pentapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-08-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
Ipamorelin is a synthetic pentapeptide classified as a growth hormone secretagogue. Its sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combines three non-proteinogenic residues with a C-terminal amide. The N-terminal aminoisobutyric acid unit and the two aromatic D-amino acids distinguish it from peptides assembled only from standard L-amino acids. Its formula is C38H49N9O5, corresponding to an average mass near 711.9 Da. At neutral pH the molecule carries a net positive charge, a property that shapes its behaviour in chromatographic and electrophoretic systems.
The compound was developed at Novo Nordisk during the 1990s as part of a programme seeking secretagogues with improved selectivity. It was described in the peer-reviewed literature in 1998 alongside related pentapeptides from the same series. Investigators advanced it because it raised growth hormone output in animal models while leaving other pituitary hormones comparatively unaffected. The development code NNC 26-0161 appears in earlier reports, and ipamorelin later became the common designation in published work.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue family. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues that resist enzymatic breakdown. Researchers at Novo Nordisk described the compound in the 1990s while searching for agents that release growth hormone with fewer side effects than earlier secretagogues. The molecule acts as an agonist at the ghrelin receptor, also called GHS-R1a, which is expressed in the pituitary and in several peripheral tissues.
Selectivity distinguishes ipamorelin from first-generation secretagogues such as GHRP-6. At doses that reliably raise growth hormone, it shows little stimulation of adrenocorticotropic hormone or cortisol release in animal models, and it does not markedly raise prolactin or appetite. Binding at GHS-R1a on pituitary somatotrophs triggers calcium influx and pulsatile growth hormone secretion. Because the compound mimics the natural ghrelin signal, the release pattern tends to follow the body's own rhythm rather than producing a sustained elevation.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Pentapeptide with C-terminal amide |
| Average mass | Approximately 711.9 Da | Value derived from the formula |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and aqueous acetonitrile | Dissolution aided by acidic diluents |
| Common synonyms | Ipamorelin; NNC 26-0161 | Code name used in early reports |
Ipamorelin is a synthetic pentapeptide first described in the 1990s by researchers at Novo Nordisk during a program to develop selective growth hormone secretagogues. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues, alpha-aminoisobutyric acid and D-2-naphthylalanine. The C-terminus is amidated, and the material is supplied as a white lyophilized powder. The molecular formula is C38H49N9O5 and the monoisotopic mass is approximately 711.85 daltons. The short chain and modified residues give it greater resistance to enzymatic degradation than many larger peptide hormones.
At the molecular level, ipamorelin acts as an agonist at the growth hormone secretagogue receptor type 1a, the same G protein-coupled receptor that binds ghrelin. Receptor activation couples to Gq/11 signaling, raising intracellular calcium through inositol trisphosphate and diacylglycerol, which in turn promotes exocytosis of growth hormone from pituitary somatotroph cells. Ipamorelin binds this receptor with high affinity and shows weak activity at other secretagogue-related targets in vitro. Its action requires the intact receptor and is not reversed by growth hormone-releasing hormone antagonists.
Lyophilized material is generally stored cold and dry, with desiccant, and protected from light. In solution the peptide is more vulnerable: the histidine side chain can oxidize, and repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. A mildly acidic aqueous buffer is often used for short-term handling because it limits several degradation routes. Accurate prediction of long-term stability under a given set of conditions is difficult, and published stability data remain sparse.
Published discussion of this compound is uneven. Some references describe it as a tool for probing growth hormone regulation, while others focus on analytical characterization or on comparisons with related secretagogues. Statements about selectivity, half-life and potency often trace back to a small number of original reports that later authors cite secondhand. Readers evaluating a claim should therefore check whether a figure reflects a direct measurement or a repeated citation, and whether the underlying study was conducted in animals, in isolated cells or in human volunteers.
