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 2026-01-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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。
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.
Most published work on ipamorelin comes from rodent studies and small early-phase human trials. Subcutaneous and intravenous routes have been used, while oral delivery is limited by poor absorption and rapid breakdown in the gut. The reported plasma half-life is short, on the order of two hours, and varies with species and assay method. Whether chronic use produces meaningful clinical benefit remains unresolved, and long-term safety data in humans are sparse. No major regulatory agency has approved the compound as a therapeutic drug.
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.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C38H49N9O5 | 五肽，C 端酰胺化 |
| 分子量 | 约 711.85 g/mol | 游离碱形式 |
| 外观 | 白色至类白色冻干粉 | 研究用材料的常见形态 |
| 溶解性 | 溶于水及 DMSO 等极性溶剂 | 建议现配现用 |
| 储存温度 | -20 °C 或更低 | 干燥、避光、限制冻融次数 |
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.
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.
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.
=== EC 1.99.2 Oxygenases (now covered by EC 1.13) === EC 1.99.2.1: deleted, now EC 1.13.11.12, lipoxygenase EC 1.99.2.2: deleted, now EC 1.13.11.1, catechol 1,2-dioxygenase EC 1.99.2.3: deleted, now EC 1.13.11.3, protocatechuate 3,4-dioxygenase EC 1.99.2.4: deleted, now EC 1.13.11.4, gentisate 1,2-dioxygenase EC 1.99.2.5: deleted, now EC 1.13.11.5, homogentisate 1,2-dioxygenase EC 1.99.2.6: deleted, now EC 1.13.99.1, inositol oxygenase
does not necessarily reflect the intermolecular forces between the molecules, it is the energy cost associated with disrupting the pattern and may be thought of as a region where optimum arrangement does not occur and the reduction of enthalpy associated with ideal self-assembly did not occur. An example of this can be seen in a system of hexagonally packed cylinders where defect regions of lamellar structure exist. If
== Form and appearance == Heinz bodies appear as small round inclusions within the red cell body, though they are not visible when stained with Romanowsky dyes. They are visualized more clearly with supravital staining (e.g., with new methylene blue, crystal violet or bromocresol green).
Chief Information Office Contractor Assurance and Continuous Improvement Environment, Safety and Health Government and External Relations Independent Audit and Oversight Office of General Counsel Prime Contract Management Office Quality Assurance Office Security Organization LLNS, LLC Parent Oversight Office The laboratory is organized into four principal directorates, each headed by a principal associate director:
Sources: en.wikipedia.org
(See also Nuclear weapon design.) Hypothetically, as little as 4 kg of plutonium—and maybe even less—could be used to make a single atomic bomb using very sophisticated assembly designs. Plutonium-238 is potentially more efficient isotope for nuclear reactors, since it has smaller critical mass than uranium-235, but it continues to release much thermal energy (0.56 W/g) by decay even when the fission chain reaction is stopped by control rods. Its application is limited by its high price (about US$1000/g). This isotope has been used in thermopiles and water distillation systems of some space satellites and stations. The Galileo and Apollo spacecraft (e.g. Apollo 14) had heaters powered by kilogram quantities of plutonium-238 oxide; this heat is also transformed into electricity with thermopiles. The decay of plutonium-238 produces relatively harmless alpha particles and is not accompanied by gamma rays. Therefore, this isotope (~160 mg) is used as the energy source in heart pacemakers where it lasts about 5 times longer than conventional batteries. Actinium-227 is used as a neutron source. Its high specific energy (14.5 W/g) and the possibility of obtaining significant quantities of thermally stable compounds are attractive for use in long-lasting thermoelectric generators for remote use. 228Ac is used as an indicator of radioactivity in chemical research, as it emits high-energy electrons (2.18 MeV) that can be easily detected. 228Ac-228Ra mixtures are widely used as an intense gamma-source in industry and medicine.
== Interactions == Hyperglycemic action may be caused by danazol, chlorpromazine, glucocorticoids, progestogens, or β-2 agonists. Its hypoglycemic action may be potentiated by phenylbutazone, alcohol, fluconazole, β-blockers, and possibly ACE inhibitors. It has been found that rifampin increases gliclazide metabolism in humans in vivo.
The most common liver injuries from weight loss and bodybuilding supplements involve hepatocellular damage with resulting jaundice, and the most common supplement ingredients attributed to these injuries are green tea catechins, anabolic steroids, and the herbal extract, aegeline. Weight loss supplements have also had adverse psychiatric effects. Some dietary supplements may also have adverse interactions with prescription medications that may enhance side effects or decrease therapeutic effects of medications.
