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PubMed1996

Triggered propagated contractions in rat cardiac trabeculae. Inhibition by octanol and heptanol.

We studied the role of Ca2+ diffusion through gap junctions (GJs) in triggering and propagation of damage-induced contractions in cardiac muscle (TPCs) by evaluating effects of the GJ blockers octanol and heptanol (O&H) on TPCs. TPCs were elicited in trabeculae from rat right ventricle superfused with Krebs-Henseleit solution at 20 degrees C and 0.7 to 1.75 mmol/L [Ca2+]o. Force was measured with a silicon strain gauge; sarcomere length, by laser diffraction techniques. O&H (3 to 300 mumol/L) decreased force, propagation velocity, and triggering rate of TPCs in a dose-dependent manner. At 300 mumol/L, O&H decreased TPC force to 21.3% and 25.7%, propagation velocity to 15.4% and 13.0%, and triggering rate to 26.5% and 25.7%. At 300 mumol/L. O&H decreased twitch force to 79.0% and 77.8% and reduced time to 90% relaxation by 10% to 15%. Above 1 mmol/L, O&H abolished twitch force and TPCs. Image analysis of spread of the fluorescence profile of microinjected fura 2 salt revealed an effective diffusion coefficient for fura 2 of 21.0 +/- 3.3 microns2/s, which decreased to 12.6+/-1.5 and 7.07 +/- 0.7 microns2/s after 1 and 3 hours of exposure, respectively, to 100 mumol/L octanol, with a time constant of decline of 1.5+/-0.5 hours. These results are consistent with the hypothesis that propagation of TPCs is due to Ca(2+)-induced Ca2+ release mediated by Ca2+ diffusion from cell to cell through GJs. Reduction of propagation velocity reduces the number of activated sarcomeres in the TPC, which reduces TPC force. O&H slow triggering of TPCs, presumably by blocking Ca2+ diffusion from myocytes within damaged areas to adjacent normal cells.

Animals↗
PubMed1990

Fundamental properties of local anesthetics. II. Measured octanol:buffer partition coefficients and pKa values of clinically used drugs.

Because local anesthetic molecules interact with ion channel proteins embedded in membranes to effect impulse blockade, and because their clinical potency often depends on both vascular absorption and distribution into the tissue surrounding the site of deposition, the ability to partition into these various compartments is an important determinant of local anesthetic action. Therefore, the hydrophobic nature of local anesthetics used clinically was characterized by the octanol:buffer partition coefficients of their charged (P+) and neutral (Po) species. This was accomplished by previously described optical methods in which direct spectrophotometric measurement of both the pH-dependent distribution coefficient (Q) and of the ionization permit calculation of the pKa and partition coefficients. The rates of alkaline hydrolysis of ester-linked molecules also were measured to assess potential interference of such hydrolysis with the physicochemical assays. Results indicate that the hydrophobicity of a local anesthetic is increased by manipulation of the molecular structure at three sites: (a) the aromatic ring; (b) the intermediate linking group; and (c) the tertiary amine. Po for the agents studied was 10(3)-10(5) times greater than P+. Although there is no systematic relationship between hydrophobicity and pKa, the latter is greater with ester-linked (pKa = 8.59-9.30) than with amide-linked (pKa = 7.92-8.21) local anesthetics. All of the charged species, with the exception of bupivacaine, selectively partition into the aqueous environment (P+ less than 1.0). The temperature dependence of partitioning of the local anesthetics, measured at 25 and 36 degrees C, indicates an entropy-driven hydrophobic uptake. Solutions buffered with bicarbonate and including 5% CO2 showed the same local anesthetic partitioning as that of CO2-free solutions, suggesting that potentiation of impulse blockade by CO2 is not due to increased membrane uptake. Correlations of physicochemical properties of local anesthetics with potencies on isolated nerve confirm that the more potent local anesthetics have greater octanol:buffer partition coefficients, and that the ester-linked local anesthetics are more potent than their amide-linked counterparts having the same hydrophobicities. The correlations of structure with potency also suggest that the extracellular protonated species may contribute to impulse blockade.

Anesthetics, Local↗
PubMed1997

Skin permeation of parabens in excised guinea pig dorsal skin, its modification by penetration enhancers and their relationship with n-octanol/water partition coefficients.

