Melanotan II (MT-II): Complete Research Guide — Non-Selective Melanocortin Receptor Pharmacology, Human Data & White-Label Pricing (2026)
- Melanotan II (MT-II, CAS: 121062-08-6) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH), MW 1,024.2 Da, developed at the University of Arizona by Hruby, Hadley, Dorr and colleagues in the 1980s–90s as a stable, potent, non-selective melanocortin receptor agonist (Hadley & Dorr, Peptides, 2006 — PMID: 16426078).
- MT-II activates MC1R, MC3R, MC4R, and MC5R with no significant MC2R binding — making it the broadest-spectrum melanocortin receptor agonist in the research category and a foundational pharmacological tool for the melanocortin system prior to the development of selective analogs.
- Published human clinical data includes two double-blind, placebo-controlled crossover studies (n=10 and n=20, Wessells et al., University of Arizona, 1998–2000) documenting MC4R-mediated activity, and a Phase I safety evaluation in healthy subjects (Dorr et al., Life Sci, 1996).
- MT-II is the parent compound from which PT-141 (bremelanotide / Vyleesi, research-grade 2019) was derived: PT-141 was developed by systematically reducing MC1R activity while preserving MC4R agonism — the molecular lineage that connects MT-II directly to the only research-grade melanocortin peptide.
- Research-grade MT-II is available in a 10mg configuration (Research Use Only) with batch-specific COAs through the YPB catalog.
- 22,000 monthly US searches; $75.05 gross margin per unit at Premier tier (75%); unique research positioning as the broadest-spectrum melanocortin agonist and historical origin compound of the melanocortin compound development lineage. Updated April 2026.
What Is Melanotan II and Where Does It Come From?
Parent Compound of PT-141 Lineage
Non-Selective MC1R–MC4R Agonist
Melanotan II (CAS: 121062-08-6), also designated MT-II or MT-2, is a synthetic cyclic heptapeptide designed as a stable, potent analog of alpha-melanocyte-stimulating hormone (α-MSH). Updated April 2026. The compound was developed at the University of Arizona by Victor Hruby, Mac Hadley, Robert Dorr, and Norman Levine — the same research group that established the foundational pharmacology of the melanocortin receptor system — with initial synthesis and characterization in the late 1980s and early 1990s. Hadley and Dorr reviewed two decades of work on melanocortin peptide therapeutics, noting MT-II’s role as the primary research tool for studying non-selective melanocortin receptor agonism prior to the development of receptor-subtype-selective analogs (Hadley & Dorr, Peptides, 2006 — PMID: 16426078).
MT-II’s chemical structure — Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH — incorporates four key modifications from native α-MSH: (1) norleucine (Nle) substitution for methionine at position 4, preventing oxidative degradation; (2) D-phenylalanine substitution at position 7 for enhanced receptor binding stability; (3) lactam bridge cyclization between Asp and Lys residues, constraining the conformation for improved receptor selectivity and metabolic stability; and (4) N-terminal acetylation. These modifications extend the half-life of MT-II to approximately 33 minutes, compared to seconds for endogenous α-MSH, making it tractable as a research tool where native α-MSH is too rapidly cleared to be useful.
MT-II is not research-grade, is not approved as a therapeutic agent in any jurisdiction, and is sold exclusively for in vitro and laboratory research purposes.
