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Bremelanotide is a synthetic cyclic heptapeptide developed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation and appetite signalling. Its structure contains seven amino acid residues joined by a lactam bridge that closes the ring between two side chains. The molecular formula is C50H68N14O10 and the nominal molecular mass is near 1025 daltons. Much of the early laboratory literature refers to the same molecule by the development code PT-141.
The compound emerged from a research programme examining melanocortin analogues for effects on skin pigmentation. During early human studies, participants reported spontaneous erections as an unexpected side effect, which redirected development toward sexual function rather than tanning. An intranasal formulation was investigated in clinical trials but did not reach market approval. A subcutaneous injectable version later completed the regulatory process, and the nasal route does not appear in approved labelling.
Clinical programmes in this area have relied mainly on randomised, double-blind, placebo-controlled designs in premenopausal women. Primary endpoints usually combine a validated questionnaire covering desire domains with counts of satisfying sexual events and a separate measure of distress. Reported outcomes show statistically significant but modest average improvement over placebo, with wide individual variation. Adverse events such as nausea, flushing, and headache occur frequently and can limit tolerability. Whether short-term trial gains translate into lasting change for most users is an open question.
Evidence outside the studied population is sparse. Trials have concentrated on premenopausal women with a defined diagnosis, and data for postmenopausal women, men, and people taking interacting medications remain limited. Non-prescription use of the peptide for comparable goals is widespread but is not supported by published controlled data. Observed changes in blood pressure have drawn attention to cardiovascular monitoring during use. The literature generally frames the compound as a targeted receptor agonist rather than a general libido enhancer, and basic questions about mechanism and long-term safety are unresolved.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Cyclic heptapeptide backbone |
| Molecular mass | Approximately 1025 Da | Nominal mass of the free peptide |
| Appearance | White to off-white lyophilised powder | Typical for purified synthetic peptides |
| Solubility class | Freely soluble in water | Organic solubility is limited |
| Typical storage temperature | −20 °C or below | Protect from moisture and light |
Bremelanotide acts as a non-selective agonist at melanocortin receptors, with reported activity at MC1R, MC3R, MC4R and MC5R. The proposed basis for its central effects is activation of MC4R populations in the hypothalamus, a region associated with appetite and reproductive signalling. Because the peptide carries a net positive charge and polar side chains, it does not cross biological membranes freely, which is one reason oral administration is not the standard route. Effects generally appear within an hour of parenteral administration and are described as centrally mediated rather than peripheral.
Bremelanotide, developed under the code PT-141, is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone. Its structure is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a lactam bridge joining the aspartate and lysine side chains. The molecule has the formula C50H68N14O10 and a monoisotopic mass near 1025 daltons. It is commonly prepared as the acetate salt and appears as a white to off-white lyophilised powder in solid form. The free acid is the pharmacologically relevant species, while the counter-ion improves handling and dissolution.
Early research on PT-141 grew out of work on melanotan II, a related cyclic peptide studied for pigmentation. Investigators observed that centrally acting melanocortin agonists also influenced sexual behaviour in animal models, and the programme shifted toward that endpoint. A nasal formulation was evaluated in clinical trials but showed inconsistent absorption, and later studies used subcutaneous administration instead. Regulatory approval in the United States followed in 2019 for a defined population of premenopausal women with acquired, generalised hypoactive sexual desire disorder. That approval was specific to that group rather than a broad indication.
Reconstitution is usually performed with sterile water or a dilute acetic acid solution, and the choice of solvent affects both dissolution speed and final pH. Complete dissolution should be confirmed by visual inspection before any aliquot is taken, since undissolved particles can concentrate in the sampling volume. Repeated freeze-thaw cycles are the most common cause of gradual loss of purity, so dividing a stock into single-use aliquots at the first opportunity is standard practice. Working solutions kept refrigerated are generally used within days rather than weeks.
Identity and purity are established with orthogonal methods rather than a single test. Reverse-phase high-performance liquid chromatography with ultraviolet detection gives a purity figure by area normalization, while mass spectrometry confirms the expected molecular ion. Amino acid analysis or peptide mapping can detect sequence errors that a mass value alone would miss, and residual counterion content is sometimes measured separately. Common impurities include truncated sequences, oxidized residues, and deamidated products; reporting them individually is more informative than a single composite purity number.
