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PubMed1988

The interaction of n-alkanols with lipid bilayer membranes: a 2H-NMR study.

The interaction of eight n-alkanols with bilayers of dimyristoylphosphatidylcholine (DMPC) has been studied by deuterium nuclear magnetic resonance (2H-NMR). At comparable temperatures and concentrations of solute in the bilayer, order parameters measured at the 1-methylene segment of the n-alkanols show a maximum for n-dodecanol. For both n-dodecanol and n-tetradecanol, orientational ordering shows a maximum at the C-4 to C-7 methylene segments, with labels at both ends of the n-alkanol exhibiting reduced order. These observations are consistent with earlier findings for n-octanol and n-decanol. Unlike the longer chain n-alkanols, ordering in n-butanol decreases from the hydroxyl group end to the methyl group end of the molecule. Orientational ordering at nine inequivalent sites in DMPC, has also been measured as a function of temperature, for bilayers containing n-butanol, n-octanol, n-dodecanol and n-tetradecanol. At the 3R,S sites on the glycerol backbone, for comparable temperatures and solute concentrations, n-butanol produces a larger disordering than the other n-alkanols. This result probably reflects the greater fraction of time spent by the hydroxyl group of n-butanol in the vicinity of the lipid polar head group compared with the hydroxyl group in longer chain n-alkanols. It was found that n-octanol orders the acyl chains of DMPC, unlike n-butanol which disorders them, and the longer chain n-alkanols which have little effect. Within experimental error, the effect of n-dodecanol on order at all sites in DMPC is the same as n-tetradecanol. The influence of n-alkanols on DMPC ordering at twelve sites has been compared with that of cholesterol which is shown to interact with DMPC bilayers in a distinctly different manner from the n-alkanols.

Alcohols↗

PubMed1990

Hemolysis of erythrocytes and fluorescence polarization changes elicited by peptide toxins, aliphatic alcohols, related glycols and benzylidene derivatives.

Hemolysis rates of human erythrocytes induced by C2 and C8-C14 straight chain 1-alkanols, 1,2-alkanediols and the corresponding benzylidene derivatives (benzaldehyde acetals) have been studied and compared with hemolysis rates obtained by three peptide toxins. The peak of activity occurs at C12 for the alkanols and glycols and at C10 for the benzylidene derivatives. The most active compound is 1-dodecanol, followed by 1,2-dodecanediol and the C10 benzylidene acetal, which show 50% hemolysis at 15, 99 and 151 microM, respectively, at 37 degrees C. A few lysolecithins and longer chain cis-unsaturated alcohols were studied for comparison purposes, and were found to be more active than 1-dodecanol. The most active were the 16:0 lysolecithin and cis-9-tetradecene-1-ol, which gave 50% hemolysis at concentrations of 2.8 and 5.6 microM respectively. The hemolytic activities of 1-dodecanol, 1,2-dodecanediol and the C10 benzylidene acetal were compared to activities of Pyrularia thionin and melittin with cow, horse, sheep, pig and human erythrocytes. Whereas the peptide toxins showed clear specificity for human erythrocytes, no selectivity was shown by any of the other compounds tested. Addition of the thionin or Naja naja kaouthia cardiotoxin to erythrocyte ghosts caused a slight but reproducible increase in the order of the phospholipid bilayer, as measured with the fluorescent probe NBD-PC. Cardiotoxin gave a greater response than did the P thionin, and extensively iodinated P thionin gave a smaller change than did P thionin. Similar results were obtained with melittin, but this peptide gave a markedly greater response than all other peptides. Addition of dodecanol or the C10 benzylidene acetal caused a marked increase in membrane fluidity. All of these data indicate that the organic compounds interact directly with and are incorporated nonspecifically into the membrane lipid bilayer, but the peptide toxins interact specifically with some component on the surface of the membrane, either a protein or specific phospholipid domain, followed by insertion into the membrane and decreasing phospholipid movement.

Alcohols↗

PubMed2004

Functional diversity of cytochrome P450s of the white-rot fungus Phanerochaete chrysosporium.

