Melanotan 1

Melanotan 1 (MT-1 / Afamelanotide) Peptide: Comprehensive Research Guide

Melanotan 1 (MT-1), also known as afamelanotide, is a synthetic linear tridecapeptide analog of the naturally occurring alpha-melanocyte-stimulating hormone (α-MSH), specifically designed for enhanced stability and selective melanocortin 1 receptor (MC1R) activation. With the amino acid sequence Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂, Melanotan 1 was originally developed in the 1980s by researchers at the University of Arizona as a potential sunless tanning and photoprotective agent. Since its discovery, Melanotan 1 has become a valuable research tool in dermatology, photobiology, and melanocortin receptor biology, and has been approved in some countries for the treatment of rare photosensitivity disorders.

Melanotan 1’s remarkable biological activity stems from its potent and relatively selective activation of the melanocortin 1 receptor (MC1R), which is primarily expressed in melanocytes (skin and hair pigment cells), keratinocytes, and immune cells. Its incorporation of norleucine (Nle) at position 4 and D-phenylalanine (D-Phe) at position 7 confers enhanced receptor binding affinity, metabolic stability, and resistance to proteolytic degradation compared to native α-MSH. Unlike Melanotan 2 (MT-2), which is a cyclic heptapeptide with broad melanocortin receptor activity, Melanotan 1 is a linear peptide with greater MC1R selectivity, resulting in potent skin pigmentation effects with fewer systemic side effects. Researchers worldwide utilize high-purity Melanotan 1 to investigate melanocortin receptor biology, skin pigmentation mechanisms, photoprotection, skin cancer prevention, and potential therapeutic applications for various dermatological conditions.

Molecular Structure and Pharmacological Properties

Melanotan 1 is a synthetic linear tridecapeptide with a molecular structure specifically engineered for enhanced MC1R selectivity and metabolic stability. Key molecular properties:

• AMINO ACID SEQUENCE: Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂
• MOLECULAR FORMULA: C₇₈H₁₁₁N₂₁O₁₉
• MOLECULAR WEIGHT: 1646.9 Da (free base); ~1707 Da (acetate salt, typical)
• STRUCTURE: Linear tridecapeptide with N-terminal acetylation, C-terminal amidation, and two non-natural amino acid substitutions: norleucine (Nle) at position 4 (replacing methionine for stability) and D-phenylalanine (D-Phe) at position 7 (enhancing receptor binding and selectivity)
• SOLUBILITY: Soluble in water, PBS, bacteriostatic water, and dilute acetic acid; solubility may be enhanced by gentle warming or sonication
• pI: Approximately 10.5 (basic peptide due to Arg and Lys residues)
• HALF-LIFE: Approximately 2-4 hours in plasma (significantly longer than α-MSH’s ~10 minutes due to Nle and D-Phe substitutions); even longer when administered as a subcutaneous implant
• RECEPTOR ACTIVITY: Potent and relatively selective MC1R agonist with EC50 in the nanomolar range; lower activity at MC3R, MC4R, and MC5R compared to Melanotan 2; minimal activity at MC2R (ACTH receptor)
• BIOAVAILABILITY: Good subcutaneous bioavailability when administered by injection or implant; poor oral bioavailability due to peptide degradation in the gastrointestinal tract

Mechanism of Action and Receptor Signaling

Melanotan 1 exerts its biological effects primarily through selective activation of the melanocortin 1 receptor (MC1R), a G-protein coupled receptor (GPCR) belonging to the class A rhodopsin-like family. MC1R is predominantly expressed in melanocytes (skin and hair follicle pigment cells), with lower expression in keratinocytes, immune cells (including macrophages, monocytes, and neutrophils), endothelial cells, and certain brain regions. Upon Melanotan 1 binding, MC1R activates multiple intracellular signaling cascades:

• Gs-ADENYLATE CYCLASE PATHWAY: The primary signaling pathway for MC1R involves Gs protein activation, leading to adenylate cyclase stimulation, increased cyclic AMP (cAMP) production, and protein kinase A (PKA) activation. In melanocytes, PKA phosphorylates the cAMP response element-binding protein (CREB), which upregulates the expression of microphthalmia-associated transcription factor (MITF), the master regulator of melanocyte development and function. MITF then stimulates the expression of key melanogenic enzymes, including tyrosinase, tyrosinase-related protein 1 (TRP-1), and tyrosinase-related protein 2 (TRP-2/DCT), leading to increased melanin synthesis and melanosome production. This pathway is responsible for Melanotan 1’s skin pigmentation and tanning effects.
• Gq/11-PLC PATHWAY: MC1R can also couple to Gq/11 proteins under certain conditions, leading to phospholipase C (PLC) activation, inositol trisphosphate (IP₃) production, and intracellular calcium mobilization. This pathway may contribute to some of the rapid, non-genomic effects of Melanotan 1, including melanosome translocation within melanocytes and transfer to keratinocytes, as well as modulation of immune cell function.
• MAPK/ERK PATHWAY: MC1R activation can stimulate the mitogen-activated protein kinase (MAPK) pathway, including ERK1/2 phosphorylation, through β-arrestin-dependent and independent mechanisms. This pathway is involved in melanocyte proliferation, survival, differentiation, and gene expression, and may contribute to Melanotan 1’s effects on melanocyte maintenance and skin photoprotection. ERK signaling can also phosphorylate and activate MITF, further enhancing melanogenic gene expression.
• β-ARRESTIN PATHWAY: Like many GPCRs, MC1R undergoes agonist-induced phosphorylation and β-arrestin recruitment, leading to receptor desensitization, internalization, and recycling. β-arrestin also acts as a signaling scaffold, activating MAPK and other pathways independently of G proteins. Melanotan 1’s specific receptor phosphorylation and β-arrestin recruitment patterns may contribute to its unique pharmacological profile compared to other MC1R agonists, including its prolonged duration of action and reduced desensitization compared to native α-MSH.
• ANTIOXIDANT AND DNA REPAIR PATHWAYS: In addition to stimulating melanin production, MC1R activation in melanocytes and keratinocytes upregulates antioxidant defense mechanisms and DNA repair pathways. Melanotan 1 can increase the expression and activity of antioxidant enzymes (such as superoxide dismutase, catalase, and glutathione peroxidase), reduce reactive oxygen species (ROS) production, and enhance nucleotide excision repair (NER) of UV-induced DNA damage (including cyclobutane pyrimidine dimers and 6-4 photoproducts). These effects contribute to Melanotan 1’s photoprotective effects beyond simply increasing melanin content.

