Melanotan I

Melanotan-I is a linear 13-residue peptide whose sequence mirrors the full α-MSH backbone with norleucine substituted for methionine at position 4 and D-phenylalanine substituted for L-phenylalanine at position 7. These two substitutions confer resistance to enzymatic degradation while preserving the bioactive conformation that engages the melanocortin-receptor family. The molecule binds MC1R, MC3R, MC4R, and MC5R with affinity profiles documented across the published literature, distinguishing it from the cyclic Melanotan-II analog by virtue of its retained linear architecture. Pharmacokinetic descriptors documented in published animal-model investigations include extended plasma residence relative to native α-MSH but shorter than the cyclic Melanotan-II. Interaction profile in the literature spans non-selective melanocortin-receptor agonism with cAMP-signaling activation at each receptor subtype. All activity descriptors here are framed as documented in published work.

Experimental domains documented in the published literature include melanocortin-receptor binding-affinity assays across MC1R / MC3R / MC4R / MC5R subtypes, structure-activity investigations probing the role of the position-4 norleucine and position-7 D-phenylalanine substitutions in enzymatic stability and receptor engagement, melanocyte-cell signaling assays, comparative work alongside cyclic Melanotan-II to dissect linear-versus-cyclic architectural contributions to receptor pharmacology, and screening assays for melanocortin-receptor-active ligand discovery. Investigators have also characterized the molecule in studies of receptor desensitization kinetics. Use in laboratory research extends to mechanism-elucidation paradigms where the linear analog serves as a defined α-MSH-derived reference. The reference standard is supplied for these and equivalent in-vitro and animal-model experimental contexts only, with no associated guidance for human, clinical, cosmetic, or veterinary application.

Each lot is characterized by reverse-phase HPLC for chromatographic purity and by mass spectrometry for molecular-ion confirmation against the C78H111N21O19 empirical formula. Purity is reported as an HPLC-area percentage on the Certificate of Analysis distributed with every lot, alongside the molecular-weight match within instrument tolerance. The position-4 and position-7 amino-acid substitutions are confirmed by tandem mass spectrometry when included in the lot's release specification. Peptide content where applicable is determined by amino-acid analysis or nitrogen-content assay following the analytical method specified on the COA. Residual solvent and water content are reported categorically when these parameters are part of the lot's release specification. The COA records the lot identifier, manufacturing date, and analytical method versions used. Researchers requiring batch-level analytical detail should reference the COA distributed with the supplied material.

For laboratory storage, the lyophilized reference standard should be held at −20°C in its sealed, light-protected container until ready for analytical use. Allow vials to equilibrate to ambient temperature before opening to avoid moisture condensation on the lyophile. Reconstitution for in-vitro experimental use is typically performed in bacteriostatic water or a researcher-selected buffer compatible with the downstream assay; once reconstituted, store the working solution at 2–8°C and characterize stability in the relevant buffer prior to extended storage. Avoid repeated freeze-thaw cycles of reconstituted material — single-use aliquots are preferred for experiments where peptide integrity is assay-critical. These handling parameters reflect general best-practice for lyophilized peptide reference standards and do not constitute preparation guidance for human, cosmetic, or veterinary application.