Key Characteristics
| Parameter | Value |
|---|---|
| Chemical Name | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH (N-acetyl-Nle4, cyclic[Asp5,D-Phe7,Lys10]-α-MSH(4-10)-amide) |
| Common Names | Melanotan II, MT-II, MT-2, Melanotan-2 |
| CAS Number | 121062-08-6 |
| Molecular Formula | C50H69N15O9 |
| Molecular Weight | 1,024.2 Da |
| Amino Acids | 7 (cyclic heptapeptide; lactam bridge between Asp and Lys residues) |
| Half-Life | Approximately 33 minutes (SC administration in preclinical models); dramatically extended versus endogenous α-MSH (<5 minutes) |
| Receptor Profile | Non-selective agonist: MC1R (high affinity), MC3R, MC4R, MC5R; no significant MC2R binding |
| Alternative Names | MT-II; Melanotan-2; MT 2; MTII; [Nle4,D-Phe7]-α-MSH cyclic analog |
| FDA Status | Not approved. Research-grade compound; not equivalent to PT-141 (bremelanotide/Vyleesi). |
| WADA Status | Prohibited — Peptide Hormones, Growth Factors, Related Substances and Mimetics (S2), WADA Prohibited List 2025 |
| Storage | Lyophilized: −20°C. Reconstituted: 2–8°C, use within 14 days |
| Developers | Hruby, Hadley, Dorr, Levine et al., University of Arizona, Tucson (1980s–1990s) |
How Does Melanotan II Work? Primary Mechanisms of Action
MT-II’s pharmacological profile is defined by its non-selective melanocortin receptor agonism — simultaneous high-affinity activation across four of the five melanocortin receptor subtypes. This breadth distinguishes it from both endogenous α-MSH (which is cleared too rapidly for sustained receptor engagement) and from selective analogs developed later, making MT-II the primary reference tool for studying whole-system melanocortin receptor pharmacology.
MC1R Agonism and the Melanogenesis Pathway
MC1R is expressed predominantly on melanocytes in the epidermis, where it mediates the production of eumelanin (brown/black pigment) and pheomelanin (red/yellow pigment) in response to α-MSH. MT-II binding at MC1R activates adenylyl cyclase via Gαs, elevating cAMP, which activates protein kinase A (PKA). PKA phosphorylates the microphthalmia-associated transcription factor (MITF), upregulating transcription of tyrosinase and related melanogenic enzymes. The published result is a shift toward eumelanin production — visible as increased pigmentation — occurring independently of UV photon exposure. This MC1R-mediated melanogenesis pathway activity is the primary feature distinguishing MT-II from PT-141 in research contexts, as PT-141 was specifically engineered to reduce MC1R engagement while preserving MC4R activity.
MC4R Agonism: Central Neural Arousal and Energy Regulation
MT-II activates MC4R in the hypothalamus — specifically in the paraventricular nucleus (PVN) and medial preoptic area (MPOA) — producing the same CNS-mediated arousal signaling documented for PT-141 via dopamine and oxytocin pathway modulation. The University of Arizona clinical studies (Wessells et al., 1998–2000) demonstrated that MT-II produced erections in men with both psychogenic and organic erectile dysfunction via this central MC4R pathway (Wessells et al., J Urol, 1998 — PMID: 9679884). The MC4R activity of MT-II was the primary pharmacological observation that catalyzed the PT-141 development program at Palatin Technologies.
In addition to sexual function research, published literature has extensively documented MC4R’s role in energy homeostasis. Cone and colleagues demonstrated that ICV administration of MT-II inhibits hyperphagia in four different obese mouse models, establishing MC4R as a central regulator of feeding behavior and energy balance — an observation that underpins ongoing research into MC4R agonism for metabolic applications.
MC3R and MC5R Agonism
MC3R is expressed centrally in hypothalamic circuits involved in energy balance, feeding behavior, and autonomic regulation. MT-II’s MC3R activity contributes to appetite-suppressant and autonomic effects observed in preclinical and early clinical studies. MC5R is expressed in exocrine glands (sebaceous, lacrimal, salivary) and has been studied in the context of inflammatory marker regulation and sebaceous gland activity. MT-II’s MC5R engagement produces secondary effects on sebum and exocrine secretion that are not observed with MC1R/MC4R-selective analogs, making MT-II relevant for research protocols specifically investigating MC5R biology.
What Systems Has Melanotan II Been Investigated For?
MT-II’s published research applications reflect its multi-receptor profile: melanogenesis research (MC1R), sexual function and arousal research (MC4R), energy homeostasis and feeding behavior (MC3R/MC4R), and exocrine gland biology (MC5R).
