RPHPLC as a tool for determining the congenericity of a set of 2,4-dihydroxythiobenzanilide derivatives

During the chemometric analysis of 2,4-dihydroxythiobenzanilides by of RPHP LC, four of the derivatives were observed to have unexpectedly high lipophi licity. These substances also behaved abnormally as mobile phase pH was inc reased. The high hydrophobicity and the lack of dissociation of these subst ances result from the formation of additional internal hydrogen-bond. Lack of congenericity was also observed in biological investigations - the 2-hyd roxy-4 nitro derivative behaved as a typical outlier during analysis of qua ntitative structure-activity relationships (QSAR). Chromatographic investig ations can, therefore, be used to reveal lack of congenericity in series of bioactive analogues; this can be important in studies of QSAR acid quantit ative structure-retention relationships.