Melanotan 2
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Research Use Only
These products are for laboratory research only and not intended for medical use. They are not FDA-approved to diagnose, treat, cure, or prevent any disease. By purchasing, you certify they will be used solely for research and not for human or animal consumption.
Research Summary
24 PubMed CitationsOverview Melanotan II (MT-II) is a synthetic, cyclic heptapeptide analog of the endogenous 13-amino-acid hormone α-melanocyte-stimulating hormone (α-MSH). It was originally synthesized at the University of Arizona in the late 1980s by Victor Hruby, Mac Hadley, and Robert Dorr.[1] Chemically, MT-II is defined as Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂, a shortened variant of α-MSH with key modifications: a lactam bridge cyclization (Asp→Lys) increases enzymatic resistance, and D-Phenylalanine substitution enhances potency. These make MT-II "superpotent" compared to native α-MSH and enable it to cross the blood-brain barrier — a key distinction from the linear Melanotan I (afamelanotide).[1][3] MT-II acts as a non-selective agonist at melanocortin receptors MC1R, MC3R, MC4R, and MC5R with high nanomolar affinity (Ki ~1.1–1.3 nM), but does NOT bind MC2R (the ACTH receptor). This broad receptor activation drives its diverse effects — tanning, erectogenic, anorexigenic, and social behavioral modulation.[2] The active metabolite of MT-II — Bremelanotide (PT-141) — was FDA-approved in 2019...
Melanotan 2 — Research Data at a Glance
| Property | Value |
|---|---|
| PubMed Citations Referenced | 24 |
| Contributing Researchers | 3 |
| Storage Conditions | Lyophilized powder: -20°C, dark, airtight, protected from moisture. |
| Purity Standard | ≥99% (HPLC verified, 3rd-party COA) |
| Research Use Only | Not for human consumption. RUO only. |
Compare Melanotan 2 with Other Peptides
Overview
Overview
Melanotan II (MT-II) is a synthetic, cyclic heptapeptide analog of the endogenous 13-amino-acid hormone α-melanocyte-stimulating hormone (α-MSH). It was originally synthesized at the University of Arizona in the late 1980s by Victor Hruby, Mac Hadley, and Robert Dorr.[1]
Chemically, MT-II is defined as Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂, a shortened variant of α-MSH with key modifications: a lactam bridge cyclization (Asp→Lys) increases enzymatic resistance, and D-Phenylalanine substitution enhances potency. These make MT-II "superpotent" compared to native α-MSH and enable it to cross the blood-brain barrier — a key distinction from the linear Melanotan I (afamelanotide).[1][3]
MT-II acts as a non-selective agonist at melanocortin receptors MC1R, MC3R, MC4R, and MC5R with high nanomolar affinity (Ki ~1.1–1.3 nM), but does NOT bind MC2R (the ACTH receptor). This broad receptor activation drives its diverse effects — tanning, erectogenic, anorexigenic, and social behavioral modulation.[2]
The active metabolite of MT-II — Bremelanotide (PT-141) — was FDA-approved in 2019 under the brand name Vyleesi for hypoactive sexual desire disorder in premenopausal women. MT-II itself remains unapproved by any regulatory body.[3]
Mechanism of Action
Mechanism of Action
Melanocortin Receptor Binding
MT-II is a non-selective agonist at four of five melanocortin receptors (MCRs), all members of the GPCR superfamily:
| Receptor | Primary Location | Function When Activated | Affinity |
|---|---|---|---|
| MC1R | Melanocytes (skin) | Eumelanin synthesis → tanning/photoprotection | High |
| MC3R | Hypothalamus, NAcc | Energy homeostasis, feeding behavior | Ki ~1.3 nM |
| MC4R | Hypothalamus (PVN), spinal cord | Erectile function, appetite suppression, thermogenesis | Ki ~1.1 nM |
| MC5R | Exocrine glands, lymphocytes | Sebum production, immune modulation | Moderate |