MgCl2 + 2 K → Mg + 2 KCl Most potassium compounds are ionic. Owing to the high hydration energy of the K+ ion, these salts often exhibit excellent water solubility. The main species in water solution are the aquo complexes [K(H2O)n]+ where n = 6 and 7. Although typically insoluble in organic solvents, potassium salts dissolve in polar organic solvents in the presence of crown ethers and cryptand. These organic ligands envelop K+ ions, giving lipophilic coordination complexes. Similar complexation phenomena are found for some ion-binding antibiotics.
Although lysosomal-mediated degradation is an efficient means by which to neutralize an infection and prevent colonization, several pathogens parasitize macrophages, exploiting them as a host cell for growth, maintenance and replication. Parasites like Toxoplasma gondii and mycobacteria are able to prevent fusion of phagosomes with lysosomes, thus escaping the harmful action of lysosomal hydrolases. Others avoid lysosomes by leaving the phagocytic vacuole, to reach the cytosolic matrix where their development is unhindered. In these instances, macrophages may be triggered to actively destroy phagocytosed microorganisms by producing a number of highly toxic molecules and inducing deprivational mechanism to starve it. Finally, some microbes have enzymes to detoxify oxygen metabolites formed during the respiratory burst. When insufficient to ward off the threat, alveolar macrophages can release proinflammatory cytokines and chemokines to call forth a highly developed network of defensive phagocytic cells responsible for the adaptive immune response. During COVID-19 infection, alveolar macrophages play a dual role by acting as the first line of defense against SARS-CoV-2 in the alveolar space, while also contributing to the hyperinflammatory response through excessive cytokine production, which can exacerbate lung damage and acute respiratory distress syndrome (ARDS).
Sources: en.wikipedia.org
=== Salt Concentration === Most enzymes cannot tolerate extremely high salt concentrations. The ions interfere with the weak ionic bonds of proteins. Typical enzymes are active in salt concentrations of 1-500 mM. As usual there are exceptions such as the halophilic algae and halophilic bacteria.
==== Fibrates ==== Fibrates, known as derivatives of fibric acids, are peroxisome proliferator-activated receptor alpha (PPAR-α) agonists primarily used for lowering TG levels and management of atherogenic dyslipidemia. Typical drugs of the class include fenofibrate, bezafibrate, ciprofibrate and gemfibrozil. Through activation of PPAR-α receptors, fibrates decreases circulating TG via upregulation of lipoprotein lipase (LPL) expression and downregulation of apolipoprotein C-III (ApoC-III) gene expression. LPL is a hepatic enzyme involved in lipolysis, whereas ApoC-III is an inhibitor of LPL. Comparable to statins and ezetimibe, fibrates are usually well-tolerated with mild adverse reactions, with the exception of gemfibrozil. Some of the more prevalent side effects are minor gastrointestinal disturbances such as abdominal pain and cholithiasis on account of the increased excretion of biliary cholesterol. Among atypical adverse effects, myositis can occur in patients under gemfibrozil therapy, especially in those with renal insufficiency or under co-treatment with statins. In contrast, the risk of myopathy is much lower if fenofibrate is used in replacement of gemfibrozil owing to its different pharmacokinetic pathway. Other rare effects are increased serum transaminase levels, agranulocytosis and anaemia. As fenofibrate possess the same binding mechanism as warfarin in the blood, this combination should be addressed with caution as fenofibrate may potentiate the anticoagulant effect of warfarin.
=== Eid al-Fitr ceasefire (19–24 March) === On 18 March, Pakistan and Afghanistan both announced that they would observe a "temporary pause" in hostilities during the Islamic holiday of Eid al-Fitr, on the request of Saudi Arabia, Qatar, and Turkey. Pakistan's information minister said the ceasefire would run from midnight on 19 March to midnight on 24 March. On 19 March, Taliban claimed that despite the ceasefire Pakistan conducted 72 mortar attacks in Kunar province firing 25 artillery shells in Nari District only, and that two civilians were killed in shelling in Nuristan Province. On the Pakistani side meanwhile, a civilian was killed and three wounded in an Afghan mortar attack on Kurram District. On 22 March, Taliban claimed that Pakistani artillery strikes in Kunar killed a person and wounded another, and also claimed that Pakistani forces attacked a vehicle in Paktia province causing no casualties. Pakistani forces killed two TTP insurgents in an attempted attack on an under-construction Police Station in Kurram District. On 23 March, TTP militants kidnapped six people from Orakzai District.
