pentapeptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Human data remain limited and come mainly from small, short-term studies conducted decades ago. The peptide has not received approval as a medicine from major regulators, so current availability is largely as a research chemical. Reported effects on growth hormone pulsatility, appetite, and body composition should be read as preliminary, since few independent groups have replicated the original findings. Analytical characterization of research-grade material varies between suppliers, which complicates comparison across studies. Regulatory status also differs by country, and some jurisdictions classify it as a prescription-only or otherwise restricted item.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class. It acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. The compound was designed in the 1990s during a search for agents that release growth hormone with fewer off-target hormonal effects than earlier secretagogues. It appears in the research literature under several sequence-based names. Material supplied for laboratory work is normally a lyophilized solid, and it is not marketed as an approved therapeutic in major jurisdictions.
从用途定位看，ipamorelin 目前主要以研究用肽的身份被讨论，未见主要药品监管机构将其批准为治疗药物。市售材料通常标注仅供研究使用，不得用于人体或诊断程序。文献中它常与生长激素促分泌素、GHS-R1a 激动剂、胃饥饿素拟似物等表述并列出现。既有研究的样本量普遍偏小，因此对其效应强度与一致性的描述应保持谨慎。
Ipamorelin 是一种合成五肽，序列为 Aib-His-D-2-Nal-D-Phe-Lys-NH2，分子式 C38H49N9O5，游离碱分子量约 711.85 g/mol。它属于生长激素促分泌素（GHS）家族，作用靶点是胃饥饿素受体 GHS-R1a。该化合物由诺和诺德的研究团队在二十世纪九十年代末报道，设计目标是提高对生长激素释放的选择性。C 端酰胺化与 N 端 Aib 残基是两个用于抵抗肽酶降解的结构特征。
在 GHS 家族中，早期肽类如 GHRP-6 与 GHRP-2 会同时促进生长激素、皮质醇与催乳素的释放，并明显增加食欲。Ipamorelin 在动物与早期人体研究中表现出对生长激素释放的相对选择性，对上述其他激素的影响较小。这种差异通常归因于受体结合模式与下游信号偏向的不同，而完整的分子解释仍有待补充。需要区分的是，选择性是研究观察中的相对程度，并非绝对界限。
| 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 |
Selectivity is the property most often attached to this peptide. Published animal and early human studies record increases in growth hormone release after administration, with adrenocorticotropic hormone and cortisol responses remaining small by comparison. Effects on appetite-related pathways also appear weaker than those reported for several earlier secretagogues. Reviews that compare members of the growth hormone secretagogue family cite these findings frequently, though the receptor-level explanation for the selectivity continues to be debated rather than settled.
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.
Structural features distinguish the molecule from earlier secretagogues. An alpha-aminoisobutyric acid residue near the N-terminus and a D-naphthylalanine substitution increase receptor affinity, while C-terminal amidation improves resistance to exopeptidases. These modifications are associated with reduced stimulation of appetite and of the hypothalamic-pituitary-adrenal axis compared with hexarelin or growth hormone releasing peptide-6. Whether the same profile applies at every dose level studied is a matter of ongoing investigation rather than settled consensus.
Ipamorelin is a synthetic pentapeptide that acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. Its sequence incorporates non-natural residues, which slows enzymatic breakdown relative to short native peptides. In laboratory and early clinical work the compound is described as a selective growth hormone secretagogue because it raises growth hormone with comparatively little effect on other pituitary outputs. The degree to which that selectivity holds across species and dosing regimens remains an open question in the published literature.
Signal transduction begins when the peptide binds GHSR-1a on pituitary somatotrophs. The receptor couples to Gq/11 proteins, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate into inositol trisphosphate and diacylglycerol. Inositol trisphosphate releases calcium from intracellular stores, and the resulting rise in cytosolic calcium drives growth hormone vesicle fusion. Concurrent Gs coupling and cyclic AMP elevation have also been reported, and the relative contribution of each arm to the overall secretory response is not fully settled.
Quality control for research-grade ipamorelin is not governed by a single harmonized pharmacopeial monograph, so certificates of analysis vary between suppliers. Common tests include appearance, solubility, water content, peptide content by quantitative amino acid analysis, and residual counterion measurement. Independent verification by an outside laboratory is often used to confirm identity and purity claims. Salt form, counterion content, and residual solvent levels are frequently unspecified, which complicates direct comparison between lots and leaves reproducibility partly unresolved.
