Derived chromatographic indices as effective tools to study the self-aggregation process of bile acids.

Reversed-phase high-performance liquid chromatography (RP-HPLC) is more and more adopted as a fruitful tool for the estimation of several physico-chemical properties of diverse classes of organic compounds. In this frame, derived chromatographic indices have been proposed as effective parameters to measure the lipophilicity (log P or log D) of compounds. Instead, a limited attention has been directed towards the chromatographic evaluation of the Critical Micellar Concentration (CMC), one of the most important parameters employed to study the bile acid physico-chemical profile. We have recently reported on the effectiveness of the derived chromatographic index phi(0) for the study of the self-aggregation process of bile acids. Here we show that this index is independent upon the adopted chromatographic environment so as to be instrumental for the evaluation of the hydrophobic/hydrophilic balance of bile acids. Molecular modelling studies have also been undertaken with the aim of rationalizing the experimental findings.