Discovery of an 8-Aza-5-thiaProstaglandin E1 Analog as a Highly Selective EP4 Receptor Agonist

For the purpose of discovering an orally available EP4 subtype-selective agonist, a series of 8-aza prostaglandin E1 (PGE1) analogs were synthesized and evaluated for their affinity for PGE2 receptor subtypes. Additionally, the structure–activity relationships of these compounds were studied. Among the tested compounds, the 8-aza PGE1 analog 6 and 8-aza-5-thiaPGE1 analog 12 had highly potent EP4 receptor affinity, good functional activity, and excellent subtype-selectivity. Furthermore, these analogs demonstrated good stability in human liver microsomes. As a result, we concluded that these two series of 8-aza PGE1 analogs could be promising chemical leads for an orally available EP4 subtype-selective agonist.