The biological effects of Melanotan 1 can be primarily attributed to MC1R activation in two main cell types:

• MELANOCYTES: MC1R activation in melanocytes stimulates melanin synthesis (melanogenesis), melanocyte proliferation and survival, melanosome maturation and transfer to keratinocytes, and antioxidant/DNA repair responses. This results in increased skin pigmentation (tanning), enhanced photoprotection, and potentially reduced skin cancer risk. Melanotan 1’s effects on melanocytes are particularly important for individuals with fair skin, red hair, and MC1R genetic variants that reduce receptor function and increase skin cancer susceptibility.
• IMMUNE CELLS AND KERATINOCYTES: MC1R is also expressed in immune cells (macrophages, monocytes, neutrophils, lymphocytes) and keratinocytes, where its activation has anti-inflammatory and immunomodulatory effects. Melanotan 1 can reduce pro-inflammatory cytokine production (TNF-α, IL-1β, IL-6), inhibit inflammatory cell recruitment and activation, promote anti-inflammatory cytokine production (IL-10), and modulate immune cell polarization. These effects may contribute to Melanotan 1’s potential therapeutic benefits in inflammatory skin conditions (such as psoriasis, atopic dermatitis, and contact dermatitis) and other inflammatory disorders.

Research Applications

1. Dermatology and Skin Pigmentation Research

Melanotan 1 is most widely studied in dermatology for its potent skin pigmentation and tanning effects:

• Melanin Production and Skin Tanning: Research into Melanotan 1’s ability to stimulate melanin production in skin melanocytes, leading to skin darkening (tanning) without exposure to ultraviolet (UV) radiation. Melanotan 1 activates MC1R on melanocytes, stimulating the melanogenesis pathway, including tyrosinase activation, melanin synthesis (both eumelanin and pheomelanin), and melanosome transfer to keratinocytes. Studies have shown that Melanotan 1 can produce significant, dose-dependent skin darkening in both fair-skinned and dark-skinned individuals, with the degree and durability of pigmentation depending on dose, duration, administration route, and individual MC1R genotype. Unlike UV-induced tanning, Melanotan 1-induced tanning does not require UV exposure and can be achieved in individuals who tan poorly or not at all with sun exposure.
• Photoprotection and Skin Cancer Prevention: Studies investigating Melanotan 1’s potential to protect the skin from UV-induced damage, including sunburn (erythema), photoaging, DNA damage, immunosuppression, and skin cancer development. Melanin, particularly eumelanin (brown-black pigment), acts as a natural sunscreen by absorbing and scattering UV radiation, scavenging reactive oxygen species, and reducing UV-induced DNA damage. Research has shown that Melanotan 1-induced tanning can significantly increase the minimal erythema dose (MED), reduce UV-induced skin damage and inflammation, and potentially reduce the risk of skin cancer development, particularly in high-risk populations (such as fair-skinned individuals, redheads, organ transplant recipients, and those with a history of skin cancer or precancerous lesions). In addition to melanin-mediated photoprotection, Melanotan 1’s direct antioxidant and DNA repair-enhancing effects may provide additional photoprotection beyond simply increasing skin pigmentation.
• Erythropoietic Protoporphyria (EPP) Treatment: Clinical research into Melanotan 1 (afamelanotide) for the treatment of erythropoietic protoporphyria (EPP), a rare genetic disorder characterized by severe photosensitivity due to accumulation of protoporphyrin IX in the skin, leading to painful burning, itching, swelling, and scarring upon sun exposure. Melanotan 1-induced skin pigmentation can reduce the penetration of visible and UV light into the skin, reducing phototoxic reactions and improving tolerance to sun exposure. Afamelanotide has been approved in the European Union and the United States for the treatment of EPP in adults, administered as a subcutaneous implant that provides sustained release over approximately 60 days. Research is ongoing to investigate its use in other photodermatoses and in pediatric populations.
• Melanocortin 1 Receptor (MC1R) Biology: Research into MC1R structure, function, signaling, regulation, pharmacology, and genetic variation using Melanotan 1 as a standard, potent, and relatively selective agonist ligand. MC1R genetic polymorphisms are strongly associated with skin pigmentation phenotypes (including red hair, fair skin, freckling, poor tanning ability, and increased skin cancer risk), with certain variants resulting in reduced or absent receptor function. Melanotan 1 is used to study how different MC1R variants respond to agonist stimulation, whether pharmacological MC1R activation can overcome the reduced function associated with certain polymorphisms, and how MC1R signaling influences melanocyte biology, skin photoprotection, and skin cancer risk. Research is also investigating biased agonism at MC1R, where different agonists may preferentially activate different signaling pathways (G protein vs β-arrestin), potentially allowing for the development of melanocortin agonists with improved efficacy and reduced side effects.
• Vitiligo and Pigmentation Disorders: Studies investigating Melanotan 1’s potential for the treatment of vitiligo and other pigmentation disorders. Vitiligo is an autoimmune condition characterized by the destruction of melanocytes, leading to depigmented skin patches. Melanotan 1 may stimulate melanocyte proliferation, migration, and melanin production in remaining melanocytes or melanocyte stem cells, potentially promoting repigmentation of vitiligo lesions, particularly when combined with UV therapy (narrowband UVB or excimer laser), topical immunomodulators (such as calcineurin inhibitors or corticosteroids), or other treatments. Research is ongoing to investigate the optimal combination therapies and patient populations most likely to benefit from Melanotan 1 treatment for vitiligo and other hypopigmentation disorders.
• Melanoma Research: Research into the complex role of MC1R signaling in melanoma development, progression, and treatment. While MC1R activation is generally associated with photoprotection and reduced DNA damage (and thus reduced melanoma risk), the role of melanocortin signaling in established melanoma is complex and context-dependent. Some studies suggest that MC1R signaling may promote melanoma cell proliferation, survival, and metastasis in certain contexts, while others suggest protective effects. Melanotan 1 is used as a research tool to study MC1R expression and signaling in melanoma cells, melanoma stem cells, and the tumor microenvironment, and to investigate whether melanocortin agonists or antagonists may have therapeutic potential in melanoma treatment or prevention. Research is also investigating the relationship between MC1R genotype, Melanotan 1 response, and melanoma risk.
• Skin Aging and Photoaging: Emerging research into Melanotan 1’s potential effects on skin aging and photoaging, including its ability to reduce UV-induced collagen degradation, matrix metalloproteinase (MMP) activation, oxidative stress, inflammation, and cellular senescence. While Melanotan 1’s tanning effects are well-characterized, its broader effects on skin health, aging, barrier function, and extracellular matrix remodeling are areas of active investigation. Some studies suggest that MC1R activation may have anti-aging effects on the skin beyond photoprotection, including promoting collagen synthesis, improving skin elasticity, reducing wrinkle formation, and enhancing skin barrier function. Research is ongoing to investigate the potential of Melanotan 1 and related MC1R agonists for skin rejuvenation and anti-aging applications.

