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PubMed2026

Vortex-assisted liquid-liquid microextraction based on natural deep eutectic solvents for the determination of pyrethroid pesticides in urine.

A novel, facile, and environmentally friendly analytical method was developed based on vortex-assisted liquid-liquid microextraction and high-performance liquid chromatography with diode-array detection for detecting pyrethroid pesticides (PPs) in urine. Natural deep eutectic solvents (NADESs) were prepared using plant essential oil-derived monoterpenoids (thymol, carvacrol, and menthol) combined with aromatic primary alcohols (benzyl alcohol, phenethyl alcohol, and phenylpropyl alcohol) as hydrogen bond donors and acceptors. These solvents served as environmentally benign extraction media, thereby avoiding the use of conventional volatile, toxic organic solvents. NADESs are naturally derived, easy to prepare, biodegradable, and environmentally friendly solvents. Hydrophobic and π-π interactions between the NADESs and PPs may contribute to enhancing the affinity of PPs toward the NADESs phase. Vortex technology, accelerating mass transfer between the sample and extractant phases, enables fast extraction of PPs. Under optimized conditions, the method achieved a low detection limit (0.002 mg L-1), satisfactory precision with relative standard deviations (0.3%-2.4%), and acceptable recovery (80.7%-86.2%). The method demonstrated excellent performance in urine analysis and was feasible as a facile and green strategy for monitoring the content of PPs in biological matrices and assessing exposure risk.

Liquid Phase Microextraction↗
PubMed1979

[The solubilizer of diazepam (valium)--its action on respiration (author's transl)].

Investigations carried out in volunteers showed that when compared with physiological saline the solubilizer of diazepam caused hyperventilation. Among the constituents of the solubilizer propylene glycol and ethyl alcohol have to be excluded, likely benzyl alcohol was due to the respiratory response. Benzyl alcohol has local anesthetic properties and its action on respiration has never been examined up to now. Therefore a further study was performed to compare ampoule solutions of diazepam with or without benzyl alcohol in the solubilizer used. The solutions were given intravenously, the dose of diazepam was 0.35 mg/kg, that of benzyl alcohol 1.1 mg/kg respectively. The measurements showed that solutions containing benzyl alcohol produced a statistical significant increase of respiratory rate and of minute volume. In case of intravenous administration of Valium using ampoule solutions diazepam and in addition a second active substance are applicated. The latter defined as benzyl alcohol has stimulating effects on respiration.

Adult↗
PubMed1978

The interaction of short-chain aralkyl alcohols and amines with the erythrocyte membrane.

Erythrocytes in isotonic saline are hemolyzed by benzyl alcohol and by 2-phenylethanol, but not by the corresponding amines nor by the ring-or side-chain-hydroxylated analogs. All these compounds could however interact with the erythrocyte membrane since: a) they facilitated the hemolytic effect of benzyl alcohol and/or of phenylelytic effect of benzyl alcohol and/or of phenylethanol; b) they exerted a protective effect against controlled hypotonic hemolysis.

Alcohols↗
PubMed1975

Acid-base catalysis in the yeast alcohol dehydrogenase reaction.

The effect of pH on steady state kinetic parameters for the yeast alcohol dehydrogenase-catalyzed reduction of aldehydes and oxidation of alcohols has been studied. The oxidation of p-CH3 benzyl alcohol-1,1-h2 and -1,1-d2 by NAD+ was found to be characterized by large deuterium isotope effects (kH/kD = 4.1 plus or minus 0.1) between pH 7.5 and 9.5, indicating a rate-limiting hydride trahsfer step in this pH range; a plot of kCAT versus pH could be fit to a theoretical titration curve, pK = 8.25, where kCAT increases with increasing pH. The Michaelis constnat for p-CH3 benzyl alcohol was independent of pH. The reduction of p-CH3 benzaldehyde by NADH and reduced nicotinamide adenine dinucleotide with deuterium in the 4-A position (NADD) cound not be studied below pH 8.5 due to substrate inhibition; however, between pH 8.5 and 9.5, kCAT was found to decrease with increasing pH and to be characterized by significant isotope effects (kH/kD = 3.3 plus or minus 0.3). In the case of acetaldehyde reduction by NADH and NADD, isotope effects were found to be small and exxentially invariant (kH/kD = 2.O plus or minus 0.4) between pH 7.2 and 9.5, suggesting a partially rate-limiting hydride transger step for this substrate; a plot of kCAT/K'b (where K'b is the Michaelis constant for acetaldehyde) versus pH could be fit to a titration curve, pK = 8.25. The titration curve for acetaldehyde reduction has the same pK but is opposite in direction to that observed for p-CH3 benzyl alcohol oxidation. The data presented in this paper indicate a dependence on different enzyme forms for aldehyde reduction and alcohol oxidation and are consistent with a single active site side chain, pK = 8.25, which functions in acid-base catalysis of the hydride transfer step.

