Conformational analysis of geometric isomers of pitavastatin together with their lactonized analogues

Molecules. 2013 Oct 28;18(11):13283-96. doi: 10.3390/molecules181113283.

Abstract

Super-statins are synthetic inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, which is the rate-limiting enzyme responsible for the biosynthesis of cholesterol. All of the super-statins with a C=C double bond spacer between the heterocyclic and the dihydroxycarboxylic moiety that are currently on the market exist as E-isomers. To extend the understanding of conformational and thermodynamic preferences of Z-isomeric super-statin analogues, this study focused on analyzing pitavastatin and its lactonized derivatives via NMR spectroscopy and ab initio calculations. Z-isomeric pitavastatin analogues exist in solution as a pair of interconverting rotamers, where the Gibbs free energies between the major and minor rotamers are within 0.12 and 0.25 kcal mol-1 and the rotational energy barriers are between 15.0 and 15.9 kcal mol-1. The analysis of long-range coupling constants and ab initio calculations revealed that rotation across the C5'-C7 single bond is essential for generating a pair of atropisomers. The overall comparison of the results between Z-isomeric pitavastatin and rosuvastatin analogues demonstrated that the former are to some extent more flexible to attain numerous conformations. Demonstrating how structural differences between super-statin analogues induce distinctive conformational preferences provides important insight into the super-statins' conformational variability and may well improve future drug design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Quinolines / chemistry*
  • Thermodynamics

Substances

  • Quinolines
  • pitavastatin