Hydro-lipophilic properties of chlorinated and brominated 1-hydroxynaphthalene-2-carboxanilides

1-Hydroxy-N-phenylnaphthalene-2-carboxamide and a series of other seventeen carboxanilides in the anilide part of dichlorinated, trichlorinated and dibrominated, tribrominated and chlorinated/brominated have recently been reported as biologically active compounds mainly with antibacterial, antimycobacterial and anticancer effects. Since lipophilicity is one of the factors influencing the bioavailability (absorption, distribution, metabolism, elimination) and activity and even toxicity of bioactive compounds, all the derivatives were investigated for their lipophilic and hydrophilic properties. All eighteen compounds were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC). The procedure was performed under isocratic conditions with methanol as the organic modifier in the mobile phase using an end-capped non-polar C18 stationary reversed-phase column. The lipophilicity values are expressed as the logarithm of the capacity factor k (for the mobile phase water : methanol) and the distribution coefficients D at pH values of 6.5 and 7.4 (for the mobile phase buffer : methanol), as well as the calculated values of log P/Clog P by various methods. The unsubstituted derivative is the least lipophilic, 1-hydroxy-N-(3,4,5-trichlorophenyl)naphthalene-2-carboxamide and N-(4-bromo-3-chlorophenyl)-1-hydroxynaphthalene-2-carboxamide are the most lipophilic. The mutual correlations between the experimental and predicted lipophilicity values are low, in addition, there are large deviations in the cross-correlations between log k and log D, which is due to the presence of a free ionizable phenolic group in the molecule.