Alcohol Oxidoreductases↗
PubMed1975

Effect of pH on the liver alcohol dehydrogenase reaction.

New transient kinetic methods, which allow kinetics to be carried out under conditions of excess substrate, have been employed to investigate the kinetics of hydride transfer from NADH to aromatic aldehydes and from aromatic alcohols to NAD+ as a function of pH. The hydride transfer rate from 4-deuterio-NADH to beta-naphthaldehyde is nearly pH independent from pH 6.0 to pH 9.9; the isotope effect is also pH independent with kappa-H/kappaD congruent to 2.3. Likewise, the rate of oxidation of benzyl alcohol by NAD+ changes little with pH between pH 8.75 and pH 5.9; the isotope effect for this process is between 3.0 and 4.4. Earlier substituent effect studies on the reduction of aromatic aldehydes were consistent with electrophilic catalysis by either zinc or a protonic acid. The pH independence of hydride transfer is consistent with electrophilic catalysis by zinc since such catalysis by protonic acid (with a pK between 6.0 and 10.0) would show strong pH dependence. However, protonic acid catalysis cannot be excluded if the pKa of the acid catalyst in the ternary NADH-E-RCOH complex were smaller than 6.0 or smaller than 10.0. The two kinetic parameters changing significantly with pH are the kinetic binding constant for ternary complex formation with aromatic alcohol and the rate of dissociation of aromatic alcohols from enzyme. This is consistent with base-catalyzed removal of a proton from alcohol substrated and consequent acid catalysis of protonation of a zinc-alcoholate complex. The equilibrium constant for hydride transfer from benzaldehyde to benzyl alcohol at pH 8.75 is K-eq equals kappa-H/kappa-H equals 42; this constant has important consequences concerning subunit interactions during liver alcohol dehydrogenase catalysis.

Alcohol Oxidoreductases↗
PubMed1977

Conduction-blocking concentrations of anesthetics increase with nerve axon diameter: studies with alcohol, lidocaine and tetrodotoxin on single myelinated fibers.

The equilibrium blocking concentrations of benzyl alcohol, lidocaine and tetrodotoxin just sufficient to block nerve impulse conduction were determined on myelinated single fibers of the bullfrog. For all three anesthetics it was found that the fastest conducting fibers (45 m/sec; about 18 micron diameter) required about 4 times higher blocking concentrations than the slowest fibers (8 m/sec; about 3 micron diameter). The drugs did not affect the frog sciatic nerve length constant (2 mm), using tetrodotoxin to block the action potential. In agreement with Uehara's single fiber study using urethane (Uehara, Y.:Jap. J. Physiol. 10: 267-274, 1960), it is concluded that smaller myelinated fibers are more sensitive to anesthetic blockade.

Action Potentials↗
PubMed1978

Effect of pH on the process of ternary-complex interconversion in the liver-alcohol-dehydrogenase reaction.

