Lipophilicity indices derived from the liquid chromatographic behavior observed under bimodal retention conditions (reversed phase/hydrophilic interaction): application to a representative set of pyridinium oximes.
The liquid chromatographic behavior observed under bimodal retention conditions (reversed phase and hydrophilic interaction) offers a new basis for the determination of some derived lipophilicity indices. The experiments were carried out on a representative group (30 compounds) of pyridinium oximes, therapeutically tested in acetylcholinesterase reactivation, covering a large range of lipophilic character. The chromatographic behavior was observed on a mixed mode acting stationary phase, resulting from covalent functionalization of high purity spherical silica with long chain alkyl groups terminated by a polar environment created through the vicinal diol substitution at the lasting carbon atoms (Acclaim Mixed Mode HILIC 1 column). Elution was achieved by combining different proportions of 5 mM ammonium formiate solutions in water and acetonitrile. The derived lipophilicity indices were compared with logP values resulting from different computational algorithms. The correlations between experimental and computed data sets are significant. To obtain a better insight on the transition from reversed phase to hydrophilic interaction retention mechanisms, the variation of the thermodynamic parameters determined through the van׳t Hoff approach was also discussed.
University of Medicine and Pharmacy "Carol Davilla", Department of Pharmacology, Toxicology and Clinical Psychopharmacology, #8 Floreasca Street, Bucharest 014461, Romania.
Victor
V
Voicu
Babeş-Bolyai University, Faculty of Chemistry and Chemical Engineering, Department of Chemistry, Arany Janos Street, No 11, Cluj-Napoca 400028, Romania.
Costel
C
Sârbu
University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Avenue, No. 90, Bucharest 050663, Romania.
Florentin
F
Tache
University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Avenue, No. 90, Bucharest 050663, Romania.
Florina
F
Micăle
University of Medicine and Pharmacy Carol Davila, Faculty of Pharmacy, Department of Drug Industry and Pharmaceutical Biotechnology, Traian Vuia Street # 6, Bucharest 020956, Romania.
Ştefan Flavian
ŞF
Rădulescu
National Research Institute of Police Science, 6-3-1, Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
Koichi
K
Sakurada
National Research Institute of Police Science, 6-3-1, Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
Hikoto
H
Ohta
University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Avenue, No. 90, Bucharest 050663, Romania. Electronic address: avmedved@yahoo.com.
Andrei
A
Medvedovici
Bimodal chromatographic retention; Lipophilicity indices; Pyridinium oximes