Theoretical and experimental investigation of 1,4-dihydropyridine-based hexahydroquinoline-3-carboxylates: Photophysics and bovine serum albumin binding studies

Abstract

In this article, the binding affinity of 1,4-dihydropyridine-based hexahydroquinoline-3-carboxylates with bovine serum albumin (BSA) was studied by electronic spectroscopies, quantum calculations, and molecular docking. These compounds were obtained by the one-pot microwave-assisted method via a modified Hantzsch reaction. The photophysical characterization showed in organic solutions absorption maxima in the UV region, ascribed to spin and symmetry allowed electronic transitions (1)pi-pi*. In addition, they presented a main fluorescence emission in the violet-blue regions (406-445 nm), with a relatively large Stokes shift (54-81 nm), depending on the structure of the compounds. BSA fluorescence quenching experiments based on the intrinsic fluorescence of the Trp residues were successfully applied to these compounds, indicating strong interaction with BSA by a static mechanism. The docking simulations corroborated the strong interaction between the studied compounds and BSA, where the surroundings of Trp213 seemed to be the preferred interaction site for all compounds and were responsible for the fluorescence quenching effects.