A MC4R agonist that is selective over MC1R, MC3R, and MC5R human receptors expressed in CHO cells (IC50s = 1.2, 2,067, 761, and 326 nM, respectively); activates mutant MCR4s, which have been linked to obesity, in HeLa cells expressing the mutant receptors (EC50s = 0.23, 2.60, 39.7, and 43.6 for Wt, R165Q, C271Y, and N97D, respectively); increases the number of penile erections by 92% in a rat ex copula model of penile erection (5 mg/kg, i.v.); inhibits food intake after overnight fast and decreases nocturnal feeding behavior in mice