1. Kinetic relationships referring to multiple-turnover conditions have been derived for the slowest exponential transient appearing in two-substrate enzyme reactions proceeding by an ordered ternary-complex mechanism. The validity of these and previously derived theoretical relationships for this mechanism has been tested by application to the liver alcohol dehydrogenase reaction. 2. All essential features of the transient-state kinetics of alcohol oxidation by NAD+ in the liver alcohol dehydrogenase system can be qualitatively and quantitatively explained in view of the compulsory-order mechanism in the proposed scheme. There is no kinetic evidence for any half-of-the-sites reactivity of the enzyme. A consistent set of rate constants is reported for the enzymic oxidation of benzyl alcohol at pH 8.75. 3. Transient-state rate parameters for benzyl alcohol/benzaldehyde catalysis by liver alcohol dehydrogenase have been determined at different pH. The interpretation of such rate parameters is critically discussed with reference to their informative value for the purpose of determination of rate constants (k and k') for the process of ternary-complex interconversion in the proposed scheme. It is concluded that the apparent rate constant (k') for hydride transfer from benzyl alcohol to NAD+ is dependent on a proton dissociation step with a pKa of 6.4, whereas the rate constant (k) for hydride transfer from NADH to benzaldehyde exhibits no corresponding dependence on proton association. 4. The asymmetric pH dependence of the forward and reverse rate of ternary-complex interconversion during liver alcohol dehydrogenase catalysis appears to reflect an obligatory step of alcohol/alcoholate ion equilibration occurring at the ternary-complex level. It is suggested that the observed pKa 6.4 dependence of the transient rate of alcohol oxidation can be attributed to a coupled acid-base system involving minimally the enzyme-bound alcohol and the protein residues Ser-48 and His-51.

Alcohol Oxidoreductases↗
PubMed1975

Kinetic equivalence of the active sites of alcohol dehydrogenase from horse liver.

The reduction, catalysed by liver alcohol dehydrogenase, of benzaldehyde in the presence and absence of pyrazole, and the oxidation of benzyl alcohol and cyclohexanol in the presence of isobutyramide, has been measured by the stopped-flow technique. In performing these experiments particular care was taken to purify the enzyme, coenzymes, substrates and inhibitors, and to minimise as much as possible the effects of a blank substrate reaction. The calculation of the amount of substrate converted to product during the various phases of the transient process was based on the absorption coefficients for the enzyme-coenzyme and enzyme-coenzyme-inhibitor complexes determined in the absence of substrate. The results show that the two active sites of liver alcohol dehydrogenase are kinetically equivalent and that the enzyme does not exhibit half-of-the-sites reactivity.

Alcohol Oxidoreductases↗
PubMed1979

New bronchodilators. Synthesis and bronchodilating activity of some 3-(alkoxymethyl)-alpha-(N-substituted aminomethyl)-4-hydroxybenzyl alcohols.

A series of 3-(alkoxymethyl)-alpha-(N-substituted aminomethyl)-4-hydroxybenzyl alcohols was synthesized as potential bronchodilators. The ability to prevent effects against histamine-induced bronchoconstriction in guinea pigs was studied to determine their bronchodilating activity. Introduction of a methoxymethyl group in place of the m-hydroxyl group of beta-adrenergic catecholamines afforded compounds especially effective in delaying histamine-induced bronchoconstriction in guinea pigs. Appropriate N-substitution also enhanced the potency of these catecholamine analogues. 4-Hydroxy-3-(methoxymethyl)-alpha-[N-[4-(methoxymethyl)-alpha-methylphenyl]aminoethyl]benzyl alcohol hemifumarate (3r) was the most potent compound in this series.

Airway Resistance↗
PubMed1975

Purification and properties of isoenzymes of cinnamyl-alcohol dehydrogenase from soybean-cell-suspension cultures.

Two isoenzymes of an NADP+ -dependent cinnamyl alcohol dehydrogenase and an NAD+ - dependent aliphatic alcohol dehydrogenase were extracted from cell suspension cultures of soybean (Glycine max L., var. Mandarin) which form lignin during growth. These enzymes could be separated from each other by chromatography on DEAE-cellulose and hydroxyapatite. The cinnamyl alcohol dehydrogenase isoenzymes were partially purified by (NH4)2SO4 fractionation, and column chromatography on DEAE-cellulose, Sephadex G-100, and hydroxyapatite. The molecular weight of the enzymes were estimated by the elution volumes from a Sephadex G-100 column and were found to be about 43,000 (isoenzyme 1) and 69,000 (isoenzyme 2). Maximum rates of reaction were observed in the case of coniferyl alcohol oxidation at pH 9.2 (Isoenzyme 1) and pH 8.8 (isoenzyme 2); in the reverse reaction pH 6.5 was optimal for isoenzyme 2. Whereas isoenzyme 1 is specific for coniferyl alcohol, isoenzyme 2 can also oxidize cinnamyl alcohol and a number of substituted cinnamyl alcohols, Km values for substituted cinnamaldehydes are 3-11 times lower than for the corresponding alcohols. Neither isoenzyme reacted with benzyl alcohol, anisic alcohol or ethanol. Substrate inhibition for the forward and reverse reaction was found with isoenzyme 2 but not with isoenzyme 1. The equilibrium constant was determined to be about 10(9) in favour of coniferaldehyde reduction. The possible role of the cinnamyl alcohol dehydrogenase in lignin biosynthesis is discussed.