The functional diversity of cytochrome P450s (P450s) of the white-rot basidiomycete, Phanerochaete chrysosporium, was studied. A series of compounds known to be P450 substrates of other organisms were utilized for metabolic studies of P. chrysosporium. Metabolic conversions of benzoic acid, camphor, 1,8-cineol, cinnamic acid, p-coumaric acid, coumarin, cumene, 1,12-dodecanediol, 1-dodecanol, 4-ethoxybenzoic acid, and 7-ethoxycoumarin were observed with P. chrysosporium for the first time. 1-Dodecanol was hydroxylated at seven different positions to form 1,12-, 1,11-, 1,10-, 1,9-, 1,8-, 1,7-, and 1,6-dodecandiols. The effect of piperonyl butoxide, a P450 inhibitor, on the fungal conversion of 1-dodecanol was also investigated, indicating that hydroxylation reactions of 1-dodecanol were inhibited by piperonyl butoxide in a concentration-dependent manner. With 11 substrates, 23 hydroxylation reactions and 2 deethylation reactions were determined and 6 products were new with the position of hydroxyl group incorporated. In conclusion, fungal P450s were shown to have diverse and unique functions.

Alkanes↗

PubMed1996

Enhancement of homomeric glycine receptor function by long-chain alcohols and anaesthetics.

1. The effects of n-alcohols (ethanol to dodecanol) and anaesthetics on strychnine-sensitive glycine receptors were studied in Xenopus oocytes expressing homomeric alpha 1 or alpha 2 glycine receptor subunits, with the two electrode voltage-clamp recording technique. 2. The glycine-induced chloride conductance of homomeric alpha glycine receptors was potentiated by all the alcohols tested when an EC2 concentration of glycine was used. Homomeric alpha 1 and alpha 2 receptors were potentiated similarly by the n-alcohols, except that low concentrations of ethanol produced greater potentiation with alpha 1, as previously reported. 3. Increasing the n-alcohol carbon number has been shown to increase the potency of the alcohols up to decanol at concentrations corresponding to EC50s for producing loss of righting reflex in tadpoles. However, dodecanol was no more potent than decanol, and only modest potentiation (30-60%) was obtained with dodecanol, in contrast to marked (150-200%) potentiation with the other alcohols. Thus, a "cut-off' occurred at about dodecanol. 4. Propofol, alphaxalone, pentobarbitone, halothane and enflurane, reversibly potentiated the function of homomeric alpha 1 glycine receptors at concentrations which represent approximately twice the EC50 for production of anaesthesia in mammals, but ketamine and etomidate were ineffective. 5. Two novel cyclobutane compounds were tested; the anaesthetic compound (1-chloro-1,2,2-trifluorocyclobutane) from 0.5 to 5 mM potentiated the action of glycine in a concentration-dependent manner; however, the non-anaesthetic analogue (1,2-dichloro-hexfluorocyclobutane) had no effect on glycine receptor function at concentrations (25 to 80 microM) predicted to be anaesthetic, based on the lipid solubility of this compound. 6. These results suggest that the alpha subunits of strychnine-sensitive glycine receptors contain sites of action for n-alcohols, propofol, alphaxalone, pentobarbitone and volatile anaesthetics, but not for ketamine and etomidate. Potentiation of glycine receptor function may contribute to the anaesthetic action of n-alcohols and volatile agents.

Anesthetics↗

PubMed1977

Inactivation of lipid-containing viruses by long-chain alcohols.