2. Photobiology and Photomedicine Research

Melanotan 1 is extensively studied in photobiology for its effects on skin photoprotection and light-tissue interactions:

• UV Photoprotection Mechanisms: Research into the detailed mechanisms by which Melanotan 1-induced skin pigmentation and MC1R activation protect the skin from UV-induced damage. This includes studies of melanin photophysics (including the ability of eumelanin to act as a UV filter, free radical scavenger, and antioxidant), the role of melanin in reducing UV-induced DNA damage (including cyclobutane pyrimidine dimers, 6-4 photoproducts, and oxidative DNA lesions), the effects of skin pigmentation on UV penetration into the skin, and the direct effects of MC1R signaling on DNA repair pathways, antioxidant defenses, and cellular stress responses. Understanding these mechanisms is critical for optimizing the use of Melanotan 1 and related compounds for photoprotection and skin cancer prevention.
• Photodynamic Therapy and Photosensitivity Disorders: Studies investigating Melanotan 1’s potential to reduce photosensitivity reactions in various photodermatoses and in patients undergoing photodynamic therapy (PDT) or other light-based treatments. In addition to EPP (discussed above), Melanotan 1 may be beneficial for other photosensitivity disorders, including solar urticaria, chronic actinic dermatitis, polymorphous light eruption, and drug-induced photosensitivity. By increasing skin pigmentation and reducing light penetration into the skin, Melanotan 1 may reduce phototoxic and photoallergic reactions, improve tolerance to sun exposure and light-based therapies, and enhance the quality of life for patients with photosensitivity disorders. Research is ongoing to investigate the efficacy and safety of Melanotan 1 in various photodermatoses and to identify the patient populations most likely to benefit.
• Visible Light and Blue Light Protection: Emerging research into Melanotan 1’s potential to protect the skin from visible light (including blue light from electronic devices and indoor lighting) and infrared radiation, in addition to UV radiation. While UV radiation is the primary cause of skin photoaging and skin cancer, visible light and infrared radiation can also contribute to skin damage, particularly in individuals with darker skin tones, through the generation of reactive oxygen species, induction of pigmentation, and degradation of extracellular matrix components. Melanotan 1-induced skin pigmentation may reduce the penetration of visible and infrared light into the skin, potentially providing protection against these wavelengths as well. Research is ongoing to investigate the full spectrum of photoprotection provided by Melanotan 1-induced pigmentation and its implications for skin health in our modern light environment.
• Photocarcinogenesis and Skin Cancer Prevention: Research into Melanotan 1’s potential for the prevention of skin cancer, including melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Skin cancer is the most common cancer worldwide, and UV radiation is the primary environmental risk factor. Melanotan 1-induced skin pigmentation can reduce UV penetration into the skin and UV-induced DNA damage, potentially reducing the risk of skin cancer development, particularly in high-risk populations. In addition to melanin-mediated photoprotection, Melanotan 1’s direct effects on DNA repair, antioxidant defenses, and immune function may contribute to skin cancer prevention. Research is ongoing in animal models and human clinical trials to investigate the efficacy of Melanotan 1 and related compounds for skin cancer prevention, particularly in high-risk populations such as organ transplant recipients (who have a dramatically increased risk of SCC), individuals with xeroderma pigmentosum (a rare genetic disorder of DNA repair resulting in extreme skin cancer susceptibility), and fair-skinned individuals with a history of multiple skin cancers or precancerous lesions.

3. Immunology and Inflammation Research

Melanotan 1 is studied in immunology for its anti-inflammatory and immunomodulatory effects, primarily through MC1R activation on immune cells:

