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Melanotan 1 (MT1) and Melanotan 2 (MT2) are synthetic melanocortin peptides derived from alpha-melanocyte-stimulating hormone, but they are not interchangeable research tools. MT1 is a linear, afamelanotide-related peptide studied primarily for MC1R-selective peripheral melanocortin signaling, while MT2 is a cyclic lactam analogue studied for broader melanocortin receptor activity across peripheral and central pathways.
Research-use-only materials for qualified laboratory and research settings. Batch-specific documentation and third-party testing standards apply.
Melanotan 1 (MT1, afamelanotide-related, CAS 75921-69-6) is a linear synthetic melanocortin peptide studied primarily for selective MC1R interaction and peripheral pigmentation-related signaling models. Melanotan 2 (MT2, CAS 121062-08-6) is a cyclic lactam analogue studied for broader melanocortin receptor engagement across MC1R, MC3R, and MC4R. MT1 is the more targeted MC1R research compound, while MT2 is the broader melanocortin research compound.
Melanotan 1 (MT1) is a synthetic linear melanocortin peptide studied primarily for selective interaction with the melanocortin-1 receptor (MC1R). It is closely associated with afamelanotide-class compounds in the research literature and is commonly discussed in relation to pigmentation signaling, melanocyte biology, and peripheral MC1R pathway models.
Its linear structure limits blood-brain barrier permeability, keeping its primary research profile focused on peripheral receptor pathways rather than central melanocortin signaling. This makes MT1 a more targeted research tool when the objective is to isolate MC1R-related activity from broader MC3R and MC4R pathway involvement.
For a deeper standalone review of MT1 structure, receptor relevance, research context, and handling considerations, see the Melanotan I (MT1) Research Guide.
MT1 is the more selective melanocortin research tool. It is studied mainly for MC1R signaling and peripheral pigmentation-pathway models, without the same broad central receptor profile associated with MT2.
Melanotan 2 (MT2) is a synthetic cyclic lactam analogue of alpha-melanocyte-stimulating hormone. Its cyclic structure differentiates it fundamentally from MT1 and contributes to a broader receptor profile across MC1R, MC3R, and MC4R.
This broader receptor engagement makes MT2 more commonly referenced in multi-pathway melanocortin research, neuroendocrine signaling models, appetite and energy-balance pathway studies, and comparative receptor activity investigations.
MT2 is the broader melanocortin research tool. Its cyclic structure gives it a wider receptor profile than MT1, which means it can introduce more experimental variables and requires tighter study design controls.
The correct compound depends on the receptor question being studied. MT1 and MT2 should not be selected based on name similarity. They should be selected based on receptor selectivity, central pathway relevance, and experimental design.
MT1 is the better fit when a study needs a cleaner, more targeted melanocortin profile centered on MC1R and peripheral signaling.
MT2 is the better fit when a study requires broader melanocortin receptor activity across MC1R, MC3R, and MC4R.
MT1 and MT2 share a common origin in alpha-MSH-related melanocortin peptide chemistry, but their structural differences produce meaningfully different research-use profiles.
| Property | Melanotan 1 (MT1) | Melanotan 2 (MT2) |
|---|---|---|
| Full classification | Synthetic linear melanocortin peptide, afamelanotide-related | Synthetic cyclic lactam analogue of alpha-MSH |
| CAS number | 75921-69-6 | 121062-08-6 |
| Structural conformation | Linear peptide chain | Cyclic lactam ring structure |
| Origin compound | Analogue derived from alpha-melanocyte-stimulating hormone | Cyclic analogue derived from alpha-melanocyte-stimulating hormone with conformational modification |
| Blood-brain barrier permeability | Poor in standard research models, primarily peripheral activity | Greater central-access profile than MT1 due to cyclic structure |
| Research selectivity | More selective for MC1R-centered research questions | Broader melanocortin receptor research profile |
| Luxara Labs purity standard | ≥99% with third-party HPLC and MS documentation | ≥99% with third-party HPLC and MS documentation |
The practical difference between MT1 and MT2 comes down to receptor access and receptor selectivity. Both belong to the broader melanocortin research family, but they are used to answer different experimental questions.