Skin penetration of methyl, ethyl, propyl and butyl parabens through excised guinea pig dorsal skin was examined, and effects of the penetration enhancers, l-menthol plus ethanol itself and N-dodecyl-2-pyrrolidone, were observed. Permeability of coefficients of the parabens correlated with n-octanol/water partition coefficients. Addition of 1% l-menthol in 15% ethanol about sixteen times increased the permeability coefficient of methyl paraben, whereas this enhancer decreased that of butyl paraben to about one fifth of the control value. A similar, though weaker, tendency was observed for the effects of 15% ethanol itself. 0.025% suspension of N-dodecyl-2-pyrrolidone increased the permeability coefficient of methyl paraben about seven times, whereas it did not change that of butyl paraben significantly. Therefore, dependency of the permeability coefficients of the parabens on n-octanol/water partition coefficients almost disappeared in the presence of this compound. A spin label study with stratum corneum lipid liposomes revealed that increase of fluidity of the lipid bilayer by these penetration enhancers corresponded with their enhancement effects on skin penetration of methyl paraben. Perturbation of stratum corneum lipid lamella thus seems to be related with their enhancement of the absorption of hydrophilic paraben.

Animals↗
PubMed2006

Effect of lipase immobilization on resolution of (R, S)-2-octanol in nonaqueous media using modified ultrastable-Y molecular sieve as support.

The lipase from Penicillium expansum PED-03 (PEL) was immobilized onto modified ultrastable-Y (USY) molecular sieve and the resolution of (R, S)- 2-octanol was carried out in a bioreactor in nonaqueous media by the immobilized lipase. It was found that the conversion rate, enantiomeric excess (ee) value, and enantioselectivity (E) value of the resolution catalyzed by PEL immobilized on modified USY molecular sieve were much higher than those of the reaction catalyzed by free PEL and PEL immobilized on other supports. Immobilized on modified USY molecular sieve, the PEL exhibited obvious activity within a wider pH range and at a much higher temperature and showed a markedly enhanced stability against thermal inactivation, by which the suitable pH of the buffer used for immobilization could be "memorized." The conversion rate of the reaction catalyzed by PEL immobilized on modified USY molecular sieve reached 48.84%, with excellent enantioselectivity (average E value of eight batches >460) in nonaqueous media at "memorial" pH 9.5, 50 degrees C for 24 h, demonstrating a good application potential in the production of optically pure (R, S)-2-octanol.

Bioreactors↗
PubMed2004

Universal predictive models on octanol-air partition coefficients at different temperatures for persistent organic pollutants.

Owing to the importance of octanol-air partition coefficients (KOA) in describing the partition of organic pollutants from air to environmental organic phases, the paucity of KOA data at different environmental temperatures, and the difficulty or high expenditures involved in experimental determination, the development of predictive models for KOA is necessary. Approaches such as this are greatly needed to evaluate the environmental fate of the ever-increasing list of production chemicals. Partial least squares (PLS) regression with 18 molecular structural descriptors was used to develop predictive models based on directly measured KOA values of selected chlorobenzenes, polychlorinated biphenyls (PCBs), polychlorinated naphthalenes, polychlorinated dibenzo-p-dioxins/dibenzofurans, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, and organochlorine pesticides (OPs). An optimization procedure resulted in two temperature-dependent universal predictive models that explained at least 91 % of the variance of log KOA. Model 1 was the more general of the two models that could be used for all the persistent organic pollutant (POP) classes investigated. Although model 1 performed poorly for select OPs, this was attributed to wide variability in structural types within this subset of POPs and their diversity compared to the other POP classes that were investigated. The exclusion of the structurally complex OP subset resulted in a more precise model, model 5. Intermolecular dispersive interactions (induced dipole-induced dipole forces) between octanol and solute molecules play a decisive role in governing KOA and its temperature dependence. Further investigations are needed to better characterize the steric structures of the POPs under study, especially of OPs.

Air↗
PubMed1999

[Estimation of the octanol-water partition coefficients of PAHs by solid-phase microextraction].

Eleven PAHs were analyzed by solid-phase microextraction-gas chromatography/ion trap detector and their partition coefficients were obtained at equilibrium. When the polymer coating of the fiber may be viewed as one kind of organic solvent, the linear free energy relationship between the polydimethylsiloxane-water partition coefficient (Ksw) and octanol-water partition coefficient (Kow) was established by solid-phase microextraction, which was log Ksw = 0.9318 log Kow-0.2056 with good correlation coefficient 0.9504. The linear equation may be used to estimate the octanol-water partition coefficient of other PAHs and similar H acceptors compounds. Being compared with Leo's method which was based on the additive-constitutive nature of the partition coefficient, the solid-phase microextraction method may distinguish efficiently Kow of the isomer.

Chromatography, Gas↗
PubMed1976

[Influence of dinitrophenol, octanol and toluene upon pH-dependence of ca-ATPase activity of heavy meromyosin].

