Pentapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-03-28 and is reviewed periodically as new material appears.
The molecule contains five residues, including alpha-aminoisobutyric acid, D-2-naphthylalanine, and D-phenylalanine, and it ends in a lysine amide. Non-natural and D-configured residues make the chain less susceptible to common peptidases, which helps explain its resistance to rapid breakdown. Its molecular formula is C38H49N9O5, corresponding to a free-base mass near 711.9 daltons. The C-terminal amide removes a negative charge and is a recurring feature in receptor-active peptides of this family. These structural choices are usually discussed as the basis for its selectivity profile.
Published animal and early human work describes growth hormone release that is separated from comparable rises in adrenocorticotropic hormone and cortisol. Prolactin changes are reported as small in the same studies. Selectivity is attributed to binding at the ghrelin receptor and to the downstream signaling that follows, rather than to differences in how quickly the peptide is cleared. Authors commonly label the compound selective rather than potent, because the same mass produces a smaller growth hormone response than some older secretagogues tested in parallel. Whether that profile holds across species and routes of administration remains an open question.
Reversed-phase high-performance liquid chromatography is the standard method for purity assessment, most often on a C18 column with a water and acetonitrile gradient and trifluoroacetic acid or formic acid as an ion-pairing agent. Mass spectrometry by electrospray or matrix-assisted laser desorption confirms the expected mass and reveals truncated or modified sequences. Amino acid analysis and sequencing provide orthogonal structural evidence. Typical impurities include deletion sequences, oxidized products, and dimeric species. Detection wavelength, usually 214 or 220 nanometers, should be reported because response factors differ between peptides.
Purity is normally reported as a percentage of total peak area, a figure that does not account for water content, residual solvents, or counterions. Trifluoroacetate and acetate are the most frequent counterions in lyophilized peptides, and they shift the true peptide content away from the mass of the powder. A separate quantitative assay is therefore needed to state content accurately. Certificates of analysis often omit these details, which makes batch-to-batch comparison difficult and limits conclusions drawn when results from different suppliers are compared.
Lyophilized material is generally held at minus twenty degrees Celsius or lower, protected from moisture and light. Repeated excursions to room temperature cause condensation inside the vial and gradual moisture uptake, both of which shorten shelf life. Containers should be allowed to equilibrate before opening so that water does not condense on the solid. Dividing a batch into single-use aliquots reduces freeze-thaw cycling. Solid peptide handled this way is usually considered stable for months to years, while the same material in solution degrades on a much shorter timescale.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Value for the free base |
| Molar mass | 711.9 g/mol | Calculated from the formula |
| Appearance | White to off-white powder | Typical lyophilized form |
| Mechanism class | Ghrelin receptor agonist | Also described as a secretagogue |
| Half-life | About 2 hours | Reported for human circulation |
At the cellular level, ipamorelin binds the growth hormone secretagogue receptor, also called the ghrelin receptor. Activation of this receptor on pituitary somatotroph cells triggers a signaling cascade that leads to release of growth hormone into circulation. Because release follows a pulsatile pattern, studies often report peak concentration and total area under the curve rather than a single time point. Selectivity for this receptor is the property most frequently discussed in comparative work.
Compared with older secretagogues such as hexarelin or GHRP-6, ipamorelin shows weaker stimulation of cortisol, prolactin, and appetite in the animal models used for early characterization. Whether that selectivity is preserved across longer human exposures remains an open question, because published clinical data are limited in size and duration. Reported effects on food intake are generally described as modest. The compound is therefore treated in the literature as a relatively selective research tool rather than a fully characterized therapeutic agent.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Researchers at a pharmaceutical company first described it in the 1990s while screening small peptides for growth hormone releasing activity. Its chain contains five amino acid residues, two of which are non-natural building blocks, including 2-aminoisobutyric acid and a naphthylalanine derivative. The molecule was designed to act at the ghrelin receptor while avoiding several effects observed with earlier secretagogues.
Material supplied for research use is normally a white to off-white lyophilized powder. The solid is hygroscopic and is handled in a low-humidity environment to limit water uptake. Bulk quantities are frequently shipped in sealed vials under inert gas. Once reconstituted in water or a neutral buffer, the solution is less stable than the dry powder and is usually divided into single-use aliquots.
Long-term storage of the dry powder is typically at minus twenty degrees Celsius or lower, protected from light and moisture. Solutions are commonly kept frozen and thawed only once, because repeated freeze-thaw cycles can promote aggregation and loss of measurable peptide content. Buffers near neutral pH are preferred over strongly acidic or strongly basic conditions. Shipping at ambient temperature is acceptable for short periods when the powder remains sealed and desiccated.