Melanogenesis Pathway Research
MC1R-mediated melanogenesis has been studied with MT-II and related analogs as the primary research tool for characterizing the cAMP/PKA/MITF/tyrosinase signaling cascade in melanocytes. Published work from the University of Arizona group confirmed that MT-II potently activates this pathway, producing measurable increases in eumelanin synthesis in melanocyte cell culture and animal models. The compound’s structural properties that confer MC1R affinity — particularly the D-Phe7 substitution and lactam cyclization — have been extensively characterized in structure-activity relationship (SAR) studies that informed the design of afamelanotide (Scenesse), the research-grade selective MC1R agonist for erythropoietic protoporphyria.
Central Melanocortin System Research (MC4R)
MC4R’s role in sexual function was first characterized in human subjects using MT-II as the primary research tool. Wessells et al. published the first double-blind, placebo-controlled crossover study of a melanocortin receptor agonist in human subjects with psychogenic erectile dysfunction (n=10, J Urol, 1998, PMID: 9679884), followed by a second study in men with organic risk factors for ED (n=10, Urology, 2000, PMID: 11018622). The combined study reviewed by Wessells et al. (2000, PMID: 11035391) enrolled 20 men and documented that MT-II initiated erections in 17 of 20 subjects in the absence of sexual stimulation — a result that directly motivated development of PT-141 as a refined, MC1R-reduced derivative for the sexual dysfunction indication (Wessells et al., Int J Impot Res, 2000 — PMID: 11035391).
Energy Homeostasis Research
MC4R’s role as a central regulator of energy balance was characterized in part using MT-II as the melanocortin agonist reference compound. Published preclinical data demonstrated that ICV MT-II administration significantly reduced food intake and body mass in multiple rodent models, including genetically obese models where leptin-mediated pathways were non-functional. This MT-II-based research established the MC4R as a potential target for energy homeostasis research and laid groundwork for subsequent MC4R-selective compound development.
What Does the Human Research Data Show So Far?
MT-II has been evaluated in a limited number of controlled human studies, primarily conducted by the University of Arizona research group that developed the compound. Human data is more limited than for PT-141 (bremelanotide / Vyleesi), which underwent a full FDA approval program with 1,247+ subjects.
Human Safety Summary
| Study | Route | N | Dose | Adverse Events | Year |
|---|---|---|---|---|---|
| Phase I Safety Study — Dorr et al., University of Arizona | SC injection | Not fully disclosed (Phase I) | Multiple doses (dose-escalation) | Nausea most common; yawning reported; stretch/yawn complex in some subjects. No serious compound-related adverse events at studied doses. | 1996 |
| Crossover Study (Psychogenic ED) — Wessells et al. | SC injection | 10 | 0.025 mg/kg SC | Nausea and yawning. At 0.025 mg/kg, 12.9% of subjects experienced severe nausea. No serious compound-related adverse events. | 1998 |
| Crossover Study (Organic ED) — Wessells et al. | SC injection | 10 | 0.025 mg/kg SC | Nausea and yawning consistent with Study 1. No serious compound-related adverse events. | 2000 |
| Combined Study Review — Wessells et al. | SC injection | 20 | 0.025 mg/kg SC | Nausea and yawning most common. 12/19 doses at 0.025 mg/kg produced the stretch/yawn/nausea complex. No serious adverse events. | 2000 |
The primary adverse event profile across all published MT-II studies was nausea, yawning, and the “stretch-yawn complex” — adverse events attributed to MC3R/MC4R activation in brainstem areas. No serious compound-related adverse events were reported in any published study at the studied doses. As of April 2026, no large-scale randomized controlled trial has been published for MT-II specifically (distinguishing it from PT-141, which underwent full Phase 3 RCT development via the RECONNECT program). All MT-II from YPB is Research Use Only and is not intended for human potential wellness benefit.
How Does Melanotan II Compare to Other Melanocortin Research Peptides?