• Anti-Inflammatory Effects: Research into Melanotan 1’s anti-inflammatory effects, including its ability to reduce pro-inflammatory cytokine production, inhibit inflammatory cell activation and recruitment, and modulate inflammatory signaling pathways. MC1R is expressed in various immune cells, including macrophages, monocytes, neutrophils, dendritic cells, and lymphocytes, and MC1R activation has been shown to have potent anti-inflammatory effects in various models of inflammation. Melanotan 1 can reduce the production of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8, MCP-1), inhibit the activation and nuclear translocation of NF-κB (a key pro-inflammatory transcription factor), reduce inflammatory cell recruitment to sites of inflammation, promote the production of anti-inflammatory cytokines (IL-10, TGF-β), and modulate immune cell polarization (promoting anti-inflammatory M2 macrophage phenotype over pro-inflammatory M1 phenotype). These anti-inflammatory effects make Melanotan 1 a valuable research tool for investigating the role of MC1R signaling in inflammation and for exploring potential therapeutic approaches for various inflammatory disorders.
• Inflammatory Skin Diseases: Studies investigating Melanotan 1’s effects in inflammatory skin conditions, including psoriasis, atopic dermatitis (eczema), contact dermatitis, rosacea, acne, and hidradenitis suppurativa. In these conditions, inflammation plays a central role in disease pathogenesis, and MC1R activation in skin immune cells and keratinocytes may help reduce inflammation and promote skin healing. Research in animal models and preliminary human studies has shown that melanocortin agonists, including Melanotan 1, can reduce skin inflammation, improve skin barrier function, and alleviate disease symptoms in various inflammatory skin conditions. The combination of anti-inflammatory effects with skin pigmentation and wound healing effects may make Melanotan 1 particularly useful for inflammatory skin conditions associated with pigmentation abnormalities or impaired wound healing. Research is ongoing to investigate the efficacy and safety of Melanotan 1 and related MC1R agonists in various inflammatory skin diseases and to identify optimal treatment regimens and patient populations.
• Wound Healing and Tissue Repair: Research into Melanotan 1’s effects on wound healing, tissue repair, and regeneration, particularly in the skin and other tissues. In addition to its effects on melanin production and inflammation, Melanotan 1’s anti-inflammatory, immunomodulatory, and growth factor-modulating effects may contribute to wound healing and tissue repair. Studies have shown that melanocortin agonists can accelerate wound healing, reduce scar formation, promote re-epithelialization, enhance angiogenesis, improve collagen deposition and organization, and accelerate tissue remodeling in various wound models, including surgical wounds, diabetic wounds, pressure ulcers, venous ulcers, and burn wounds. The effects on wound healing may involve MC1R activation in keratinocytes, fibroblasts, endothelial cells, and immune cells, and may be mediated through reduced inflammation, enhanced cell migration and proliferation, increased growth factor production (including VEGF, FGF, and TGF-β), and improved extracellular matrix remodeling. The potential of Melanotan 1 and related melanocortin agonists for wound healing and tissue repair is an area of active investigation, particularly for chronic, non-healing wounds that are difficult to treat with conventional therapies.
• Systemic Inflammatory Disorders: Emerging research into Melanotan 1’s potential for systemic inflammatory disorders, including inflammatory bowel disease (IBD), rheumatoid arthritis, multiple sclerosis, sepsis, acute respiratory distress syndrome (ARDS), and ischemia-reperfusion injury. While Melanotan 1 is relatively selective for MC1R, which is primarily expressed in the skin and immune cells, MC1R is also expressed in other tissues, and systemic administration of Melanotan 1 may have anti-inflammatory effects beyond the skin. Research in animal models has shown that melanocortin agonists can reduce inflammation and tissue damage in various models of systemic inflammation, including colitis, arthritis, experimental autoimmune encephalomyelitis (EAE, a model of multiple sclerosis), sepsis, and ischemia-reperfusion injury. The anti-inflammatory effects may be mediated through MC1R activation on immune cells and through modulation of systemic inflammatory responses. While Melanotan 1’s primary clinical development has focused on dermatological indications, its potential for systemic inflammatory disorders is an area of ongoing preclinical research.

4. Endocrinology and Metabolic Research

While Melanotan 1 is more MC1R-selective than Melanotan 2, it still has some activity at other melanocortin receptors and is studied in metabolic research:

• Energy Metabolism and Body Weight: Research into Melanotan 1’s effects on energy metabolism, appetite, body weight, and body composition. While Melanotan 1 is relatively selective for MC1R, it has some activity at MC3R and MC4R, which are critical regulators of energy homeostasis, appetite, and body weight. At higher doses, Melanotan 1 may reduce appetite and food intake, increase energy expenditure, and promote weight loss, although these effects are typically less pronounced than with Melanotan 2 or selective MC4R agonists due to its greater MC1R selectivity. Research is investigating the receptor subtypes and neural circuits underlying Melanotan 1’s metabolic effects, and whether these effects can be dissociated from its skin pigmentation effects through the development of more selective or tissue-targeted melanocortin agonists. The metabolic effects of Melanotan 1 may also be relevant for understanding the relationship between skin pigmentation, MC1R genotype, and metabolic health, as some studies have suggested associations between MC1R variants and body weight, insulin sensitivity, and metabolic syndrome risk.
• Glucose Homeostasis and Insulin Sensitivity: Studies investigating Melanotan 1’s effects on glucose metabolism, insulin sensitivity, glucose tolerance, pancreatic beta-cell function, and hepatic glucose production. Melanocortin signaling plays an important role in glucose homeostasis, and MC1R, MC3R, and MC4R are all expressed in tissues involved in glucose regulation, including the hypothalamus, pancreas, liver, adipose tissue, and skeletal muscle. Research has shown that melanocortin agonists can influence glucose metabolism and insulin sensitivity, although the effects are complex and may depend on the specific receptor subtypes activated, dose, route of administration, and metabolic context. While Melanotan 1’s primary effects are on skin pigmentation, its potential effects on glucose metabolism and insulin sensitivity are areas of investigation, particularly in the context of understanding the metabolic effects of melanocortin receptor activation and the development of melanocortin-based therapies for metabolic disorders.
• Adipose Tissue Biology and Lipid Metabolism: Research into Melanotan 1’s effects on adipose tissue biology, lipid metabolism, and body fat distribution. MC1R and other melanocortin receptors are expressed in adipose tissue, and melanocortin signaling can influence adipocyte differentiation, lipolysis, fatty acid oxidation, and adipokine secretion. Studies have shown that melanocortin agonists can influence adipose tissue function and lipid metabolism, potentially through both central (hypothalamic) and peripheral (direct effects on adipose tissue) mechanisms. While Melanotan 1’s effects on adipose tissue and lipid metabolism are less pronounced than those of more potent MC4R agonists due to its MC1R selectivity, research is investigating these effects to better understand the role of MC1R signaling in adipose tissue biology and to explore the potential of MC1R-targeted therapies for obesity and metabolic disorders. Some studies have also suggested associations between MC1R genotype, body fat distribution, and lipid profiles, which may be related to the effects of melanocortin signaling on adipose tissue function.