This report describes the inactivation of lipid-containing viruses by several long-chain alcohols. A striking peak in antiviral activity was found for saturated alcohols having chain lengths from 10 to 14 carbons. Viruses having different membrane structure showed different susceptibilities to alcohols having different chain lengths and structural features. Decanol, dodecanol, and tetradecanol readily inactivated herpes simplex virus and the enveloped bacterial virus phi6. The lipid-containing virus PM2 was susceptible to decanol and dodecanol but comparatively unsusceptible to tetradecanol. The branched-chain alcohol phytol, a naturally occurring component of chlorophyll, was active against phi6 and herpes simplex virus but not against PM2. Polyoma virus and the bacteriophage phi23-1-a, which do not contain lipids, were not susceptible to inactivation by any of the alcohols tested. Experiments were also carried out to determine the effects of these compounds on cells. At 0.5 mM, decanol lysed human embryonic lung cells, erythrocytes, and the bacterial hosts for phi6 and PM2. Dodecanol, tetradecanol, and phytol at this concentration were less damaging to cells. At 0.05 mM, none of the alcohols caused observable cytopathic effects on human embryonic lung cells, although several of the alcohols at this concentration were active against herpes simplex virus. Our findings suggest that dodecanol, tetradecanol, and phytol may warrant further studies as potential antiviral agents, particularly for topical application to virus-infected areas of the skin.

Antiviral Agents↗

PubMed1987

Early feeding of a high-cholesterol diet enhances intestinal permeability to lipids in rabbits.

This study was undertaken in young and growing rabbits to establish the of feeding a high- (2%) cholesterol diet (HC) on the intestinal in vitro uptake of a homologous series of saturated fatty acids, dodecanol, cholesterol, and bile acids. In the jejunum there was an increase in the uptake of myristic acid and dodecanol in HC as compared with animals fed Purina Chow, whereas in the ileum the uptake of stearic acid, cholesterol, and taurocholic acid was reduced. There was increased jejunal uptake of medium-chain length fatty acids, increased incremental change in free energy (integral of delta Fw----l), increased uptake of palmitic, taurocholic acid, and glycocholic acid and reduced uptake of myristic acid and dodecanol in animals fed the high-cholesterol diet for 10 days followed by Purina Chow for 18 days (HC-chow), as compared with HC. There was also increased ileal uptake of palmitic acid in HC-chow as compared with HC but reduced ileal uptake of stearic acid, cholesterol, taurocholic acid, and glycocholic acid. In the colon, there was increased uptake of stearic acid and dodecanol in HC-C as compared with HC, but reduced uptake of cholesterol, taurocholic acid and glycocholic acid. These changes in lipid uptake were not explained by alterations in the mucosal surface area or in the animals' body weight gain. It is proposed that early feeding experiences with a high-cholesterol diet may alter the normal development of intestinal transport of lipids with increased jejunal permeability to medium-chain fatty acids and increased effective resistance of the intestinal unstirred water layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Some properties of the fatty alcohol oxidation system and reconstitution of microsomal oxidation activity in intestinal mucosa.

This paper describes the metabolism of fatty alcohols by microsomal and cytosolic fractions from intestinal mucosa. Microsomes of rabbit intestinal mucosa had a high activity of [1-14C]dodecanol oxidation as did those of liver. The intestinal cytosolic fraction also exhibited oxidation activity to a lesser extent than the microsomes did. The reaction product was determined as lauric acid using thin-layer chromatography. Laurylaldehyde was detected as another product, when semicarbazide was added to the incubation system. Cyclodextrins exhibited a stimulation effect similarly to bovine serum albumin on the microsomal activity. We have compared the stimulatory effects of dimethyl-beta-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin and alpha-cyclodextrin, which decrease in that order. Effects of NAD+ and dodecanol concentrations, pH and pyrazole on microsomal activity were compared with those on cytosolic activity. Dodecanol oxidation activity was solubilized and reconstituted with a fatty alcohol dehydrogenase and a fatty aldehyde dehydrogenase separated from the intestinal microsomes. These findings indicate that both the dehydrogenases participate in microsomal oxidation of fatty alcohols to fatty acids with fatty aldehydes as intermediates in the reaction.

Alcohol Oxidoreductases↗

PubMed2004

Quantification of sodium dodecyl sulfate in microliter biochemical samples by gas chromatography.