It is found that dinitrophenol, octanol and toluene produce similar effects on pH-dependence of ATPase of myosin and heavy meromyosin (HMM), i.e. they decrease or remove the neutral suppression of ATPase activity. The appearance of pH-dependence curves is simplified and approaches the form, which is characteristic for the ionisation curve of one; in the last resort two groups, participating in the enzyme activity. The activity of HMM is higher and the zone of the neutral suppression is diminished at low ionic strength, the activation by the modifiers being observed at the significantly lesser degree. CaATPase activation by dinitrophenol, octanol and toluene is suggested to be of the same nature and is accounted for the masking of "the inhibiting" ionizable group of the enzyme with near to neutral pK. This masking may be the result of the conformational changes occuring at the deformation of hydrofobic regions. The ionization of "the activity inhibiting" group of the enzyme depends directly or indirectly on the concentration of potassium chloride and the increase of KCl concentration bring to the inhibition of ATPase activity.

Adenosine Triphosphatases↗
PubMed2004

Application of TLSER method in predicting the aqueous solubility and n-octanol/water partition coefficient of PCBs, PCDDs and PCDFs.

The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n-octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans (PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(alpha), energy of the lowest unoccupied molecular orbit( E(LUMO)), energy of the highest occupied molecular orbit( E(HOMO)), the most positive charge on a hydrogen atom (q+), and the most negative atomic partial charge(q-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n-octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.

1-Octanol↗
PubMed2005

Analysis of anticancer platinum(II)-complexes by microemulsion electrokinetic chromatography: separation of diastereomers and estimation of octanol-water partition coefficients.

Microemulsion electrokinetic chromatography (MEEKC) was applied for the separation and lipophilicity estimation of oxaliplatin and eight novel anticancer oxaliplatin derivatives. Solubility and permeability have to be balanced in modern drug development, and the octanol-water partition coefficient (log P) still represents one of the most useful quantifiable parameters providing a reasonable estimation of a drug's lipophilicity. Therefore, the capacity factors from MEEKC were correlated to log P values derived by the traditional shake flask method. The MEEKC method was accomplished using a microemulsion of heptane/sodium dodecyl sulfate (SDS)/butanol in phosphate buffer at pH 7.4 and 37 degrees C with all analytes being in a neutral state during the run. This experimental setup allowed a baseline separation of all platinum complexes within 11 min. Remarkably, beside the very good resolution and precision of the measurements, separation of diastereomers of the complexes and quantification of the diastereomeric ratios could be achieved. Correlating the capacity factors with the corresponding log P values resulted in a linear dependency with a correlation factor of r = 0.9935. Consequently, the applied MEEKC method was found to be a highly valuable technique not only for the separation of platinum complexes but as well for the estimation of the octanol-water partition coefficient with many advantages in comparison to other methods.

Antineoplastic Agents↗
PubMed1983

Genetics of octanol and alpha-glycerophosphate dehydrogenases in the mosquito Aedes (Finlaya) togoi.

Genetic studies were performed on octanol dehydrogenase (EC 1.1.1.73) and alpha-glycerophosphate dehydrogenase (EC 1.1.1.8) in the mosquito Aedes (Finlaya) togoi by agar gel electrophoresis. The electrophoretic survey revealed two octanol dehydrogenase loci (Odh-1, Odh-2) and one alpha-glycerophosphate dehydrogenase locus (alpha-Gpdh) in this species. Five alleles were observed at the Odh-2 locus in seven laboratory strains, whereas the alpha-Gpdh locus was completely monomorphic in six of seven strains examined and the second allele at this locus was detected in only one strain at a frequency of 0.14. Both loci code for dimeric enzymes. Linkage studies on Odh-2 and alpha-Gpdh suggested that the gene arrangement and recombination units were Odh-2--(25.8)--M (sex locus)--(30.5)--s (strawcolored larva) and M--(25.6)--alpha-Gpdh--(15.4)--s. These results, together with linkage data previously reported, give the following gene linkage on the sex chromosome: Odh-2--Est-3 (carboxylesterase)--Acph (acid phosphatase)--M--alpha-Gpdh--s--Est-2 (carboxylesterase). The total map length of this arrangement is approximately 75 map units.

Aedes↗
PubMed2000

Certification by the Karl Fischer method of the water content in SRM 2890, Water Saturated 1-Octanol, and the analysis of associated interlaboratory bias in the measurement process.

