Melanotan II PERMANENTLY Darkened My Skin! melanotan II C50H69N15O9 CID 92432 PubChem Melanotan II synthetic tanning drug molecule, illustration Stock Image F029 9531 Science Photo Library 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 95% (HPLC), MC3 R MC4 R melanocortin agonist, lyophilized solid Sigma Aldrich Melanotan II CAS#: 121062 08 6