L 741742 is an effective and highly selective antagonist of the D4 dopamine receptor (Ki: 1700, 770, and 3.5 nM at cloned humanD2, D3, and D4 receptors).
CAY10680 is a dopamine-sparing, benzothiazinone compound that selectively inhibits both MAO-B activity (IC50 = 34.9 nM in human) and adenosine A2A receptors (Ki = 39.5 nM in human). It demonstrates significantly less potent inhibitory values for other adenosine receptor subtypes (Kis > 1 μM) and MAO-A (IC50 ≥ 10 μM). At 1-20 μM, CAY10680 has been shown to abolish cAMP accumulation in CHO cells transfected with adenosine A2A receptors. In the central nervous system adenosine A2A receptor expression is localized to dopamine-innervated areas where heteromeric complexes are formed with dopamine D2receptors. Because inhibition of adenosine A2A receptors has been shown to enhance D2receptor function, the blockade of adenosine A2A receptors has emerged as a potential treatment for Parkinson's disease. An additional strategy in the treatment of Parkinson's disease has been to block the activity of monoamine oxidase B (MAO-B), the enzyme involved in dopamine catabolism.
The biological effects of prostaglandin D2 (PGD2) are transduced by at least two 7-transmembrane G protein-coupled receptors, designated DP1 and CRTH2/DP2. In humans, CRTH2/DP2 is expressed on Th2 cells, eosinophils, and basophils where it mediates the chemotactic activity of PGD2. CAY10597, as a racemic mixture, is a potent CRTH2/DP2 receptor antagonist that binds to the humanreceptor with a Ki value of 37 nM. The R enantiomer is slightly more potent exhibiting Ki values of 23 and 22 nM at the human and murine CRTH2/DP2 receptor, respectively. The R enantiomer of CAY10597 inhibits eosinophil chemotaxis induced by 13,14-dihydro-15-keto-prostaglandin D2 with an IC50 value of 40 nM.