15(R)​-​15-​Methyl prostaglandin D2

15(R)-15-Methyl prostaglandin D2 (15(R)-15-methyl PGD2) is a metabolically stable synthetic analog of PGD2. The physiological actions of PGD2 include regulation of sleep, lowering of body temperature, inhibition of platelet aggregation and relaxation of vascular smooth muscle. PGD2 mediates its effects by 2 distinct G-protein-coupled receptors, DP1and CRTH2/DP2. 15(R)-15-Methyl prostaglandin D2 is a potent, selective agonist for the CRTH2/DP2 receptor. The EC50 values for eosinophil CD11b expression, actin polymerization, and chemotaxis are 1.4, 3.8, and 1.7 nM, respectively, each of which is approximately 3-5 fold lower than those for PGD2. In contrast the EC50 for the DP1-mediated increase in platelet cAMP by 15(R)-15-methyl PGD2 is >10 μM.