5. Neuroscience and Behavior Research

Melanotan 1 is studied in neuroscience for its potential effects on brain function, behavior, and neuroprotection, primarily through MC1R and other melanocortin receptors in the brain:

• Neuroprotection and Neurodegeneration: Emerging research into Melanotan 1’s potential neuroprotective effects in models of neurodegenerative diseases, stroke, traumatic brain injury, and neuroinflammation. MC1R is expressed in certain brain regions, including the substantia nigra, striatum, hippocampus, and cortex, and melanocortin signaling has been shown to have anti-inflammatory, antioxidant, anti-apoptotic, and neurotrophic effects in the central nervous system. Studies have shown that melanocortin agonists, including Melanotan 1, can reduce neuronal damage, improve functional outcomes, and enhance recovery in animal models of stroke, spinal cord injury, traumatic brain injury, and neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. The neuroprotective effects may involve MC1R activation in neurons and glial cells, and may be mediated through reduced neuroinflammation, oxidative stress, and apoptosis, as well as enhanced neurogenesis, synaptic plasticity, and trophic factor production. While Melanotan 1’s primary clinical development has focused on dermatological indications, its potential for neurological disorders is an area of ongoing preclinical research, and the development of brain-penetrant MC1R agonists may open new avenues for neuroprotective therapies.
• Pain Perception and Analgesia: Research into Melanotan 1’s effects on pain perception, nociception, and analgesia. Melanocortin receptors are expressed in pain-processing pathways in the brain, brainstem, and spinal cord, and melanocortin signaling can modulate pain sensitivity. Studies have shown that melanocortin agonists can have both pro-nociceptive (pain-enhancing) and anti-nociceptive (pain-reducing) effects depending on the specific receptor subtypes activated, dose, route of administration, and pain modality. Melanotan 1, with its relative MC1R selectivity, may have different effects on pain perception compared to non-selective melanocortin agonists like Melanotan 2. Research is investigating the role of MC1R signaling in pain processing and the potential of MC1R-selective agonists or antagonists for the treatment of pain conditions, particularly inflammatory pain and neuropathic pain where MC1R-expressing immune cells may play a role.
• Mood, Anxiety, and Behavior: Studies investigating Melanotan 1’s effects on mood, anxiety, depression, emotional processing, stress responses, and behavior. Melanocortin receptors, including MC1R, MC3R, and MC4R, are expressed in brain regions involved in mood and emotion regulation, including the amygdala, hippocampus, hypothalamus, prefrontal cortex, and nucleus accumbens. While Melanotan 1 is more MC1R-selective than Melanotan 2, it may still have some effects on mood and behavior through MC1R and other melanocortin receptors in the brain. Research has shown that melanocortin signaling can influence mood, anxiety, stress responses, social behavior, and reward processing, although the effects are complex and may depend on the specific receptor subtypes, brain regions, and behavioral context. The potential of Melanotan 1 and related melanocortin agonists for mood and anxiety disorders is an area of emerging research, particularly in the context of understanding the neuropsychiatric effects of melanocortin receptor activation and the development of melanocortin-based therapies for psychiatric disorders.

Product Specifications

Parameter	Value
Compound Name	Melanotan 1 (MT-1) / Afamelanotide Acetate
Amino Acid Sequence	Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂
CAS Number	75921-69-6
Molecular Formula	C₇₈H₁₁₁N₂₁O₁₉ · xC₂H₄O₂
Molecular Weight	1646.9 Da (free base); ~1707 Da (acetate salt, typical)
Purity	≥98% (HPLC verified)
Appearance	White to off-white lyophilized powder
Solubility	Soluble in water, PBS, bacteriostatic water, dilute acetic acid
Structure	Linear tridecapeptide; N-acetylated; C-amidated; contains Nle and D-Phe
Acetate Content	≤15% (w/w)
Water Content	≤5% (Karl Fischer)
Endotoxin	<1 EU/mg (LAL method)
Storage	-20°C, sealed, protected from light and moisture
Shelf Life	24 months from date of manufacture

Reconstitution and Handling Guidelines

For optimal results in laboratory research:

1. Allow the vial to equilibrate to room temperature before opening to prevent condensation
2. Reconstitute with bacteriostatic water, sterile water, 0.9% NaCl, or PBS to a desired concentration (typically 1-10 mg/mL; Melanotan 1 may require gentle warming or sonication for complete dissolution)
3. Gently swirl or invert the vial until complete dissolution; avoid vigorous shaking, which can cause foaming and peptide degradation
4. For cell culture experiments, filter-sterilize the reconstituted solution using a 0.22 μm filter
5. Aliquot into working volumes to avoid repeated freeze-thaw cycles
6. Store lyophilized powder at -20°C; store reconstituted solutions at -20°C or -80°C for long-term use
7. Reconstituted solutions are stable for 7-14 days at 2-8°C (in bacteriostatic water) and up to 3 months at -20°C
8. Avoid exposure to strong proteases, extreme pH, and high temperatures
9. Note: Melanotan 1 is light-sensitive and should be protected from light during storage and handling

Frequently Asked Questions (FAQ)

Q1: What is the difference between Melanotan 1 and Melanotan 2?

Melanotan 1 (MT-1, afamelanotide) and Melanotan 2 (MT-2) are both synthetic analogs of α-melanocyte-stimulating hormone (α-MSH), but they differ significantly in molecular structure, receptor selectivity, pharmacokinetics, and biological effects:
– Structure: Melanotan 1 is a linear 13-amino acid peptide (identical to α-MSH but with methionine at position 4 replaced by norleucine for stability), while Melanotan 2 is a cyclic 7-amino acid peptide with a lactam bridge, N-terminal acetylation, C-terminal amidation, and incorporation of D-phenylalanine and norleucine.
– Receptor selectivity: Melanotan 1 is relatively selective for MC1R (the melanocortin receptor responsible for skin pigmentation), with lower activity at MC3R, MC4R, and MC5R. Melanotan 2 is a non-selective agonist that activates all five melanocortin receptors (MC1R-MC5R) with high potency, particularly MC1R and MC4R.
– Biological effects: Due to its MC1R selectivity, Melanotan 1 primarily produces skin pigmentation and tanning effects, with fewer systemic side effects. Melanotan 2 produces strong tanning effects but also causes significant systemic effects due to its broad receptor activity, including appetite suppression, increased energy expenditure, sexual arousal, flushing, nausea, and increased blood pressure.
– Pharmacokinetics: Melanotan 1 has a longer half-life (~2-4 hours) and is typically administered as a subcutaneous implant for sustained release (providing ~60 days of continuous release). Melanotan 2 has a shorter half-life (~1-2 hours) and is typically administered by subcutaneous injection 1-2 times daily.
– Clinical development: Melanotan 1 (afamelanotide) has been approved in the EU and US for the treatment of erythropoietic protoporphyria (EPP) and is in clinical development for other photodermatoses. Melanotan 2 has not been approved for any clinical indication due to its side effect profile and non-selective receptor activation, although it has been widely used in research and has contributed to the development of more selective melanocortin agonists.
In summary, Melanotan 1 is a more selective, longer-acting MC1R agonist primarily used for skin pigmentation and photoprotection with fewer systemic side effects, while Melanotan 2 is a more potent but less selective agonist with broader biological effects including tanning, appetite suppression, and sexual function effects.