| MC2R | Adrenal cortex | ACTH receptor — NO MT-II binding | None |
Primary Signaling: cAMP-PKA Pathway
Upon MCR binding, MT-II activates Gs-coupled adenylate cyclase → increased intracellular cAMP → PKA activation:[2]
- Melanogenesis (MC1R): PKA → CREB phosphorylation → MITF transcription → tyrosinase upregulation → eumelanin production
- Erectile function (MC4R/CNS): Hypothalamic PVN activation → dopaminergic/oxytocinergic downstream → neuronal NO release → intracavernosal pressure increase[5]
- Appetite suppression (MC3R/MC4R): Hypothalamic MCR activation → reduced food intake + increased thermogenesis[6]
- Social behavior (MC4R): Selective nucleus accumbens activation → oxytocin-dependent social learning[7]
Off-Target: Mast Cell Activation
MT-II cross-reacts with MRGPRB2/MRGPRX2 receptors on mast cells, causing pseudo-allergic histamine release → H1 receptor activation → hypothermia (in mice). Subcutaneous dosing reduces histamine release by 63% vs. intraperitoneal.[8]
vs. Related Compounds
| Compound | Structure | BBB | Key Difference |
|---|---|---|---|
| MT-II | Cyclic heptapeptide | Yes | Non-selective MCR agonist; tanning + erectogenic + anorexigenic |
| Melanotan I (Afamelanotide) | Linear [Nle⁴,D-Phe⁷]-α-MSH | No | Tanning only (peripheral MC1R); no CNS effects; TGA/EMA approved for EPP |
| Bremelanotide (PT-141) | Deaminated MT-II metabolite | Yes | FDA-approved (Vyleesi) for HSDD; reduced tanning activity |
| α-MSH (native) | Linear tridecapeptide | Limited | Short half-life; rapidly degraded; weak potency |
Research Applications
Research Applications
Melanotan II research spans dermatology, sexual medicine, neuroendocrinology, oncology, and behavioral neuroscience across 7+ indication categories:
- Skin Pigmentation & Photoprotection — MC1R stimulation → eumelanin synthesis → tanning without UV exposure; as few as 5 low doses induced visible tanning in Phase I trials.[1]
- Sexual Dysfunction — 80% of men with psychogenic ED achieved clinically apparent erections (0.025 mg/kg SC); tip rigidity >80% for 38 min vs 3 min placebo (p=0.0045); enhanced proceptive behaviors in female rats.[3][9]
- Metabolic Regulation & Obesity — Central MC3R/MC4R activation: intraabdominal fat -35% (low dose) to -55% (high dose); iBAT thermogenesis 3-fold increase; appetite suppression via NAcc.[6][10]
- Autism & Social Behavior — Sociability index increased from 3.1 to 26.3 (p<0.0001) in MIA autism model mice; oxytocin-dependent NAcc activation in social contexts; partner preference facilitation in prairie voles.[11][7]
- Neuroprotection & Nerve Regeneration — 20 µg/kg SC every 48h enhanced sensory function recovery in rat sciatic nerve crush model.[12]
- Addiction Research — Synergistic augmentation of naltrexone to reduce binge-like ethanol intake in mice.[13]
- Oncology — Topical MT-II suppressed melanoma tumor growth via MC1R → PTEN upregulation + COX-2/PGE2 inhibition; systemic use carries melanoma risk.[14]
Biochemical Characteristics
| Property | Value |
|---|---|
| Molecular Formula | C₅₀H₆₉N₁₅O₉ |
| Molecular Weight | 1024.18 Da |
| CAS Number | 121062-08-6 |
| PubChem CID | 92432 |
| Sequence | Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
| Structure | Cyclic heptapeptide; lactam bridge (Asp-Lys); Ac-Nle replaces α-MSH Ser-Tyr-Ser-Met; D-Phe replaces L-Phe |
| Parent Molecule | α-MSH (alpha-melanocyte-stimulating hormone) |
| InChI Key | JDKLPDJLXHXHNV-MFVUMRCOSA-N |
| Half-Life (Human) | ~1–2 hours (enhanced vs α-MSH by cyclic structure) |
| BBB Penetration | Yes (unlike Melanotan I) |
| Receptor Profile | Non-selective MCR agonist: MC1R, MC3R (Ki 1.3 nM), MC4R (Ki 1.1 nM), MC5R; NO activity at MC2R |
Identifiers
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| Identity Confirmation | |
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Preclinical Research Summary