Dual diagnosis (also called co-occurring disorders (COD) or dual pathology) is the condition of having a mental illness and a comorbid substance use disorder. There is considerable debate surrounding the appropriateness of using a single category for a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcohol use disorder, or it can be restricted to specify severe mental illness (e.g. psychosis, schizophrenia) and substance use disorder (e.g. cannabis use), or a person who has a milder mental illness and a drug dependency, such as panic disorder or generalized anxiety disorder and is dependent on opioids. Diagnosing a primary psychiatric illness in people who use substances is challenging as substance use disorder itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness. Those with co-occurring disorders face complex challenges. They have increased rates of relapse, hospitalization, homelessness, and HIV and hepatitis C infection compared to those with either mental or substance use disorders alone.
== External links == Boston University School of Medicine: Michael F. Holick Harvard Catalyst Profiles: Michael Holick Search Results for author Holick MF on PubMed. Last capture of VitaminDhealth.org Dr. Holick’s current webpage
Many libraries utilize peptide chains much shorter than 70 amino acids. For 20 encoded amino acids at maximally 70 positions, this results in an upper limit of 2070, or more than 10 quindecillion (1×1091), possible combinations, not accounting for the potential use of amino acids with post-translational modifications or amino acids not encoded in the genetic code, such as selenocysteine and pyrrolysine. Peptide libraries generally encompass only a fraction of this diversity, selected for depending on the needs of the experiment, for instance keeping some amino acids constant at certain positions. Large random peptide libraries are often used for the synthesis of certain peptide molecules, such as ultra-large chemical libraries for the discovery of high-affinity peptide binders. Any increase in the library size severely affects parameters, such as the synthesis scale, the number of library members, the sequence deconvolution and peptide structure elucidation. To mitigate these technical challenges, an algorithm-supported approach to peptide library design may use molecular mass and amino acid diversity to simplify the laborious permutation identification in complex mixtures when using mass spectrometry. This approach is used to avoid mass redundancy. Biological reagent companies, such as Pepscan, ProteoGenix, Mimotopes, GenScript and many others, manufacture customized peptide libraries.
=== Structure === Scaffolds are used in tissue engineering to create an environment with similar mechanical properties of the native tissue. Scaffolds must be biocompatible and have high compressive strength. Scaffolds can be created from hydrogels, polymers or other material. Hydrogels are lightly cross-linked polymer networks swollen with water. Degree of crosslinking, porosity, and polymer composition can be tuned to create a hydrogel with similar properties to native cartilage. Researchers have been exploring the use of hydrogels as a cartilage substitute since the 1970s.
Sources: en.wikipedia.org
==== Non-collagen ==== Hydroxyproline is found in few proteins other than collagen. For this reason, hydroxyproline content has been used as an indicator to determine collagen and/or gelatin amount. However, the mammalian proteins elastin and argonaute 2 have collagen-like domains in which hydroxyproline is formed. Some snail poisons, conotoxins, contain hydroxyproline, but lack collagen-like sequences. Hydroxylation of proline has been shown to be involved in targeting Hypoxia-inducible factor (HIF) alpha subunit (HIF-1 alpha) for degradation by proteolysis. Under normoxia (normal oxygen conditions) EGLN1[1] protein hydroxylates the proline at the 564 position of HIF-1 alpha, which allows ubiquitylation by the von Hippel-Lindau tumor suppressor (pVHL) and subsequent targeting for proteasome degradation. DYRK1A, DYRK1B, protein kinase B, eEF2, IKK2, p53, FOXO3A, CEP192 are also reportedly hydroxylated by PHD1. p53 and MAPH6 are also hydroxylated by PHD3. Free hydroxyproline appears to be an antioxidant, like free proline.