MT-II occupies the foundational position in the melanocortin research peptide category: the non-selective parent compound from which selective analogs were derived. Each subsequent compound in the lineage was designed to retain one or more of MT-II’s activities while reducing others.
| Parameter | Melanotan II | PT-141 (Bremelanotide) | Afamelanotide | α-MSH (Endogenous) |
|---|---|---|---|---|
| Origin | University of Arizona, 1980s–90s; parent compound of melanocortin compound lineage | Derived from MT-II; MC1R activity selectively reduced; Palatin Technologies | Linear [Nle4,D-Phe7]-α-MSH; Clinuvel compound | Endogenous 13-AA neuropeptide; POMC precursor |
| Receptor Profile | Non-selective: MC1R, MC3R, MC4R, MC5R (no MC2R) | MC4R > MC3R > MC1R (reduced); selective CNS profile | Highly selective MC1R; linear structure | MC1R–MC5R (endogenous non-selective) |
| MC1R Activity | High (melanogenesis research) | Low (selectively reduced from MT-II) | Very high (primary indication) | High (endogenous tanning signal) |
| MC4R Activity | High (CNS arousal, energy homeostasis) | High (primary pharmacological target) | Low (limited CNS activity) | Moderate (rapid clearance limits CNS reach) |
| Half-Life | ~33 minutes (vs <5 min for α-MSH) | ~2.7 hours (cyclic lactam with reduced MC1R) | ~33 hours (SubQ implant formulation) | <5 minutes (rapid plasma clearance) |
| FDA Status | Not approved; RUO only | Approved (Vyleesi 2019, HSDD in premenopausal women) | Approved (Scenesse, EPP) | Not applicable (endogenous molecule) |
| PubMed Publications | 200+ (Melanotan II / MT-II) | 300+ (bremelanotide) | 150+ (afamelanotide) | 2,000+ (α-MSH all contexts) |
| Research-Grade Available? | Yes — RUO | Yes — RUO | Limited | Yes (research reagent) |
For researchers requiring isolated MC4R CNS pharmacology without MC1R melanogenesis as a confounding variable, the PT-141 Research Guide covers the selective MC4R compound derived from MT-II. For researchers studying the role of copper peptides in skin biology through a non-melanocortin pathway, GHK-Cu provides a gene-expression-level approach to dermal research that complements melanocortin receptor pharmacology without receptor overlap.
What Should Researchers Know About MT-II Stability and Handling?
MT-II at 1,024.2 Da is a small-to-mid weight peptide with a lactam bridge that provides greater metabolic stability than linear α-MSH analogs of comparable sequence.
Storage and Reconstitution Protocol
Lyophilized MT-II is stable at −20°C for up to 24 months when protected from moisture and light. The lactam bridge (Asp-Lys cyclization) confers resistance to DPP-IV and exopeptidase degradation, accounting for the substantially extended half-life relative to native α-MSH. Reconstitution with bacteriostatic water is recommended; once reconstituted, solutions should be held at 2–8°C and used within 14 days. The Nle4 substitution (norleucine for methionine) eliminates oxidative degradation at the sulfur-containing residue — a specific instability present in native α-MSH but absent in MT-II.
COA Verification
At 1,024.2 Da, HPLC purity (≥98%) combined with mass spectrometry is the standard verification protocol. MS confirmation should verify the cyclic lactam form at MW 1,024.2 Da — distinct from linear precursor forms. Researchers should additionally confirm the Nle4 substitution and D-Phe7 configuration are correct, as these residues are critical for receptor binding specificity. All YPB MT-II batches include lot-traceable COA documentation accessible through the COA Library.
Key Research Findings: Melanotan II in 2026
Key Research Findings
- Foundational melanocortin system research tool: MT-II was the primary non-selective agonist used to characterize MC1R, MC3R, MC4R, and MC5R pharmacology before selective analogs existed; it remains the broadest-spectrum melanocortin reference compound in preclinical research.
