Discovery of S-(2-guanidylethyl)-isothiourea (VUF 8430) as a potent nonimidazole histamine H4 receptor agonist

During an in-house database screen, we identified S-(2-guanidylethyl)-isothiourea as a high affinity agonist for the histamine H-4 receptor, with a 33-fold selectivity over the histamine H-3 receptor and negligible affinity for the other histamine receptor subtypes. This nonimidazole ligand is introduced as a useful and complementary pharmacological tool that enables further unraveling of the physiological roles of the H-4 receptor.