Melanotan II

Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), developed at the University of Arizona by Dr. Victor Hruby and colleagues. Its amino acid sequence (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) was designed to be resistant to enzymatic degradation while maintaining high affinity for melanocortin receptors. MT-II is a non-selective melanocortin agonist — it activates MC1R (skin pigmentation), MC3R (energy homeostasis), MC4R (sexual function and appetite), and MC5R (exocrine gland function) — giving it a multi-system pharmacological profile that produces tanning, pro-sexual, and appetite-suppressing effects simultaneously.

The tanning mechanism operates through MC1R activation on melanocytes in the basal layer of the epidermis. MC1R signaling increases intracellular cAMP, which activates the MITF transcription factor (microphthalmia-associated transcription factor), upregulating the expression of tyrosinase and related enzymes in the melanin synthesis pathway. This drives the conversion of L-tyrosine to L-DOPA to dopaquinone and ultimately to eumelanin — the brown/black pigment responsible for skin darkening. The critical distinction is that MT-II stimulates eumelanin production constitutively, independent of UV exposure. While UV radiation also activates melanogenesis, MT-II produces melanin upregulation that can occur without sun exposure or dramatically enhance the tanning response to minimal UV exposure. The resulting eumelanin provides genuine photoprotection — it absorbs UV radiation and dissipates it as heat, reducing DNA damage in epidermal cells.

Research on Melanotan II documents dose-dependent increases in skin pigmentation, with visible darkening typically appearing within 1-2 weeks of initial administration. Studies confirm that MT-II-induced tanning provides measurable UV protection, reducing erythema (sunburn) response and DNA photoproduct formation. The compound's MC4R-mediated effects on sexual function have been well-characterized — MT-II was the parent compound from which PT-141 (Bremelanotide) was derived specifically for sexual dysfunction applications. Appetite-suppressing effects through MC4R/MC3R activation have also been documented, though these are generally considered secondary effects in tanning-focused research.

MT-II is suited for researchers investigating melanogenesis, UV photoprotection, melanocortin receptor pharmacology, and skin pigmentation biology. It is the most potent melanogenic peptide available and provides the added research dimensions of melanocortin-mediated sexual function and appetite modulation.

Reconstitute the 10mg vial with 2ml bacteriostatic water (yielding 5mg/ml). Administer via subcutaneous injection. Research protocols typically begin with a loading phase: 0.25-0.5mg per day for 2-4 weeks until the desired level of pigmentation is achieved, followed by a maintenance phase of 0.5-1mg once or twice weekly. Minimal UV exposure (10-20 minutes of natural sunlight or brief tanning bed sessions) during the loading phase accelerates and enhances the melanogenic response. MT-II has a half-life of approximately 33 minutes, but the melanogenic process it initiates — melanocyte activation, melanin synthesis, melanosome transfer — unfolds over days. Transient facial flushing and mild nausea may occur after initial doses; these typically resolve with continued use. Store at 2-8C after reconstitution. Protect from light.

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