Description
Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of α-melanocyte-stimulating hormone (α-MSH), a naturally occurring peptide hormone involved in melanogenesis and related signaling cascades [5]. The compound belongs to the melanocortin peptide class and was developed to explore structure-activity relationships at melanocortin receptors (MCRs), a family of G protein-coupled receptors with roles in pigmentation biology, energy regulation, and neuromodulation [3].
Structurally, MT-II incorporates a lactam bridge that constrains its conformation, contributing to potent but non-selective agonist activity across multiple human MCR subtypes [3]. This cyclic architecture has made it a useful scaffold for medicinal chemistry investigations. Researchers have, for example, applied stapling strategies derived from natural product motifs to MT-II analogs in order to probe chemoselectivity and receptor binding affinity, with several modified analogs achieving nanomolar binding constants [1].
In laboratory settings, MT-II serves as a reference agonist for dissecting MCR signaling pathways and for benchmarking novel synthetic ligands designed to achieve receptor subtype selectivity [3]. Preclinical studies have also employed MT-II to interrogate relationships between melanotropin receptor activation and neurobehavioral endpoints, including memory and anxiety-related phenotypes in zebrafish models [4]. Its well-characterized pharmacophore and commercial availability as a research-grade peptide make it a standard tool in investigations of melanocortin biology.
References
[1] 5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II. Chemistry (Weinheim an der Bergstrasse, Germany), 2024. https://pubmed.ncbi.nlm.nih.gov/38285527/
[3] CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists. Journal of Medicinal Chemistry, 2022. https://pubmed.ncbi.nlm.nih.gov/35188390/
[4] Melanotan-II reverses memory impairment induced by a short-term HF diet. Biomedicine & Pharmacotherapy, 2023. https://pubmed.ncbi.nlm.nih.gov/37478579/
[5] Melanotan II. Wikipedia. https://en.wikipedia.org/wiki/Melanotan_II
