Stereoselectivity of photoinduced interaction of nonsteroidal anti-inflammatory drug S-ketoprofen with (L/D)-Trp-Leu-Pro-Phe peptide in solution studied by NMR, CIDNP and molecular dynamics simulation.
Selyutina Olga Yu OY, Polyakov Nikolay E NE, Molokoedov Alexander S AS, Sidorova Maria V MV et al.
The stereoselectivity of chiral drug interactions with enzymatic active sites and cellular receptors is a subject of significant scientific interest. This interest is driven, firstly, by the pronounced differences in the therapeutic activity of drug enantiomers and, secondly, by the emerging role of amino acid chiral inversion in peptides associated with pathologies such as Alzheimer's, Parkinson's, and type II diabetes. To probe the fundamental steps of such biomolecular interactions, electron transfer (ET) serves as a well-defined elementary chemical process. Prior investigations of photoinduced ET in chiral donor-acceptor dyads, incorporating (S)-ketoprofen and (L/D)-tryptophan, have revealed stereoselective and spin-selective phenomena. Extending this work, the present study examines the interaction of (S)-ketoprofen with the L- and D-enantiomers of tryptophan within the tetrapeptide tryptophan-leucine-proline-phenylalanine (WLPF), in homogeneous non-aqueous solutions. Utilizing NMR spectroscopy, chemically induced dynamic nuclear polarization (CIDNP) to detect transient paramagnetic intermediates, and molecular modeling, we have demonstrated that (S)-ketoprofen exhibits stereoselective interaction with the peptide epimers. Furthermore, it was shown that the D-epimer of the peptide has a greater tendency to aggregation than the L-epimer. The stereoselective light-induced formation of the ketoprofen ketyl radicals provides a plausible mechanistic basis for ketoprofen's phototoxic side effects.