The melanocortin system consists of five G-protein-coupled receptors, MC1R through MC5R. MC1R is strongly associated with melanocyte and pigmentation-pathway research. MC3R and MC4R are centrally expressed and are commonly studied in energy balance, appetite signaling, and neuroendocrine pathway models. MC2R is the ACTH receptor, while MC5R is associated with exocrine gland and peripheral tissue signaling.
| Receptor | Primary Location | Associated Research Context | MT1 Activity | MT2 Activity |
|---|---|---|---|---|
| MC1R | Melanocytes, skin, peripheral tissue | Pigmentation signaling, melanocyte biology, photoprotection-pathway research | Primary target | Active |
| MC2R | Adrenal cortex | ACTH receptor biology | Not a primary target | Not a primary target |
| MC3R | Brain, hypothalamus, peripheral tissue | Energy homeostasis, appetite signaling, metabolic pathway research | Minimal central activity | Active in central-context models |
| MC4R | Brain, hypothalamus, brainstem | Energy balance, neuroendocrine signaling, behavioral pathway research | Minimal central activity | Active in central-context models |
| MC5R | Exocrine glands, skin, peripheral tissue | Exocrine gland and peripheral signaling research | Limited | Limited |
Receptor selectivity is the most important practical distinction between MT1 and MT2. The compounds should not be treated as interchangeable simply because both belong to the melanocortin peptide category.
| Research Dimension | Melanotan 1 (MT1) | Melanotan 2 (MT2) |
|---|---|---|
| Receptor selectivity | Higher selectivity toward MC1R | Broader engagement across MC1R, MC3R, and MC4R |
| Primary receptor context | MC1R-centered peripheral research | Peripheral and central melanocortin receptor research |
| Research emphasis | Pigmentation signaling, melanocyte biology, MC1R-specific models | Multi-pathway melanocortin research, neuroendocrine signaling, appetite and energy-balance models |
| Research scope | Narrower, useful when MC1R isolation is the research objective | Broader, useful when multi-receptor melanocortin engagement is the research objective |
| Experimental controls | Fewer receptor variables to account for | More receptor variables and central-pathway controls to account for |
The most functionally important difference between MT1 and MT2 is how structure affects receptor access. MT1 is linear. MT2 is cyclic. That structural difference changes the way each compound is studied in peripheral and central melanocortin models.
| Feature | Melanotan 1 (MT1) | Melanotan 2 (MT2) |
|---|---|---|
| Structural conformation | Linear peptide chain | Cyclic lactam ring structure |
| Blood-brain barrier profile | Poor permeability in standard research models | Greater central-access profile than MT1 due to cyclic conformation |
| Central receptor access | Limited access to centrally expressed MC3R and MC4R pathways | Greater relevance to MC3R and MC4R central pathway research |
| Research scope implication | Peripheral-only or primarily peripheral research design | Peripheral and central melanocortin research design |
| Metabolic stability | Moderate, with linear peptide susceptibility to enzymatic cleavage | Greater conformational stability due to cyclic structure |
| Research complexity | Lower complexity because fewer receptor systems are involved | Higher complexity because central receptor engagement can affect multiple pathways |
The table below summarizes the most important practical differences between Melanotan 1 and Melanotan 2 for research planning, compound selection, and documentation review.
| Feature | Melanotan 1 (MT1) | Melanotan 2 (MT2) |
|---|---|---|
| CAS number | 75921-69-6 | 121062-08-6 |
| Structural type | Linear peptide | Cyclic lactam analogue |
| Derived from | Alpha-melanocyte-stimulating hormone | Alpha-melanocyte-stimulating hormone with cyclic modification |
| Primary receptor focus | MC1R | MC1R, MC3R, MC4R |
| Receptor selectivity | Higher MC1R selectivity | Lower selectivity, broader melanocortin receptor profile |
| Blood-brain barrier profile | Poor permeability, primarily peripheral research activity | Greater central-access profile, central and peripheral research activity |
| Central receptor relevance | Limited relevance to central MC3R and MC4R models | Relevant to central MC3R and MC4R pathway models |
| Primary research focus | Pigmentation signaling, melanocyte biology, MC1R pathway research | Multi-pathway melanocortin research, neuroendocrine signaling, appetite and energy-balance modeling |
| Research complexity | Lower, with fewer receptor variables | Higher, with broader receptor involvement |
| Literature scope | More narrow, MC1R and pigmentation-focused | Broader, melanocortin and neuroendocrine-focused |
| Canadian regulatory status | Not approved for therapeutic use, research use only | Not approved for therapeutic use, research use only |
| Luxara Labs purity standard | ≥99% with third-party HPLC and MS documentation | ≥99% with third-party HPLC and MS documentation |
| Lyophilized storage | -20°C, protected from light and moisture | -20°C, protected from light and moisture |
| Post-reconstitution storage | 2-8°C, protected from light | 2-8°C, protected from light |
After comparing receptor selectivity and structural differences, researchers should review current product-specific details, lot documentation, storage notes, and availability before selecting material for a study.