A novel gas chromatography (GC) method has been developed to accurately quantitate sodium dodecyl sulfate (SDS) in aqueous biochemical samples. This method is based on the quantitative conversion of SDS to 1-dodecanol in the GC injection port at elevated temperature, and the thermal degradation product 1-dodecanol was analyzed to determine SDS concentration. It was found that the addition of guanidinium chloride (GnHCl) to SDS samples (via direct dilution with GnHCl/MeOH solution) is necessary to ensure accurate quantitation. The presence of GnHCl enables quantitative conversion of SDS to 1-dodecanol, improves sensitivity, and virtually eliminates interference from proteins and other chemicals commonly present in biochemical samples. The method features direct analysis of diluted SDS samples, is free from interference, and is capable of quantifying less than 1 ng SDS in biochemical samples. It is also suitable for samples with limited volume, with as little as 1 microl sample being sufficient for quantitation.

Animals↗

PubMed2004

Inhibition of firefly luciferase by alkane analogues.

We reported that anesthetics increased the partial molal volume of firefly luciferase (FFL), while long-chain fatty acids (LCFA) decreased it. The present study measured the actions of dodecanol (neutral), dodecanoic acid (negatively charged), and dodecylamine (positively charged) hydrophobic molecules on FFL. The interaction modes are measured by (1) ATP-induced bioluminescence of FFL and (2) fluorescence of 2-(p-toluidino)naphthalene-6-sulfonate (TNS). TNS fluoresces brightly in hydrophobic media. It competes with the substrate luciferin on the FFL binding. From the Scatchard plot of TNS titration, the maximum binding number of TNS was 0.83, and its binding constant was 8.27 x 10(5) M(-1). Job's plot also showed that the binding number is 0.89. From the TNS titration of FFL, the binding constant was estimated to be 8.8 x 10(5) M(-1). Dodecanoic acid quenched the TNS fluorescence entirely. Dodecanol quenched about 25% of the fluorescence, whereas dodecylamine increased it. By comparing the fluorescence of TNS and bioluminescence of FFL, the binding modes and the inhibition mechanisms of these dodecane analogues are classified in three different modes: competitive (dodecanoic acid), noncompetitive (dodecylamine), and mixed (dodecanol).

Amines↗

PubMed1996

Ether-bond scission in the biodegradation of alcohol ethoxylate nonionic surfactants by Pseudomonas sp. strain SC25A.

Pseudomonas sp. strain SC25A, previously isolated for its ability to grow on alcohol ethoxylates (PEG dodecyl ethers) as sole source of carbon and energy, was shown to be capable of growth on the dodecyl ethers of mono-, di, tri- and octaethylene glycols. Comparative growth yields for this series of alcohol ethoxylate nonionic surfactants indicated that, whereas all of the carbon of monoethylene glycol dodecyl ether (MEGDE) was assimilable, only the alkyl chains were assimilated from the higher ethoxamers. These results are interpreted in terms of a primary biodegradation mechanism in which the scission of the dodecyl-ether bond is the first step. In the case of MEGDE this step separates the dodecyl chain from a C2 fragment, both of which are readily assimilable; for the higher ethoxamers, the assimilable dodecyl chain is accompanied by an ether-containing PEG derivative which would require further rounds of either scission before assimilation. Whole cells and cell extracts converted [1-14C]MEGDE initially and very rapidly to radiolabelled dodecanol. Disappearance of [14C]dodecaol was accompanied by production of [14C]dodecanal. [14C]Dodecanoic acid was present at relatively low concentrations throughout the incubation periods. [14C]Dodecan-1, 12-dioic acid was produced in significant quantities (up to 25% radiolabel), and the onset of its production coincided with the peak concentration of dodecanal, the disappearance of which mirrored the appearance of the dioic acid. Under anaerobic conditions in the presence of cell extracts, dodecanol (55% of radiolabel) and dodecanal (22%) accumulated rapidly from MEGDE, but there was little subsequent conversion to mono- or dicarboxylic acids. These results are interpreted in terms of a pathway initiated by dodecyl-ether cleavage to produce dodecanol, which is subsequently oxidized to dodecanal and dodecanoic acid. The formation of dodecan-1, 12-dioic acid, probably from dodecanal, may represent a means of harbouring carbon under non-growing conditions.

Biodegradation, Environmental↗

PubMed2002

Toxic effect of aliphatic alcohols against susceptible and permethrin-resistant Pediculus humanus capitis (Anoplura: Pediculidae).

