A practical reference on cyclic heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-16 and is reviewed periodically as new material appears.
Handling procedures emphasize minimizing moisture uptake, since the dried solid is hygroscopic and can draw water when warmed to room temperature before a vial is opened. Laboratories record lot number, purity, counter-ion content, and residual solvent data supplied by the producer. Impurity profiles are compared run to run, and any shift in retention time or peak shape prompts re-verification against a reference standard. Certificates of analysis are treated as claims to be checked rather than accepted at face value.
Identity and purity testing for this peptide typically relies on reversed-phase high-performance liquid chromatography with ultraviolet detection, reported as area-percent purity. Mass spectrometry, usually in tandem mode, confirms molecular mass and supports quantification in biological matrices. Sequence confirmation may use peptide mapping after enzymatic digestion, while nuclear magnetic resonance and circular dichroism supply supplementary structural detail. No single technique establishes identity alone, so laboratories compare retention time, mass, and fragment pattern against a verified reference standard.
Outside the approved product, bremelanotide circulates as a research chemical sold by peptide vendors, often labelled PT-141. Such material is not manufactured under pharmaceutical quality standards, and independent testing has repeatedly found content that differs from the label. Analytical certificates supplied with a purchase are not strong evidence of purity because they are usually generated by the seller. Online discussion tends to blur the distinction between the approved drug and unregulated powder, which complicates interpretation of reported experiences.
PT-141 is the original development code for bremelanotide, a synthetic peptide first studied as a potential tanning and sexual-response agent in the 1990s. Researchers at a small American biotechnology firm designed it as a shortened analogue of melanotan II, which itself came from work on alpha-melanocyte-stimulating hormone. Early screening focused on pigmentation, but behavioural observations in animal models redirected attention toward sexual motivation. That shift made PT-141 one of the first melanocortin compounds investigated specifically for effects on desire rather than on skin colour.
Clinical development proceeded through two routes of administration. An intranasal formulation advanced first, but variable absorption and tolerability problems led to a switch to subcutaneous injection. The United States Food and Drug Administration approved the subcutaneous product in 2019 for hypoactive sexual desire disorder in premenopausal women. Marketing rights subsequently changed hands, and commercial availability has fluctuated since approval. Use in men, in postmenopausal women, and in combination with other agents remains outside the approved label.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white solid | Lyophilized powder form |
| Solubility class | Freely soluble in water | Also dissolves in polar organic solvents |
| Typical storage temperature | Minus 20 degrees Celsius or lower | Desiccated and protected from light |
| Typical analytical method | Reversed-phase HPLC with UV detection | Purity reported by area normalization |
| Common synonyms | PT-141; bremelanotide | Research code and assigned generic name |
Early clinical work used an intranasal formulation, and later programmes switched to subcutaneous delivery for more consistent absorption. A subcutaneous product received regulatory approval in the United States in 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder. Approval followed phase 3 trials in which active treatment separated from placebo on desire and distress measures, though the average difference was modest. Labeling carries a caution about transient blood pressure elevation, so cardiovascular history is assessed before prescribing. Questions about durability of benefit beyond several months remain open.
Published discussion sits at the intersection of peptide chemistry, neuroendocrinology and sexual medicine. Trial reports emphasise change scores on validated instruments, while mechanistic papers focus on hypothalamic circuits and receptor selectivity. Because placebo response in this field is large, effect sizes are usually reported with confidence intervals rather than as isolated averages. Reviews note that female and male data sets are not interchangeable and should be read separately. Diagnostic terminology has been revised over time, which complicates comparison between older and newer studies.
Bremelanotide is a synthetic cyclic heptapeptide that acts on a family of G-protein-coupled receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide associated with pigmentation and several central signalling pathways. A lactam bridge constrains the ring and slows enzymatic breakdown, which distinguishes it from the linear parent molecule. Research interest moved over time from pigment biology toward central nervous system effects, particularly circuits connected to sexual desire. Parenteral delivery is used because oral bioavailability is poor.
