Abstract
Hydrophobicity constant π, which was introduced by Hansch, of sulfonamides was measured in the systems of n-octyl alcohol-water (designated π0) and chloroform-water (designated πc). A good linear correlation was obtained between π0 and πc. πc could be expressed in terms of log Sw, solubility of unionized molecules in water, and log Sc, solubility in chloroform. Binding of sulfonamides to human plasma protein, rabbit plasma and rabbit blood was measured following an equilibrium. dialysis method. A good correlation was obtained in any couple of the three measurements. The protein binding was found to be subjected to molecular weight of sulfonamides. Thus, an analysis was performed of the structure-activity relationship of sulfonamides between the bacteriostatic activity against Escherichia coli and the drug's physicochemical parameters including molecular weight.
