MT-2

Research Overview

Melanotan II serves as a valuable research tool for investigating melanocortin receptor systems and their diverse physiological roles. This synthetic peptide analog was developed to overcome the limitations of natural α-MSH, including poor enzymatic stability and short half-life. Research applications span pigmentation biology, energy homeostasis, sexual function pathways, and feeding behavior regulation across multiple experimental models.

The peptide’s designation derives from its melanotropic (melanin-stimulating) properties observed in early research. MT-2 demonstrates significantly enhanced potency and stability compared to endogenous α-MSH, achieved through cyclization and strategic amino acid modifications including norleucine (Nle) substitution and D-phenylalanine incorporation. These structural modifications prevent enzymatic degradation while maintaining receptor binding affinity.

MT-2 research encompasses investigations into melanocortin receptor subtypes (MC1R through MC5R), their tissue distribution, signaling pathways, and physiological functions. The peptide’s non-selective receptor activation profile allows researchers to study multiple melanocortin pathways simultaneously or investigate receptor-specific effects through comparative studies with selective agonists.

Molecular Characteristics

Complete Specifications:

• CAS Registry Number: 121062-08-6
• Molecular Weight: 1,024.24 Da
• Molecular Formula: C₅₀H₆₉N₁₅O₉
• Amino Acid Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂
• PubChem CID: 92432
• Peptide Classification: Synthetic cyclic heptapeptide, melanocortin receptor agonist
• Appearance: White to off-white lyophilized powder
• Solubility: Water, bacteriostatic water, dimethyl sulfoxide (DMSO)

The peptide’s cyclic structure forms through lactam bridge formation between the aspartic acid side chain and lysine epsilon-amino group, creating a constrained seven-membered ring. This cyclization restricts conformational flexibility while protecting terminal ends from exopeptidase degradation. The D-phenylalanine at position 7 provides additional enzymatic resistance and influences receptor binding characteristics.

Pharmacokinetic Profile in Research Models

MT-2 pharmacokinetic characterization in preclinical research reveals important properties for experimental design:

Absorption and Bioavailability:

• Subcutaneous bioavailability: Enhanced compared to linear α-MSH analogs
• Demonstrates improved stability against peptidase degradation
• Multiple administration routes investigated: SC, IV, intranasal
• Gradual absorption profile following subcutaneous administration

Distribution and Elimination:

• Plasma half-life: Approximately 33 minutes in rodent models
• Extended biological activity beyond plasma presence
• Blood-brain barrier penetration demonstrated in research studies
• Tissue distribution includes skin, brain, and adipose tissue

Pharmacodynamic Characteristics:

• Duration of melanotropic effects: 8-48 hours post-administration in research models
• Dose-dependent receptor activation across MC receptor subtypes
• Receptor binding affinity: High nanomolar to low micromolar range
• Sustained biological effects despite relatively short plasma half-life

These pharmacokinetic properties inform research protocol design, particularly regarding dosing schedules and timing of outcome measurements in experimental models.

Research Applications

Melanocortin Receptor Pharmacology Studies

MT-2 serves as a research tool for investigating melanocortin receptor systems:

• Receptor Binding Studies: Investigation of ligand-receptor interactions, binding affinities, and receptor selectivity
• Signal Transduction Research: Analysis of cAMP generation, MAPK pathway activation, and downstream signaling cascades
• Receptor Desensitization Studies: Examination of receptor internalization, recycling, and long-term signaling regulation
• Structure-Activity Relationship Research: Comparative studies with modified peptides to understand structural requirements for activity
• Receptor Distribution Mapping: Investigation of melanocortin receptor expression patterns across tissues and cell types

Research protocols employ receptor binding assays, cell-based functional assays, and tissue-specific expression studies to characterize MT-2’s melanocortin receptor pharmacology.

Pigmentation Biology Research

Given MT-2’s melanotropic properties, substantial research focuses on pigmentation mechanisms:

• Melanogenesis Studies: Investigation of melanin synthesis pathways, tyrosinase activation, and eumelanin production
• Melanocyte Biology: Research on melanocyte proliferation, dendricity, and melanosome transfer mechanisms
• MC1R Signaling Research: Examination of MC1R-mediated cAMP signaling and transcription factor activation (MITF, CREB)
• Photoprotection Studies: Investigation of UV-independent pigmentation and DNA damage protection mechanisms
• Pigmentation Regulation: Analysis of factors modulating melanogenic responses to MC receptor activation

Laboratory studies utilize cultured melanocytes, skin explants, and pigmentation animal models to examine MT-2’s effects on melanogenesis and pigmentation biology.

Energy Homeostasis and Feeding Behavior Research

MT-2 research investigates melanocortin pathways in energy regulation:

• MC4R-Mediated Appetite Studies: Investigation of hypothalamic melanocortin system in feeding behavior regulation
• Energy Expenditure Research: Examination of metabolic rate, thermogenesis, and energy utilization pathways
• POMC Neuron Studies: Research on proopiomelanocortin neuronal circuits and appetite-regulating pathways
• Leptin Pathway Interactions: Investigation of melanocortin system integration with leptin signaling
• Body Weight Regulation: Studies examining long-term effects on body composition and metabolic parameters

Research protocols include feeding behavior assays, metabolic cage measurements, body composition analysis, and hypothalamic pathway investigations in rodent models.

