PT-141 (Bremelanotide) — wholesale 10-vial kits

Research context

PT-141 is the research designation for bremelanotide, a cyclic melanocortin receptor agonist that came out of melanocortin chemistry at the University of Arizona and was developed by Palatin Technologies. It is structurally the deamidated relative of melanotan II: the same lactam-bridged ring built on the α-MSH pharmacophore His-D-Phe-Arg-Trp, but ending in a free carboxylic acid instead of melanotan II's C-terminal amide. The FDA-approved labeling gives the structure as Ac-Nle-cyclo-(Asp-His-D-Phe-Arg-Trp-Lys-OH), so the molecule carries an acetylated N-terminal norleucine, a side-chain lactam between the aspartate and the lysine, and a free acid terminus.

Those three features define its behaviour as a reference ligand. The Asp–Lys lactam locks the pharmacophore into a constrained ring, which raises melanocortin-receptor affinity relative to linear α-MSH fragments and removes the cleavable backbone that linear analogs expose; the D-phenylalanine blocks proteolysis at the most labile position and fixes the ring geometry; and the N-terminal acetyl and the non-proteinogenic norleucine remove the free amine and the methionine of the natural sequence, so there is no oxidation-prone residue. The cyclization also lowers the measured mass relative to the equivalent linear peptide by the water lost in forming the bridge, which is the quickest LC-MS check that the ring is closed.

On receptor pharmacology, the approved labeling states that bremelanotide non-selectively activates several melanocortin receptor subtypes with the order of potency MC1R, MC4R, MC3R, MC5R, MC2R — so MC1R, not MC4R, heads the potency list, and the label notes MC1R and MC4R as the most relevant at the concentrations studied. That makes it a useful broad-spectrum reference agonist for melanocortin panels, but not a selective MC4R tool: selectivity work needs a subtype-selective comparator alongside it.

Laboratory use follows: cAMP accumulation and β-arrestin recruitment assays across recombinant MC1R–MC5R lines, competition binding against radiolabelled NDP-α-MSH, structure–activity series on cyclic α-MSH analogs, melanocortin signaling studies in hypothalamic and melanocyte models, and analytical reference use where distinguishing bremelanotide from melanotan II matters — the two differ only at the C-terminus and are routinely confused in trade material. The constrained ring and the absence of oxidation-prone residues also make it a stable system-suitability peptide for melanocortin assay work, and because the lactam is formed between side chains rather than along the backbone, it is a worked example when developing methods that must confirm cyclization rather than sequence alone.

Regulatory position, stated factually: bremelanotide is the active ingredient of an FDA-approved drug product (NDA 210557, approved June 21, 2019). Its approved labeling is the primary public source for the molecule's structure and receptor-potency ordering. The PT-141 supplied by WholesalePeptide.us is not that drug product; it is a research reference standard sold for in-vitro, analytical and preclinical laboratory research only.

The intramolecular lactam bridge lowers the mass relative to the linear sequence. Identity on each lot COA is confirmed by LC-MS against the cyclic structure, and the counter-ion is stated separately, since the material is commonly supplied as the acetate.

Research areas

• MC4R and MC3R receptor pharmacology
• central melanocortin signaling
• cyclic α-MSH analog structure–activity
• receptor selectivity profiling
• cAMP and β-arrestin assays across MC1R–MC5R
• differentiation of bremelanotide from melanotan II by LC-MS

U.S. regulatory status of the compound (as an active ingredient): FDA-approved active ingredient (bremelanotide, Vyleesi, 2019). Supplied here as a research reference material, not the drug product. The material sold here is a research reference chemical, not a drug product.

Handling and storage

• Store lyophilized vials at −20 °C, sealed, protected from light and moisture.
• Let the vial equilibrate to room temperature before opening to limit condensation.
• Reconstitute in an appropriate sterile buffer or solvent according to your laboratory SOP.
• Aliquot reconstituted material and avoid repeated freeze–thaw.