How receptor activation translates into a change in desire is not established in detail. Proposed steps include modulation of dopaminergic signalling in reward circuits and downstream effects on autonomic tone. Human data consist mainly of clinical trials measuring self-reported outcomes rather than direct measurements of brain activity or transmitter release. The transient rise in blood pressure sometimes observed after administration is likewise reported consistently but explained only partly by known melanocortin pathways.
Melanocortin receptors form a family of five G-protein-coupled proteins, labelled MC1R through MC5R, that respond to peptides derived from pro-opiomelanocortin. Alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone are the best-known endogenous ligands. The receptors are distributed differently across tissues, so a single agonist can produce effects in the brain, skin, adrenal gland and vasculature. This distribution explains why one peptide can influence both pigmentation and motivated behaviour.
Reported pharmacodynamic effects include transient rises in blood pressure and heart rate, flushing, nausea and headache, appearing soon after dosing and resolving within hours. These responses were dose-related in early studies and shaped the label's cardiovascular cautions and blood pressure monitoring advice. Gastrointestinal upset is the most frequent reason cited for discontinuation in trials. Whether the vascular signal attenuates with repeated use is not settled. Central effects on desire are described as emerging over weeks rather than immediately, which points to a cumulative rather than acute process.
The compound binds several melanocortin receptor subtypes rather than a single target, with the strongest functional activity reported at MC4R and measurable activity at MC1R, MC3R and MC5R. MC4R populations are dense in hypothalamic nuclei that integrate energy balance, autonomic tone and reproductive behaviour, which is the anatomical basis for the proposed pro-desire effect. Because binding is not subtype-selective, pigmentary and vascular effects accompany central activity. Improving subtype selectivity is an active area of analogue design. Direct causal mapping from receptor occupancy to reported desire change in humans is not fully established.
Hayley Clay (Kiernan Shipka) is Whitney Halberstram’s executive assistant at Tender. Recruited from an escort agency, she previously serviced wealthy clients to obtain compromising material, including an emir connected to Al-Mi’raj, Pierpoint's new owner. While at Tender, she spends a night with James Dycker, a financial journalist investigating the company, and later learns his identity. Before leaving her apartment, Dycker urges her to question the circumstances of her predecessor’s departure. Hayley asks Whitney directly; he claims the former assistant suffered from Crohn’s disease and that he privately funded her treatment. After Henry Muck becomes CEO, Hayley also serves as his assistant, and during a business trip to Vienna, Yasmin arranges a threesome involving Henry and Hayley. As Dycker continues probing Tender’s laundering of illegal payments, Hayley files a sexual assault complaint against him. Combined with an article arranged by Yasmin alleging Dycker colluded with short sellers, the accusation leads to his dismissal. Whitney promotes Yasmin to head of communications, and Yasmin elevates Hayley to a senior communications role. Following reports exposing Tender’s fraudulent African profits, Hayley reviews Whitney’s emails and discovers her predecessor also came from the same escort agency. She resigns, confronting Whitney over employing her underage cousin Dolly to seduce Eric Tao. Hayley then approaches Yasmin, revealing that their threesome was recorded and that she is an escort, seeking leverage within British high society.
=== Materials === Over time a wide variety of materials have been used for infant feeding vessels (see History). The materials now most commonly used in baby bottle containers are glass and some types of plastics. Food-grade stainless steel and silicone rubber are also used. Each of these four materials—plastic, glass, silicone and stainless steel—has advantages and disadvantages. The standard materials used in teats/nipples are latex rubber and silicone. A number of countries have regulations about allowable food contact materials. Ideally, the material making up the bottle should react as little as possible with the material in the bottle. No material is completely inert, but glass and stainless steel are relatively neutral materials which tend to remain stable and not interact with foods. The disadvantages of glass are that it tends to be heavy and can break more easily. Plastics are lightweight and resistant to breaking. Manufacturers find them easy to form into a variety of shapes. A wide variety of plastics have been developed, some of which are not well understood in terms of reactivity. Some plastics have been found to be reactive with fluids such as breast milk and infant formula. Chemicals such as Bisphenol A (BPA) may "leach" from a bottle into the substance it holds. In addition, plastics may be more likely to break down when heated or cooled, for example, when being heated in a microwave or being boiled to sterilize them. Polycarbonate plastic was frequently used in baby bottles before 2011, and is still used in some countries.
