Resomelagon (AP1189) is a potent, orally active melanocortin receptor (MR) agonist that induces Ca2+ mobilization and ERK1/2 phosphorylation, demonstrating anti-inflammatory activity useful in obesity and chronic inflammation research [1] [2].

Resomelagon (AP1189), across concentrations ranging from 0-1000 µM for an 8-minute duration in HEK293A cells, enhances melanocortin signaling by inducing ERK1/2 phosphorylation and facilitating Ca2+ mobilization. Additionally, at a concentration of 1 nM over 30 minutes in peritoneal macrophages, it exhibits anti-inflammatory properties by inhibiting the release of TNF-α and suppressing efferocytosis. Western Blot analysis confirms that in HEK293A cells, ERK1/2 phosphorylation expression escalates in a dose-dependent manner, further supporting its role in activating these cellular pathways.

Resomelagon (AP1189), administered at doses ranging between 0-10 mg/kg through intraperitoneal, intravenous, and oral routes to male C57BL/6J wild-type (WT) and BALB/c mice over a period of 24 hours, effectively promotes acute inflammation resolution in vivo. At higher doses of 25-50 mg/kg, taken orally daily for 8 days, it significantly reduces arthritis symptoms in these mouse models. These effects include dose-dependent inhibition of neutrophil and monocyte infiltration and a marked reduction in arthritis symptoms, evidenced by lower clinical scores (42% decrease), reduced paw swelling (87% reduction), a lesser number of animals with all four paws affected (50% decrease), and decreased severity of inflammation (70% reduction).