The calibration of Karl Fischer instruments and reagents and the compensation for instrumental bias are essential to the accurate measurement of trace levels of water in organic and inorganic chemicals. A stable, nonhygroscopic standard, Water Saturated Octanol, which is compatible with the Karl Fischer reagents, has been prepared. This material, Standard Reference Material (SRM) 2890, is homogeneous and is certified to contain 39.24 +/- 0.85 mg water/mL (expanded uncertainty) of solution (47.3 +/- 1.0 mg water/g solution, expanded uncertainty) at 21.5 degrees C. The solubility of water in -octanol has been shown to be nearly constant between 10 degrees C and 30 degrees C (i.e., within 1% of the value at 21.5 degrees C). The results of an interlaboratory comparison exercise illustrate the utility of SRM 2890 in assessing the accuracy and bias of Karl Fischer instruments and measurements.

Journal Article↗
PubMed2001

Halogenated methyl-phenyl ethers (anisoles) in the environment: determination of vapor pressures, aqueous solubilities, Henry's law constants, and gas/water- (Kgw), n-octanol/water- (Kow) and gas/n-octanol (Kgo) partition coefficients.

Halogenated methyl-phenyl ethers (methoxybenzenes, anisoles) are ubiquitous organics in the environment although they are not produced in industrial quantities. Modelling the fate of organic pollutants such as halogenated anisoles requires a knowledge of the fundamental physico-chemical properties of these compounds. The isomer-specific separation and detection of 60 of the 134 possible congeners allowing an environmental fingerprinting are reported in this study. The vapor pressure p0(L) of more than 60 and further physico-chemical properties of 26 available congeners are given. Vapor pressures p0(L), water solubilities S(L)W, and n-octanol/water partition coefficients Kow were determined by capillary HR-GC (High Resolution Gas Chromatography) on a non-polar phase and by RP-HPLC (Reversed Phase High Performance Liquid Chromatography) on a C18 phase with chlorobenzenes as reference standards. From these experimental data the Henry's law constants H, and the gas/water Kgw and gas/n-octanol Kgo partition coefficients were calculated. We found that vapor pressures, water solubilities, and n-octanol/water partition coefficients of the halogenated anisoles are close to those of the chlorobenzenes. A similar environmental fate of both groups can, therefore, be predicted.

Anisoles↗
PubMed1999

Vapour pressures, aqueous solubilities, Henry's law constants, partition coefficients between gas/water (Kgw), n-octanol/water (Kow) and gas/n-octanol (Kgo) of 106 polychlorinated diphenyl ethers (PCDE)

Modelling the environmental fate of persistent organic pollutants like polychlorinated diphenyl ethers (PCDE) requires the knowledge of a number of fundamental physico-chemical properties of these compounds. We report here the physico-chemical properties of 106 PCDEs, which are over 50% of all possible congeners. Vapour pressures P(OL), water solubilities S(H2O), and n-octanol/water partition coefficients K(OW) were determined with chromatographic methods. With these experimental data the Henry's law constants H, gas/water K(GW) and gas/n-octanol K(GO) partition coefficients were calculated. Vapour pressures and water solubilities and n-octanol/water partition coefficients of the PCDEs are close to those of similar groups of organochlorine compounds like polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs). A similar environmental fate can be predicted and was partially already been observed.

Journal Article↗
PubMed2000

The n-octanol and n-hexane/water partition coefficient of environmentally relevant chemicals predicted from the mobile order and disorder (MOD) thermodynamics.

The quantitative thermodynamic development of the mobile order and disorder theory in H-bonded liquids is extended in order to predict the partition coefficient. With respect to the classical predictive methods, the great advantage of the present approach resides in the possibility of predicting partition coefficient not only in the reference n-octanol/water partitioning system, but also in any mutually saturated two-phase system made up of two largely immiscible solvents. Constructed from the various free energy contributions encoded in the distribution process, the model furthermore provides a useful tool to understand both the origin and the factors, like the solute molar volume, that determine the partitioning of non-electrolytes between two immiscible liquid phases. From the comparison of the relative magnitude of the terms which contribute to the overall log P value, much information can also be gained concerning the variation of the partition coefficients of the same substances in different distribution systems. For example, the model has successfully been applied to the log P prediction of a number of environmentally important chemicals of varying structure, size and chemical nature in the n-octanol/water and n-hexane/water systems. Whatever the complexing or non-complexing substances studied, the hydrophobic effect always represent the driving force that rules distribution processes in the aqueous environments. As the dominant contribution to the partition coefficient in any organic/aqueous binary system, it is evidenced why hydrophobicity is usually considered to be a good measure of lipophilicity.

Environmental Pollutants↗
PubMed2003

Quantitative structure-property relationships for octanol-air partition coefficients of polychlorinated naphthalenes, chlorobenzenes and p,p'-DDT.