Wenger's first match was a 2–0 away victory over Blackburn Rovers on 12 October 1996, however, he did suggest "one or two changes" to Rice in Arsenal's UEFA Cup defeat to Borussia Mönchengladbach on 24 September, nine days prior to taking charge of the club. The interference upset club captain Tony Adams, who on his first meeting with the manager expressed his disappointment: "I said to him that he had put our entire season in jeopardy by doing what he had done." Wenger chose to take the criticism on board upon arrival, and made an effort listening to Adams' assessment of the club. This particular approach of management resonated with the other players, who were sceptical of his ideas at first. The English players often set up pranks on Wenger to relieve hostility and nicknamed him "Inspector Clouseau", due to his clumsy nature. Adams said his sense of humour helped build team spirit: "Not only does Wenger love a good laugh, but he can laugh at himself. He is this gangly wise man". Malicious rumours concerning Wenger's private life surfaced during November 1996, to the extent that the City of London reported that his exit from Arsenal was imminent. Having returned from a trip to Strasbourg to visit his parents, Wenger attended a press meeting and strongly refuted the claims: "If something comes out that is wrong, I will attack.
=== Post-World War II period === The federation and football overall was disrupted by World War II. After the war, a socialist federation was formed and the football federation reconstituted. It was one of the founding members of the UEFA in 1954.
=== Laboratory methods === In general, on the typical laboratory scale, the direct reaction of a haloalkane with sodium hydrosulfide is inefficient owing to the competing formation of sulfides (overalkylation). Instead, alkyl halides are converted to thiols via an S-alkylation of thiourea. This multistep, one-pot process proceeds via the intermediacy of the isothiouronium salt, which is hydrolyzed in a separate step:
Sources: en.wikipedia.org
DynoPlot in PyMOL wiki Link to Ramachandran Plot Map of alpha-helix and beta-sheet locations Archived 2006-10-11 at the Wayback Machine Link to Ramachandran plot calculated from protein structures determined by X-ray crystallography compared to the original Ramachan. Proteopedia Ramachandran Plot
=== Middle Eastern countries === As of March 2026, Nando's has five restaurants in Bahrain; two in Manama and one each in Amwaj Islands, Isa Town and Saar. In Qatar, Nando's has been established since 2001, with the first restaurant located on Salwa Road. As of October 2022, Nando's has eight branches in Qatar, seven of which are located in Doha while one is in Al Wakrah. In Saudi Arabia, Nando's opened its first restaurant within the country on 12 December 2016 in Riyadh, and opened its first branch in Jeddah on 8 December 2018 As of March 2026, Nando's has nine branches in Saudi Arabia; three in Riyadh, three in Jeddah; and one each in Dhahran, Dammam and Khobar. Nando's opened its first restaurant within the United Arab Emirates in Dubai (along Sheikh Zayed Road) in 2002 and opened its first branch in Abu Dhabi in 2014. As of August 2021, Nando's has 19 branches in the UAE; 13 in Dubai, three in Abu Dhabi and one each in Sharjah, Al Ain and Ras Al Khaimah. As a former market, Israel was home to a successful Nando's franchise network throughout the 1990s and 2000s, with the Israeli operation involving the Brozin brothers alongside the international Nando's business. The first Israeli branch opened in Herzliya in 1993, and by 1996 there were branches in Tel Aviv, Herzliya and Haifa, with plans for further expansion. By March 2004, the network had grown to 15 restaurants. In December 2005, Nando's Israel was acquired by Israeli businessman Yuval Doron's Eddy Global Holdings. Kenny Brozin remained chief executive of the Israeli operation until June 2006.
