A novel and useful descriptor for hydrophobicity, partition coefficient micellar-water, and its application to a QSAR study of antiplatelet agents.

Herein we describe the introduction and application of a novel and useful descriptor, logarithm of micelle-water partition coefficients (log Pmw), for hydrophobicity of compounds. A QSAR study using log Pmw on antiplatelet activities ex vivo of 2-substituted phenyl and benzimidazolyl-5-methyl-4-(3-pyridyl)imidazoles showed its usefulness. Antiplatelet activities could be rationalized by means of only log Pmw with an excellent correlation (r = 0.772, s = 0.257, F = 11.07 **, n = 18), while use of other descriptors such as CLOGP values and retention factors (k') failed. Pmw values can easily be obtained using a normal HPLC system using a micelle aqueous solution as the mobile phase. HPLC techniques offer the advantage of tolerating lower sample purity, smaller sample size, and being dynamic range, compared with the flask-shaking method for measurement of logarithm of 1-octanol/water partition coefficients (log P), which is widely used in QSAR study. These indicated that log Pmw could be a useful descriptor for hydrophobicity of compounds.