==== Gastrointestinal tract ==== Secondary consequences of uremia on the gastrointestinal tract in cats are mainly fibrosis and mineralization of the gastric mucosa, but no gastric ulcers, so that the gastric acid blockers such as omeprazole, which have long been recommended for therapy, are no longer indicated. Mirtazapine has been shown to stimulate the appetite and reduce uraemic nausea.
=== No development reported === AD-6626 – aldehyde dehydrogenase 2 (ALDH2) inhibitor – alcoholism AM-6527 (AM6527) – cannabinoid CB1 receptor antagonist – substance-related disorders Amitifadine (DOV-21947; EB-1010) – serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) – alcoholism, opioid-related disorders, smoking withdrawal, substance-related disorders Arbaclofen extended release – GABAB receptor agonist – opioid-related disorders BMB-101 – serotonin 5-HT2 receptor agonist – opioid-related disorders Bupropion/mecamylamine (INT-0003; QuitPak) – combination of bupropion (norepinephrine–dopamine reuptake inhibitor (NDRI), nicotinic acetylcholine receptor negative allosteric modulator) and mecamylamine (non-selective nicotinic acetylcholine receptor antagonist) – smoking withdrawal Cannabidiol (CBD; cannabidiol transderma/topical gel/patch; Zygel; ZYN-002) – cannabinoid/various actions – alcoholism, substance-related disorders CM-1212 – undefined mechanism of action – alcoholism, substance-related disorders CPP-115 – GABA transaminase (GABA-T) inhibitor – substance-related disorders CT-044 analogues - CERSCI Therapeutics – reactive oxygen species (ROS) inhibitors (CT-044 analogues) – opioid-related disorders CX-717 (CX717) – AMPA receptor positive allosteric modulator (ampakine) – substance-related disorders Cyproheptadine/prazosin (KT-110; Periactine/Alpress) – combination of cyproheptadine (various actions) and prazosin (α1-adrenergic receptor antagonist) – substance-related disorders DCR-AUD (DCR-A1203; NN-6020) – aldehyde dehydrogenase 2 (ALDH2) inhibitor, RNA interference – alcoholism Dimethyltryptamine (DMT; EBRX-101) – non-selective serotonin receptor agonist, serotonin 5-HT2A receptor agonist, and serotonergic psychedelic – smoking withdrawal GLWL-01 – ghrelin O-acyltransferase (GOAT) inhibitor – alcoholism GSK-598809 (GSK598809) – dopamine D3 receptor antagonist – smoking withdrawal, substance-related disorders GSK-1521498 – μ-opioid receptor inverse agonist – cocaine-related disorders GTS-21 (DMXB-A; DMBX-anabaseine) – nicotinic acetylcholine receptor agonist – smoking withdrawal Icalcaprant (ABBV-1354; CVL-354) – κ-opioid receptor antagonist – substance-related disorders Levodopa (CVT-301; CXG-89; Inbrija) – dopamine precursor (non-selective dopamine receptor agonist) – smoking withdrawal Mazindol controlled release (NLS-0; NLS-1; NLS-10; NLS-13; NLS-2; Nolazol; Quilience) – serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) – opioid-related disorders Midomafetamine (MDMA; ecstasy) – serotonin–norepinephrine–dopamine releasing agent (SNDRA), serotonin 5-HT2 receptor agonist, and entactogen – substance-related disorders Mifepristone (C-1073; Corlux; Corluxin; Korlym; Mifegyne; Mifeprex; RU-38486; RU-486) – glucocorticoid, progesterone, and androgen receptor antagonist – smoking withdrawal Modafinil oral (ASB) – atypical dopamine reuptake inhibitor (DRI) – cocaine-related disorders Naloxone nasal spray (-12; LT-20; LT-21; LT-22; Naloxon B; Narcan Nasal Spray; OPNT-001) – μ-opioid receptor antagonist – cocaine-related disorders, substance-related disorders Nalmefene implant (nalmefene six-month implant) – μ-opioid receptor antagonist, κ-opioid receptor weak partial agonist – opioid-related disorders Naloxone buccal/intransal gel (Exonal) – opioid receptor antagonist – opioid-related disorders