Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn MT 2 (Melanotan II) Polar Peptides Imagine just wanting to be jacked and tan and you end up like this? Melanotan II is a peptide that increases the melanin in your skin and can give men a boner that Melanotan II Peptide Cosmetic & Skin Research Compound Melanotan II is a synthetic peptide that mimics the bodys natural melanocortin hormones, primarily activating receptors involved in skin pigmentation, appetite, and central nervous system signaling. MELANOTAN 2 (10ml 20mg) peptide to stimulate melanin synthesis.