Monohydroxyflavones: Distribution Coefficients and Affinities for Reverse-Phase (C18) and Immobilized Artificial Membrane (IAM) Adsorbents

Abstract

Distribution coefficients (D) were measured for flavone, monohydroxyflavones, and monomethoxyflavones equilibrated between 1-octanol and aqueous buffer (50 mM MOPS, pH=7.4). The values of LogD were used to determine substitution constants referred to as π values. Hydroxyl groups at the 3 or 5 position of flavone had positive π values (increased hydrophobicity) while hydroxyl groups at other positions had negative π values (increased hydrophilicity). For each monohydroxyflavone, chromatographic capacity factors (k’) were determined for both reverse phase (C-18) and immobilized artificial membrane (IAM) columns. For the IAM column, relatively large k’ values were observed for both 3-hydroxyflavone and 5-hydroxyflavone indicating that hydroxyl groups at positions 3 and 5 of flavones promote high affinities for phospholipid structures. These results should aid in refinement of quantitative structure activity relationships (QSAR's) that are useful for drug development based on flavonoids as lead compounds.