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Results for “Physicochemical properties”

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At least 19 recordsLinked to original sources

PubMed2001

Two glycine containing 2-chloroethylnitrosoureas--a comparative study on some physicochemical properties, in vivo antimelanomic effects and immunomodulatory properties.

Physicochemical properties such as alkylating and carbamoylating activity and in vivo antimelanomic effects against B16 melanoma of the spin labeled (nitroxyl free radical containing) glycine nitrosourea (SLCNUgly) and its nonlabeled analogue (ChCNUgly), synthesized in our laboratory are studied and compared to those of antitumour drug 3-cyclohexyl-1-(2-chloroethyl)-1-nitrosourea (CCNU). We have demonstrated that introducing of glycine moiety in the nitrosourea structure in practice does not affect either alkylating or carbamoylating activity. On the other hand replacement of cyclohexyl moiety in ChCNUgly structure with nitroxyl free radical leads to a decrease in carbamoylating activity and an increase in alkylating activity. Compound ChCNUgly showed in vivo a higher antimelanomic activity against B16 melanoma in comparison with CCNU and SLCNUgly. It completely inhibited B16 melanoma growth (TGI=100%) at a dose 64.0 mg/kg. Moreover, we established that joint i.p. application in normal mice of SLCNUgly plus a new immunostimulator (C3bgp) formerly isolated in our laboratory led to a 75% restoration in immune function with respect to antibody production measured by Jerne hemolytic plaque assay. In contrast, no immunostimulation was found after joint application of C3bgp plus ChCNUgly or CCNU at the same experimental conditions. Based on these preliminary results, a possibility for developing of new combination immunochemotherapy schemes for treatment of human cancers is discussed.

Adjuvants, Immunologic↗

PubMedDate not supplied

[Effect of ultraviolet irradiation on properties and physicochemical properties of lactate dehydrogenase].

Catalytic and some physicochemical properties of lactate dehydrogenase have been studied as affected by UV-irradiation. The degree of lactate dehydrogenase inactivation has been determined both at UV-irradiation of a free enzyme and of the enzyme in complex with NADH. It is shown that at pH 7.4 NADH makes a photosensitizing effect on the enzyme. Based on the analysis of changes in the absorption spectrum and molecular weight of lactate dehydrogenase caused by UV-irradiation it is supposed that this irradiation induces the process of unrolling-rolling up of the protein globule.

Animals↗

PubMed1982

Klebsiella pneumoniae enterotoxin. II. Physicochemical properties of enterotoxin.

Physicochemical properties and systemic effects of the enterotoxin of Klebsiella pneumoniae has been studied. The enterotoxin had a molecular weight between 10 000 to 50 000. It was protein in nature, and heat and acid stable, inducing a dilatatory response in the gut. It haemolyzed the erythrocytes of various animals including man. It had a capillary permeability activity. In addition, when administered parenterally it increased the level of blood glucose, serum cholesterol, serum alkaline phosphatase and serum acid phosphatase.

Acid Phosphatase↗

PubMed2003

Determination of physicochemical properties of halofantrine.

The physicochemical properties of halofantrine hydrochloride (HF HCl)--a phenanthrene methanol antimalarial, were determined practically in this study since such experimental values are still unknown. The solubility in different solvents were determined and found to be 0.67%w/v in methanol (slightly soluble); 0.4%w/v in both n-octanol and acidified acetonitrile (slightly soluble); 0.09%w/v (very slightly soluble) and less than 0.002%w/v in warm water (50 degrees C) (practically insoluble). Halofantrine hydrochloride was found to be practically insoluble in water (at room temperature), n-hexane and phosphate buffer solution of pH 7.4. The partition coefficient between n-octanol and water gave a log p in the range of 3.20-3.26 (mean 3.20 +/- 0.04) and this was at variance with the log P of 8.5 estimated theoretically in literature. The value also confirms the lipophilicity of HF HCl. The ionisation constant (pKa) determined in partly aqueous solvent (40% methanol) ranged between 8.10 and 8.20 (mean 8.18 +/- 0.05) and confirms the monobasicity of halofantrine. This value also differed from the theoretical estimation of 9.6. The values obtained confirm the often unpredictable and erratic absorption of HF HCl, which bears direct relationship to the physicochemical properties and support the need for better formulations with improved drug delivery potentials.

Antimalarials↗

PubMed2005

Quantitative study of electrostatic and steric effects on physicochemical property and biological activity.