=== Scottish === Daughters of Scotland - Incorporated in Ohio on October 3, 1899. Membership is open only to those of Scottish blood. Rituals had signs, oaths, and prayers. Grand Lodge dissolved in the early 1970s, though some local groups continued to meet afterwards. Order of Scottish Clans Sons of Scotland Benevolent Association - Founded 1876 in Toronto. Incorporated in Ontario in 1880, and on the federal level in 1937. Headquartered in Toronto, the association's lodges are called "Subordinate Camps", and the national structure is "Grand Camp", which meets in conventions triennially. Slogan "Lealty, Loyalty, Liberality". In the late 1970s, it still had an initiation ceremony and "affinity for fraternal ritualism", annual passwords, and regalia. In addition to insurance, it sponsors Scottish dancing and piping competitions, and parades in Scottish kilts. Membership is open to men and women of Scottish descent or their spouses. Five classes of membership - insured, central camp, juvenile, associate, and at large. Members are chosen by blackball. 1973 membership 12,887; 1979 membership 12,640 in 80 camps. 9,000 members in 1995. Charitable activities include Kidney Foundation of Canada and Alzheimer's disease organizations. Lost a third of its membership over the 1980s.
=== Cancer === Inflammation orchestrates the microenvironment around tumours, contributing to proliferation, survival and migration. Cancer cells use selectins, chemokines and their receptors for invasion, migration and metastasis. On the other hand, many cells of the immune system contribute to cancer immunology, suppressing cancer. Molecular intersection between receptors of steroid hormones, which have important effects on cellular development, and transcription factors that play key roles in inflammation, such as NF-κB, may mediate some of the most critical effects of inflammatory stimuli on cancer cells. This capacity of a mediator of inflammation to influence the effects of steroid hormones in cells is very likely to affect carcinogenesis. On the other hand, due to the modular nature of many steroid hormone receptors, this interaction may offer ways to interfere with cancer progression, through targeting of a specific protein domain in a specific cell type. Such an approach may limit side effects that are unrelated to the tumor of interest, and may help preserve vital homeostatic functions and developmental processes in the organism. There is some evidence from 2009 to suggest that cancer-related inflammation (CRI) may lead to accumulation of random genetic alterations in cancer cells.
Sources: en.wikipedia.org
== List of major publications in English == Vladimir Kh. Khavinson. Peptides and Ageing. // Neuroendocrinology Letters. — Vol. 23, Suppl. 3, Special Issue. — 2002. — 144 p. Khavinson, Malinin. Gerontological Aspects of Genome Peptide Regulation. // Basel (Switzerland): Karger AG. — 2005. — 104 p. Khavinson. Peptidergic regulation of ageing. // SPb.: Humanistica. — 2009. — 48 p. Khavinson, Morozov, Anisimov. Experimental Studies of the Pineal Gland Preparation Epithalamin. // The Pineal Gland and Cancer. — Bartsch C., Bartsch H., Blask D.E., Cardinali D.P., Hrushesky W.J.M., Mecke D. (Eds.) — Springer-Verlag, Berlin, Heidelberg. — 2001. — P. 294–306. Vladimir N. Anisimov, Vladimir Kh. Khavinson. Small Peptide-associated Modulation of Aging and Longevity. // Modulating Aging and Longevity. — Kluwer Academic Publishers (Printed in the United Kingdom) — Suresh I.S. Rattan (ed.). — 2003. — P. 279–301. Vladimir N. Anisimov, Vladimir Kh. Khavinson. Pineal Peptides as Modulators of Aging. // Aging Interventions and Therapies. — World Scientific. — Suresh I.S. Rattan (ed.). — 2005. — P. 127–146. Khavinson, Mikhailova. Health and Aging in Russia. // Global Health and Global Aging. / (ed. by Mary Robinson et al.); foreword by Robert Butler. — 1st ed. — 2007. — P. 226–237. Khavinson, Neroev, Trofimova, Osokina. Unique method for restoration of retinal functions in case of different diseases. // SPb. — 2011. — 32 p.
