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Biomedical subjects

A Hulshoff

Publications and source records attributed to A Hulshoff.

41 records · Page 3Linked to original sources
PubMed1976

A comparison of the determination of partition coeficients of 1,4-benzodiazephines by high-performance liquid chromatography and thin-layer chromatography.

Relative partition coefficients (P) of 1,4-benzodiazepines were determined by a reversed-phase thin-layer chromatographic (RP-TLC) technique in the systemoleyl alcohol-water, and by high-performance liquid chromatography (HPLC) using several column packing materials. RMw values, obtained by RP-TLC, correlated well with log P values determined directly in the system oleyl alcohol-water and with the literature values for the system 1-octanol-water. Th log k' w values from the HPLC experiments could be determined with greater precision, but the correlations of log k'w with log Poleyl alcohol and log Poctanol were not as good as those found for the Rmw values.

Benzodiazepines↗
PubMed1976

A reversed-phase thin-layer chromotographic method for the determination of relative partition coefficients of very lipophilic compounds.

A reversed-phase thin-layer chromatographic method has been developed for the determination of partition coefficients. A support phase has been chosen, following investigation of the lack of adsorptive properties, which has a minimal effect on the pH of the buffer system. A stationary phase has been chosen to give deltaRm values of the same magnitude as Hansch pi values for a series of phenothiazines. The method can be applied to molecules of a wide range of lipophilicity following preliminary investigations of suitable phase-volume ratios and of the pH and composition of the binary mobile phase, providing adsorption on the support phase is excluded.

Adsorption↗
PubMedDate not supplied

Electrochemistry of potential bioreductive alkylating quinones: its use in the development of new aziridinylquinones.

The concept of bioreductive alkylation as a mechanism of action of quinone-containing anticancer agents was investigated, using electrochemical techniques. According to this concept, an electrochemical step (reduction of the quinone ring) is followed by one or more chemical steps, leading to formation of the actual alkylating species. The proper use of electrochemical analysis of potential bioreductive alkylating quinones in the design of new analogs is limited. Up to now, the only electrochemical parameter frequently used in structure-activity relationship studies, is the half-wave potential of the quinone reduction. However, reliable information can only be obtained from the found value of this parameter when the reduction mechanism has been elucidated. Furthermore, it only gives information about the first step of the model. More detailed electrochemical analysis of potential bioreductive alkylating quinones, in combination with a biological evaluation, is required to gain more insight in their mechanism of action and to yield quantitative information about substituent effects on both the electrochemical and the chemical step(s) of the model. Results of such studies of a series of aziridinylquinones indicate, that the biological activity in vitro is correlated with the ease of protonation of the aziridines after quinone reduction, which is in accordance with the concept of bioreductive activation. No correlation with the ease of protonation of the aziridines prior to quinone reduction or with the quinone reduction step itself can be found.

Alkylating Agents↗