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.
Compared with earlier growth hormone secretagogues such as GHRP-6 and hexarelin, ipamorelin has been reported to produce less stimulation of adrenocorticotropic hormone, cortisol, and prolactin in animal and early human studies. This selectivity is usually attributed to differences in receptor subtype interactions and to the tissue distribution of the receptor. Effects on appetite appear weaker than those of ghrelin itself, although the supporting evidence base is small. Whether these differences produce a distinct clinical profile remains an open question, since controlled human trials are limited.
=== Audiovisual work === After military service in World War I, Jones returned to Hallock where he worked as a mechanic while learning about electronics. Jones built a transmitter for the town's first radio station. He also invented a device to combine sound with motion pictures. This attracted the attention of local entrepreneur Joseph A. Numero of Minneapolis, Minnesota. Numero owned a company that manufactured audio equipment called Ultraphone Sound Systems Inc. and was later renamed Cinema Supplies Inc. He hired Jones in 1927 as an electrical engineer to improve the audio equipment made by his firm. Jones worked on converting silent movie projectors into audiovisual projectors. He also patented a ticket-dispensing machine for movie theaters.
=== 2014 FDA Form 483 === In December 2014 the FDA issued a Form 483 letter over concerns discovered during an inspection of its Srikakulam facility. No specific violations were mentioned in the letter.
=== Reorganization after 1949 === Following the Communist party took over Chengdu in 1949, the institution underwent several reorganizations and name changes. In 1951, West China Union University was renamed West China University. In 1953, following the nationwide restructuring of higher education, it became the Department of Stomatology and affiliated stomatological hospital of Sichuan Medical College. China's first dedicated oral and maxillofacial surgery ward was also established there in 1953. A Research Institute of Stomatology was established in 1958. In 1966, a purpose-built stomatological hospital building was completed, while postgraduate education expanded in the following decades. The institution became an authorized master's-degree training site in stomatology in 1978 and a doctoral-degree training site in 1981. In 1985, Sichuan Medical College was renamed the West China University of Medical Sciences, and the dental institution became its College of Stomatology and affiliated stomatological hospital. The hospital was recognized as a Grade-III, Class-A stomatological specialist hospital in 1997.
The molecular mass (m) is the mass of a given molecule, often expressed in units of daltons (Da). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quantity relative molecular mass is the unitless ratio of the mass of a molecule to the atomic mass constant (which is equal to one dalton). The molecular mass and relative molecular mass are distinct from but related to the molar mass. The molar mass is defined as the mass of a given substance divided by the amount of the substance, and is expressed in grams per mole (g/mol). That makes the molar mass an average of many particles or molecules (weighted by abundance of the isotopes), and the molecular mass the mass of one specific particle or molecule. The molar mass is usually the more appropriate quantity when dealing with macroscopic (weigh-able) quantities of a substance. The definition of molecular weight is most authoritatively synonymous with relative molecular mass, which is dimensionless; however, in common practice, use of this terminology is highly variable. When the molecular weight is given with the unit Da, it is frequently as a weighted average (by abundance) similar to the molar mass but with different units. In molecular biology and biochemistry, the mass of macromolecules is referred to as their molecular weight and is expressed in kilodaltons (kDa), although the numerical value is often approximate and representative of an average.
Carl von Linde, an engineering professor at the Technical University of Munich in Germany, patented an improved method of liquefying gases in 1876, creating the first reliable and efficient compressed-ammonia refrigerator. His new process made possible the use of gases such as ammonia (NH3), sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants, which were widely used for that purpose until the late 1920s despite safety concerns. In 1895 he discovered the refrigeration cycle.
Sources: en.wikipedia.org
===== Behavioral treatments ===== A 2018 systematic review and network meta-analysis of 50 trials involving 12 different psychosocial interventions for amphetamine, methamphetamine, or cocaine addiction found that combination therapy with both contingency management and community reinforcement approach had the highest efficacy (i.e., abstinence rate) and acceptability (i.e., lowest dropout rate). Other treatment modalities examined in the analysis included monotherapy with contingency management or community reinforcement approach, cognitive behavioral therapy, 12-step programs, non-contingent reward-based therapies, psychodynamic therapy, and other combination therapies involving these. Additionally, research on the neurobiological effects of physical exercise suggests that daily aerobic exercise, especially endurance exercise (e.g., marathon running), prevents the development of drug addiction and is an effective adjunct therapy (i.e., a supplemental treatment) for amphetamine addiction. Exercise leads to better treatment outcomes when used as an adjunct treatment, particularly for psychostimulant addictions. In particular, aerobic exercise decreases psychostimulant self-administration, reduces the reinstatement (i.e., relapse) of drug-seeking, and induces increased dopamine receptor D2 (DRD2) density in the striatum. This is the opposite of pathological stimulant use, which induces decreased striatal DRD2 density.
