RP TLC-based lipophilicity assessment of some natural and synthetic coumarins

Abstract

The lipophilic character of twelve coumarins was investigated by reversed-phase thin-layer chromatography (RP TLC) on RP-18 silica. The three different binary solvent systems composed of water and organic modifier (methanol, tetrahydrofuran or acetonitrile) were used in order to determine retention parameter (RM0) and octanol-water partition coefficient (log POW) as a measure of the lipophilicity of the tested compounds. Lipophilicity parameter (log POW) was experimentally determined using eight standard solutes with known log POW values which were analyzed under the same chromatographic conditions as the target substances. Lipophilicity parameters together with 2D molecular descriptors were subjected to the multivariate statistical analysis (principal component analysis (PCA) and partial least square (PLS) regression) in order to reveal the most influential factors governing the retention, i.e., lipophilicity of the investigated compounds. The quantitative structure-retention relationship models reveal the importance of descriptors which describe the size and the shape of the molecule as well as their polar properties. © 2012 Sociedade Brasileira de Química.