HS014 TFA is a potent and selective melanocortin-4 (MC4) receptor antagonist, with Kis of 3.16, 108, 54.4 and 694 nM for human MC4, MC1, MC3 and MC5 receptors respectively. HS014 TFA modulates the behavioral effects of morphine in mice. HS014 TFA increases food intake in free-feeding rats.