Determination of the lipophilicity of new azaphenothiazines by reversed-phase thin-layer chromatography

Summary

The lipophilicity R _M0 and log P _TLC of thirteen novel, potentially biologically active, 12 H-quino[3,4- b][1,4]benzothiazinium salts have been determined by reversed-phase thin-layer chromatography using RP-18 silica plates and methanol-aqueous Tris buffer solution mixtures as mobile phases. R _M values of the compounds were linearly dependent on methanol concentration; extrapolation of these to 0% methanol gave the lipophilicity R _M0. log P _TLC was obtained from R _M0 by use of a calibration curve obtained for five standards of known experimental lipophilicity (log P). Lipophilicity log P _calcd for the thirteen quinobenzothiazines was calculated by use of nine software products. The values determined were discussed in terms of structure-lipophilicity relationships. The results indicate that chromatographic lipophilicity R _M0 can be used as a measure of the lipophilicity of the azaphenothiazine derivatives investigated.