The octanol-air partition coefficient (K(OA)) is a key descriptor of chemicals partitioning between the atmosphere and environmental organic phases. Quantitative structure-property relationships (QSPR) are necessary to model and predict K(OA) from molecular structures. Based on 12 quantum chemical descriptors computed by the PM3 Hamiltonian, using partial least squares (PLS) analysis, a QSPR model for logarithms of K(OA) to base 10 (logK(OA)) for polychlorinated naphthalenes (PCNs), chlorobenzenes and p,p'-DDT was obtained. The cross-validated Q(2)(cum) value of the model is 0.973, indicating a good predictive ability of the model. The main factors governing logK(OA) of the PCNs, chlorobenzenes, and p,p'-DDT are, in order of decreasing importance, molecular size and molecular ability of donating/accepting electrons to participate in intermolecular interactions. The intermolecular dispersive interactions play a leading role in governing logK(OA). The more chlorines in PCN and chlorobenzene molecules, the greater the logK(OA) values. Increasing E(LUMO) (the energy of the lowest unoccupied molecular orbital) of the molecules leads to decreasing logK(OA) values, implying possible intermolecular interactions between the molecules under study and octanol molecules.

Journal Article↗
PubMed2003

Quantitative relationships between molecular structures, environmental temperatures and octanol-air partition coefficients of polychlorinated biphenyls.

A quantitative model that incorporates information on both environmental temperatures (T) and molecular structures, for logarithm of octanol-air partition coefficient to base 10 (logK(OA)) of polychlorinated biphenyls (PCBs) was developed. Partial least squares (PLS) analysis together with 16 theoretical molecular structural descriptors was used to develop the Quantitative relationships between structures, environmental temperatures and properties (QRSETP) model. The cross-validated Q(cum)(2) value for the optimal QRSETP model is 0.976, indicating a good predictive ability for logK(OA) of PCBs at different environmental temperatures. T, E(LUMO) (the energy of the lowest unoccupied molecular orbital), molecular size or average molecular polarizability (alpha), and the net atomic charges on chlorine, hydrogen and carbon atoms of PCB molecules, are major factors governing logK(OA). The lower the E(LUMO), the greater the intermolecular interactions between octanol and PCB molecules, and thus the greater the logK(OA) values. Because of intermolecular dispersive forces, the more chlorine atoms in PCB molecules, the greater the molecular size or alpha, the greater the logK(OA). The largest negative net atomic charge on a carbon atom (q(C)(-)) and molecular size or average molecular polarizability (alpha) are major factors governing temperature dependence of logK(OA). PCB molecules with low q(C)(-) values and more chlorines (big size or alpha) tend to have strong temperature dependence, due to intermolecular electrostatic interactions and dispersive forces, respectively.

Journal Article↗
PubMed2003

Estimation of octanol-water partition coefficients for neutral and weakly acidic compounds by microemulsion electrokinetic chromatography using dynamically coated capillary columns.

Microemulsion electrokinetic chromatography (MEEKC) using dynamically coated capillary columns is shown to be suitable for estimating the octanol-water partition coefficient (log P) for neutral and weakly acidic compounds at pH 3. The solvation parameter model is used to demonstrate that the retention properties of sodium dodecyl sulfate (1.4% w/v), n-butanol (8% v/v) and n-heptane (1.2% v/v) microemulsion are strongly correlated with the octanol-water partition system. For compounds of varied structure and log P values from 0.3 to 5.15, the correlation model is able to estimate log P to better than 0.25 log units. The dynamically coated columns consisting of a bilayer of poly(vinylsulfonate) adsorbed on top of polybrene provide a suitable electroosmotic flow at pH 3 without interfering in the retention properties of the microemulsion. For automated measurements the microemulsion run buffer should be replenished after 10 runs to maintain a stable cycle time and the coated columns replaced after 40-70 runs, depending on sample properties.

Acids↗
PubMed2002

Estimating octanol-air partition coefficients of nonpolar semivolatile organic compounds from gas chromatographic retention times.

Relative gas chromatographic retention times on a non-polar stationary phase can be used to determine the octanol-air partition coefficient (K(OA)) and the energy of phase transfer between octanol and the gas phase (delta(OA)U) for semivolatile, nonpolar organic compounds. The only prerequisites are knowledge of the temperature-dependent K(OA) of a standard reference compound and directly measured K(OA) values at one temperature for a sufficient number of calibration compounds. It is shown that the technique is capable of predicting the K(OA) of polychlorinated benzenes, biphenyls and naphthalenes as well as polybrominated diphenyl ethers within the environmentally relevant temperature range with an average deviation from directly measured values of <0.2 log units.

Journal Article↗