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K C James

Publications and source records attributed to K C James.

11 recordsLinked to original sources
PubMed1979

Quantitative structure--activity relationships and carminative activity II: steric considerations.

The unexplained variation in the relationships between carminative activities and octanol--water distribution coefficients of various classes of compounds was explained. The steric substituent constant (Es) value, van der Waals volume, and molecular connectivity were introduced into a previously derived correlation. Each parameter brought about an improvement, and molecular connectivity was the most successful. Correlations containing molecular connectivity was the most successful. Correlations containing molecular connectivity terms explained the excess variation. The results were in agreement with a mechanism in which carminative activity depended on the availability of the oxygen atom in the functional group of the molecule and was reduced when the substituent attached to the oxygen hindered the interaction between the oxygen atom and the receptor.

Animals↗
PubMed1979

Inter-relationships between solubilities, distribution coefficients and melting points of some substituted benzoic and phenylacetic acids.

Ten 4-hydroxy and 4-alkoxy benzoic and phenylalkanoic acids have been investigated. Solubilities in aqueous buffer at pH 1.2 were determined, together with distribution coefficients between the buffer and either octanol or isopropyl myristate. When plotted against the total number of carbon atoms in the side chains, log octanol/water distribution coefficients gave two parallel straight lines, one for the substituted benzoic acids, and the other for the substituted phenylalkanoic acids. The slopes approximated to 0.5, the generally accepted value for methylene. Similar plots could be obtained with isopropyl myristate, provided the hydroxy acid results were ignored, and also when log aqueous solubilities were plotted against carbon number, although there was considerable scatter. The differences between the distribution coefficient results were explained in terms of solute-solvent interactions, and the scatter attributed to variations in the heats of fusion of the solutes. Yalkowsky's equation (1977), linking aqueous solubilities and melting points with distribution coefficients, was applied to the results, and found to be of limited predictive value.

Benzoates↗
PubMed1979

An in vitro model for assessing drug availability from lipophilic vehicles.

An apparatus for studying the rate of release of a solute from a water-immiscible solvent into an acidic, aqueous liquid, followed by permeation through a simulated lipid membrane, is described. The object was to imitate the absorption of a drug after oral administration in a soft gelatin capsule. Rate constants of transfer were determined for a series of substituted benzoic acids, using octanol and isopropyl myristate as solvents. The quantity of solute in the acidic phase did not correlate with the solvent-water distribution coefficient, but was linearly related to the rate constant for transfer from solvent to water. A dynamic system was therefore postulated, rather than one in which the two phases are in equilibrium. In vivo studies on two of the solutes confirmed the in vitro observations. No simple relationship could be derived between blood concentrations and any in vitro parameter, but the rank order of magnitude of the blood concentrations fitted the postulated dynamic mechanism.

Benzoates↗
PubMed1978

Quantitative structure-activity relationships and carminative activity.

Carminative activities of 34 alcohols, esters, ethers, phenols, and carbonyl compounds were determined using the guinea pig isolated ileum preparation and are expressed as the ability to produce a 50% inhibition (ID50) of a standard response to carbachol. Aqueous solubilities were measured at 37 degrees using either UV absorption or GLC. The ratios of solubility to ID50 were reasonably constant, suggesting nonspecific biological activity, similar to that previously observed with general anesthetics. Hansch analysis indicated that carminative activities were largely controlled by solubility, as indicated by octanol-water distribution coefficients. The principal remaining factor appeared to be the steric availability of the oxygen atom in the functional group of the compound.

Animals↗
PubMed1976

Anabolic and androgenic activities, in rat, of some nandrolone and androstanolone esters.

The anabolic and androgenic activities of the formate to undecanoate esters of nandrolone and formate to valerate esters of androstanolone, after intramuscular injection, have been determined in rat. The response to a given dose was measured as cumulative weight (the area under the plot of weight of indicator organ against time). Levator anus muscle was used to assess anabolic activity, and the sum of the cumulative weight for prostate and seminal vesicles for androgenic activity. Log dose-log cumulative weights plots were parallel, and biological activities were expressed as the cumulative weight corresponding to a 2 muM dose, calculated from the regression lines. Anabolic-androgenic ratios for both series were calculated and were found to be minimum in the region of the propionate and butyrate. The anabolic-androgenic ratios of the nandrolone esters continued to increase after the minimum, as the series ascended. This method is believed to give a reliable assessment of anabolic and androgenic activities of steroid esters.

Anabolic Agents↗