- Parent compound of the PT-141 / Vyleesi lineage: PT-141 (research-grade as Vyleesi 2019) was derived from MT-II by selectively reducing MC1R activity while preserving MC4R agonism; this lineage makes MT-II directly relevant to the only approved melanocortin peptide compound.
- MC4R human erectogenic activity confirmed (1998–2000): Wessells et al. documented MC4R-mediated activity in two crossover studies (n=30 combined) at the University of Arizona; 17 of 20 subjects in the combined review showed the documented effect without sexual stimulation (PMID: 11035391).
- MC1R cAMP/PKA/MITF/tyrosinase cascade characterized: Structure-activity relationship studies with MT-II informed the design of afamelanotide (Scenesse), confirming that D-Phe7 and lactam cyclization are key determinants of MC1R binding affinity.
- MC4R energy homeostasis role established: Published preclinical data using MT-II demonstrated inhibition of hyperphagia in multiple obese mouse models via central MC4R, establishing the receptor’s role in energy regulation research.
- ~33-minute half-life vs <5-minute α-MSH: Structural modifications (Nle4, D-Phe7, lactam) extend stability >6-fold over the endogenous ligand, enabling sustained receptor engagement in research protocols.
- Nausea and yawning are the primary tolerability signals: Attributed to MC3R/MC4R activation in brainstem regions; consistent with the profile observed for PT-141 at higher doses; no serious adverse events in any published study.
- 200+ PubMed publications: Spanning receptor pharmacology, melanogenesis biology, sexual function, energy homeostasis, and compound development SAR studies from the foundational University of Arizona program.
Browse the Full Research Catalog
Why Is Melanotan II a High-Demand Research Compound?
Melanotan II generates 22,000 monthly US searches, sustained by its historical position as the non-selective melanocortin reference compound, the PT-141 lineage connection, and ongoing research interest in MC4R biology across energy homeostasis and sexual function contexts.
Search Volume and Consumer Interest
MT-II occupies a unique search niche: researchers familiar with the melanocortin system consistently search for the parent compound alongside selective derivatives. The PT-141 approval in 2019 generated significant press attention that elevated awareness of the entire melanocortin category, including the non-selective parent compound. Research groups studying the melanocortin system comparatively — requiring both non-selective (MT-II) and selective (PT-141, afamelanotide) agonist profiles — source both compounds. The BPC-157 Research Guide and PT-141 Research Guide together cover adjacent categories frequently searched alongside melanocortin compounds.
Publication Context
PubMed indexes 200+ publications for Melanotan II and MT-II as of April 2026. The University of Arizona studies (1996–2000) and the subsequent work characterizing MC4R biology — most of which used MT-II as the primary pharmacological tool — continue to be cited in new publications on melanocortin receptor pharmacology, maintaining sustained AI search citation rates across Perplexity, ChatGPT Search, and Google AI Overviews.
Market Demand Indicators
| Demand Indicator | Melanotan II Data Point |
|---|---|
| Monthly US searches | 22,000/mo |
| PubMed publications (total) | 200+ (Melanotan II / MT-II combined) |
| PubMed publications (2020+) | 20+ new publications since 2020 |
| Clinical human data | Phase I + 2 double-blind crossover studies (n=30 combined); no serious adverse events |
| Lineage connection | Parent compound of PT-141 (research-grade Vyleesi 2019) — research context elevated by approval |
| Regulatory status | Not approved in any jurisdiction; RUO only |
| Keyword difficulty range | Low-medium competition (KD <20) |
| Catalog positioning | Non-selective reference compound pairs with PT-141 for comparative melanocortin receptor research |
How Can Researchers Offer Melanotan II Under Their Own Brand?
YourPeptideBrand.com provides white-label dropship for MT-II in a standalone 10mg research configuration. Its position as the parent compound of the melanocortin compound lineage, combined with 200+ publications and the PT-141 approval halo, makes it a natural companion SKU for white-label brands already offering PT-141.
