Endogenous melanocortin receptor agonist (Ki values are 0.12, 31, 660 and 5700 nM for MC1, MC3, MC4 and MC5 receptors respectively). Anti-inflammatory peptide; antagonizes proinflammatory mediators, including TNF-α, IL-6 and NO and induces anti-inflammatory cytokine IL-10. Inhibits food intake and induces penile erections following i.c.v. administration. MW (observed): 1664.9.