Preclinical Research Summary
Key Preclinical Studies
| Study | Model | Key Findings | Ref |
|---|---|---|---|
| Côté et al. (2017) | F344BN rats — ICV 0.04–1 µg/day × 40d | Fat pads -35% to -55% (p<0.01/0.001); iBAT thermogenesis 3-fold ↑; food intake returned to normal by day 5 — weight loss via ↑ energy expenditure | [6] |
| Vemulapalli et al. (2001) | NZW rabbits — 66–133 µg/kg IV | Cavernosal pressure 3.2-fold ↑ (p<0.05); abolished by MC3/4 antagonist SHU 9119, pudendal nerve transection, or L-NAME → centrally-mediated NO release | [5] |
| Minakova et al. (2019) | MIA autism-model mice — ICV 2.5 µg/day × 7d | Sociability index 3.1 → 26.3 (p<0.0001); anxiety unchanged; rescued social deficits to control levels | [11] |
| Ford et al. (2024) | Prairie voles (WT vs Oxtr-KO) — IP/ICV | Social context → NAcc Fos ↑ (p<0.01) in WT but NOT Oxtr-KO; non-social → PVN activation only → oxytocin-dependent social learning mechanism | [7] |
| Jain et al. (2018) | C57BL/6J mice — 10 mg/kg IP | Plasma histamine 4-fold ↑ (p<0.0001); profound hypothermia abolished in mast cell-deficient mice; SC route ↓ histamine 63% | [8] |
| Eliason et al. (2022) | C57BL/6J mice — NAcc microinjection | All doses ↓ food intake at 1,2,4,6h (p<0.05); decreased lever-pressing motivation; no aversive state or metabolic rate change | [10] |
| Wu et al. (2020) | B16-F10 melanoma mice — topical | Dramatically slowed tumor growth; ↑PTEN, ↓COX-2/PGE2, induced cell death; inhibited migration/invasion | [14] |
Human Clinical Data
| Study | Population | Key Results | Ref |
|---|---|---|---|
| Dorr et al. (1996) — Phase I | n=3 healthy males; 0.01–0.025 mg/kg SC | Visible tanning in 2/3 subjects; spontaneous erections 1–5h post-dose; mild nausea; recommended Phase I dose: 0.025 mg/kg | [1] |
| Wessells et al. (1998) — Psychogenic ED | n=10 men; 0.025 mg/kg SC, double-blind crossover | 80% response rate; tip rigidity >80% for 38 min vs 3 min placebo (p=0.0045) | [3] |
| Wessells et al. (2000) — Organic ED | n=10 men; 0.025 mg/kg SC, double-blind crossover | 63% erection rate (12/19 injections vs 1/21 placebo); tip rigidity >80% for 45.3 min vs 1.9 min (p=0.047); enhanced sexual desire | [9] |
Safety Concerns — Case Reports (Unregulated Use)
| Event | Details | Ref |
|---|---|---|
| Priapism | 22-hour painful erection (unknown dose); 60-year-old required surgical shunting after 10 mg injection | [15] |
| Rhabdomyolysis | 39-year-old male: 6 mg SC → CPK 17,773 IU/L; tachycardia, hypertension, agitation, renal dysfunction | [16] |
| Renal Infarction | 45-year-old male: 50% right kidney infarction after 10 mg injections; likely sympathomimetic vasoconstriction | [17] |
| Melanoma/Nevi Changes | 16-year-old female (FAMMM): darkened/enlarged nevi + dysplastic nevus after 2 months (0.5 mg/day); melanoma in situ reports | [18] |
| Common Side Effects | Nausea (dose-dependent), facial flushing, fatigue, yawning/stretching, decreased appetite, darkened moles | [1] |
Pharmacokinetics & Dosing Summary
| Parameter | Value |
|---|---|
| Human Half-Life | ~1–2 hours (enhanced vs α-MSH by cyclic structure) |
| BBB Penetration | Yes (unlike Melanotan I) |
| Active Metabolite | Bremelanotide (PT-141) — deaminated, lacks C-terminal amide |
| ED Research Dose | 0.025 mg/kg SC (Phase I optimal for erection with manageable side effects) |
| Contraindications | Cardiovascular disease; personal/family melanoma history; PDE5 inhibitor combination (priapism risk) |
The products offered on this website are furnished for in-vitro studies only. In-vitro studies (Latin: in glass) are performed outside of the body. These products are not medicines or drugs and have not been approved by the FDA to prevent, treat or cure any medical condition, ailment or disease. Bodily introduction of any kind into humans or animals is strictly forbidden by law.
