STUDIES WITH NEW KYNURENIC ACID ANALOGUES: STRUCTURAL EVALUATION AND ELECTROPHYSIOLOGICAL EFFECTS
01/29/2020
Tamás Dudás1, István Szatmári2, 3, Evelin Fehér1, 4, Tamás Farkas1, Bálint Lőrinczi2, 3, Ferenc Fülöp2, 3, 5, László Vécsei4, 6, József Toldi1
1 Department of Physiology, Anatomy and Neuroscience, University of Szeged, Közép fasor 52, H-6726Szeged, Hungary
2 Institute of Pharmaceutical Chemistry University of Szeged, Eötvös u. 6, Szeged 6720, Hungary
3 Institute of Pharmaceutical Chemistry, University of Szeged, Interdisciplinary Excellence Centre
4 Department of Neurology, Interdisciplinary Excellence Centre, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Semmelweis u. 6, Szeged, H-6725, Hungary
5 Stereochemistry Research Group of the Hungarian Academy of Sciences, Eötvös utca 6, Szeged H-6720, Hungary
6 MTA-SZTE Neuroscience Research Group, Semmelweis u. 6, Szeged 6725, Hungary
Kynurenic acid (KYNA), a metabolite of tryptophan, as an excitatory amino acid receptor antagonist is an effective neuroprotective agent in case of excitotoxicity, which is the hallmark of brain ischemia and several neurodegenerative processes. Therefore, kynurenine pathway, KYNA itself, and its derivatives came into the focus of research. During the past fifteen years, our research group has developed several neuroactive KYNA derivatives, some of which proved to be neuroprotective in preclinical studies. In this study, the synthesis of these KYNA derivatives and their evaluation with divergent molecular characteristics are presented together with their most typical effects on the monosynaptic transmission in CA1 region of the hippocampus of the rat. Their effects on the basic neuronal activity (on the field excitatory postsynaptic potentials: fEPSP) were studied in in vitro hippocampal slices in 1 and 200 μM concentrations. KYNA and its derivative 4 in both 1 and 200 μM concentrations proved to be inhibitory, while derivative 8 only in 200 μM decreased the amplitudes of fEPSPs. Derivative 5 facilitated the fEPSPs in 200 μM concentration. This is the first comparative study which evaluates the structural and functional differences of formerly and newly developed KYNA analogs. Considerations on possible relations between molecular structures and their physiological effects are presented. KEYWORDS: Mannich reaction; excitatory amino acid receptors; kynurenic acid; neuroprotection