Your body already makes a hormone that tells your skin to tan. Melanotan 2 is a synthetic peptide engineered to mimic that hormone but in a version that's more potent and longer lasting than Targeting the central melanocortin system for the treatment of metabolic disorders Nature Reviews Endocrinology Your body already makes a hormone that tells your skin to tan. Melanotan 2 is a synthetic peptide engineered to mimic that hormone but in a version that's more potent and MELANOTAN EXPLAINED! Benefits, Risks, Side Effects