The effectiveness of 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, and 1-dodecanol was evaluated by immersion method against susceptible and permethrin-resistant head lice, Pediculus humanus capitis De Geer, from Buenos Aires, Argentina. All the tested alcohols showed knockdown effect at 10 min and mortality 18 h after treatment. The highest activity was found for the 1-dodecanol (KC50 2.55%, LC50 2.28%) and the lowest for 1-octanol (KC50 8%, LC50 4.46%). The toxicity to the head lice systematically increased with the increase in carbon atoms in the n-aliphatic alcohol moiety, and with the octanol:water coefficient (r2 = 0.94). The pediculicidal activity of 1-dodecanol was not correlated with resistance to permethrin, because no significant difference was observed between toxicity parameters in the susceptible (MAR) and the permethrin-resistant populations which had different resistant levels (RR 5.77 x for E49 population, RR 9.5 x for HL population and RR > 35.3 x for GH population). The pediculicidal effect of aliphatic alcohols demonstrated in this study and the lack of correlation with the permethrin resistance may prove to have a practical value for use in susceptible and permethrin-resistant head lice control.

Alcohols↗

PubMed1976

Interactions between anesthetics and lipid mixtures. Normal alcohols.

The effects of normal alcohols up to 1-dodecanol on phase transitions in phosphatidylcholines and phosphatidylethanolamines have been studied using chlorophyll a as fluorescent probe. With the phosphatidylcholines, alcohols up to octanol cause a lowering of the transition temperature, and a broadening of the transition, whereas for dipalmitoylphosphatidylethanolamine, only a lowering of the transition is observed. The lowering of the phase transition temperature in dipalmitoylphosphatidylcholine by butanol and hexanol is close to that expected for ideal behavior, but the behavior of the longer chain alcohols becomes less ideal. The effects of these alcohols on mixtures of lipids have been studied, and they illustrate the care necessary if these plots of temperatures of onset and completion of gel phase formation are to be called "phase diagrams". The effect of 1 -octanol on mixtures of lipids is to increase the proportion of lipid present in the lipid-crystalline state. In contrast, 1-decanol causes an increase in the phase transition temperature for dimyristoylphosphatidylcholine, although it lowers the transition temperature for dipalmitoylphosphatidylcholine, and 1 -dodecanol raises the transition temperature for both of these phosphatidylcholines, although it lowers that for dipalmitoylphosphatidylethanolamine. Dodecanol appears to behave in these lipid bilayer membranes as a lipid with a phase transition temperature of ca. 55 degrees C. Anesthesia is discussed as a phenomenon of liquidus extension: alcohols up to 1 -octanol increase the proportion of lipid in the liquidus state and result in anesthesia, whereas the longer alcohols do not, and result in catalepsy.

Anesthetics↗

PubMed2002

Formulating chlorinated hydrocarbon microemulsions using linker molecules.

Previously we reported on the use of lipophilic, hydrophilic, and combined linkers for formulating microemulsions of trichloroethylene and tetrachloroethylene. These linker molecules augment the interaction between the surfactant and oil phase (lipophilic linkers) or between the surfactant and water phase (hydrophilic linkers). Combining both linkers can increase the solubilization capacity several-fold. This formulation technique shows potential advantage in reducing surfactant costs and remedial times, as well as allowing the use of more environmentally friendly additives when designing surfactant-enhanced remediation systems. In this paper, we evaluate the relative importance of the surfactant and each linker in increasing the system's solubilization capacity. This interpretation is based on solubilization curves, partitioning studies, and formulation studies. The solubilization curves show that optimum linker performance is reached at an equimolar ratio of dodecanol, used as a lipophilic linker, and sodium mono and dimethyl naphthalene sulfonate, used as a hydrophilic linker. Furthermore, this equimolar combination was able to replace the anionic surfactant sodium dihexylsulfosuccinate. Dodecanol partitioning at optimum formulation shows that the poor performance of lipophilic linkers alone is due to their low partitioning into the middle phase. Adding hydrophilic linkers into this system increases the fraction of dodecanol in the middle phase, thereby further enhancing the solubilization capacity of the system. A variation of the combined linker approach is introduced by changing a lipophilic linker, oleic acid, into a surfactant (soap), with further increases in the solubilization capacity by 4- to 5-fold.