For Laboratory Research Only. Not for human use, medical use, diagnostic use, or veterinary use.
ALL ARTICLES AND PRODUCT INFORMATION PROVIDED ON THIS WEBSITE ARE FOR INFORMATIONAL AND EDUCATIONAL PURPOSES ONLY.
Authors & Attribution
✍️ Article Author
Dr. Victor J. Hruby, PhD
Victor J. Hruby, PhD, is a Regents Professor in the Department of Chemistry and Biochemistry at the University of Arizona. He led the design and synthesis of the superpotent melanotropic peptides, creating the cyclic lactam analog structure of Melanotan II that provided increased stability and potency compared to the natural hormone α-MSH. His key publications include: 'Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: Design based on molecular dynamics' (1989), 'Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study' (1996), and 'Melanocortin Receptors, Melanotropic Peptides and Penile Erection' (2007). Victor Hruby is referenced as a foundational chemist in melanocortin peptide research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →🎓 Scientific Journal Author
Dr. Mac E. Hadley, PhD
Mac E. Hadley, PhD (deceased), was a Professor of Cell Biology & Anatomy at the University of Arizona. He collaborated on the biological characterization of melanocortin analogs and is credited with discovering the erectogenic properties of Melanotan II through self-experimentation — inadvertently injecting a double dose, experiencing an 8-hour erection along with nausea and yawning, which pivoted research toward sexual dysfunction. Key publications: 'Evaluation of melanotan-II in a pilot phase-I clinical study' (1996), 'Discovery that a melanocortin regulates sexual functions in male and female humans' (2005), and 'Melanocortin peptide therapeutics: Historical milestones' (2006). Mac Hadley is referenced as a foundational biologist in melanocortin peptide research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →Dr. Mac E. Hadley, PhD is being referenced as one of the leading scientists involved in the research and development of Melanotan 2. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor. The purpose of citing the doctor is to acknowledge, recognize, and credit the exhaustive research and development efforts conducted by the scientists studying this peptide.
🔬 Contributing Researcher
Dr. Robert T. Dorr, PhD
Robert T. Dorr, PhD (deceased), was a Professor in the College of Medicine (Pharmacology Department) at the University of Arizona. He led the therapeutic development scientific program and conducted the initial pilot Phase I clinical trials involving human volunteers to evaluate the safety, tanning activity, and side effects of Melanotan II. Key publications: 'Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study' (1996), 'Increased Eumelanin Expression and Tanning is Induced by a Superpotent Melanotropin in Humans' (2000), and 'Melanocortin peptide therapeutics: Historical milestones' (2006). Robert Dorr is referenced as a foundational pharmacologist in melanocortin peptide research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →Dr. Robert T. Dorr, PhD is being referenced as one of the leading scientists involved in the research and development of Melanotan 2. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor. The purpose of citing the doctor is to acknowledge, recognize, and credit the exhaustive research and development efforts conducted by the scientists studying this peptide.
Referenced Citations
Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 1996;58(20):1777-1784.
DOIHadley ME, Dorr RT. Melanocortin peptide therapeutics: Historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-930.
PubMedWessells H, Fuciarelli K, Hansen J, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: Double-blind, placebo controlled crossover study. The Journal of Urology. 1998;160(2):389-393.
PubMedFDA Warning Letters regarding unauthorized marketing of Melanotan products.
FDA.govVemulapalli R, Kurowski S, Salisbury B, et al. Activation of central melanocortin receptors by MT-II increases cavernosal pressure in rabbits by the neuronal release of NO. British Journal of Pharmacology. 2001;134(8):1705-1710.
DOICôté I, et al. Activation of the central melanocortin system chronically reduces body mass without the necessity of long-term caloric restriction. Canadian Journal of Physiology and Pharmacology. 2017.
PubMedFord CL, McDonough AA, Horie K, Young LJ. Melanocortin agonism in a social context selectively activates nucleus accumbens in an oxytocin-dependent manner. Neuropharmacology. 2024;247:109848.
DOIJain S, Panyutin A, Liu N, et al. Melanotan II causes hypothermia in mice by activation of mast cells and stimulation of histamine 1 receptors. American Journal of Physiology-Endocrinology and Metabolism. 2018;315(3):E357-E366.