Nicotine abuse vaccine (Niccine) – nicotinic acetylcholine receptor agonist – smoking withdrawal Nicotine/cannabidiol chewing gum (nicotine/CBD; CVSI-007) – combination of nicotine (nicotinic acetylcholine receptor agonist) and cannabidiol (CBD) (cannabinoid/various actions) – smoking withdrawal Noribogaine derived therapeutic – various actions (noribogaine derivative) – opioid-related disorders OMS-405 (OMS405) – PPARγ agonist – alcoholism Ondansetron (AD-04) – serotonin 5-HT3 receptor antagonist – opioid-related disorders, smoking withdrawal Ondansetron/topiramate (AD-01; AD/TO-01) – combination of ondansetron (serotonin 5-HT3 receptor antagonist) and topiramate (various actions) – alcoholism Ondelopran (LY-2196044; Odelepan; Odelepran; OpRA) – opioid receptor antagonist – alcoholism OPNT-005 (OPNT005; adjuvanted heroin analogue vaccine; diamorphine analogue vaccine; heroin vaccine) – immunostimulant (vaccine against heroin) – heroin-related disorders PF-5402536 (NIC7-001; PF-5402536) – immunostimulant (smoking vaccine) – smoking withdrawal Pomaglumetad methionil (DB103; LY-2140023; LY-2812223; LY-404039 prodrug) – metabotropic glutamate mGlu2 and mGlu3 receptor receptor agonist (pomaglumetad prodrug) – substance-related disorders PPL-103 – μ-opioid receptor agonist, δ-opioid receptor agonist, κ-opioid receptor agonist – substance-related disorders Pregnenolone methyl ether (3β-methoxypregnenolone; MAP-4343) – microtubule-associated protein (MAP) stimulant and tubulin polymerization promoter – substance-related disorders Psilocybin (MYCO-001; MYCO-003) – non-selective serotonin receptor agonist, serotonin 5-HT2A receptor agonist, and serotonergic psychedelic – substance-related disorders PT-150 (PT150; ORG-34517; SCH-900636) – androgen and glucocorticoid receptor antagonist – alcoholism Research programme: alcoholism therapeutics - ADial Pharmaceuticals – various actions – alcoholism Research programme: allosteric modulators - Addex Therapeutics – various actions – substance-related disorders Research programme: GPCR modulators - Nxera Pharma – various actions – cocaine-related disorders, substance-related disorders Research programme: nociceptin receptor agonists - Astraea Therapeutics – nociceptin receptor agonist, opioid receptor agonist – alcoholism, substance-related disorders Research programme: smoking cessation therapies - Ophidion – smoking withdrawal – nicotinic acetylcholine receptor agonists Research programme: tryptamine based therapeutics - PsyBio Therapeutics – serotonin 5-HT2A receptor agonists – substance-related disorders RTI-598929 – μ-opioid receptor antagonist and κ-opioid receptor antagonist – heroin-related disorders Saracatinib (AZD-0530) – Src-family kinase inhibitor – alcoholism SBP-9330 – metabotropic glutamate mGlu2 receptor modulator – smoking withdrawal SEL-068 (tSVP; immunomodulatory nanoparticle vaccine for smoking cessation) – immunomodulator (smoking vaccine) – smoking withdrawal Serdexmethylphenidate (KP-484; KP-1077; KP-1077H; KP-1077IH; KP-1077N; KP-879) – norepinephrine–dopamine reuptake inhibitor (NDRI) (dexmethylphenidate prodrug) – substance-related disorders TRV-734 (TRV734) – μ-opioid receptor biased agonist – opioid-related disorders VDM-001 – opioid receptor antagonist – alcoholism, opioid-related disorders Zolunicant (18-methoxycoronaridine; 18-MC; MM-110) – α3β4 nicotinic acetylcholine receptor antagonist – substance-related disorders
Sources: en.wikipedia.org
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。
公开资料中它主要以研究用肽的形式出现，未获主要监管机构批准用于治疗。可得材料通常标注仅供研究使用。任何临床用途的宣称都缺少监管依据。
序列中的 Aib 与 D-2-Nal 等非天然残基可提高对肽酶的抵抗能力，并影响受体结合的构象。这类修饰在合成肽设计中较为常见。它们也使常规氨基酸分析需要额外步骤才能确认序列。
Aib 即 α-氨基异丁酸，是一种非蛋白质源氨基酸，其侧链为两个甲基。它在肽链中倾向于诱导螺旋构象并限制骨架的柔性。这种刚性被认为有助于抵抗蛋白酶切割。