The physicochemical properties and biological activities are highly dependent on the electrostatic and steric effects of compounds. The characterization of these structural features will help to elucidate the quantitative structure-property/activity relationship (QSPR/QSAR). In this paper, two novel structural descriptors, lone-pair electrons index (LEI) and molecular volume index (MVI) were developed to quantify the molecular electrostatic and steric effects, respectively. One of the most attractive traits of these two descriptors is that the calculation is very easy, especially for LEI, which only takes the heteroatoms into account. Four data sets on diverse physicochemical properties and biological activities were selected as examples to evaluate the utility of these descriptors. One or two-variable multiple linear regression (MLR) models against the four data sets obtained such correlation results as follows: correlation coefficient R = 0.9998 and standard deviation s = 0.095 for the partition coefficient of halide benzenes; R = 0.9689 and s = 0.248 for the toxicity of heterocyclic nitrogen-containing compounds to miracidium; R = 0.9645 and s = 0.209 for the antifungal activity of benzyl alcohols to aspergillus niger; R = 0.9530 and s = 0.206 for the toxicity of substituted phenols against tetrahymena pyriformis. Leave-one-out cross validation was also carried out to evaluate the stability of each model and good results were obtained.

Animals↗

PubMed1991

Non-sequence databases for biological activity and physicochemical properties.

A biological activity database and a physicochemical property database are described. They are intended to complement the protein sequence database of PIR-International. The Biological Activity Database and the Physicochemical Property Database contain information regarding the biological activity and the physicochemical properties of proteins, respectively. In addition they also provide information about wild-type molecules with which information concerning variant molecules may be compared. Data on artificial variant molecules are stored in the Artificial Variant Database which is described separately.

Amino Acid Sequence↗

PubMed2001

Effects of amino acid substitution on the physicochemical properties of artificial proteins with random sequences.

Physicochemical properties of four random proteins, each consisting of about 150 amino acid residues with different sequence identity, were compared to know the correlation between the physicochemical properties and its sequence. The results showed that the extent of the sequence alterations correlated well with the extent of differences in CD spectra, roughly with those in pH-solubility profiles and sedimentation velocity, and not with that in the binding of a hydrophobic fluorescent dye (ANS). Therefore, proteins with similar sequences can have different physicochemical properties, indicating that the extent of mutational effects varies in response to the sequence being altered. This warrants the evolution of a protein in a sequence-specific manner.

Journal Article↗

PubMed1997

Physicochemical properties of enrofloxacin.

The physicochemical properties of enrofloxacin, a fluoroquinolone that inhibits the activity of bacterial DNA gyrase, are described. Its spectral, solubility and related physicochemical characteristics are discussed. The dissociation behaviour of enrofloxacin was examined by UV spectrophotometry at 25 degrees C in a series of buffers ranging from pH 1 to 10. The corresponding macro- and microscopic dissociation constants were calculated. The apparent n-octanol-water partition coefficients were measured from pH 2 to 10.

Anti-Infective Agents↗

PubMed1996

Comparison of cosmetic and physicochemical properties of six topical corticosteroid creams.

The cosmetic and physicochemical properties of six topical corticosteroid creams were evaluated and compared. The following creams were provided in blinded tubes: Elocon, Westcort, Lidex, Kenalog, Valisone, and Cutivate. The following properties were evaluated in vitro: stiffness (hardness), grittiness, color, odor, homogeneity (phase separation), pH, weight loss, and tackiness (stickiness). Samples of the creams were evaluated by light microscopy and scanning electron microscopy to identify particle and droplet distribution, particulate contamination, and microscopic homogeneity of the products. Cutivate ranked number 1 in each category and received the best overall score for each of the cosmetic and physicochemical properties evaluated. The cosmetic and physicochemical properties of Elocon, Westcort, Lidex, and Kenalog were found to be similar to one another with regard to overall score but inferior to Cutivate. Valisone was also good with regard to overall score but was ranked less acceptable due to a strong odor.

Administration, Topical↗

PubMed2001

Spin labelled nitrosoureas and triazenes and their non-labelled clinically used analogues--a comparative study on their physicochemical properties and antimelanomic effects.

Physicochemical properties, such as half life time (tau0.5), alkylating and carbamoylating activity and in vivo antimelanomic effects against B16 melanoma of spin labeled (containing nitroxyl free radical moiety) amino acid nitrosoureas, synthesized in our laboratory, have been studied and compared to those of the antitumor drug N'-cyclohexyl-N-(2-chloroethyl)-N-nitrosourea (lomustine, CCNU). We have shown that the introduction of amino acid moieties and the replacement of cyclohexylamine with nitroxyl moiety leads to a faster decomposition, higher alkylating, lower carbamoylating activity, better antimelanomic activity and lower general toxicity, when compared to those of CCNU. It was also established that spin labeled triazenes, previously synthesized by us, were more stable in phosphate saline than their nonlabeled analogue, 5-(3,3-dimethyltriazene-1-yl)-imidazole-4-carboxamide (dacarbazine, DTIC). A higher cytotoxicity to B16 melanoma cells than to YAC-1 and lymphocytes was demonstrated for all spin labeled triazenes, in comparison with DTIC. An assumption has been made to explain the lower general toxicity of the spin labeled nitrosoureas compared to that of CCNU. Based on the results presented, we accept that a new trend for synthesis of more selective and less toxic nitrosourea and triazene derivatives as potential antimelanomic drugs might be developed.