DOIWessells H, Levine N, Hadley ME, Dorr RT, Hruby VJ. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology. 2000;56(4):641-646.
DOIEliason NL, Martin L, Low MJ, Sharpe AL. Melanocortin receptor agonist melanotan-II microinjected in the nucleus accumbens decreases appetitive and consumptive responding for food. Neuropeptides. 2022;96:102289.
DOIMinakova E, Lang J, Medel-Matus JS, et al. Melanotan-II reverses autistic features in a maternal immune activation mouse model of autism. PLoS ONE. 2019;14(1):e0210389.
DOITer Laak MP, et al. Melanotan II promotes peripheral nerve regeneration in a rat sciatic nerve crush model. 2003.
PubMedEvans-Brown M, Dawson RT, Chandler MD, McVeigh J. Use of melanotan I and II in the general population. BMJ. 2009;338:b566.
DOIWu JC, Tsai HE, Hsiao YH, et al. Topical MTII Therapy Suppresses Melanoma Through PTEN Upregulation and Cyclooxygenase II Inhibition. International Journal of Molecular Sciences. 2020;21(2):681.
DOIDreyer BA, Amer T, Fraser M. Melanotan-induced priapism: a hard-earned tan. BMJ Case Reports. 2019;12(2):e227644.
DOINelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clinical Toxicology. 2012;50(10):1169-1173.
DOIPeters B, Hadimeri H, Wahlberg R, Afghahi H. Melanotan II: a possible cause of renal infarction. CEN Case Reports. 2020;9(2):159-161.
DOISivyer GW. Dermatological changes with melanotan II use in a FAMMM patient. Dermatology Practical & Conceptual. 2012.
PubMedRyakhovsky VV, Khachiyan GA, Kosovova NF, et al. The first preparative solution phase synthesis of melanotan II. Beilstein Journal of Organic Chemistry. 2008;4:39.
DOIHjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology. 2014;228(1):34-36.
PubMedGiuliano F, Clement P, Droupy S, et al. Melanotan-II: Investigation of the inducer and facilitator effects on penile erection in anaesthetized rat. Neuroscience. 2006;138(1):293-301.
DOILi G, Zhang Y, Wilsey JT, Scarpace PJ. Unabated anorexic and enhanced thermogenic responses to melanotan II in diet-induced obese rats. Journal of Endocrinology. 2004;182(1):123-132.
DOIKing SH, et al. Melanocortin Receptors, Melanotropic Peptides and Penile Erection. Current Topics in Medicinal Chemistry. 2007;7(11):1111-1119.
PubMedWessells H, Levine N, Hadley ME, Dorr RT, Hruby VJ. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. International Journal of Impotence Research. 2000;12(Suppl 4):S74-S79.
DOIRUO Disclaimer
For Research Use Only (RUO). This product is intended solely for in-vitro research and laboratory experimentation. It is not a drug, food, cosmetic, or medical device and has not been approved by the FDA for any human or veterinary use. It must not be used for therapeutic, diagnostic, or any other non-research purpose. Pure US Peptide does not condone or encourage the use of this product for anything other than strictly defined research applications. Users assume full responsibility for compliance with all applicable regulations and guidelines.
Certificate of Analysis (COA)
Every batch is strictly tested by accredited third-party laboratories (ISO 17025) to ensure 99%+ purity.
Latest Lab Report
Storage & Handling
Summary
Lyophilized powder: -20°C, dark, airtight, protected from moisture. Reconstituted: 2–8°C, use within 2–4 weeks. Avoid repeated freeze-thaw cycles.
Recommended Laboratory Storage Conditions
Lyophilized Powder: Store at -20°C in dark, airtight container protected from moisture and light. Stable for months to years under these conditions.
Reconstitution: Use sterile water or bacteriostatic water. Maintain sterile technique during handling.
Solution: Refrigerate at 2–8°C after reconstitution. Use within 2–4 weeks to prevent degradation.
Handling: Do not subject to repeated freeze-thaw cycles. Use sterile techniques during reconstitution and administration.
Form: Lyophilized white powder in sealed vials. Also sold illicitly as nasal sprays (unreliable absorption).
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