What White-Labeling Means
White-label operators receive pre-built RUO-compliant product pages with molecular data tables, receptor profile descriptions, and COA library links. Operators set retail pricing and keep the margin; YPB handles all fulfillment. Download the full product catalog for all 60+ SKU pricing tiers.
Melanotan II Wholesale Pricing & Margin Analysis
| SKU | Compound | Premier ($497/mo) | Core ($297/mo) | Suggested MSRP | Premier Margin |
|---|---|---|---|---|---|
| YPB.270 (RUO) | Melanotan II 10mg | $24.95 | $29.94 | $100.00 | $75.05 (75%) |
Use the YPB Profit Calculator to model projected monthly revenue at your target pricing and volume. MT-II at Premier tier generates $75.05 gross margin per unit at $100 MSRP — a 75% margin rate. White-label brands offering both MT-II and PT-141 capture comparative melanocortin research buyers from both non-selective and selective agonist search audiences, maximizing catalog coverage from a single melanocortin category content investment. 250+ white-label research brands are already live on the platform.
Who This Is For
MT-II is best positioned for white-label brands targeting researchers and practitioners with interest in melanocortin system pharmacology, sexual function research, or energy homeostasis biology. Brands already offering PT-141 can cross-sell MT-II as the non-selective parent compound for comparative receptor research protocols, or to buyers specifically interested in whole-system melanocortin agonism including MC1R melanogenesis pathway research.
Methodology & Data Sources
Methodology & Data Sources
Scientific literature: PubMed, Embase, and ClinicalTrials.gov searched for “Melanotan II,” “MT-II,” “melanotan-2,” “[Nle4,D-Phe7]-alpha-MSH cyclic,” and CAS 121062-08-6. Search conducted through April 2026.
Key sources: Hadley & Dorr (2006) Peptides (PMID: 16426078); Dorr et al. (1996) Life Sci; Wessells et al. (1998) J Urol (PMID: 9679884); Wessells et al. (2000) Urology (PMID: 11018622); Wessells et al. (2000) Int J Impot Res (PMID: 11035391); Fan et al. (1997) MC4R energy homeostasis preclinical data.
Search volume data: Google Ads keyword data via DataForSEO, April 2026. Monthly US searches for “Melanotan II,” “MT-2,” “melanotan 2,” and close variants combined.
Pricing data: YPB Full Pricing Catalog, current as of April 2026. Premier ($497/mo) and Core ($297/mo) membership tiers. Margin calculated as MSRP minus Premier wholesale price.
Limitations: Human data for MT-II specifically consists of small-N crossover studies (n=10 per study); no large-scale randomized controlled trial has been published. Long-term safety data in humans is not available. MT-II is not approved for any potential wellness benefit; it is not equivalent to PT-141 (bremelanotide/Vyleesi). This article is for educational purposes and does not constitute medical or research protocol advice.