Alcohol Oxidoreductases↗
PubMed1979

Determination of erythrocyte membrane-buffer partition coefficients by numerical analysis of multicomponent spectra.

A method suitable for the measurement of erythrocyte membrane-buffer partition coefficients by u.v.-spectrophotometry is described. This method is characterized by a proper correction for inconstant background absorption in case of bad signal to noise ratios. For this purpose the multicomponent u.v.-spectrum of a compound in the presence of absorbing materials lost by erythrocyte membranes is decomposed into its constituent spectra by means of numerical analysis. Application of this method to the determination of partition coefficients of benzhydrol, 4-bromophenol and benzyl alcohol yields satisfactory agreement with literature values for the latter two coefficients.

Benzhydryl Compounds↗
PubMed1978

Evaluation of virucidal compounds for inactivation of rhinovirus on hands.

Antimicrobial liquids and foams were applied to the hands to determine their virucidal activity against rhinoviruses. Dilute solutions (1%) of iodine in ethyl alcohol or in water were most effective in causing inactivation of rhinovirus when applied immediately after viral contamination. Iodine also had a residual virucidal activity which persisted on the hands for up to 1 h. Less effective inactivation of rhinovirus was observed with foams containing 0.23% hexachlorophene and 58% ethyl alcohol and another containing 0.2% benzalkonium chloride and 50% ethyl alcohol. Ethyl alcohol alone or in a mixture with benzyl alcohol was the least effective preparation tested.

Anti-Infective Agents, Local↗
PubMed1976

Annular lipids determine the ATPase activity of a calcium transport protein complexed with dipalmitoyllecithin.

Pure complexes of dipalmitoyllecithin (DPL, 16:0) which Ca2+, Mg2+ dependent ATPase from sarcoplasmic reticulum are unusual in retaining significant ATPase activity down to about 30 degrees C, well below the transition temperature of the pure lipid at 41 degrees C. A minimum of about 35 lipid molecules per ATPase is required to maintain maximal ATPase activity, but the complexes are progressively and irreversibly inactivated at lower lipid to protein ratios. Complexes containing more than the minimum lipid requirement show very similar temperature profiles of activity about 30 degrees C over a wide range of lipid to protein ratios, up to 1500:1. Spin-label studies indicate that, at lipid to protein ratios of less than about 30 lipids per ATPase, no DPL phase transition can be detected, but at all higher ratios, a phase transition occurs at about 41 degrees C. In all of these complexes there are breaks in the Arrhenius plots of ATPase activity at 27--32 degrees C and at 37.5--38.5 degrees C. Experiments with perturbing agents, such as cholesterol and benzyl alcohol which have well-defined effects on the DPL phase transition, indicate that these breaks in the Arrhenius plots of ATPase activity cannot be attributed to a depressed and broadened phase transition in the lipids near the protein molecules. These results are interpreted as evidence for a phospholipid annulus of at least 30 lipid molecules with interact directly with the ATPase and cannot undergo a phase transition at 41 degrees C. This structural interaction of the ATPase with the annular DPL molecules has a predominant effect in determining the form of the temperature-activity profiles. However, the perturbation of the DPL phase transition does not extend significantly beyond the annulus since a phase transition which starts at 41 degrees C can be detected as soon as extraannular lipid is present in the complexes. We suggest that it may be a general feature of membrane structure that penetrant membrane proteins interact with their immediate lipid environment so as to cause only a minimal perturbation of the lipid bilayer.

Adenosine Triphosphatases↗
PubMed1979

[Identification of an antimicrobially active constituent isolated from propolis (author's transl)].

