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PubMed2005

[Correlation between octanol-air partition coefficients and retention parameters of polychlorinated biphenyls on gas chromatographic columns].

Octanol-air partition coefficient (Koa) is a key descriptor for describing the partitioning of organic pollutants, especially persistent organic pollutants (POPs), between air and environmental organic phases. Thus it is necessary to determine or predict the Koa values of these compounds. A novel method was introduced to describe the quantitive relationship between the octanol-air partition coefficients and gas chromatographic (GC) retention parameters A, B values of polychlorinated diphenyls (PCBs) which are typical persistent organic pollutants. By the correlation analysis between GC retention parameters A, B values of PCBs on DB-1, DB-5 and DB-1701 columns, and their octanol-air partition coefficients, a good linear relationship was found. The stepwise multiple linear regression was used to derive binary equations with the correlation coefficients greater than 0.99, and the standard deviations are less than 0.11. In addition, based on the 153 experimental A, B values and 56 predicted A, B values, the Koa values of the remaining 190 PCBs were predicted.

Air↗
PubMed1984

[Quantitative determination of the irritating effect on human skin of butanol, octanol, acetaldehyde and crotonaldehyde].

A method was elaborated for quantitative assessment of the irritating effect of the solvents after a 24-hour contact with healthy subjects. The irritating effect of octanol is weaker, with statistical significance, than that of butanol. Croton aldehyde proved to be the strongest irritator. The threshold skin irritating concentrations are 12% octanol, 7.8% butanol, 1.2% acetaldehyde and 0.12% croton aldehyde in plant oil. The following allergic concentrations in plant oil are recommended for epicutaneous testing of subjects with occupational or every day home contact allergy versus paints, varnishes, glues, cleaning and defatting agents and anticorrosive preparations: 6% octanol, 4% butanol, 0.6% acetaldehyde and 0.06% croton aldehyde.

Acetaldehyde↗
PubMed2002

Quantitative relationships between molecular structures, environmental temperatures and octanol-air partition coefficients of PCDD/Fs.

A concise quantitative model that incorporates information on both environmental temperature (T) and molecular structures, for logarithm of octanol-air partition coefficient (K(OA)) to base 10 (logK(OA)) of PCDDs, was developed. Partial least squares (PLS) analysis together with 14 quantum chemical descriptors were used to develop the quantitative relationships between structures, environmental temperatures and properties (QRSETP) model. It has been validated that the obtained QRSETP model can be used to predict logK(OA) of other PCDDs. Molecular size, environmental temperature (T), q+ (the most positive net atomic charge on hydrogen or chlorine atoms in PCDD molecules) and E(LUMO) (the energy of the lowest unoccupied molecular orbital) are main factors governing logK(OA) of PCDD/Fs under study. The intermolecular dispersive interactions and thus the size of the molecules play a leading role in governing logK(OA). The more chlorines in PCDD molecules, the greater the logK(OA) values. Increasing E(LUMO) values of the molecules leads to decreasing logK(OA) values, implying possible intermolecular interactions between the molecules under study and octanol molecules. Greater q+ values results in greater intermolecular electrostatic repulsive interactions between PCDD and octanol molecules and smaller logK(OA) values.

Journal Article↗
PubMed1998

[Studies on the oxidation reaction of octanol-2 with nitric acid by infrared spectroscopy].

In this paper, the reaction process of oxidation of octanol-2 with nitric acid has been studied by IR spectroscopy. It is found that the main components of non-sapoifiable matter are different in different oxidation degrees. The relation between oxidation products and the amount of nitric acid are investigated,the reaction mechanism has also been studied. Experimental results show that the oxidation process of octanol-2 is as follows: first, octanol-2 is oxidated to octanone-2, or to nitrate, nitrite and nitrile copmpounds, then these compounds are reoxidated to caproic acid in the meantime some by-products, such as valeric, enanthic acids are also found in oxidated products.

English Abstract↗
PubMed1982

Distribution of bile salts between 1-octanol and aqueous buffer.

