Melanotan 2 (MT-2) is a synthetic cyclic heptapeptide — a ring-shaped chain of seven amino acids — designed as an analog of alpha-melanocyte-stimulating hormone (alpha-MSH). Its molecular formula is C₅₀H₆₉N₁₅O₉, and it has a molecular weight of 1024.20 g/mol. The CAS registry number is 121062-08-6. The key structural feature that distinguishes MT-2 from its linear predecessor Melanotan 1 is a lactam bridge, an internal bond that connects two amino acids within the chain and forces the peptide into a cyclic (ring) shape. This cyclic structure makes the molecule more compact and more resistant to breakdown by enzymes. Melanotan 2 was first synthesized in the 1990s, building on the earlier work that produced Melanotan 1. While MT-1 is selective for the MC1R receptor, MT-2’s cyclic structure gives it structural compatibility with multiple melanocortin receptor subtypes, including MC1R, MC3R, MC4R, and MC5R. This broad receptor-family classification is a direct consequence of its three-dimensional shape. The compound is classified as a non-selective melanocortin receptor agonist. It is supplied as a white to off-white lyophilized powder that is soluble in both water and dilute acetic acid. This product is strictly for research purposes only. Not approved for human or animal use.