Oleic Acid↗

PubMed2002

Inhibition of glycine receptor function of native neurons by aliphatic n-alcohols.

The inhibitory effects of n-alcohols (methanol to dodecanol) on glycine-activated currents were studied in neurons freshly dissociated from the ventral tegmental area of neonatal rats using whole-cell patch-clamp recording technique. Ethanol enhanced and depressed glycine-activated currents in 35% and 45%, respectively, of neurons of ventral tegmental area of neonatal rats. In this report, we extended our focus of ethanol-induced inhibition of glycine currents to other straight-chain alcohols. Aliphatic n-alcohols, which have carbon numbers less than nine, suppressed glycine currents in 45% (71/158) of the neurons. All results from this study are obtained from the 45% of cells displaying inhibition; the other 55% of the neurons were not studied. Alcohol potency increased as the number of carbon atoms increased from one to five, and was at a maximal plateau from five to nine; alcohols with 10 or more carbons did not inhibit glycine-activated currents. Thus, a 'cutoff' point in their potency for inhibition of glycine receptor function occurred at about decanol. A coapplication of dodecanol with ethanol eliminated the inhibition resulting from ethanol. Thus, dodecanol may bind to the receptor silently and compete with ethanol. These observations indicate that straight-chain n-alcohols exhibit a 'cutoff' point in their potency for inhibition of the glycine receptor function between nine and 10 carbon atoms. The inability of longer alcohols to change the activation properties of the receptors may contribute to the cutoff effect.

Alcohols↗

PubMed1989

Nonanesthetic alcohols dissolve in synaptic membranes without perturbing their lipids.

While many theories of general anesthesia postulate a lipid site of action, there has been no adequate explanation for the lack of anesthetic potency of the highly hydrophobic primary alkanols with more than 12 carbons (the cut-off). Some work suggests that these nonanesthetic alcohols do not dissolve in membranes. Other work contradicts this and suggests that an anesthetic site on a protein provides a better explanation. Here we show that both the anesthetic dodecanol and the nonanesthetic tetradecanol are taken up equally well into the tissues of animals and into isolated postsynaptic membranes. When a group of Rana pipiens tadpoles were treated with dodecanol, half were anesthetized by 4.7 microM (free aqueos concentration), and the corresponding concentration in the tissues was found to be 0.4 mmol per kg wet weight. Prolonged exposure (92 hr) to tetradecanol produced even higher tissue concentrations (0.7 mmol per kg wet weight), yet no anesthetic effects were observed. Furthermore, general anesthetics are thought to act on postsynaptic membranes but both alkanols partitioned into postsynaptic membranes from Torpedo electroplaques. The spin label, 12-doxyl stearate, was incorporated into these membranes. The lipid order parameter it reported was decreased by the anesthetic alcohols (octanol, decanol, and dodecanol), whereas the nonanesthetic alcohols either did not change it significantly (tetradecanol) or actually increased it (hexadecanol and octadecanol). Thus, although lipid solubility is unable to account for the pharmacology of the cut-off in potency of the long-chain alcohols, lipid perturbations provide an accurate description.

Alcohols↗

PubMed1983

Physicochemical characterization of the human nail: permeation pattern for water and the homologous alcohols and differences with respect to the stratum corneum.

In order to develop a basic concept of the permeability of the human nail plate and thus create a better understanding of the toxic potentials and therapeutic possibilities of substances applied to the nail, avulsed cadaver nails have been placed in specially constructed diffusion chambers and their permeation by water and the n-alkanols through dodecanol, all in high aqueous dilution, has been investigated. The permeability coefficient of water is 16.5 X 10(-3) cm h-1 and that for methanol is 5.6 X 10(-3) cm h-1. Ethanol's permeability coefficient measured 5.8 X 10(-3) cm h-1. Permeability coefficients decreased systematically thereafter to a low value of 0.27 X 10(-3) cm h-1 at n-octanol. The middle chain length alkanols, n-pentanol through n-octanol, have similar permeability coefficients but n-decanol and n-dodecanol show higher rates of permeation. The data suggest that, as a membrane, the hydrated human nail plate behaves like a hydrogel of high ionic strength to the polar and semipolar alcohols. Declining permeability rates appear linked to decreased partitioning into the complex matrix of the plate as the compounds become hydrophobic. The results for n-decanol and n-dodecanol introduce the possibility that a parallel lipid pathway exists which favours the permeation of these exceedingly hydrophobic species.