The distribution of four bile salts: sodium cholate (I), sodium deoxycholate (II), sodium chenodeoxycholate (III), and sodium ursodeoxycholate (IV), between aqueous buffer and 1-octanol has been measured as a function of temperature between 25 and 55 degrees and as a function of bile salt concentration at concentrations less than 0.1 mole/liter in the aqueous phase. The distribution isotherms obtained have been explained on the basis of reversible association in the aqueous phase. The treatment assumes that the bile acid exists as a monomer in the organic phase, which is verified by vapor pressure osmometry. A graphical method has been employed to estimate the association constants in the aqueous phase for the various equilibria encountered. An aggregation number of four for IV and 12 for I, II, and III has been estimated. From the results, thermodynamic functions associated with the transfer of each of the bile salts from water to octanol and those associated with association processes in the aqueous phase were calculated. These results are consistent with previous findings that the premicellar association of bile salts occurs by hydrophobic interaction. The thermodynamics of transfer of bile salts revealed an unfavorable enthalpic and favorable entropic contribution for all four bile salts. However, for IV, which is an epimer of III, both enthalpic and entropic contributions are reduced, compared to III, suggesting a pronounced effect of stereochemical orientation on hydrophobic interaction.

1-Octanol↗
PubMed1985

Effects of octanol on canine subendocardial Purkinje-to-ventricular transmission.

The effects of 0.2 mM octanol on action potential propagation were investigated using in vitro preparations of canine papillary muscles. In these preparations an action potential initiated in the superficial Purkinje (P) layer propagates across specific Purkinje-ventricular junction (PVJ) sites into the underlying ventricular (V) layer. The conduction delay at PVJ sites increased from 4.85 +/- 1.55 to 8.85 +/- 3.34 (mean +/- SD) ms (n = 10, P less than 0.005), an 82% increase. However, propagation within the V syncytium was much less affected, with a decrease of conduction velocity by only 10% and a decrease in the maximal rate of rise of the action potential of 23%. The results indicate that octanol, which has previously been shown to increase gap junctional resistance, has a preferential effect on PVJ sites, as predicted by the hypothesis that there is a restricted pathway for intracellular current flow from P cells to V cells at these sites.

1-Octanol↗
PubMed1996

[Equilibrium solubility of new potential drugs in water, 1-octanol and cyclohexane].

A method was developed for the determinations of the exact value of isotherm solubility equilibrium of organic compounds in various solvents, that can be used as a standard operating procedure, too. It was used for the determination of equilibrium solubility data of twenty two new organic compounds in three solvents: water, 1-octanol and cyclohexane. The data of ten imidazo-quinazolone and twelve pyrido-quinazolone derivatives were compared with their chemical structures moreover within and between the structural and solvents series. It was proved, that these compounds are not ideal solutes, due to a specific interaction with the solvents which is constant for the imidazo-quinazolones, while it is randomly altering at the different pyrido-quinazolones. The octanol/water partitioning data were calculated using octanol and water solubility data, and those were compared with separately, accurately measured data obtained by the traditional shake-flask method. Our data support, that--as it can be found in most of the literature--at compounds which form special interaction with the solvent the partition coefficient cannot be calculated from the solubility data, and reversely the water solubility cannot be estimated using the determined partition coefficient and some correction factors. It was demonstrated, that the calculated partition coefficient can be biased randomly up to and order of magnitude, and in some cases even the tendency of those is false in a series.

1-Octanol↗
PubMed2003

Determination of octanol-water partition coefficients for carbonate esters and other small organic molecules by microemulsion electrokinetic chromatography.

Microemulsion electrokinetic chromatography (MEEKC) was assessed as a tool for determination of octanol-water partition coefficients using 34 solutes encompassing 8 carbonate esters. It was confirmed that microemulsions containing 1.44-2.88% w/w SDS, 6.49% w/w 1-butanol, and 0.82% w/w n-heptane constitute a good model of octanol-water partitioning in the pH range of 1.4-7.4. Use of the migration index concept led to improved repeatability of the MEEKC method compared to the use of retention factors. Using a dynamical coating, a high electroosmotic flow at pH 1.4 and 4.75 was achieved expanding the practical pH working range of the MEEKC system. The correlation obtained between the migration index and log P was unaffected by pH indicating that the properties of the microemulsion droplets and, thus, partitioning are independent of pH. No evidence for congeneric behavior was found for the sample set comprising solutes with different hydrogen bonding properties suggesting that simple reference compounds can be used as calibrators. Lipophilicity estimates for the series of carbonate esters were obtained. The increase in lipophilicity with chain length was smaller than expected from the Hansch substituent constant, pi.