In molecular biology and biotechnology, a fluorescent tag, also known as a fluorescent dye, fluorescent label or fluorescent probe, is a molecule that is attached chemically to aid in the detection of a biomolecule such as a protein, antibody, or amino acid. Generally, fluorescent tagging, or labeling, uses a reactive derivative of a fluorescent molecule known as a fluorophore. The fluorophore selectively binds to a specific region or functional group on the target molecule and can be attached chemically or biologically. Various labeling techniques such as enzymatic labeling, protein labeling, and genetic labeling are widely utilized. Ethidium bromide, fluorescein and green fluorescent protein are common tags. The most commonly labelled molecules are antibodies, proteins, amino acids and peptides which are then used as specific probes for detection of a particular target.
Hydrogels with reversible chemistry are required to allow for fluidization during injection/printing followed by self-healing of the original hydrogel structure. Investigate cell biomechanical functions combined with holotomography microscopy Provide absorption, desloughing and debriding of necrotic and fibrotic tissue Tissue engineering scaffolds. When used as scaffolds, hydrogels may contain human cells to repair tissue. They mimic 3D microenvironment of cells. Materials include agarose, methylcellulose, hyaluronan, elastin-like polypeptides, and other naturally derived polymers. Sustained-release drug delivery systems. Ionic strength, pH and temperature can be used as a triggering factor to control the release of the drug. Light-stimulated drug release systems. Using light as an exogenous stimulus, temporal control also opens possibilities for on-off switchable release of molecular cargoes through hydrogel-polymersome composites. The swelling behavior exhibited by charged hydrogels can be used as a valuable tool for investigating interactions between charged polymers and various species, including multivalent ions, peptides, and proteins. This response arises due to fluctuating osmotic swelling forces resulting from the exchange of counterions within the gel matrix. Particularly significant is its application in assessing the binding of peptide drugs to biopolymers within the body, as the swelling response of the gel can provide insights into these interactions. Window coating/replacement: Hydrogels are under consideration for reducing infrared light absorption by 75%.
The β and γ phases are obtained by annealing the most stable α-Al2S3 phase at several hundred degrees Celsius. Compressing aluminum sulfide to 2–65 bar results in the δ phase where vacancies are arranged in a superlattice of tetragonal symmetry. Unlike Al2O3, in which the Al(III) centers occupy octahedral holes, the more expanded framework of Al2S3 stabilizes the Al(III) centers into one third of the tetrahedral holes of a hexagonally close-packed arrangement of the sulfide anions. At higher temperature, the Al(III) centers become randomized to give a "defect wurtzite" structure. And at still higher temperatures stabilize the γ-Al2S3 forms, with a structure akin to γ-Al2O3. Molecular derivatives of Al2S3 are not known. Mixed Al-S-Cl compounds are however known. Al2Se3 and Al2Te3 are also known.
The seeds contain saponins but no calcium oxalate raphide crystals, chelidonic acid (unlike Asparagales) or cysteine derived sulphur compounds (allyl sulphides), another distinguishing feature from the characteristic alliaceous odour of the Allioideae. Fritillaria in particular contains steroidal alkaloids of the cevanine and solanum type. Solanidine and solanthrene alkaloids have been isolated from some Fritillaria species. Tulipa contains tulipanin, an anthocyanin.
Sources: en.wikipedia.org
Chemical degradation such as hydrolysis and oxidation proceeds more slowly as temperature falls. Cold storage also limits microbial growth in reconstituted material. Repeated warming should be avoided because thermal cycling stresses the peptide.
Retention time supports consistency but does not establish structure by itself. A different compound can elute at a similar time under one set of conditions. Mass spectrometry or comparison with a verified standard is normally required alongside the chromatographic result.
The lactam bridge constrains the peptide backbone and limits attack by some exopeptidases. It does not protect against hydrolysis of amide bonds inside the ring or against oxidative modification of susceptible residues. Stability therefore still depends heavily on storage conditions.
PT-141 is a research code for bremelanotide, a cyclic peptide that activates melanocortin receptors. It was developed for sexual dysfunction and later approved under a brand name as a subcutaneous injection. The same code is widely used by suppliers selling non-pharmaceutical material.