Q2: What purity level is recommended for research?

For most research applications, ≥98% purity (HPLC verified) is recommended. Our Melanotan 1 meets this standard and undergoes comprehensive quality control, including mass spectrometry verification (confirming molecular weight of ~1647 Da free base), amino acid analysis, chiral purity verification (confirming D-Phe configuration), peptide mapping, endotoxin testing (<1 EU/mg), and microbial screening. For highly sensitive in vivo studies, cell culture experiments, or clinical research, we can provide ≥99% purity with additional quality testing (including residual solvent testing, heavy metal analysis, bioburden testing, and biological activity verification in MC1R receptor binding and cAMP activation assays) upon request. Note that Melanotan 1's linear structure and non-natural amino acids (Nle and D-Phe) require careful manufacturing and purification to achieve high purity, and our GMP manufacturing process ensures consistent quality across batches with full traceability and comprehensive quality documentation. Researchers should note that Melanotan 1 is a potent biologically active compound, and even small impurities could potentially affect experimental results, particularly in sensitive receptor binding, signaling, or in vivo studies, making high-purity material essential for reliable research.

Q3: Can Melanotan 1 be used in cell culture experiments?

Yes, Melanotan 1 is suitable for cell culture experiments with a wide range of cell types expressing melanocortin receptors, particularly MC1R, including melanocytes (normal human epidermal melanocytes, B16 melanoma cells, Melan-A cells), keratinocytes (HaCaT, normal human epidermal keratinocytes), immune cells (macrophages, monocytes, neutrophils, T cells, dendritic cells), endothelial cells (HUVEC, HAEC), fibroblasts (NHDF, 3T3), and various recombinant cell lines expressing specific melanocortin receptor subtypes (e.g., HEK293 cells transfected with MC1R, MC3R, MC4R, or MC5R). Melanotan 1 is soluble in standard culture media, although it may require gentle warming or sonication for complete dissolution at high concentrations. Typical working concentrations range from 1 nM to 10 μM, depending on the cell type, receptor expression level, and assay. The EC50 for MC1R activation is typically in the nanomolar range (1-100 nM). Melanotan 1 is generally well-tolerated by cells at concentrations up to 10 μM, although higher concentrations may cause cytotoxicity in some cell types. For extended experiments (>48-72 hours), refresh media with fresh Melanotan 1 every 24-48 hours, as the peptide may degrade over time in culture media at 37°C. Filter-sterilize reconstituted solutions before adding to cell cultures. Melanotan 1’s relative MC1R selectivity makes it a valuable tool for studying MC1R-specific signaling and biological effects, although researchers should note that at higher concentrations it may also activate other melanocortin receptor subtypes, and appropriate controls (including receptor-specific antagonists or receptor knockdown/knockout approaches) should be used to confirm MC1R-specific effects.

Q4: What is the typical dosage range for animal studies?

Dosage varies by species, administration route, and research objective. Melanotan 1 is generally well-tolerated with a wider therapeutic window than Melanotan 2, and side effects (including flushing, nausea, and appetite suppression) are typically milder and less frequent due to its greater MC1R selectivity. Common dosage ranges include:
– Rodents (acute): 0.1-50 mg/kg (IP/SC/IV), typically administered once or twice daily
– Rodents (chronic): 0.1-10 mg/kg/day (SC injection or osmotic minipump), typically for 1-12 weeks
– Rabbits/guinea pigs: 0.1-10 mg/kg (SC/IV)
– Primates: 0.01-1 mg/kg (SC/IV)
– Humans (clinical research/approved use): 0.01-0.1 mg/kg (SC injection), typically administered once daily or every other day for tanning; or 16 mg subcutaneous implant every 60 days for EPP treatment (afamelanotide)
Melanotan 1 is typically administered by subcutaneous injection or implant due to poor oral bioavailability. For skin pigmentation studies, a “loading phase” of higher doses (0.5-1 mg/kg/day in rodents, 0.5-1 mg/day in humans) for 1-2 weeks is often used to achieve initial pigmentation, followed by a “maintenance phase” of lower doses (0.25-0.5 mg/kg 1-3 times per week in rodents, 0.25-0.5 mg 1-3 times per week in humans) or sustained-release implants to maintain pigmentation. For photoprotection and skin cancer prevention studies, doses that achieve significant skin pigmentation without causing systemic side effects are typically preferred. For anti-inflammatory and wound healing studies, doses in the range of 0.1-5 mg/kg in rodents are commonly used. Researchers should consult relevant literature and perform dose-response studies to optimize protocols for their specific applications, and should carefully monitor animals for side effects, particularly at higher doses. Note that Melanotan 1’s effects can be variable between individuals and species, and the degree of skin pigmentation response is strongly influenced by MC1R genotype and baseline skin pigmentation.

Q5: How does Melanotan 1 compare to other melanocortin agonists?

