» The Investigation Of The Dependence Of Biological Activity The Group Of Thiobenzanilide Derivatives On Their Lipophilicity

The Investigation Of The Dependence Of Biological Activity The Group Of Thiobenzanilide Derivatives On Their Lipophilicity

THE INVESTIGATION OF THE DEPENDENCE OF BIOLOGICAL ACTIVITY THE GROUP OF THIOBENZANILIDE DERIVATIVES ON THEIR LIPOPHILICITY

A. Persona1, K. Jóźwiak2, B. Senczyna3, A. Niewiadomy3

1Department of Analytical Chemistry, M. Curie Skłodowska University of Lublin, Poland

2Department of Inorganic and Analytical Chemistry, Medical Univeristy of Lublin, Poland

3Department of Chemistry, University of Agriculture, Lublin, Poland

Transport processes through cell membrane are vitally important to all live forms, since all cells must exchange materials with their environment. The biological activity of the compound is connected with the form of investigated compounds in the phase with contact with biological membrane. The lipid bilayer is responsible for the barrier function of membrane, particularly its impermeability to hydrophobic solutes. The lipophilicity of the compound has significant influence on the partition coefficients between non-polar and aqueous phase.

Thiobenzanilides and similar compounds are found to show strong biological activity as antimicrobial, antimycotic and tuberculostatic agents[1-2]. In addition, they are relatively weakly toxic to higher organisms. The biological activity of this type of compounds is predominantly a function of their lipophilicity [3-4]. The spectrophotometric investigations of the 2,4-dihydroxythiobenzanilide derivatives (Fig. 1.) were performed. The dissociation constants were determined and the permeation process from aqueous to organic phase was investigated.

Fig. 1. The general formula of investigated thiobenzanilides.

The lipophilicity was characterized by half-life () of the compound, which can be defined as the time required for half the solute quantity to be

permeated from aqueous to n-octanol phase. The UV-VIS spectra were obtained by use of UV 530 Julabo spectrophotometer equipped with Peltier thermostat. The correlation between the biological activity of investigated series of thiobenzanilides and their lipophilic properties was expressed by equation:

where MIC – Minimal Inhibitory Concentration which inhibits the growth of investigated strain of microorganisms.

The experimental values of determined in pH = 8 show good correlation with literature data of biological activity determined on Gram positive bacteria [5] according to above equation (Fig. 2.).

Values of were good correlated with theoretical lipophilicity scale (logP) and parameters obtained by means of RP-HPLC [5].

Fig. 2. Correlation between and bacteriostatic activity determined on Enterococcus faecalis.