tracheal relaxant

Ayanin 是从Croton schiedeanus Schlecht 中分离得到的黄酮类物质。它是非选择性的磷酸二酯酶抑制剂，在呼吸道疾病中有研究的价值，如过敏性哮喘等。

Yubeinine 是一种生物碱类天然产物，可以起到气管松弛作用。

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