Melanotan 1 is one of several melanocortin agonists used in research, each with distinct receptor selectivity, pharmacokinetics, and biological effects:
– vs. α-MSH (native hormone): α-MSH is the native 13-amino acid melanocortin peptide that activates MC1R-MC5R with varying affinity. It has a very short half-life (~10 minutes) due to rapid proteolytic degradation, making it impractical for most in vivo studies. Melanotan 1 is a more stable, potent, and longer-acting analog that retains α-MSH’s MC1R selectivity but with enhanced pharmacological properties (due to Nle and D-Phe substitutions).
– vs. Melanotan 2 (MT-2): As discussed in Q1, Melanotan 2 is a more potent but less selective cyclic heptapeptide with broad melanocortin receptor activity and significant systemic side effects. Melanotan 1 is more MC1R-selective, longer-acting, and has fewer systemic side effects, making it more suitable for studies focused on skin pigmentation, photoprotection, and MC1R-specific effects.
– vs. Bremelanotide (PT-141): Bremelanotide is a cyclic heptapeptide closely related to Melanotan 2 (it is the active metabolite of Melanotan 2, with the N-terminal acetylation removed). It has similar receptor selectivity to Melanotan 2 but with a slightly different pharmacological profile, and has been approved for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. Bremelanotide is more focused on sexual function and has less skin pigmentation potency compared to Melanotan 1.
– vs. Setmelanotide: Setmelanotide is a cyclic octapeptide MC4R agonist that is relatively selective for MC4R (with some activity at other receptors). It has been approved for the treatment of rare genetic forms of obesity caused by MC4R pathway deficiencies. Setmelanotide has stronger and more sustained appetite-suppressing and weight-loss effects than Melanotan 1, with minimal skin pigmentation effects due to its MC4R selectivity.
– vs. THIQ (MC4R selective agonist): THIQ is a small molecule (non-peptide) MC4R-selective agonist that has been investigated for the treatment of obesity and sexual dysfunction. It has better oral bioavailability and receptor selectivity than peptide agonists like Melanotan 1, but may have different pharmacological properties and side effect profiles.
– vs. SHU9119 (melanocortin antagonist): SHU9119 is a cyclic peptide that acts as a potent antagonist at MC3R and MC4R and a partial agonist/antagonist at MC1R. It is widely used in research to block melanocortin signaling and study the physiological roles of melanocortin receptors.
In summary, Melanotan 1 is a potent, relatively MC1R-selective, peptide melanocortin agonist with strong skin pigmentation and photoprotective effects and fewer systemic side effects than non-selective agonists like Melanotan 2, making it a valuable research tool for studying MC1R biology, skin pigmentation, photoprotection, and related dermatological conditions. For studies requiring other receptor-specific effects (such as MC4R-mediated appetite suppression or sexual function), more selective agonists like setmelanotide or bremelanotide may be more appropriate.

Q6: Is Melanotan 1 stable in solution?

Melanotan 1 is moderately stable in solution, with better stability than native α-MSH but less stability than some other peptide analogs due to its linear structure and tryptophan residue (which is susceptible to oxidation). In neutral aqueous solutions (pH 6-8) at refrigerated temperatures (2-8°C), reconstituted Melanotan 1 is stable for approximately 7-14 days, particularly when reconstituted in bacteriostatic water (containing 0.9% benzyl alcohol) to inhibit microbial growth. For long-term storage, reconstituted solutions should be aliquoted and stored at -20°C or -80°C, where they remain stable for up to 3 months. Avoid repeated freeze-thaw cycles, as these can cause peptide degradation and aggregation. Melanotan 1 is light-sensitive (particularly due to the tryptophan and tyrosine residues), and solutions should be protected from light during storage and handling. It is also susceptible to oxidation, and solutions should be protected from air and oxidizing agents. Avoid exposure to extreme pH (below pH 4 or above pH 9 for extended periods), high temperatures (>40°C), and strong proteases, as these conditions can cause degradation. For in vivo experiments, Melanotan 1 solutions should be prepared fresh or stored refrigerated for no more than 7-14 days, and should be protected from light during administration. For cell culture experiments, Melanotan 1 may degrade over time in culture media (particularly at 37°C), and media should be refreshed with fresh peptide every 24-48 hours for extended experiments. Note that Melanotan 1 can cause foaming when dissolved, and gentle swirling or inversion is recommended rather than vigorous shaking. If foaming occurs, allow the solution to stand until the foam dissipates before use. The high stability of lyophilized Melanotan 1 (24 months at -20°C) makes it convenient for long-term storage, and researchers are encouraged to store the peptide in lyophilized form and reconstitute only the amount needed for immediate use. For extended in vivo studies requiring sustained release, subcutaneous implants (such as the afamelanotide implant used clinically for EPP) may provide more stable and prolonged peptide delivery compared to repeated injections, and researchers may consider implant formulations for long-term studies.

Q7: Can Melanotan 1 be used in combination with other peptides or treatments?

Yes, Melanotan 1 is frequently used in combination with other agents in research settings, and some of the most common combinations include:
– Combination with UV therapy or phototherapy: Used in dermatology research for vitiligo, psoriasis, and other skin conditions, combining Melanotan 1’s melanocyte-stimulating and photoprotective effects with UV-induced melanogenesis and immunomodulation. This combination may enhance repigmentation in vitiligo and improve treatment outcomes for other skin conditions, but may also increase the risk of UV-induced skin damage if not carefully monitored.
– Combination with KPV: Used in dermatology and inflammation research, combining Melanotan 1’s skin pigmentation and MC1R-mediated anti-inflammatory effects with KPV’s potent anti-inflammatory and antimicrobial effects (KPV is a tripeptide derived from α-MSH with direct intracellular NF-κB inhibitory activity). This combination may be particularly useful for inflammatory skin conditions, wound healing, and photoprotection research, as the two peptides have complementary mechanisms of action.
– Combination with BPC-157 or TB-500: Used in wound healing and tissue repair research, combining Melanotan 1’s skin healing, anti-inflammatory, and photoprotective effects with the tissue repair and regenerative effects of BPC-157 or TB-500. This combination may be particularly effective for skin wound healing, burn recovery, and tissue regeneration studies.
– Combination with GHK-Cu: Used in dermatology and skin aging research, combining Melanotan 1’s skin pigmentation and photoprotective effects with GHK-Cu’s collagen-stimulating, skin rejuvenating, and wound healing effects. This combination may be beneficial for anti-aging skincare research, wound healing, and skin barrier repair.
– Combination with growth hormone secretagogues (GHRPs, GHRH analogs): Used in body composition and anti-aging research, combining Melanotan 1’s metabolic and body composition effects (at higher doses) with growth hormone-releasing effects. This combination may have additive or synergistic effects on body composition, skin health, and anti-aging, but may also increase side effects.
– Combination with antioxidants or sunscreens: Used in photoprotection research, combining Melanotan 1’s melanin-mediated photoprotection and DNA repair-enhancing effects with the antioxidant or UV-blocking effects of other agents. This combination may provide enhanced protection against UV-induced skin damage, photoaging, and skin cancer.
– Combination with topical immunomodulators (calcineurin inhibitors, corticosteroids): Used in vitiligo and inflammatory skin disease research, combining Melanotan 1’s melanocyte-stimulating effects with the immunomodulatory and anti-inflammatory effects of topical agents. This combination may enhance repigmentation in vitiligo and improve treatment outcomes for inflammatory skin conditions.
Researchers should carefully design combination studies, including appropriate controls for each agent alone and in combination, to assess synergistic, additive, or antagonistic effects. Note that Melanotan 1 is generally well-tolerated with a wider therapeutic window than Melanotan 2, but combination with other agents may increase the risk of adverse effects, particularly at higher doses. Researchers should carefully monitor animals or study participants for side effects when using Melanotan 1 in combination with other agents, and should consult relevant literature for information on potential drug interactions.

