Design, Synthesis and Biological Evaluation of a Family of Excitatory Amino Acid Transporter 3 (EAAT3) Preferring Inhibitors

Author

Terri Lynn Mavencamp, The University of Montana

Year of Award

2008

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Neuroscience

Department or School/College

Department of Biomedical and Pharmaceutical Sciences

Committee Chair

Christopher S. Esslinger

Commitee Members

Richard J. Bridges, Diana I. Lurie, Mark L. Grimes, Michael P. Kavanaugh

Keywords

Benzyl Aspartate, EAAT3, Glutamate, Pharmacology, Transporters

Abstract

This work describes the synthesis and initial characterization of the biological activity of a family of EAAT3 preferring inhibitors, L-β-benzyl aspartate (L-β-BA) and L-β-BA derivatives. L-β-BA and derivatives were initially synthesized in an approximate 2:1 ratio of diasteromers (threo:erythro), using base promoted enolate addition. Kinetic analysis of 3H-D-aspartate uptake into C17.2 cells expressing the hEAATs demonstrated that L-threo-β-BA is the more potent diastereomer (Ki values of 9 µM for EAAT1, 10.0 µM for EAAT2 and 0.8 µM for EAAT3), acts competitively, and exhibits a 10-fold preference for EAAT3 compared to EAAT1 and EAAT2. Electrophysiological recordings of EAAT-mediated currents in Xenopus oocytes further identified L-β-BA as a non-substrate inhibitor. Derivatives of L-β-BA were prepared and characterized for the ability to inhibit 3H-D-aspartate uptake into hEAAT1-3 expressing C17.2 cells. Computational modeling and analysis of structure activity data suggest the area the aromatic moiety of L-β-BA derivatives probe is 1) 3-dimentionally confined, 2) more tolerant of substitutions at the 3 and 5 positions than the 4 position, 3) at least partially distinct from the area probed by L-TBOA and 4) more accessible in the EAAT3 protein than EAAT1 and EAAT2. Computational modeling supports the pharmacological data and lends insight into the selectivity observed with L-β-BA derivatives. Docking studies suggest that H-bonding interactions of L-β-BA derivatives with key residues in the binding site position L-β-BA analogues in a unique manner that is better tolerated in the EAAT3 protein than in the EAAT1 and EAAT2 proteins.

Recommended Citation

Mavencamp, Terri Lynn, "Design, Synthesis and Biological Evaluation of a Family of Excitatory Amino Acid Transporter 3 (EAAT3) Preferring Inhibitors" (2008). Graduate Student Theses, Dissertations, & Professional Papers. 303.
https://scholarworks.umt.edu/etd/303