Animals↗

PubMed2005

Improving data quality for environmental fate models: a least-squares adjustment procedure for harmonizing physicochemical properties of organic compounds.

Physicochemical properties (vapor pressure, aqueous solubility, octanol solubility, Henry's law constant, and octanol-air and octanol-water partition coefficients) and their temperature dependencies are required for fate modeling of environmental pollutants. To be internally consistent, measured values for these properties often must be adjusted. The goal of adjusting the property values for consistency is to more accurately estimate the true values. However, consistency and accuracy are not synonymous. If there are systematic errors in one property, then adjustment for consistency may reduce the accuracy of other property data. Here, we provide methods for achieving consistency and improving accuracy in the selection of partitioning properties from literature sources. First, we show that a widely used procedure does not always minimize the adjustments of property values derived from the literature when harmonizing them according to thermodynamic constraints. In such cases, the final adjusted values (FAVs) are unnecessarily different from the literature-derived values (LDVs) selected from measurements. We present an improved procedure based on the theory of least squares that minimizes the adjustment of LDVs and allows quantitative propagation of uncertainty from LDVs to FAVs. When this procedure is applied to partitioning properties for 30 organic chemicals, FAVs obtained differ by up to 30% from those calculated with the current adjustment procedure. Second, we point out that the adjustment procedure is only appropriate for correcting random errors in measurement data. Biased LDVs must be identified and corrected prior to harmonization. Using a set of 16 PCB congeners as a case study, we provide methods to identify biased data and discuss possible sources of bias. We present a new interpretation of property data for the PCBs and a new set of internally consistent properties and quantitative structure-property relationships that we recommend as the best currently available.

Environmental Pollutants↗

PubMed2002

Influence of physicochemical properties on pharmacokinetics of non-viral vectors for gene delivery.

The influence of physicochemical properties on the in vivo pharmacokinetics of gene delivery vectors after systemic administration is reviewed based on our studies. We have been studying the development of DNA delivery systems, such as plasmid DNA complexed with cationic polymers (polyplexes) and cationic liposomes (lipoplexes). Even if target-recognizable ligand is incorporated into the system, the overall physicochemical properties, notably size and charge, are predominant factors influencing in vivo disposition characteristics of the vector. Based on this consideration, liver cell-specific carrier systems via receptor-mediated endocytosis were successfully developed by optimizing physicochemical characteristics. In conclusion, rational design of gene delivery vectors requires an understanding of their pharmacokinetics in relation to the physicochemical properties. Optimization of the physicochemical properties is important for successful in vivo gene delivery by non-viral vectors.

Animals↗

PubMed2003

[The importance and approaches of physicochemical properties analysis of active compounds of traditional Chinese herbs in development of new medicine].

Biological activity and physicochemical properties are two key factors to screen active compounds of traditional Chinese herbs during early discovery phases. As a great number of the compounds are got in the world, a new strategy is developed to research the physicochemical properties of the compositions of herbs, so that the election of active compounds from the compositions has become more effective and more economical than before. The new strategy and associated technology have emerged and it was used extensively. The physicochemical properties of the compounds of traditional Chinese medicine(TCM) relate to pharmaceutical and ADME (Absorption, distribution, metabolism and elimination), and development, clinical effect and safety are evaluated with the properties. Therefore, the physicochemical properties are important in the development of TCM.

Absorption↗

PubMed1981

Physicochemical property modification strategies based on enzyme substrate specificities I: rationale, synthesis, and pharmaceutical properties of aspirin derivatives.

A rationale is developed for drug physicochemical property modification based on making derivatives that are substrates for known enzymes. The approach requires knowledge of the enzyme-substrate specificities to select the appropriate derivative. As a class, the digestive enzymes represent possible reconversion sites. It is shown that by using only known specificities of these enzymes, the physicochemical properties of a drug may be modified in almost any manner desired by appropriate derivative choice, with enzymatic regeneration remaining effective. The strategy is applied to making a stable aspirin derivative that is activated in vivo. Of the derivatives made, aspirin phenylalanine ethyl ester was shown to be stable in suspension form for over 4 years. It was also shown that aspirin is regenerated form the derivative in the presence of the enzymes alpha-chymotrypsin and carboxypeptidase in vitro. This biochemical approach to drug physicochemical property modification offers a new and powerful rationale for improving drug product efficacy.

Amines↗

PubMed2006

Protic ionic liquids: solvents with tunable phase behavior and physicochemical properties.