Acid-fastness is a physical property of certain bacteria, protozoa, and eukaryotic cells, as well as some subcellular structures, referring to their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name acid-fast. Historically, acid-fast stains were thought to stain lipids of the cells based on the observed characteristics of cell staining under a wide range of conditions, although the results were limited by the tools available, however as early as 1959 there were observations of how nucleic acids were acid fast. Dyes such as carbol fuchsin and auramine O penetrate the cell and bind to DNA and RNA, producing characteristic red or yellow-green fluorescence, respectively. The property of “acid-fastness” therefore reflects the organism’s ability to retain these dyes after acid–alcohol decolorization, a feature determined mainly by the integrity and composition of the outer cell wall rather than by any specific lipid chemistry. The mechanisms of acid-fastness vary by species. In the genus Mycobacterium, the property has been traditionally attributed to the high mycolic acid content of the cell wall, which indeed contributes to dye retention and resistance to decolorization.
RC(O)NR'2 + HNR"2 → RC(O)NR"2 + HNR'2 The reaction is rarely employed, but it could prove relevant to peptide synthesis. Amides are characteristically inert, but the amino substituents can be exchanged in the presence of Lewis acid and organometallic catalysts. Primary amides (RC(O)NH2) are more amenable to this reaction.
Oral fibromas are also termed irritation fibromas, focal fibrous hyperplasia, and traumatic fibromas. These lesions are nodules that occur on the buccal mucosa (i.e. mucous membranes lining the cheeks and back of the lips) or lateral tongue. They may be irritating or asymptomatic and are the most common tumor-like lesions in the oral cavity. Oral fibromas are not neoplasms; they are hyperplastic (i.e. overgrowth) reactions of fibrous tissue to local trauma or chronic irritation.
Sources: en.wikipedia.org
=== Quality control === No less than 90% of MAA particles can be between 10 - 90 micrometres in size and no particles may exceed 150 micrometres due to the risk of pulmonary artery blockade. No less than 90% of the radioactivity present in the product must be tagged to albumin particles. Thus, no more than 10% soluble impurities may be present.
== Non-functional proton coupled amino acid transporter == In hereditary disease iminoglycinuria, there is a defect in the human proton-coupled amino acid transporter 1 and 2 genes which results in a defect in the absorption of proline and glycine. Iminoglycinuria is an autosomal recessive disorder of the renal tubular. Lack of glycine and proline absorption leads to excess urinary excretions containing amino acids. If the transporters are not working properly, a drug that they usually help gain entry in to the cell might not be absorbed Their function can also be inhibited by tryptophan derivatives and allow for exploration into the function of hPAT1 and hPAT2. Additionally, mutations that lead to structural changes in amino acid binding sites play a role in their functional transport.
In the field of pharmacokinetics, the area under the curve (AUC) is the definite integral of the concentration of a drug in blood plasma as a function of time (this can be done using liquid chromatography–mass spectrometry). In practice, the drug concentration is measured at certain discrete points in time and the trapezoidal rule is used to estimate AUC. In pharmacology, the area under the plot of plasma concentration of a drug versus time after dosage (called "area under the curve" or AUC) gives insight into the extent of exposure to a drug and its clearance rate from the body.
Sources: en.wikipedia.org
It has not been approved as a therapeutic by major regulators, and the human trial record is small and dated. Material available today is mostly sold as a research chemical for laboratory use. Approval and restriction status varies by country.
It binds the ghrelin receptor, known as the growth hormone secretagogue receptor type 1a. Activation of that receptor triggers signaling that leads to growth hormone release. Selectivity for growth hormone over cortisol and prolactin is the property most often cited for this compound.
Published estimates place the circulating half-life at roughly two hours in humans. Clearance involves peptidase activity and renal handling. Because the peptide is short-lived, release patterns after administration are usually described as pulsatile rather than sustained.
It is reported as the percentage of total peak area in a reversed-phase chromatogram. That number does not reflect water content, residual solvents, or counterions. The actual peptide content is therefore lower than the stated purity figure suggests.