Displacement and nonlinear chromatographic techniques in the investigation of interaction of noncompetitive inhibitors with an immobilized alpha3beta4 nicotinic acetylcholine receptor liquid chromatographic stationary phase.
Anal Chem. 2002 Sep 15;74(18):4618-24
Jozwiak K, Haginaka J, Moaddel R, Wainer IW
A liquid chromatographic column containing immobilized alpha3beta4 nicotinic acetylcholine receptors (alpha3beta4-nAChRs) has been used to determine the equilibrium association constants (Ka), desorption rate constants (kd), and adsorption rate constants (ka) for the noncompetitive inhibitors: mecamylamine, ketamine, bupropion, and dextromethorphan. Displacement chromatography, with mecamylamine as the displacer, was used to verify that the four compounds bound to the same site on the immobilized alpha3beta4-nAChRs. Nonlinear chromatographic techniques were then utilized to calculate the Ka, ka, and kd values associated with the formation of the noncompetitive inhibitor-alpha3beta4-nAChR complexes. The ka values determined in this study ranged from 19.7 to 10.5 microM(-1) sec(-1), with a relative order of mecamylamine > dextromethorphan > or = ketamine > bupropion. The kd values determined in this study indicated that dextromethorphan-induced inhibition should produce a longer recovery time than the other three NCIs. This was consistent with results from a previous in vitro study. The data from this study indicate that the immobilized alpha3beta4-nAChR column and nonlinear chromatography can be used in the study of NCIs at the alpha3beta4-nAChR.
Lipophilicity parameter from high-performance liquid chromatography on an immobilized artificial membrane column and its relationships to bioactivity of the group of 2,4-dihydroxythiobenzanilides
Acta Pol Pharm. 2002 Sep-Oct;59(5):341-6
Jóźwiak K, Szumiło H, Senczyna B
Several groups of 2,4-dihydroxythiobenzanilide derivatives are extensively studied in our laboratories as potential antifungal or antibacterial agents. Previous papers showed that their biological activities are closely correlated with the lipophilicity determined in HPLC experiments using on octadecylsilyl stationary phase (RP-18). In the present paper we attempted to measure chromatographic indices of 2,4-dihydroxythiobenzanilides, using a silica-based immobilized artificial membrane (IAM) column especially designed to evaluating biological lipophilicity. The theoretical (extrapolated) retention in pure water the log k(w)(IAM) parameter for 23 derivatives was determined during poly-cratic experiments. Statistical analysis exhibited good correlations between the log k(w)(IAM) parameter and the biological data concerning bacteriostatic activity of these compounds. Retention on the IAM phase can be used as predictor of biological membrane permeability and biological lipophilicity of 2,4-dihydroxythiobenzanilides in spite of the acidic properties of this group of compounds.