MT1 and MT2 are best separated by structure, receptor selectivity, and receptor access. MT1 is linear and more MC1R-focused, making it useful for peripheral melanocortin pathway research where selective MC1R interpretation matters. MT2 is cyclic and broader, making it relevant to studies where MC1R, MC3R, and MC4R signaling may all be part of the research model.
Both MT1 and MT2 require careful handling to preserve research-grade integrity. Purity, documentation, temperature control, and lot traceability are especially important for melanocortin peptides because small differences in material quality can affect downstream interpretation.
| Parameter | MT1 Standard | MT2 Standard |
|---|---|---|
| Lyophilized storage | -20°C, protected from light and moisture | -20°C, protected from light and moisture |
| Post-reconstitution storage | 2-8°C, protected from light, used within the validated research window | 2-8°C, protected from light, used within the validated research window |
| Freeze-thaw cycles | Minimize repeated freeze-thaw exposure to protect peptide integrity | Minimize repeated freeze-thaw exposure even with greater cyclic stability |
| Purity requirement | ≥99% with independent third-party HPLC and MS documentation | ≥99% with independent third-party HPLC and MS documentation |
| COA requirement | Batch-specific documentation with lot traceability | Batch-specific documentation with lot traceability |
| Domestic shipping advantage | Reduced transit time, fewer customs variables, better temperature-control reliability | Reduced transit time, fewer customs variables, better temperature-control reliability |
These answers address common research questions about Melanotan 1 and Melanotan 2 from Canadian and US researchers.
The primary difference is structure and receptor selectivity. MT1 is a linear peptide studied mainly for MC1R-selective peripheral melanocortin signaling. MT2 is a cyclic lactam analogue studied for broader melanocortin receptor activity across MC1R, MC3R, and MC4R.
Researchers should choose MT1 when the goal is MC1R-focused peripheral melanocortin pathway research. Researchers should choose MT2 when the goal is broader melanocortin receptor activity involving MC1R, MC3R, and MC4R.
Yes. MT1 is generally studied as the more MC1R-selective compound, while MT2 is studied as a broader melanocortin receptor agonist with activity across MC1R, MC3R, and MC4R. For research designs that require cleaner MC1R isolation, MT1 is typically the more focused tool.
MT2 has a cyclic lactam structure that gives it a different conformational profile than linear MT1. This structure is associated with broader melanocortin receptor access, including MC3R and MC4R pathway relevance in research models.
MT1 is primarily associated with MC1R-focused research, especially melanocyte and pigmentation-pathway models. MT2 is associated with broader melanocortin receptor engagement, including MC1R, MC3R, and MC4R.
MT1 is a linear peptide and is more susceptible to enzymatic cleavage than cyclic analogues. MT2's cyclic lactam structure gives it greater conformational stability in research models. Both compounds still require proper cold-chain handling and minimal freeze-thaw cycling.
Melanotan 1 is commonly discussed as afamelanotide-related because both belong to the alpha-MSH melanocortin peptide family and are associated with MC1R research. Exact compound identity, CAS number, sequence, lot documentation, and analytical testing should always be reviewed rather than relying only on naming conventions.
Neither MT1 nor MT2 is positioned by Luxara Labs as a therapeutic product for human or veterinary use. Both are handled strictly as research-use-only materials for qualified laboratory and research contexts.
Luxara Labs emphasizes third-party analytical documentation, HPLC purity verification, mass spectrometry identity confirmation, batch-specific Certificates of Analysis, lot traceability, cold-chain handling, and research-use-only labeling.
The following peer-reviewed publications and scientific resources support the melanocortin receptor, structural, and comparative research context discussed on this page.
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