Trimetoquinol (TMQ) is a novel tetrahydroisoquinoline drug which interacts stereoselectively with beta-adrenergic (beta1-, beta2- and beta3-subtypes) and thromboxane A2 (TXA2) [alpha- and tau- subtypes] receptors. Our hypothesis is that TMQ binds in a three-point attachment to both of these receptor systems, and interactions with receptor domains include the catechol, amino and trimethoxybenzyl moieties. For the beta- adrenoceptor, we believe that TMQ binds with serines (Ser) 204 and 207 (catechol group), aspartic acid (Asp) 113 (amino group), and a third unknown region (trimethoxybenzyl group). The primary objective of this proposal is to synthesize and study highly selective photoaffinity and affinity labels of TMQ as probes of TXA2 and beta-adrenergic receptors, and to utilize mutant beta-adrenoceptor systems for defining specific receptor binding domains. Because of the major differences in optical isomers of TMQ analogs (TMQ and 8-fluoro TMQ) and high potency of the 3'-iodo and 3',5'-diiodo TMQ on TXA2 and beta-adrenergic receptors, we have designed optically active radiolabeled photoaffinity and affinity labels for probing these two distinct receptor systems. A second part of the proposal will be to synthesize a series of catechol mimetic analogs of TMQ that will investigate the importance of hydrogen bonding to receptors, and should provide more selective (beta2 versus beta1) and longer-acting (resistant to COMT metabolism) drugs than the parent molecule as beta-agonists (bronchial relaxants) and TXA2 antagonists (antiaggregatory and hypotensive activities). Radiolabeled affinity compounds will be used for biochemical characterization of molecular mass and isoelectric points of receptor proteins, and of peptide mapping and amino acid sequencing of relevant peptides. We will also examine ligand binding domains for TMQ analogs using mutant beta-adrenoceptors, and define relationships between receptor occupancy and signal transduction for TMQ analogs using cells expressing unmutated beta-adrenoceptors. Newly synthesized drugs will be evaluated for receptor specific interactions in beta-adrenergic (beta1-, beta2- and beta3-) and TXA2 (smooth muscle and endothelial cells, platelets) tissues. The main purpose is to characterize specific receptor site interactions of tetrahydroisoquinolines with beta-adrenergic and TXA2-receptor systems. Our long-term goal is to separate the desired bronchial dilation from the undesired beta2-adrenergic effects on skeletal muscle (tremors) and to differentiate between the platelet aggregatory and vasoconstrictive effects of TXA2.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL022533-10A2
Application #
3336917
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Project Start
1979-04-01
Project End
1995-11-30
Budget Start
1993-01-29
Budget End
1993-11-30
Support Year
10
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Tennessee Health Science Center
Department
Type
Schools of Pharmacy
DUNS #
941884009
City
Memphis
State
TN
Country
United States
Zip Code
38163
Nikulin, Victor I; Rakov, Igor M; De Los Angeles, Joseph E et al. (2006) 1-Benzyl-1,2,3,4-tetrahydroisoquinoline-6,7-diols as novel affinity and photoaffinity probes for beta-adrenoceptor subtypes. Bioorg Med Chem 14:1684-97
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Zheng, W; Nikulin, V I; Konkar, A A et al. (1999) 2-Amino-4-benzyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridines: novel selective beta3-adrenoceptor agonists. J Med Chem 42:2287-94
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Christoff, J J; Bradley, L; Miller, D D et al. (1997) Synthesis and evaluation of trimetoquinol derivatives: novel thromboxane A2/prostaglandin H2 antagonists with diminished beta-adrenergic agonist activity. J Med Chem 40:85-91
Shams, G; Romstedt, K J; Lust, L A et al. (1997) Beta-adrenergic receptor and platelet inhibitory activities of a new series of trimetoquinol and related benzazepine analogs. Gen Pharmacol 28:323-30
Romstedt, K J; Lei, L P; Feller, D R et al. (1996) Differential eudismic ratios in the antagonism of human platelet function by phenoxy- and thiophenoxyacetic acids. Farmaco 51:107-14
Konkar, A A; Fraundorfer, P F; Fertel, R H et al. (1996) Pharmacological activities of trimetoquinol and 1-benzyl halogen-substituted analogues on rat beta-adrenoceptor subtypes. Eur J Pharmacol 305:63-71
De Los Angeles, J E; Nikulin, V I; Shams, G et al. (1996) Iodinated analogs of trimetoquinol as highly potent and selective beta 2-adrenoceptor ligands. J Med Chem 39:3701-11

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