RPTLC investigation of the hydrophobicity and biological activity of new fungicidal compounds

Reversed-phase thin-layer chromatography (RPTLC) has been used to evaluate the hydrophobicity and antimycotic activity of dihydroxythiobenzanilides, n ewly synthesized bioactive compounds with fungicidal properties. The retent ion behavior of the compounds has been examined with water-acetone or water -methanol as mobile phases and the linear relationship between the volume f raction of the organic modifier and the logarithm of the capacity factor wa s established for every solute over a limited range. I was shown that the theoretical capacity factor obtained by extrapolation to pure aqueous mobile phase of retention data for the water-organic modifi er systems was suitable for quantitative description of the hydrophobicity of the solutes in a way closely related to the lipophilicity Hansch paramet ers, Deviations from this relationship were Pound for compounds with substi tuents which participate in strong intramolecular interactions. The equation describing the structure-activity relationship (QSAR) indicate d the importance of the hydrophobic character and the structure of substitu ents in determining the antimycotic activity of the compounds, The examined dependencies were more statistically significant for acetone-water systems than for those employing methanol-water, thus implying the greater suitabi lity of acetone as organic modifier in QSAR studies of the investigated com pounds.