19(R)-hydroxy Prostaglandin E2
19(R)-hydroxy Prostaglandin E2 (19(R)-hydroxy PGE2) is found in the semen of primates, including man. It is a potent smooth muscle relaxant and a selective agonist for the EP2 receptor. It has an EC50 value of 200 nM for relaxing cat tracheal rings which express EP2 receptors.