On isolating and identifying antimicrobially active propolis constituents, the authors detected a substance that must be regarded as a mixture of caffeic acid esters. The caffeic acid moiety was unequivocally identified by various chemical and spectroscopic methods. The results obtained from the gas chromatographic study of the alcohol fraction after hydrolysis of the isolated compound identify benzyl alcohol, phenyl ethyl alcohol and cinnamic alcohol as ester components. Furthermore, the mass spectroscopic findings are indicative of the presence of a caffeic acid pentenyl ester in the mixture. Attempts to separate this ester mixture by recrystallization and thin-layer chromatography failed.

Anti-Bacterial Agents↗
PubMed1975

The interaction of an epoxide with yeast alcohol dehydrogenase: evidence for binding and the modification of two active site cysteines by styrene oxide.

Yeast alcohol dehydrogenase is inactivated and alkylated by styrene oxide in a single exponential kinetic process. The concentration dependence of half-times for inactivation indicates the formation of an enzyme inhibitor complex, KI = 2.5 times 10(-2) M at pH 8.0. Reduced nicotinamide adenine dinucleotide (NADH), at a concentration of 3 times 10(-4) M where Kd congruent to 1 times 10(-5) M, has a small effect on kinetic parameters for inactivation. Although benzyl alcohol and acetamide-NADH increase the KI for styrene oxide in a manner consistent with their dissociation constants, substrate also increases the rate of inactivation at high styrene oxide concentrations. The reciprocal of half-times for inactivation, extrapolated to infinite styrene oxide concentration, increases with pH between 7.6 and 9.0, pK congruent to 8.5. The stoichiometry of alkylation by [3H]styrene oxide is 2.2 mol of reagent incorporated/mol of subunit, and is accompanied by the loss of 1.9 mol of sulfhydryl/mol of subunit; prior alkylation with iodoacetamide reduces the stoichiometry to 0.88:1, and increases the rate of labeling. Tryptic digests of enzyme modified with [14C]iodoacetamide or [3H]styrene oxide produce two major peptides which cochromatograph, indicating that styrene oxide and iodoacetamide modify the same cysteine residues. Previous investigators have reported that iodoacetate, iodoacetamide, and butyl isocyanate alkylate either of two reactive cysteines of yeast alcohol dehydrogenase; both cysteines cannot be modified simultaneously [Belke et al. (1974), Biochemistry 13, 3418]. The inactivation of enzyme by p-chloromercuribenzoate (PCMB) is reported here to be accompanied by the incorporation of 2.3 mol of PCMB/mol of enzyme subunits, in analogy with styrene oxide; the planarity of the alkylating agent appears to be an important factor in determining the stoichiometry of labeling.

Alcohol Oxidoreductases↗
PubMed1975

Effect of phenethyl alcohol and other organic substances on cellulas production.

Cellulase can be produced from growth in noncellulosic substrate if the growth rate of the producing organism is restricted. Phenethyl alcohol (PEA) is a growth inhibitor and was used to control the growth of M. verrucaria in attempts to obtain increased cellulase production. Cellulase yield was found to be increased without a restriction in growth rate when PEA was present in low concentrations (0.03% v/v). The effect was observed for other organisms but notably L. trabea, which produced considerable enzyme from a small quantity of mycelium. Here increased cellulase synthesis was concomitant with restricted growth. Other chemicals with PEA-like structure (e.g. benzyl alcohol) resulted in similar or more extensive cellulase synthesis. Of the substances tried, propyl alcohol was most effective, followed by acetone. PEA causes a swelling of cell walls and inhibits spore formation. This and other data given suggest that PEA affects the cytoplasmic membrane or the cell wall or both. Cellulase synthesis is considered to take place in the membrane and wall region of the cell.

Acetone↗
PubMed1979

Quantitative dexamethasone and dexamethasone sodium phosphate determinations in pharmaceutical dosage forms by high-pressure liquid chromatography.

A high-pressure liquid chromatographic procedure for quantitative dexamethasone and dexamethasone sodium phosphate determinations in all types of commercially available pharmaceutical dosage forms was developed. The method also separates dexamethasone from its phosphate salt and separates dexamethasone or its salt from a number of inactive ingredients such as benzoic acid, benzyl alcohol, some colors, creatinine, and parabens. Inactive ingredient concentrations may be estimated without additional cost. Part of the parabens present in the commercial injections may be adsorbed by the rubber closures.

Chromatography, High Pressure Liquid↗