=== Relative humidity and temperature === Inconsistent relative humidity and temperature provide the perfect environment for mold and fungi growth on waterlogged wood. Growth of mold or other bacteria requires immediate attention to control damage. Natural cellulosic materials are the best environment for mold spores to grow and mature. "Mold is a microorganism that produces enzymes that convert the cellulose in fibers to soluble sugar that is metabolized as food. Proteins are generally less susceptible, but keratinophilic fungi will feed on, and damage, these fibers as well". Similar to wood found in nature, mold and other feeding organisms are attracted to the material, this includes pests and naturally occurring fungi and bacteria. Mold is a high risk for waterlogged wood even with controlled relative humidity and temperature due to the resilient nature of the organisms and the perfect environment waterlogged wood provides as a food source to the growth of spores.
Other viruses have been implicated in its etiology, including cytomegalovirus, rubella virus, rotavirus, mumps virus, and SARS-CoV-2. Maternal infection during pregnancy has been associated with the development type 1 diabetes in the offspring; these studies implicated maternal infections with enteroviruses, cytomegalovirus and rubella virus.
Estradiol (E2), also called oestrogen, oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of female reproductive cycles such as estrous and menstrual cycles. Estradiol is responsible for the development of female secondary sexual characteristics such as the breasts, widening of the hips and a female pattern of fat distribution. It is also important in the development and maintenance of female reproductive tissues such as the mammary glands, uterus and vagina during puberty, adulthood and pregnancy. It also has important effects in many other tissues including bone, fat, skin, liver, and the brain. Though estradiol levels in males are much lower than in females, estradiol has important roles in males as well. Apart from humans and other mammals, estradiol is also found in most vertebrates and crustaceans, insects, fish, and other animal species. Estradiol is produced within the follicles of the ovaries and in other tissues including the testicles, the adrenal glands, fat, liver, the breasts, and the brain. Estradiol is produced in the body from cholesterol through a series of reactions and intermediates. The major pathway involves the formation of androstenedione, which is then converted by aromatase into estrone and is subsequently converted into estradiol. Alternatively, androstenedione can be converted into testosterone, which can then be converted into estradiol. Upon menopause in females, production of estrogens by the ovaries stops and estradiol levels decrease to very low levels.
Sources: en.wikipedia.org
While Stalin's death in 1953 slightly relaxed tensions, the situation in Europe remained an uneasy armed truce. The Soviets, who had already created a network of mutual assistance treaties in the Eastern Bloc by 1949, established a formal alliance therein, the Warsaw Pact, in 1955. It stood opposed to NATO.
== Arrangement == Cold traps should be assembled such that the down tube is connected to the source of gas whilst the cap is connected to the source of vacuum. Reversing this, connecting the down tube to the source of vacuum, places the inlet of the vacuum directly above the condensate, increasing the chances of vapour phase condensate moving up the (uncooled) down tube (towards the pump) or, should the trap begin to fill to an appreciable volume, liquid phase condensate being pulled into the pump.
These higher frequencies permit the great bandwidth required for television broadcasting. Since natural and artificial noise sources are less present at these frequencies, high-quality audio transmission is possible, using frequency modulation.
Sources: en.wikipedia.org
It is a synthetic five-amino-acid peptide that acts as a growth hormone secretagogue. Three of its residues are non-standard amino acids, and the chain ends in an amide rather than a free acid. The molecule is small enough that it can be characterised by routine peptide analytical techniques.
It has not received marketing approval as a medicine in the United States or the European Union. Supplied material is generally described and handled as a research chemical. Regulatory treatment varies by jurisdiction, and some countries restrict growth hormone secretagogues under sports or medicines legislation.
Earlier secretagogues were associated with broader hormonal responses, including measurable changes in cortisol and prolactin. Reports on this peptide describe a narrower profile in which growth hormone release is the most prominent effect. The observation is influential because it shapes how the compound is compared with other members of the same receptor family.
The peptide is Aib-His-D-2-Nal-D-Phe-Lys-NH2. Two of its residues are non-natural, which slows enzymatic degradation. The C-terminal amide is common among bioactive peptides.