Sexual Function and Reproductive Research

Research applications extend to reproductive physiology investigation:

• MC3R/MC4R Sexual Function Studies: Examination of melanocortin receptor roles in sexual behavior and arousal pathways
• Erectile Function Research: Investigation of penile erection mechanisms and neurovascular pathways
• Central Nervous System Effects: Studies on brain regions involved in sexual behavior and arousal
• Hormonal Pathway Research: Examination of testosterone, estrogen, and neuroendocrine interactions
• Mating Behavior Studies: Analysis of courtship behaviors and reproductive success in animal models

Laboratory protocols investigate sexual behavior endpoints, genital tissue responses, neural activation patterns, and endocrine measurements.

Metabolic and Cardiovascular Research

Emerging research areas include metabolic effects:

• Insulin Sensitivity Studies: Investigation of glucose metabolism and insulin signaling pathway modulation
• Cardiovascular Effects Research: Examination of blood pressure, heart rate, and vascular function
• Lipid Metabolism Studies: Research on fatty acid oxidation, lipolysis, and lipid handling
• Thermogenesis Research: Investigation of brown adipose tissue activation and energy expenditure
• Metabolic Syndrome Models: Studies examining effects in obesity, diabetes, and metabolic disorder models

Research in this area examines MT-2’s effects on metabolic parameters, glucose homeostasis, cardiovascular function, and energy balance mechanisms.

Laboratory Handling and Storage Protocols

Lyophilized Powder Storage:

• Store at -20°C to -80°C in original sealed vial
• Protect from light exposure (peptide is photosensitive)
• Desiccated storage environment required
• Stability data available for 12+ months at -20°C

Reconstitution Guidelines:

• Reconstitute with sterile water, bacteriostatic water (0.9% benzyl alcohol), or appropriate buffer
• Add solvent slowly down vial side to minimize foaming
• Gentle swirling motion recommended (avoid vigorous shaking)
• Allow complete dissolution before use (typically 2-3 minutes)
• Final pH should be 6.0-7.5 for optimal stability

Reconstituted Solution Storage:

• Short-term storage: 4°C for up to 7 days
• Long-term storage: -20°C in aliquots to avoid freeze-thaw cycles
• Single-use aliquots recommended to maintain peptide integrity
• Avoid repeated freeze-thaw cycles (maximum 2-3 cycles)
• Protect from light during storage and handling

Photosensitivity Considerations:
MT-2 demonstrates light sensitivity that can affect peptide stability. Store in amber vials or protect from light exposure. During experimental procedures, minimize light exposure time and use amber or foil-wrapped containers when possible.

Quality Assurance and Analytical Testing

Each MT-2 batch undergoes comprehensive analytical characterization:

Purity Analysis:

• High-Performance Liquid Chromatography (HPLC): ≥98% purity
• Analytical method: Reversed-phase HPLC with UV detection at 280nm
• Multiple peak integration to ensure accurate purity determination

Structural Verification:

• Electrospray Ionization Mass Spectrometry (ESI-MS): Confirms molecular weight 1,024.24 Da
• Amino acid analysis: Verifies sequence composition
• Peptide content determination: Quantifies actual peptide content by weight

Contaminant Testing:

• Bacterial endotoxin: <5 EU/mg (LAL method)
• Heavy metals: Below detection limits per USP standards
• Residual solvents: TFA and acetonitrile within acceptable limits
• Water content: Karl Fischer titration (<8%)

Documentation:

• Certificate of Analysis (COA) provided with each batch
• Third-party analytical verification available upon request
• Stability data documented for recommended storage conditions
• Batch-specific QC results traceable by lot number

Research Considerations

Experimental Design Factors:

Researchers should consider several factors when designing MT-2 experiments:

1. Concentration Selection: Determine appropriate concentrations based on receptor affinity data, experimental model, and research objectives. Published research reports concentration ranges from nanomolar to micromolar depending on application.

2. Receptor Selectivity: MT-2 activates multiple melanocortin receptor subtypes. Consider using selective agonists or antagonists for receptor-specific studies.

3. Temporal Dynamics: Account for both acute receptor activation and sustained biological effects in experimental timing and measurements.

4. Light Protection: Implement light protection protocols throughout experimental procedures due to peptide photosensitivity.

5. Control Groups: Include appropriate vehicle controls, receptor-specific controls, and comparative melanocortin peptides.

Mechanism Investigation:

MT-2’s mechanisms involve multiple receptor systems and downstream pathways:

• MC1R activation: cAMP signaling, MITF activation, melanogenesis
• MC3R/MC4R activation: Hypothalamic circuits, energy homeostasis, sexual function
• MC5R activation: Exocrine function, sebaceous gland regulation
• Secondary messenger systems: cAMP/PKA, MAPK pathways, calcium signaling

Careful experimental design helps isolate specific receptor-mediated effects and downstream pathway contributions.

Compliance and Safety Information

Regulatory Status:
Melanotan II is provided as a research chemical for in-vitro laboratory studies and preclinical research only. This product has not been approved by the FDA or any regulatory agency for human therapeutic use, cosmetic applications, or medical purposes.

Intended Use:

• In-vitro cell culture studies
• In-vivo preclinical research in approved animal models
• Laboratory investigation of melanocortin receptor pharmacology
• Academic and institutional research applications

NOT Intended For:

• Human consumption or administration
• Cosmetic or tanning applications
• Therapeutic treatment or diagnosis
• Dietary supplementation
• Veterinary therapeutic applications without appropriate oversight

Safety Protocols:
Researchers should follow standard laboratory safety practices when handling MT-2:

• Use appropriate personal protective equipment (lab coat, gloves, safety glasses)
• Handle in well-ventilated areas or fume hood
• Protect from light exposure during handling
• Follow institutional biosafety guidelines
• Dispose of waste according to local regulations for biological/chemical waste
• Consult material safety data sheet (MSDS) for additional safety information

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