Identity and purity assessment of ipamorelin relies mainly on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometers, a wavelength where the peptide backbone absorbs. Mass confirmation is typically obtained by electrospray ionization mass spectrometry or by liquid chromatography coupled to mass spectrometry, comparing the observed mass with the calculated value. Amino acid analysis and peptide mapping after enzymatic digestion can confirm the sequence. Impurity profiles include deletion peptides, truncated fragments, and oxidation products, reported as relative area percentages.
Lyophilized ipamorelin is generally held at minus twenty degrees Celsius or colder, protected from light and moisture. In solution the peptide is less stable, and degradation proceeds through hydrolysis of the amide backbone, oxidation of the histidine residue, and aggregation. Repeated freeze-thaw cycles accelerate these processes, so dividing material into single-use aliquots before freezing is common practice in research settings. Buffered formulations near neutral pH tend to show the slowest degradation, while strongly acidic or basic conditions raise hydrolysis rates. Stability data specific to ipamorelin are sparse, and much guidance is extrapolated from other short peptides.
Factor VIII was first characterized in 1984 by scientists at Genentech. The gene for factor VIII is located on the X chromosome (Xq28). The gene for factor VIII presents an interesting primary structure, as another gene (F8A1) is embedded in one of its introns.
== Biological applications == Chemiluminescence has been applied by forensic scientists to solve crimes. In this case, they use luminol and hydrogen peroxide. The iron from the blood acts as a catalyst and reacts with the luminol and hydrogen peroxide to produce blue light for about 30 seconds. Because only a small amount of iron is required for chemiluminescence, trace amounts of blood are sufficient. In biomedical research, the protein that gives fireflies their glow and its co-factor, luciferin, are used to produce red light through the consumption of adenosine triphosphate (ATP). This reaction is used in many applications, including the effectiveness of cancer drugs that choke off a tumor's blood supply. This form of bioluminescence imaging allows scientists to test drugs in the pre-clinical stages cheaply. Another protein, aequorin, found in certain jellyfish, produces blue light in the presence of calcium. It can be used in molecular biology to assess calcium levels in cells. What these biological reactions have in common is their use of ATP as an energy source. Though the structure of the molecules that produce luminescence is different for each species, they are given the generic name of luciferin. Firefly luciferin can be oxidized to produce an excited complex. Once it falls back down to a ground state a photon is released. It is very similar to the reaction with luminol.
Parathyroid hormone is efficiently removed from the blood by a receptor-mediated process in the liver and is broken down into smaller peptide fragments. The fragments derived from the amino-terminus are further degraded within the cell while the fragments derived from the carboxy-terminus are released back into the blood and cleared by the kidney. These carboxy-terminal fragments are thought to play a role in the regulation of parathyroid hormone activity. Under normal physiological conditions full-length parathyroid hormone H constitutes only 5-30% of the circulating forms of the molecule, while 70-95% is present as carboxy-terminal fragments. Following administration of Preotact, carboxy-terminal fragments make up about 60-90% of the circulating forms of the molecule. Intersubject variability in systemic clearance is about 15%.
In chemical ionization (CI), the analyte is ionized by a chemical reaction with an ionized reagent gas (itself ionized by some technique, such as by EI). The analyte gas and the reagent gas intersect, and react. The reaction then produces ionized analyte fragments by various mechanisms, including proton transfer, electron transfer, and adduct formation. The ion is then accelerated electrostatically, as in EI. CI ion sources are similar to EI sources, and most modern mass spectrometers can switch from EI to CI mode in minutes. To ensure efficiency, the amount of reagent is much higher than the analyte. Consequently, a large amount of reagent ions would end up in the mass analyzer. This is usually handled by only measuring the part of the spectrogram with m/z above those of the main species in the reagent ion stream. Common ionizing reagents for CI-MS include methane, ammonia, isobutane, and methanol. The proton affinity of the reagent gas and of the sample should be matched to ensure efficient ionization. If the proton affinity of the reagent gas is too high, ionization is inefficient. If the proton affinity of the reagent gas is too low, fragmentation is excessive. For example:
