New highly potent and selective adenosine A(3) receptor antagonists

Area of Science:

• Medicinal Chemistry
• Pharmacology
• Neuroscience

Background:

• Adenosine receptors play crucial roles in various physiological processes.
• Adenosine A(3) receptor antagonists are of therapeutic interest for several conditions.
• Optimizing screening hits is a common strategy in drug discovery.

Purpose of the Study:

• To discover and characterize novel, potent, and selective adenosine A(3) receptor antagonists.
• To identify optimal structural modifications for enhancing antagonist activity and selectivity.
• To evaluate the in vitro and in vivo efficacy of lead compounds.

Main Methods:

• Structure-activity relationship (SAR) studies were conducted.
• Optimization of a screening hit, N-[4-(4-methoxyphenyl)-thiazol-2-yl]-acetamide.
• Synthesis of novel thiazole derivatives.
• In vitro binding assays on human adenosine A(3) receptors.
• In vivo studies using rat models.

Main Results:

• A 5-(pyridin-4-yl) substituent on the 2-aminothiazole ring was identified as optimal for potency.
• N-[5-pyridin-4-yl-4-(3,4,5-trimethoxyphenyl)-thiazol-2-yl]-acetamide emerged as a highly potent antagonist.
• This lead compound demonstrated >100-fold selectivity against related adenosine receptors.
• Selective in vitro binding and in vivo blockade of the rat A(3) receptor were confirmed.

Conclusions:

• A novel class of potent and selective adenosine A(3) receptor antagonists was successfully developed.
• The lead compound, N-[5-pyridin-4-yl-4-(3,4,5-trimethoxyphenyl)-thiazol-2-yl]-acetamide, represents a promising therapeutic candidate.
• The developed compound is readily synthesizable, facilitating further research and development.