DOI
https://doi.org/10.25772/AN8S-SY74
Defense Date
2025
Document Type
Thesis
Degree Name
Master of Science
Department
Anatomy & Neurobiology
First Advisor
José-Miguel Eltit, Ph.D.
Second Advisor
Malgorzata Dukat, Ph.D.
Third Advisor
Melissa McGinn Greer, Ph.D.
Abstract
Low-affinity, high-capacity monoamine transporters OCT3 and PMAT serve as secondary clearance mechanisms for dopamine, serotonin, and norepinephrine, yet structure-activity relationships for these transporters remain poorly characterized. This study evaluated twelve synthetic quinazoline derivatives for inhibitory activity at human OCT3 and PMAT using fluorescent APP+ uptake assays in stably transfected HEK293 cells. Two complementary modification strategies were employed: (1) systematic alteration of the nitrogen heterocycle through nitrogen atom removal or substitution, and (2) introduction of diverse substituents at position 6. Results revealed distinct structure-activity relationships between transporters. OCT3 activity was primarily dependent on the position 2 primary amine, with its removal (ASH-037) causing a 3.3-fold decrease in potency, while accommodating a bulky trimethylammonium substitution (ASH-091) without much additional penalty. In contrast, PMAT maintained activity despite loss of the position 2 amine but showed extreme sensitivity to steric bulk at this position, with ASH-091 exhibiting 27-fold reduced potency. Position 6 modifications revealed that both transporters require hydrophobic substitution, with the unsubstituted ADQ showing >10-fold reduced potency at both. Furthermore, both OCT3 and PMAT accepted aromatic (NS-187, IC50= 5.35 μM) and aliphatic (ASH-149, IC50 = 5.92 μM) groups equally, representing a 74-fold improvement over ADQ. These findings establish quinazolines as a privileged scaffold for uptake-2 transporter modulation and reveal that OCT3 utilizes a dominant salt bridge within a spacious binding pocket, while PMAT employs distributed interactions within a more constrained binding site that favors large, hydrophobic groups.
Rights
© Jay Asawla
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
8-7-2025
Comments