Carbonates↗
PubMed2006

Effect of octanol:water partition coefficients of organophosphorus compounds on biodistribution and percutaneous toxicity.

Knowledge of partition coefficient (log P) data can play a critical role in understanding the pharmacokinetic and pharmacodistributive properties of toxic organophosphorus (OP) compounds. Using a recently published gas chromatographic method, the octanol:water log P values for the compounds tabun (GA), sarin (GB), cyclosarin (GF), and O-ethyl-S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) were determined to be 0.384 +/- 0.033, 0.299 +/- 0.016, 1.038 +/- 0.055, and 0.675 +/- 0.070, respectively. Based on these data, the log P value of the fluorophosphonate fragment, common to GB, soman (GD), and GF, was determined to be -2.256 +/- 0.273. The predictive value for absorption and distribution of the determined log P values was compared to measured values. The time to onset of local fasciculations (47.3, 29.0, 8.8, 8.5, and 6.3 min, respectively) in guinea pigs exposed percutaneously to equilethal doses of GA, VX, GF, GB, or GD was used as an indicator of dermal penetration. There was a good correlation (r = 0.95) between the measured log P value and the rate of onset of local fasciculations. Assuming a direct correspondence, equilibrium tissue:blood log P may be estimated from octanol:water log P. Comparison of the estimated and directly measured tissue:blood log P revealed a correlation of 0.8 for GD in liver, muscle, and adipose tissue. Our results demonstrate the use of log P data to both predict absorption and determine the distribution of OP compounds in tissues. This facilitates further estimates of in vivo OP effects from in vitro experiments.

Administration, Cutaneous↗
PubMed2001

Fast and direct method for measuring 1-octanol-water partition coefficients exemplified for six local anesthetics.

The 1-octanol-water partition coefficients (P(OW)) of six local anesthetics were determined by an improved direct method. In the experimental setup, dialysis tubing is used to separate the aqueous from the octanol phase containing the analyte. This procedure allows the application of ultrasonic agitation to shorten the equilibration time to 2 h. The measurements had a reproducibility of +/- 0.1 log units and showed an excellent agreement with the results obtained with the traditional shake-flask method. However, the correlation with the indirect determination using reversed-phase liquid chromatography was considerably poorer, showing that high-performance liquid chromatography determinations are not always very reliable. Because all the anesthetics used are nitrogen bases, the measurements were performed at two pH values. The method allows a fast and reliable direct determination of partition coefficients.

1-Octanol↗
PubMed1986

Intrinsic molecular volume as a measure of the cavity term in linear solvation energy relationships: octanol-water partition coefficients and aqueous solubilities.

A new, calculated value of the van der Waals or intrinsic molecular volume VI is shown to be at least as effective as molar volume, V (the molecular weight divided by the liquid density), as a measure of the cavity term in linear solvation energy relationships for octanol-water partition coefficients and aqueous solubilities. Use of VI obviates the need for the empirical 10-mL/mol correction factor for aromatic and alicyclic solutes which was previously required, and which is shown here to arise from an underestimate of the cavity term due to reduced free volume in the pure liquid. In addition, since VI is a calculated quantity, equations which contain this term can be extended to compounds that are solids or gases in the pure state. Octanol-water partition coefficients, log P, of gases and solids are predicted accurately by the equation: log P = 0.41 + 5.14 VI/100 - 0.29 mu - 3.58 beta, where mu is the dipole moment and beta is the hydrogen bond acceptor basicity. Aqueous solubilities of some solids are reasonably well predicted by the equation: log Sw = 0.19 - 5.79 VI/100 + 0.24 mu + 4.95 beta - 0.01 (mp - 25), where mp is the melting point. The same equation without the melting point term gives good estimates of the comparable solubility of some gases.

Chemical Phenomena↗
PubMed1988

Relationship between human milk lipid-ultrafiltrate and octanol-water partition coefficients.

