Melanotan 2 (CAS NO. 121062-08-6) was first synthesized at the University of Arizona. Researchers decided to find a more potent and stable alternative, one that would be more practical to defenses against skin cancer.

It was under development as drug candidate for female sexual dysfunction and erectile dysfunction, 
Melanotan 2I acts as a non-selective agonist of the melanocortin receptors.

The melanogenesis produced by melanotan 2 is caused by activation of the MC1 receptor, whereas its sexual effects are thought to be related to its ability to activate the MC4 receptor (though the MC3 is thought to possibly also be involved).

Melanotan II is a peptide hormone belonging to the alpha-melanocyte-stimulating hormone (alpha-MSH) class of mimetics. Melanotan II is a synthetic analog pituitary derived Melanocortin. The peptide is primarily known for its ability to help with tanning but is also used to aid in erectile function. Melanotan II, also referred to as MT-2, has no use of significance beyond tanning and erectile function.

Melanotan II (also known as MT-II or MT-2) is an injectable peptide hormone used to promote tanning. MT-II works by stimulating alpha-melanocyte receptors, which promotes formation of melanin in response to sun exposure. When a substantial amount of MT-II has been taken within recent "memory" of the skin cells, an individual tans as if he were a genetically darker type.

Melanotan II analog of alpha-melanocyte stimulating hormone (a-MSH). Melanotan peptides are safe and efficacious with growing long term data. Melanotan 2 is a freeze dried peptide sealed in a sterile multi-use vial. Tanning injections of synthetic potent a-MSH allow for development of photo-protective suntans in all skin types.