Woven bone is produced when osteoblasts produce osteoid rapidly, which occurs initially in all fetal bones, but is later replaced by more resilient lamellar bone. In adults, woven bone is created after fractures or in Paget's disease. Woven bone is weaker, with a smaller number of randomly oriented collagen fibers, but forms quickly; it is for this appearance of the fibrous matrix that the bone is termed woven. It is soon replaced by lamellar bone, which is highly organized in concentric sheets with a much lower proportion of osteocytes to surrounding tissue. Lamellar bone, which makes its first appearance in humans in the fetus during the third trimester, is stronger and filled with many collagen fibers parallel to other fibers in the same layer (these parallel columns are called osteons). In cross-section, the fibers run in opposite directions in alternating layers, much like in plywood, assisting in the bone's ability to resist torsion forces. After a fracture, woven bone forms initially and is gradually replaced by lamellar bone during a process known as "bony substitution". Compared to woven bone, lamellar bone formation takes place more slowly. The orderly deposition of collagen fibers restricts the formation of osteoid to about 1 to 2 μm per day. Lamellar bone also requires a relatively flat surface to lay the collagen fibers in parallel or concentric layers.
In 1934, Willard Libby reported that he had found weak beta activity in pure neodymium, which was attributed to a half-life over 1012 years. Almost 20 years later, it was claimed that the element occurs in natural neodymium in equilibrium in quantities below 10−20 grams of promethium per one gram of neodymium. However, these observations were disproved by newer investigations, because for all seven naturally occurring neodymium isotopes, any single beta decays (which can produce promethium isotopes) are forbidden by energy conservation. In particular, careful measurements of atomic masses show that the mass difference between 150Nd and 150Pm is negative (−87 keV), which absolutely prevents the single beta decay of 150Nd to 150Pm. In 1965, Olavi Erämetsä separated out traces of 147Pm from a rare earth concentrate purified from apatite, resulting in an upper limit of 10−21 for the abundance of promethium in nature; this may have been produced by the natural nuclear fission of uranium, or by neutron capture of 146Nd. Both isotopes of natural europium have larger mass excesses than sums of those of their potential alpha daughters plus that of an alpha particle; therefore, they (stable in practice) may alpha decay to promethium. Research at Laboratori Nazionali del Gran Sasso showed that europium-151 decays to promethium-147 with the half-life of 5×1018 years; later measurements gave the half-life as (4.62 ± 0.95(stat.) ± 0.68(syst.)) × 1018 years. It has been shown that europium is "responsible" for about 12 grams of promethium in the Earth's crust.
In September 2026, a UN-commissioned fact-finding mission panel found "reasonable grounds" to believe that the United States had committed war crimes during military strikes in Iran during the 2026 Iran war. The report highlighted two 28 February strikes that killed at least 178 civilians. U.S. president Donald Trump's threats to completely destroy Iranian power plants and other essential infrastructure during the 2026 Iran war have been widely condemned by human rights organizations, legal experts, and lawmakers as potential war crimes. The report published by the Independent International Fact-Finding Mission on Iran detailed two specific U.S. military operations on the first day of the 2026 Iran war that it determined constituted indiscriminate attacks on civilian infrastructure, the Minab School Bombing, where a U.S. Tomahawk missile strike targeted the Shajareh Tayyebeh Primary School in the southern city of Minab. The attack killed more than 150 people, including approximately 120 children. The UN mission concluded that the school was the intended point of impact rather than collateral damage, as well as the Lamerd Sports Complex Strike, where a separate U.S. airstrike utilized precision strike missiles to disperse tungsten pellets over a clearly identifiable sports complex and residential area in Lamerd. The attack resulted in the deaths of 22 civilian men and women. The Trump administration firmly rejected the allegations. White House spokeswoman Anna Kelly dismissed the findings as "unserious nonsense," stating that the U.S.
Operational aircraft of the force may be far less than official figures represent. According to a report in Le Figaro in April 2006, the Chadian Air Force consisted only of two Lockheed C-130 Hercules transports, one working Mil Mi-17 helicopter, and two non-working Mil Mi-24 helicopters. Later C-130 TT-PAF was lost in a landing accident at Abéché, on 11 June 2006.
