This is a working overview of Heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-22. Anything still debated is marked as such rather than presented as settled.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
=== Proposed long-range version === On June 26, 1972, a long-range version of the Il-86, the Il-86D (for Russian: "дальний"; transliterated: "dal’niy"; meaning "long-range"), was ordered into development by the Soviet cabinet. Design was completed in June 1976. The Il-86D would have had a marginally extended wing span, carried additional fuel, and had a range of some 8,500 km (4,600 nmi). Later announcements stated that a version of the Il-86D with Lotarev D-18 engines had entered development in March 1975. This version would have had a 147,500 kg (325,000 lb) empty weight, a 300,000 kg/660,000 lb maximum take-off weight, a fuel capacity of some 150,000 kg (330,000 lb), a wing area of 325 m2 (5,300 ft2), and a range of 10,200 km (5,500 nmi). It evolved into the Il-96.
Yariv phenylglycosides were concluded to be specific binding reagents for β-1,3-galactan chains longer than five residues. Seven residues and longer are sufficient for cross-linking, leading to precipitation of the glycans with the Yariv phenylglycosides, which are observed with classical AGPs binding to β-Yariv dyes. The same results were observed where in AGPs appear to need at least 5–7 β-1,3-linked Gal units to make aggregates with the Yariv reagent.
Beginning in 2021, the OECD expanded its terminology, stating that "PFAS are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e., with a few noted exceptions, any chemical with at least a perfluorinated methyl group (−CF3) or a perfluorinated methylene group (−CF2−) is a PFAS." The United States Environmental Protection Agency (EPA) defines PFAS more narrowly in the Drinking Water Contaminant Candidate List 5 as substances that contain "at least one of the following three structures: R−CF2−CF(R')R", where both the −CF2− and −CF− moieties are saturated carbons, and none of the R groups can be hydrogen; R−CF2−O−CF2−(R'), where both the −CF2− moieties are saturated carbons, and none of the R groups can be hydrogen; or CF3−C−(CF3)RR', where all the carbons are saturated, and none of the R groups can be hydrogen. A summary table of some PFAS definitions is provided in Hammel et al (2022).
Sources: en.wikipedia.org
=== Cancer research === There is research investigating whether high dose intravenous vitamin C administration as a co-treatment will suppress cancer stem cells, which are responsible for tumor recurrence, metastasis and chemoresistance.
==== Canaloplasty ==== Canaloplasty is a nonpenetrating procedure using microcatheter technology. To perform a canaloplasty, an incision is made into the eye to gain access to the Schlemm's canal, similarly to a viscocanalostomy. A microcatheter will circumnavigate the canal around the iris, enlarging the main drainage channel and its smaller collector channels through the injection of a sterile, gel-like material called viscoelastic. The catheter is then removed, and a suture is placed within the canal and tightened. By opening the canal, the pressure inside the eye may be relieved, although the reason is unclear, since the canal (of Schlemm) does not have any significant fluid resistance in glaucoma or healthy eyes. Long-term results are not available.
Žarković, N.; Zarković, K.; Schaur, R. J. R.; Stolc, S.; Schlag, G. N.; Redl, H.; Waeg, G.; Borović, S.; Loncarić, I.; Jurić, G.; Hlavka, V. (1999). "4-Hydroxynonenal as a second messenger of free radicals and growth modifying factor". Life Sciences. 65 (18–19): 1901–1904. doi:10.1016/S0024-3205(99)00444-0. PMID 10576434. Sharma, R.; Brown, D.; Awasthi, S.; Yang, Y.; Sharma, A.; Patrick, B.; Saini, M. K.; Singh, S. P.; Zimniak, P.; Singh, S. V.; Awasthi, Y. C. (2004). "Transfection with 4-hydroxynonenal-metabolizing glutathione S-transferase isozymes leads to phenotypic transformation and immortalization of adherent cells". European Journal of Biochemistry. 271 (9): 1690–1701. doi:10.1111/j.1432-1033.2004.04067.x. PMID 15096208.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.