The distribution into human milk lipid of 16 drugs with widely varying lipophilicity is reported. There is a high degree of correlation between milk lipid-ultrafiltrate and octanol-water partition coefficients, measured at 37 degrees C, provided digoxin and prednisolone are excluded. These steroid-based molecules may interact with free fatty acids in milk, forming micelles and thus perturbing the milk lipid-ultrafiltrate relationship. Equations are described which enable estimation of drug distribution into milk for lipid-soluble drugs, based on drug pKa and octanol-water partition coefficients.

Female↗
PubMed1999

Bioavailability, biodegradation, and acclimation of Tetrahymena pyriformis to 1-octanol.

Previous work has indicated that the ubiquitous freshwater ciliate Tetrahymena pyriformis acclimates to the presence of hydrophobic chemicals acting by nonpolar narcosis. Four explanations have been identified to explain this apparent acclimation: (1) genetic adaptation occurs resulting in a resistant population, (2) T. pyriformis quickly biodegrades hydrophobic chemicals resulting in a perceived acclimation response, (3) hydrophobic chemicals are not bioavailable, and (4) T. pyriformis contain an endogenous biochemical adaptation system which can quickly cause cellular changes resulting in acclimation. Results of biodegradation experiments indicated that the total extractable 1-octanol did not change over the duration of the experiments. Bioavailability experiments were performed using the solid-phase microextraction technique. Although there is a decrease in freely available concentrations of 1-octanol over a 2.5 log unit range of Tetrahymena population density, the freely available concentration is constant for the population densities used for population growth experiments. Genetic change is highly unlikely since acclimation occurs in less than the time required for one population division. It is hypothesized that the acclimation response seen in Tetrahymena results from partitioning of the chemical into the membrane followed by active changes in the membrane structure to restore homeostasis.

1-Octanol↗
PubMed1993

Estimation of octanol-water partition coefficients and correlation with dermal absorption for several polyhalogenated aromatic hydrocarbons.

n-Octanol-Water partition coefficients (K(ow)) were experimentally estimated for: 2,3,7,8-tetrachloro-and 2,3,7,8-tetrabromodibenzo-p-dioxin; 2,3,7,8-tetrachloro-, 2,3,7,8-tetrabromo-, and 1,2,7,8-tetrabromodibenzofuran; 1,2,3,7,8-pentachloro-, 1,2,3,7,8-pentabromo-, 2,3,4,7,8-pentachloro-, and 2,3,4,7,8-pentabromodibenzofuran; 1,2,4,6,8,9-hexachlorodibenzofuran (HxCDF), and 3,4,3',4'-tetrachlorobiphenyl (3,4,3',4'-TCB). The method involved correlation of literature K(ow) with reverse-phase high-performance liquid chromatography (RP-HPLC) retention time for a series of 23 calibration standards and estimation of K(ow) for test compounds from measured RP-HPLC retention. Retention times for all standards and test chemicals were measured in duplicate on the same octadecasilane (C18) reverse-phase column with an isocratic 85:15 methanol:water mobile phase; solutes were detected by uv absorbance (254 nm). Literature log K(ow) values used for the calibration standards had been measured exclusively by the generator column method. Log K(ow) estimates for the test compounds in the present study ranged from 5.45 for 3,4,3',4'-TCB to 6.81 for HxCDF. K(ow) estimates were then plotted against laboratory data for the in vivo 3-day dermal absorption of single equimolar doses (200 pmol and 20 nmol, or approximately 1 nmol/kg and approximately 0.1 mumol/kg) of selected test compounds in male F344 rats. Strong inverse correlations were found between octanol-water partition coefficient estimates and single-dose dermal absorption for most of the compounds studied. In addition, RP-HPLC retention time itself appeared to be as equally suited as K(ow) to such correlations with dermal absorption. The structure-activity relationships suggested in this study were sought in order to explain observed differences in the dermal absorption of polyhalogenated dibenzo-p-dioxin, dibenzofuran, and biphenyl congeners differing in number, position, and/or type (Cl or Br) of halogen substituents. Moreover, these results should be of predictive value in the risk assessment of dermal exposure to polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, and their brominated analogues.

Animals↗
PubMed1990

Large-conductance ion channel measured by whole-cell voltage clamp in single cardiac cells: modulation by beta-adrenergic stimulation and inhibition by octanol.