The phase behavior, including glass, devitrification, solid crystal melting, and liquid boiling transitions, and physicochemical properties, including density, refractive index, viscosity, conductivity, and air-liquid surface tension, of a series of 25 protic ionic liquids and protic fused salts are presented along with structure-property comparisons. The protic fused salts were mostly liquid at room temperature, and many exhibited a glass transition occurring at low temperatures between -114 and -44 degrees C, and high fragility, with many having low viscosities, down to as low as 17 mPa.s at 25 degrees C, and ionic conductivities up to 43.8 S/cm at 25 degrees C. These protic solvents are easily prepared through the stoichiometric combination of a primary amine and Brønsted acid. They have poor ionic behavior when compared to the far more studied aprotic ionic liquids. However, some of the other physicochemical properties possessed by these solvents are highly promising and it is anticipated that these, or analogous protic solvents, will find applications beyond those already identified for aprotic ionic liquids. This series of protic fused salts was employed to determine the effect of structural changes on the physicochemical properties, including the effect of hydroxyl groups, increasing alkyl chain lengths, branching, and the differences between inorganic and organic anions. It was found that simple structural modifications provide a mechanism to manipulate, over a wide range, the temperature at which phase transitions occur and to specifically tailor physicochemical properties for potential end-use applications.

Amines↗

PubMedDate not supplied

Pharmacokinetics of SM-10888 and its metabolites depending on their physicochemical properties.

To investigate how the physicochemical properties and pharmacokinetics of SM-10888 are altered by metabolic reactions, physicochemical and pharmacokinetic parameters of its phase I and phase II metabolites were determined. The metabolic pathways of SM-10888 in rats include oxidation at the C1 position (via the hydroxylated metabolite M3 to the cyclic ketone M4) and glucuronidation of both SM-10888 and M3 (SMG and M3G). Partition coefficients between n-octanol/pH 7.4 buffer (logP*) were determined to be 2.23 for SM-10888, 1.59 for M3, 2.66 for M4, -1.37 for SMG, and -1.72 for M3G. The phase I metabolite M3 showed lower lipophilicity and serum protein binding at pH 7.4, and larger renal clearance (CLr) than SM-10888. In contrast, the further oxidized metabolite M4 demonstrated higher lipophilicity and protein binding and lower CLr than SM-10888 and M3. Among these nonconjugated forms, only the pKa value of M4 was found to be below 7.4 (6.2 for M4, 8.5 for SM-10888, and 8.0 for M3), indicating that M4 exists in a more lipophilic nonionized form at the physiological pH, whereas SM-10888 and M3 are present as ionized forms. The significant shift in pKa of M4 could be the result of a cooperative effect of the electron withdrawing carbonyl group and resonating structure allowing hydrogen bond formation between CO and NH2 group, and might explain its high lipophilicity and low CLr. Glucuronidation significantly increased hydrophilicity with CLr's in excess of the glomerular filtration rate, suggesting involvement of active transport.

Aminacrine↗

PubMed1990

Physicochemical properties of commercially available mouthrinses.

This study evaluated physicochemical properties of eight commercially available mouthrinses, namely surface tension, in vivo enamel contact angle, viscosity, penetration coefficient, acidity and buffer capacity. The penetration coefficient, determined by the surface tension, contact angle and viscosity, is a measure of the ability of a liquid to penetrate into a capillary space, such as interproximal regions, gingival pockets and pores. The acidity is often determined by a compromise of the requirements for taste, enamel remineralization and stability of the solution. Among the eight mouthrinses evaluated, the physicochemical properties differed greatly, in particular, the penetration coefficient which varied by a factor of 1.8 over the products tested. Surprisingly several of the products tested were found to be extremely acidic.

Aerosols↗

PubMed1993

The effect of fluorine substitution on the physicochemical properties and the analgesic activity of paracetamol.

The physicochemical properties and analgesic action of six fluorinated analogues of 4-hydroxyacetanilide (paracetamol) have been investigated. Fluorine substitution adjacent to the hydroxyl group increased lipophilicity and oxidation potential whilst substitution adjacent to the amide had little effect on lipophilicity but led to a greater increase in oxidation potential. Lack of coplanarity and conjugation of the amide group and aromatic ring was also apparent with the analogues that had fluorine in the 2 and 6 positions. Introduction of fluorine into the amide group of paracetamol increased the lipophilicity 4-fold and also increased the oxidation potential of paracetamol. ED50 values for analgesic activity in the phenylquinone-induced abdominal constriction test on male Swiss White mice showed that ring substitution by fluorine reduced activity, especially at the 2,6-positions. Introduction of fluorine into the amide group enhanced activity significantly. Correlation of the analgesic activity with the physicochemical properties indicated that conjugation (and planarity) of the amide group with the aromatic ring is essential for activity and that ease of oxidation may also be an important factor.

Acetaminophen↗