References
- Al-Obeidi, F., de la Castrucci, A. M., Hadley, M. E., & Hruby, V. J. (1989). Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics. J Med Chem, 32(12), 2555–2561. PMID: 2585486
- Dorr, R. T., Lines, R., Levine, N., Brooks, C., Xiang, L., Hruby, V. J., & Hadley, M. E. (1996). Evaluation of Melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci, 58(20), 1777–1784. PMID: 8637402
- Wessells, H., Fuciarelli, K., Hansen, J., Hadley, M. E., Hruby, V. J., Dorr, R., & Levine, N. (1998). Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol, 160(2), 389–393. PMID: 9679884
- Wessells, H., Gralnek, D., Dorr, R., Hruby, V. J., Hadley, M. E., & Levine, N. (2000). Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology, 56(4), 641–646. PMID: 11018622
- Wessells, H., Levine, N., Hadley, M. E., Dorr, R., & Hruby, V. (2000). Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res, 12(Suppl 4), S74–79. PMID: 11035391
- Fan, W., Boston, B. A., Kesterson, R. A., Hruby, V. J., & Cone, R. D. (1997). Role of melanocortinergic neurons in feeding and the agouti obesity syndrome. Nature, 385(6612), 165–168. PMID: 8990120
- Hadley, M. E., & Dorr, R. T. (2006). Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialisation. Peptides, 27(4), 921–930. PMID: 16426078
- Wikberg, J. E. S. (1999). Melanocortin receptors: perspectives for novel compounds. Eur J Pharmacol, 375(1–3), 295–310. (Receptor subtype distribution review.) PMID: 10443584
- Cone, R. D. (2006). Studies on the physiological functions of the melanocortin system. Endocr Rev, 27(7), 736–749. (MC4R energy homeostasis review.) PMID: 17056594
Frequently Asked Questions
Melanotan II (MT-II, CAS: 121062-08-6) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH), developed at the University of Arizona by Hruby, Hadley, and Dorr as a stable, potent, non-selective melanocortin receptor agonist. In research models, published data demonstrates MT-II activates MC1R (melanogenesis pathway), MC3R and MC4R (central CNS arousal, feeding behavior, energy homeostasis), and MC5R (exocrine gland biology) without significant MC2R engagement. It is the foundational non-selective reference compound from which PT-141 (bremelanotide) was derived and is used for whole-system melanocortin receptor pharmacology research. MT-II is not research-grade and is classified for Research Use Only (RUO). Updated April 2026.
PubMed indexes 200+ publications for Melanotan II and MT-II as of April 2026. The foundational University of Arizona studies span the Phase I safety evaluation (Dorr et al., 1996, PMID: 8637402), two double-blind crossover studies in human subjects (Wessells et al., 1998, PMID: 9679884; 2000, PMID: 11018622), and the comprehensive human study review (Wessells et al., 2000, PMID: 11035391). Hadley & Dorr (2006) published a comprehensive review of two decades of melanocortin peptide therapeutics development (PMID: 16426078). New publications continue to appear in receptor pharmacology, melanogenesis biology, and compound development SAR contexts through 2025–2026.
PT-141 (bremelanotide) was derived from Melanotan II through systematic structural modification to reduce MC1R activity while preserving MC4R agonism. MT-II activates MC1R, MC3R, MC4R, and MC5R with broad non-selectivity; PT-141 prioritizes MC4R and MC3R while substantially reducing MC1R engagement. For research protocols specifically studying MC4R-mediated CNS arousal pathways in isolation, PT-141’s reduced MC1R profile avoids confounding melanogenesis pathway co-activation. For research requiring whole-system melanocortin agonism across all four non-MC2R receptor subtypes — including MC1R melanogenesis pathway characterization — MT-II is the appropriate reference compound. PT-141 received FDA approval as Vyleesi in 2019 for HSDD in premenopausal women; MT-II has not received compound approval in any jurisdiction (Hadley & Dorr, PMID: 16426078).
MT-II has an approximate half-life of 33 minutes in preclinical SC administration models — dramatically longer than endogenous α-MSH (<5 minutes). The extended stability results from three structural modifications: norleucine (Nle4) substitution eliminates methionine oxidative degradation; D-phenylalanine (D-Phe7) substitution increases receptor binding stability; and the Asp-Lys lactam cyclization confers resistance to DPP-IV and exopeptidase degradation while constraining active conformation. Lyophilized MT-II is stable at −20°C for up to 24 months. Reconstituted solutions should be held at 2–8°C and used within 14 days. COA verification should confirm the cyclic lactam form via MS at MW 1,024.2 Da and correct D-Phe7 configuration via chiral HPLC.
Yes. Published human studies for MT-II include: a Phase I safety evaluation in healthy subjects (Dorr et al., 1996, PMID: 8637402) establishing the dose-tolerability profile; two double-blind, placebo-controlled crossover studies in men with erectile dysfunction conducted at the University of Arizona (Wessells et al., 1998, n=10, PMID: 9679884; Wessells et al., 2000, n=10, PMID: 11018622); and a combined study review (Wessells et al., 2000, n=20, PMID: 11035391) documenting MC4R-mediated activity in 17 of 20 subjects. The primary adverse event across all studies was nausea and yawning. No serious compound-related adverse events were reported. As of April 2026, no large-scale RCT for MT-II has been published; the compound was not advanced through a full compound approval program.