In Lao cuisine, Lao coriander is used extensively in traditional Lao dishes such as 'mok pa' (steamed fish in banana leaf) and several coconut milk curries that contain fish or prawns. In China dill is called colloquially, 'huíxiāng' (茴香, perfume of Hui people), or more properly 'shíluó' (莳萝/蒔蘿). It is a common filling in 'baozi', 'jiaozi' and 'xianbing' and may be used as vegetarian with rice vermicelli, or combined with either meat or eggs. Vegetarian dill baozi are a common part of a Beijing breakfast. In baozi and xianbing, it often is interchangeable with non-bulbing fennel and the term 茴香 also may refer to fennel, similarly to caraway and coriander leaf, sharing a name in Chinese as well. Dill also may be stir fried as a potherb, often with egg, in the same manner as Chinese chives. In Northern China, Beijing, Inner-Mongolia, Ningxia, Gansu, and Xinjiang, dill seeds commonly are called 'zīrán' (孜然), but also 'kūmíng' (枯茗), 'kūmíngzi' (枯茗子), 'shíluózi' (莳萝子/蒔蘿子), 'xiǎohuíxiāngzi' (小茴香子) and are used with pepper for lamb meat. In the whole of China, 'yángchuàn' (羊串) or 'yángròu chuàn' (羊肉串), lamb brochette, a speciality from Uyghurs, uses cumin and pepper. In Cantonese-speaking regions such as Hong Kong and Macau, the leaves are more colloquially known as 刁草 (diu1 cou2), a partial calque of the English 'dillweed'; 'dill' transliterated into the otherwise unrelated 刁 diu1 and 'weed' translated as 草 cou2. In Taiwan, it is also commonly used as a filling in steamed buns (baozi) and dumplings (jiaozi). In Vietnam, the use of dill in cooking is regional.
Sources: en.wikipedia.org
== Geology == Motion between the Kula Plate and the North American Plate along the margin of the Bering Shelf (in the Bering Sea north of the Aleutian arc) ended in the early Eocene. The Aleutian Basin, the ocean floor north of the Aleutian arc, is the remainder of the Kula Plate that was trapped when volcanism and subduction jumped south to its current location at c. 56 Ma. The Aleutian island arc formed in the Early Eocene (55–50 Ma) when the subduction of the Pacific Plate under the North American Plate began. The arc is made of separate blocks that have been rotated clockwise. The basement underlying the islands is made of three stratigraphic units: an Eocene layer of volcanic rock, an Oligocene–Miocene layer of marine sedimentary rock, and a Pliocene–Quaternary layer of sedimentary and igneous rock.
The G beta-gamma complex (Gβγ) is a tightly bound dimeric protein complex, composed of one Gβ and one Gγ subunit, and is a component of heterotrimeric G proteins. Heterotrimeric G proteins, also called guanine nucleotide-binding proteins, consist of three subunits, called alpha, beta, and gamma subunits, or Gα, Gβ, and Gγ. When a G protein-coupled receptor (GPCR) is activated, Gα dissociates from Gβγ, allowing both subunits to perform their respective downstream signaling effects. One of the major functions of Gβγ is the inhibition of the Gα subunit.
Clinical: International assessment of diagnostics and therapy with the aim of improving clinical understanding and treatment procedures. Clinical-translational: Analysis of the significance of plasma and urine steroid profiles / liquid biopsy with the aim of identifying suitable tumor markers. Experimental: Identification of immunohistochemical characteristics and DNA sequencing with the aim of identifying drugable targets, i.e., targets for the drug treatment of tumor cells. This should ensure that healthy cells are spared from the drug as much as possible.
== See also == Russell 3000 Index – U.S. all-cap stock market index Russell 1000 Index – U.S. large-cap stock market index S&P 600 – American small-cap stock market index List of largest daily changes in the Russell 2000
==== 1.C Pore-forming toxins (proteins and peptides) ==== 1.C.3 α-Hemolysin (αHL) family 1.C.4 Aerolysin family 1.C.5 ε-toxin family 1.C.11 RTX-toxin superfamily 1.C.12 Membrane attack complex/perforin superfamily 1.C.13 Leukocidin family 1.C.14 Cytohemolysin (CHL) family 1.C.39 Thiol-activated cholesterol-dependent cytolysin family 1.C.43 Lysenin family 1.C.56 Pseudomonas syringae HrpZ cation channel family 1.C.57 Clostridial cytotoxin family 1.C.58 The Microcin E492/C24 (Microcin E492) Family 1.C.74 Snake cytotoxin (SCT) family 1.C.97 Pleurotolysin pore-forming family
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.
两者都是 GHS-R1a 激动剂，但 ipamorelin 在研究中显示出更高的生长激素释放选择性。早期资料显示它对皮质醇、催乳素与食欲的刺激弱于 GHRP-6。这些差异是相对程度，而非绝对区分。