N-Acetyl PT 141

N-Acetyl PT-141 is a chemically modified analog of PT-141 (bremelanotide), itself a cyclic peptide derived from alpha-melanocyte-stimulating hormone (alpha-MSH) that acts as an agonist at melanocortin receptors MC1R, MC3R, and MC4R. The N-acetylation modification — the addition of an acetyl group to the N-terminus of the peptide — is a commonly studied structural change used in peptide chemistry to assess the contribution of the free amino terminus to receptor binding, to alter the peptide's pharmacokinetic properties (typically increased metabolic stability), and to probe structure-activity relationships at the melanocortin receptor family without altering the core cyclic lactam scaffold responsible for high-affinity binding.

The parent compound, PT-141 (bremelanotide), was discovered from the Melanotan II series: Melanotan II (MT-II), itself a cyclic lactam analog of alpha-MSH, produced erections as a side effect in clinical sunless-tanning trials, which redirected research toward sexual dysfunction. PT-141 (bremelanotide) emerged as a cyclic analog optimized for MC4R selectivity and subcutaneous delivery, and was ultimately FDA-approved in June 2019 as Vyleesi (bremelanotide injection, 1.75 mg) for hypoactive sexual desire disorder (HSDD) in premenopausal women — making it the only FDA-approved melanocortin receptor agonist for a sexual function indication. N-Acetyl PT-141 is structurally related to bremelanotide and is studied as a reference compound in MC receptor pharmacology research to probe how N-terminal modification affects binding affinity relative to the parent cyclic peptide.

The melanocortin receptor family (MC1R through MC5R) mediates diverse physiological processes: MC1R regulates pigmentation; MC2R is the ACTH receptor; MC3R and MC4R are expressed centrally and peripherally and are implicated in energy homeostasis and sexual function; MC5R is expressed in exocrine glands. MC4R is the specific target of interest in sexual desire research: central MC4R activation in the medial preoptic area and hypothalamic nuclei has been shown in animal models to increase sexually motivated behavior independent of peripheral vascular effects. This central mechanism distinguishes melanocortin agonists from phosphodiesterase-5 (PDE5) inhibitors like sildenafil, which act peripherally on penile or vaginal vasculature and have no direct CNS activity — the orthogonal mechanisms make both compound classes research tools for mechanistic dissection of sexual arousal circuits. Peptides.SO tracks 1 N-Acetyl PT-141 listing from PureRawz, currently in stock, at $74.87/mg.

Potential Research Applications: Melanocortin receptor (MC1R, MC3R, MC4R) binding affinity and selectivity profiling studies N-terminal acetylation effects on peptide receptor binding affinity structure-activity relationships MC4R-mediated sexual motivation and arousal behavior studies in rodent models Comparison with unmodified bremelanotide (PT-141) and Melanotan II in receptor-binding assays Central vs peripheral sexual arousal mechanism dissection (vs PDE5 inhibitors) Alpha-MSH analog pharmacology and hypothalamic appetite-reproductive axis studies Pigmentation and MC1R research using melanocortin agonist tools Metabolic stability assessment of N-acetylated cyclic peptide scaffolds

Marketplace Snapshot (September 2026, Peptides.SO listings data): Tracked listings: 1 from 1 distinct supplier (PureRawz, in stock) Price: $74.87/mg Note: N-Acetyl PT-141 is a specialty analog with limited market availability compared with the parent compound PT-141/bremelanotide. Researchers primarily requiring melanocortin receptor agonism studies will typically find more supplier options for PT-141 directly.

Frequently Asked Questions: Q: What is the structural difference between N-Acetyl PT-141 and PT-141 (bremelanotide)? A: Both compounds share the same cyclic lactam peptide core derived from the Melanotan series. The only structural difference is the N-terminal modification: PT-141/bremelanotide has a free N-terminus (with an N-terminal histidine on a cyclic scaffold), while N-Acetyl PT-141 has an acetyl group capping that N-terminus. This modification is used in structure-activity relationship research to test whether the free amino terminus is required for high-affinity MC receptor binding or whether the cyclic scaffold alone confers affinity.

Q: How does bremelanotide (PT-141) differ from PDE5 inhibitors mechanistically? A: PDE5 inhibitors (sildenafil, tadalafil) act peripherally by preventing cGMP degradation in penile or vaginal smooth muscle, increasing blood flow locally in response to sexual stimulation. They have no direct CNS activity. Bremelanotide acts centrally via MC4R in the hypothalamus and medial preoptic area to activate brain circuits associated with sexual motivation and desire — an upstream, CNS-driven mechanism. This means bremelanotide can work in the absence of local sexual stimulation and in conditions where vascular response is intact but central desire circuitry is suppressed, making it a pharmacologically distinct research tool.

Q: What is the relevance of MC4R in sexual function research? A: MC4R is expressed in the medial preoptic area, paraventricular nucleus, and other hypothalamic nuclei involved in sexual behavior. MC4R agonism in rodent models increases motivated sexual behaviors (lordosis in females, mounting frequency in males) and has been shown to activate downstream oxytocin neuron circuits in the paraventricular nucleus. The FDA approval of bremelanotide for HSDD provides a clinical validation of the MC4R → central arousal axis in humans, making MC4R a well-supported target for translational sexual function research.

Q: How does N-Acetyl PT-141 compare with Melanotan II as a research tool? A: Melanotan II is a non-selective melanocortin agonist with affinity for MC1R, MC3R, MC4R, and MC5R, producing both pigmentation (MC1R) and sexual/appetite effects (MC3R, MC4R). N-Acetyl PT-141 is derived from the more MC4R-focused optimization trajectory of bremelanotide. For research requiring receptor-subtype selectivity profiling, N-Acetyl PT-141 provides data specifically about the bremelanotide scaffold's N-terminal contribution rather than the broader MT-II scaffold.

Q: Is N-Acetyl PT-141 approved for human use? A: No. N-Acetyl PT-141 is an unapproved research chemical. The parent compound bremelanotide (PT-141) is FDA-approved as Vyleesi for HSDD, but N-Acetyl PT-141 itself has no regulatory approval. Material on this platform is sold strictly for preclinical and in vitro laboratory investigation and is not for human consumption.

Related Research on Peptides.SO: peptides.so/learn/pt-141-bremelanotide-melanocortin-research peptides.so/peptide/melanotan-2-mt-2 peptides.so/learn/melanotan-i-vs-melanotan-ii-comparison-2026 peptides.so/learn/peptide-purity-testing-hplc-mass-spec peptides.so/tools/calculator peptides.so/learn/peptide-storage-best-practices

Cited Research: Pfaus JG, Shadiack A, Van Soest T, Tse M, Molinoff P. Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist. Proc Natl Acad Sci U S A. 2004;101(27):10201-10204. PubMed PMID: 15220474. Diamond LE, Earle DC, Rosen RC, et al. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. Int J Impot Res. 2004;16(1):51-59. PubMed PMID: 14963461.

For laboratory research only. Not for human or veterinary use, diagnosis, treatment, cure, or prevention of any disease. THIS PRODUCT IS NOT FOR HUMAN CONSUMPTION.