Alcohols↗

PubMed1991

Actions of n-alcohols on nicotinic acetylcholine receptor channels in cultured rat myotubes.

1. The actions of the n-alcohols from pentanol to dodecanol on nicotinic acetylcholine receptor (nAChR) channels were investigated by recording single ACh-activated channel activity from inside-out membrane patches isolated from cultured rat myotubes. Alcohols were applied to the cytoplasmic side of the membrane; aqueous concentrations ranged from 11.7 mM-pentanol to 0.02 mM-dodecanol. 2. The intermediate-chain alcohols (pentanol to octanol) caused channel currents to fluctuate between the fully open and closed state level so that openings occurred in bursts interrupted by brief gaps. Closed time distributions were fitted well with two exponential components, the fast component representing the closures within a burst. The number of gaps within a burst was dependent on alcohol concentration whereas gap duration was independent of concentration but increased with increasing chain length of the alcohol up to octanol. 3. Nonanol and decanol reduced the mean duration of bursts of openings but did not cause an increase in the number of short closed intervals within a burst. Beyond decanol there was a decline in the ability of the n-alcohols to affect channel function. A saturated solution of undecanol (0.07 mM) reduced the mean open time by 33 +/- 17%, whereas a saturated solution of dodecanol had no significant effect. 4. The current integral per burst was reduced by all the n-alcohols between pentanol and undecanol. The IC50S were as follows: hexanol, 0.53 +/- 0.14 mM; heptanol, 0.097 +/- 0.02 mM; octanol, 0.04 mM and nonanol, 0.16 +/- 0.035 mM. 5. The results were analysed in terms of an open channel block model with a long-lived closed-blocked state beyond the blocked state. Over the range of concentrations tested this describes the effects of all the n-alcohols (C5 to C12) on channel gating reasonably well. 6. Blocking rate constants (k+B) for pentanol through to nonanol were calculated to be between 2.8 and 5.7 X 10(6) M-1 S-1. These values are based on the assumption that the concentration of the alcohols at their site(s) of action was equal to the aqueous concentration applied to the membrane. 7. Equilibrium dissociation constants (KD), calculated from the blocking and unblocking rate constants (KD = k-B/k+B), decreased with increasing chain length from 8 mM for pentanol to 0.15 mM for octanol. The standard free energy per methylene group for adsorption to the site of action was calculated to be about -3.3 kJ mol-1.(ABSTRACT TRUNCATED AT 400 WORDS)

1-Octanol↗

PubMed1965

Bacterial growth as a practical indicator of extensive biodegradability of organic compounds.

The proportionality of growth, as indicated by turbidity of cultures of Pseudomonas C12B, to the initial concentration of sodium dodecyl sulfate, dodecanol, or a mixture of C(10)-C(20) secondary alcohol sulfates, each provided as sole carbon source in basal mineral salts medium, was demonstrated. Subsequently, the direct correlation of culture turbidity as a growth indicator and degradation of sodium dodecyl sulfate and the C(10)-C(20) compounds was established. Degradation of these detergents was measured by the rise in surface tension and the decrease in methylene blue values, respectively. Turbidimetry was found to be a poor indicator of degradation of dodecanol in the early hours of culture, however, and did not correlate over a significant range with degradation of substrate. Viable cell counts did parallel dodecanol degradation as measured by gas-liquid chromatography. The use of bacterial growth as a reliable, quantitative, and easily measured parameter indicating biodegradability was suggested for those organic compounds which can be shown to serve as a carbon source for a bacterium.

Alcohols↗