Membrane currents in single cardiac myocytes from adult guinea pigs were studied by means of the patch-clamp technique (whole-cell mode). During spontaneous or caffeine-induced Ca2+ release from the sarcoplasmic reticulum openings of a novel ion channel with large unitary conductance (280 pS) can be recorded. The density of these channels and/or its open-state probability are unusually low. On average in the whole-cell mode simultaneous maximum superposition of only four channels is observed. Opening events of this channel require an intracellular Ca2+ transient. Activation by [Ca2+]i, however, seems to be indirect; maximum opening activity occurs with a delay of several hundred milliseconds after peak [Ca2+]i. Single-channel activity can be enhanced by a cyclic AMP dependent process via beta-adrenergic stimulation of a cell. This can also be mimicked by caffeine, most likely via inhibition of phosphodiesterase. Octanol, an inhibitor of gap-junctional coupling in a variety of tissues, causes a concentration-dependent and reversible decrease in single-channel activity. Unitary conductance is not affected by octanol. The low density of these channels in cardiac membranes and their poor selectivity render any role in normal cardiac electrical activity unlikely. A possible relation of the channel to cardiac gap junctions is discussed.

Animals↗
PubMed2003

Prediction of n-octanol/water partition coefficients for polychlorinated dibenzo-p-dioxins using a general regression neural network.

A general regression neural network was used for the first time to study quantitative structure and property relationships of organic pollutants to correlate and predict n-octanol/water partition coefficients of polychlorinated dibenzo- p -dioxins from their topological molecular descriptors. In total, 42 polychlorinated dibenzo- p -dioxins and dibenzo- p -dioxins were available for this study-42 polychlorinated dibenzo- p -dioxins and dibenzo- p -dioxins in the training data set and 41 polychlorinated dibenzo- p -dioxins in the test data set. Partial least squares regression, back propagation network and general regression neural network models were trained using the training data set, and the accuracy of the models obtained were examined by the use of leave-one-out cross-validation. For prediction of the n-octanol/water partition coefficient, the best method is the general regression neural network. With the test data set, the correlation coefficient, root mean square error and mean absolute relative error for the general regression neural network model are 0.9276, 0.22 and 2.79%, respectively. For describing the structure of polychlorinated dibenzo- p -dioxins, the topological molecular descriptors outperform the mobile order and disorder thermodynamic method.

Algorithms↗
PubMed2001

Regiospecific effect of 1-octanol on cis-trans isomerization of unsaturated fatty acids in the solvent-tolerant strain Pseudomonas putida S12.

The solvent-tolerant bacterium Pseudomonas putida S12, which adapts its membrane lipids to the presence of toxic solvents by a cis to trans isomerization of unsaturated fatty acids, was used to study possible in vivo regiospecificity of the isomerase. Cells were supplemented with linoleic acid (C18:2delta9-cis,delta12-cis), a fatty acid that cannot be synthesized by this bacterium, but which was incorporated into membrane lipids up to an amount of 15% of total fatty acids. After addition of 1-octanol, which was used as an activator of the cis-trans isomerase, the linoleic acid was converted into the delta9-trans,delta12-cis isomer, while the delta9-cis,delta12-trans and delta9-trans,epsilon12-trans isomers were not synthesized. Thus, for the first time, regiospecific in vivo formation of novel, mixed cis/trans isomers of dienoic fatty acid chains was observed. The maximal conversion (27-36% of the chains) was obtained at 0.03-0.04% (v/v) octanol, after 2 h. The observed regiospecificity of the enzyme, which is located in the periplasmic space, could be due to penetration of the enzyme to a specific depth in the membrane as well as to specific molecular recognition of the substrate molecules.

1-Octanol↗
PubMed1983

Effects of nonsteroidal antiinflammatory drugs on the proton exchange reaction between octanol and water: its correlation with their inhibitions of inflammation and prostaglandin synthesis.

Effect of various antiinflammatory drugs on proton exchange between octanol OH and water after partition equilibrium between octanol and water at pH 7.4 was examined. These drugs accelerated the proton exchange reaction to different extents. The rate constant of the proton exchange induced by the drugs was well correlated with their biological potencies in inhibiting Carrageenan-induced edema and prostaglandin synthesis, suggesting that proton or electron movement in an apolar environment is very important for exhibition of these biological effects.

Anti-Inflammatory Agents↗