirits with protected appellations of origin (Tequila, Mezcal, Sotol, and Bacanora) was analyzed using ion and gas chromatography. Because of their production from oxalate-containing plant material, all Agave spirits contained significant concentrations of oxalate (0.1-9.7 mg/L). The two Tequila categories ("100% Agave" and "mixed") showed differences in the methanol, 2-/3-methyl-1-butanol, and 2-phenylethanol concentrations with lower concentrations in the mixed category. Mezcal showed no significant differences in any of the evaluated parameters that would allow a classification. Sotol showed higher nitrate concentrations and lower 2-/3-methyl-1-butanol concentrations. Bacanora was characterized by exceptionally high acetaldehyde concentrations and a relatively low ethyl lactate content. The methanol content was the most problematic compound regarding the Mexican standards: two Tequilas (4%), five Sotols (31%), and six Bacanoras (46%) had levels above the maximum methanol content of 300 g/hL of alcohol. In conclusion, the composition of Mexican Agave spirits was found to vary over a relatively large range.

Agave↗

Instrumental method for automated on-line fraction analysis and peak deconvolution in multicomponent-overloaded high-performance liquid chromatography.

A bi-dimensional (non-orthogonal) chromatographic system made of two columns of different length (longer along the first direction and shorter on the second) but packed with identical (or similar) materials has been employed to perform automated on-line fraction analysis and peak deconvolution of multicomponent overloaded band profiles. Multicomponent overloaded peaks, eluted from the first column, are sampled through a remotely-controlled switching valve and fractions are injected, under analytical conditions, directly into the second direction. This set-up serves a twofold purpose. First of all, it has been possible to use linear calibration curves for detector calibration (DC). Secondly, since single component peaks were resolved on the second direction, individual concentration profiles have been obtained beneath the envelop of overlapping bands. All the information necessary to operate the bi-dimensional system can be achieved by analyzing the chromatographic behavior of the mixture on the shorter column under linear conditions. Therefore, solutions of unknown concentration can be prepared and their composition reconstructed with a simple chromatographic run. Two- and three-component overloaded mixtures have been employed to validate the system.

Automation↗