Yes. YourPeptideBrand.com provides white-label dropship for MT-II in a 10mg configuration at $24.95 Premier wholesale, with a suggested MSRP of $100 generating $75.05 gross margin per unit (75% margin). White-label storefronts include pre-built RUO-compliant product pages with molecular data tables, receptor profile descriptions, and COA library links. Operators set retail pricing and keep the margin. Storefronts launch within 30 days with no inventory requirements. Use the profit calculator to model projected revenue.
Every MT-II batch includes a lot-specific COA from an independent third-party laboratory covering: qualitative ID (HPLC + MS confirmation of the cyclic lactam form at 1,024.2 Da, Nle4 substitution, and D-Phe7 configuration), HPLC purity (≥98%), endotoxin (<1 EU/mg), TAMC, and TYMC. D-Phe7 chiral configuration confirmation is included as it is critical for receptor binding selectivity. Documentation is accessible through the batch-specific COA library per order.
Premier tier members ($497/mo) access MT-II 10mg at $24.95 wholesale, generating $75.05 gross margin per unit at suggested $100 MSRP — a 75% margin rate. Core tier ($297/mo) pricing is $29.94. White-label brands offering both MT-II ($75.05 margin) and PT-141 ($93.67 margin) together capture the full melanocortin research search audience — non-selective compound researchers and selective MC4R researchers — with a combined melanocortin two-SKU basket generating $168.72 combined margin per dual-order transaction at Premier pricing.
Key Takeaways
Research Takeaways
- Foundational non-selective melanocortin reference compound: MT-II activates MC1R, MC3R, MC4R, and MC5R simultaneously, providing a whole-system melanocortin pharmacology readout unavailable from selective analogs.
- Parent compound of the PT-141/Vyleesi lineage: PT-141 (research-grade 2019) was derived by selectively reducing MT-II’s MC1R activity; understanding MT-II is essential context for interpreting the melanocortin compound development lineage.
- MC4R human activity confirmed in crossover studies (1998–2000): Wessells et al. (University of Arizona) documented MC4R-mediated activity in 17 of 20 subjects in a double-blind crossover design (PMID: 11035391).
- MC1R melanogenesis cascade characterized: SAR studies with MT-II directly informed the design of afamelanotide (Scenesse, research-grade for EPP), confirming the D-Phe7 and lactam bridge as key MC1R affinity determinants.
- MC4R energy homeostasis role established in preclinical models: Fan et al. (1997, PMID: 8990120) published foundational data on MC4R’s feeding behavior regulation using MT-II as the pharmacological tool.
- ~33-minute half-life from Nle4, D-Phe7, lactam modifications vs <5-minute native α-MSH — structural design that made MT-II a practical research tool where endogenous ligands are not.
- No large-scale RCT; not research-grade in any jurisdiction: Human data is limited to small-N crossover studies; long-term safety data is not available.
Business Takeaways
- 22,000 monthly searches at low-medium KD — melanocortin category demand elevated by PT-141/Vyleesi approval halo; MT-II captures the non-selective parent compound search audience.
- $75.05 gross margin per unit at Premier tier (75%) — among the highest margin percentages in the hormonal category.
- Natural PT-141 companion SKU — together capturing both selective and non-selective melanocortin search audiences; $168.72 combined margin per dual-order transaction.
- MC1R melanogenesis research angle differentiates white-label brand content from PT-141 guides, reducing SEO keyword overlap while sharing the same buyer segment.
Ready to add Melanotan II to your research peptide catalog? Book a consultation with the YPB team to discuss melanocortin category positioning and the full 60+ SKU platform.
[ypb_studies peptide=”melanotan-ii”]