MT-2 (Melanotan II) Research Peptide Overview

Semax is a synthetic heptapeptide analog of the ACTH(4-10) fragment with an added C-terminal Pro-Gly-Pro tripeptide that enhances stability and biological activity. This research peptide modulates neurotrophic factor expression including BDNF and NGF, and engages melanocortin receptor signaling. Semax is studied in preclinical models of neuroprotection, cognitive function, and neurotrophic signaling pathways.

What Is MT-2 (Melanotan II) ?

Melanotan II (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) was developed at the University of Arizona as a cyclic, metabolically stable analog of α-MSH. The cyclic structure (cyclized through an Asp-Lys lactam bridge) and D-Phe substitution confer resistance to proteolytic degradation while maintaining high-affinity binding across melanocortin receptor subtypes. MT-2 activates MC1R on melanocytes (driving melanogenesis), MC3R and MC4R in the hypothalamus (modulating energy homeostasis and behavior), and MC5R in exocrine glands. This pan-melanocortin activity makes MT-2 an essential reference compound for studying the integrated melanocortin system. Published research has used MT-2 extensively to characterize melanocortin receptor pharmacology, establish structure-activity relationships for cyclic peptide design, and study the physiological consequences of broad melanocortin receptor activation (Hruby et al., Journal of Medicinal Chemistry, various studies). The peptide’s non-selectivity is both its primary research advantage and the characteristic that distinguishes it from selective analogs like MT-1 and PT-141.

MT-2 (Melanotan II) Mechanism of Action in Research

MT-2 binds all five melanocortin receptor subtypes and activates Gs-coupled cAMP/PKA signaling at each. At MC1R, it drives MITF-mediated melanogenic gene transcription. At MC3R/MC4R, cAMP/PKA signaling in hypothalamic neurons modulates feeding behavior, energy expenditure, and downstream dopaminergic/oxytocinergic pathways. At MC2R, it stimulates adrenocortical steroidogenesis (though with lower potency than ACTH). At MC5R, it modulates exocrine gland function. The cyclic structure enables simultaneous engagement of multiple receptor subtypes, producing a complex physiological response pattern that reflects the integrated melanocortin system.