Sources: en.wikipedia.org
CaSO4 · 2 H2O → CaSO4 · 1/2 H2O + 1+1/2 H2O↑ The endothermic property of this reaction is relevant to the performance of drywall, conferring fire resistance to residential and other structures. In a fire, the structure behind a sheet of drywall will remain relatively cool as water is lost from the gypsum, thus preventing (or substantially retarding) damage to the framing (through combustion of wood members or loss of strength of steel at high temperatures) and consequent structural collapse. But at higher temperatures, calcium sulfate will release oxygen and act as an oxidizing agent. This property is used in aluminothermy. In contrast to most minerals, which when rehydrated simply form liquid or semi-liquid pastes, or remain powdery, calcined gypsum has an unusual property: when mixed with water at normal (ambient) temperatures, it quickly reverts chemically to the preferred dihydrate form, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice:
==== Resignation of Héctor Béjar ==== Almost immediately after his appointment as Foreign Minister, the media began reporting on Héctor Béjar's past. Béjar had been part of the National Liberation Army during the 1960s and had met Che Guevara according to his book "Peru 1965: Notes on a Guerrilla Experience." In a video published in November 2020, Béjar had said that 'terrorism began in the Navy' and that 'the Shining Path was trained by the CIA', leading to significant public backlash. Later, the Peruvian Navy put out a statement about wanting Béjar to retract, and claimed that Béjar's statement were an affront against those who fought against terrorism. Following that, Congress started an interpellation process against Béjar, which was seen by manyas a show trial that would be almost certainly followed by impeachment. However, Béjar resigned before the interpellations began. According to Béjar, Prime Minister Guido Bellido asked him to resign to prevent him from speaking before Congress, which he said was a way of censoring him. Béjar held the position of Foreign Minister for just 19 days. His replacement was the career diplomat Óscar Maúrtua. After his resignation, Béjar posted "I am free again!!!" on Facebook. Later, he would claim that this was the beginning of a soft coup against the Castillo's government. Béjar also claimed that there is a group in the Navy and the extreme right that does not want an independent foreign policy. He also claimed that his phrases were distorted and taken out of context.
==== Fragmentation tree computation ==== A fragmentation tree is a representation of the fragmentation process similar to "fragmentation diagrams" created by experts. The fragmentation tree annotates the MS2 spectrum by providing a molecular formula for each fragment peak. Peaks that do not receive an annotation are considered noise peaks. The fragmentation tree also predicts the fragmentation reactions (called losses) leading to the fragment peaks. Fragmentation trees are a valuable tool for deducing information about the fragmentation but are not a precise depiction of the actual fragmentation process. To identify the molecular formula of an unknown molecule, a separate fragmentation tree is computed for every molecular formula candidate. In other words, the method attempts to reconstruct the fragmentation process that led to this MS2 spectrum for each candidate molecular formula. This allows to compare the different hypotheses that a particular candidate is actual the correct molecular formula. The best-scoring fragmentation tree (i.e. the fragmentation process that is best explaining the spectrum) corresponds to the most likely molecular formula explanation.
AM-1235 metabolism differs only slightly from that of JWH-018. AM-1235 N-dealkylation produces 1-fluoropentane instead of pentane or other simple alkanes in general. It had been speculated that the fluoropentane might function as an alkylating agent or be further metabolized into toxic fluoroacetic acid. This is not true, however, as fluoroalkanes do not act as alkylating agents under normal conditions and odd-length fluoroalkane chains metabolize into substantially less toxic fluoropropanoic acid.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide that acts as an agonist at melanocortin receptors. It is not a hormone replacement therapy and not a vasodilator in the usual clinical sense, although it does affect vascular tone. Chemically it belongs to the melanocortin analogue family.
PT-141 was the internal development code used during early research and it persists in older publications, conference abstracts, and informal listings. The code and the approved name refer to the same molecule. Its continued use reflects habit in the literature rather than any difference in substance.
No. The intranasal form was studied in trials but was never approved, and absorption through the nasal route varies considerably between individuals. Approved labelling covers a subcutaneous injection only. Any nasal product sold outside regulated channels falls outside verified manufacturing.
The approved formulation is given by subcutaneous injection and is used on an as-needed basis rather than on a fixed daily schedule. An intranasal version was studied earlier but did not reach the same stage of development. Route of delivery strongly affects how quickly the peptide appears in circulation.