Related Research Peptides

Researchers studying Melanotan 1 often explore these complementary peptides:

• Melanotan 2 (MT-2) – More potent but less selective cyclic melanocortin agonist with broad receptor activity, strong tanning, appetite suppression, and sexual function effects
• PT-141 (Bremelanotide) – Melanotan 2 metabolite with similar receptor profile, approved for HSDD in women, used for sexual function research
• Setmelanotide – MC4R-selective agonist approved for rare genetic obesity, used for obesity and metabolic research
• KPV – Tripeptide (Lys-Pro-Val) with potent anti-inflammatory and antimicrobial effects, derived from α-MSH, commonly combined with Melanotan 1 for skin research
• BPC-157 – 15-amino acid peptide with potent cytoprotective, healing, and regenerative effects, used in combination with Melanotan 1 for wound healing
• TB-500 (Thymosin Beta-4) – 43-amino acid peptide involved in actin regulation, cell migration, angiogenesis, and tissue repair
• GHK-Cu – Tripeptide copper complex with wound healing, anti-aging, and tissue remodeling effects, used in dermatology research
• Sermorelin Acetate – GHRH analog that stimulates growth hormone secretion, used in combination with Melanotan 1 for body composition and anti-aging research
• Ipamorelin – Selective GHRP that stimulates growth hormone secretion with minimal side effects, used in combination with Melanotan 1 for anti-aging research

Quality Assurance

Our Melanotan 1 is manufactured under strict GMP conditions and undergoes comprehensive quality testing:

• HPLC purity analysis (≥98%)
• Mass spectrometry molecular weight verification (confirming ~1647 Da free base and correct amino acid composition)
• Amino acid composition analysis and sequencing
• Chiral purity verification (confirming D-Phe configuration at position 7)
• Peptide mapping and identity verification
• N-terminal acetylation and C-terminal amidation verification
• Acetate content determination (≤15%)
• Water content determination (Karl Fischer, ≤5%)
• Endotoxin testing (LAL method, <1 EU/mg)
• Microbial contamination screening (bioburden testing)
• Biological activity verification (MC1R receptor binding and cAMP activation assays)
• Residual solvent testing (TFA, acetonitrile, methanol, DMF)
• Heavy metal analysis (for high-purity grades)

Each batch is accompanied by a Certificate of Analysis (COA) detailing all test results, including purity, molecular weight, chiral purity, and biological activity. We maintain complete batch records for full traceability and regulatory compliance. Custom synthesis of Melanotan 1 analogs, labeled peptides (isotopic, fluorescent, biotinylated), modified formulations (including sustained-release implants), and combination products is available upon request. We also offer custom peptide synthesis services for researchers requiring modified Melanotan 1 sequences, selective melanocortin receptor agonists/antagonists, or related peptides.

Important Disclaimer

FOR RESEARCH USE ONLY. This product is intended exclusively for laboratory and scientific research purposes. It is not approved for human consumption, clinical diagnosis, therapeutic treatment, veterinary use, or cosmetic formulation, except where specifically approved by regulatory authorities for indicated medical uses (such as afamelanotide for erythropoietic protoporphyria). Melanotan 1 is a biologically active peptide with significant effects on skin pigmentation, photoprotection, immune function, and potentially other physiological systems; all experiments must be conducted by qualified researchers in accordance with institutional biosafety guidelines, animal care protocols, and applicable regulations. Purchasers assume full responsibility for proper handling, storage, and use of this research material. This product is not intended for self-administration or use outside of approved research settings. Researchers should note that Melanotan 1 may cause side effects including, but not limited to, skin darkening and tanning, nausea, vomiting, flushing, headache, dizziness, fatigue, decreased appetite (at higher doses), increased blood pressure (at higher doses), yawning, stretching, local injection site reactions, and in rare cases, allergic reactions or more serious adverse effects. Individuals with pre-existing medical conditions (particularly cardiovascular disease, hypertension, melanoma or skin cancer history, liver or kidney disease, or psychiatric disorders) should exercise extreme caution, and Melanotan 1 should not be used by pregnant or breastfeeding women, or by individuals under the age of 18. In vivo studies should be conducted with appropriate ethical review and careful monitoring of relevant physiological parameters, including skin pigmentation, blood pressure, heart rate, body weight, food intake, hormonal levels, and organ function. The use of Melanotan 1 for cosmetic tanning, bodybuilding, performance enhancement, or other non-research purposes is not endorsed and may be associated with significant health risks, particularly when products are obtained from unregulated sources and used without medical supervision. Researchers should be aware of the regulatory and ethical considerations surrounding the use of melanocortin agonists in both research and potential clinical settings, and should conduct studies in accordance with all applicable laws, regulations, and institutional guidelines.