A practical reference on 非天然氨基酸: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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。
Lyophilized material is generally stored frozen and protected from light and moisture. Typical recommendations place dry powder at temperatures well below freezing, while reconstituted solutions are kept cold and used within a defined window. Repeated freezing and thawing should be avoided because it can promote aggregation and loss of material. The choice of solvent matters as well; compatibility with the intended diluent should be checked before preparation. These handling practices aim to preserve both the quantity and the integrity of the peptide.
Verification of identity and purity relies on analytical methods used across peptide chemistry. Reverse-phase high-performance liquid chromatography separates components by hydrophobicity and provides a purity estimate. Mass spectrometry confirms molecular mass and helps detect modifications. Together these techniques give complementary information about whether a sample matches its expected structure. Results depend on method parameters and reference standards, so reported purity values are meaningful only when the analytical conditions are stated. Consistency between laboratories requires comparable protocols and well-characterized reference materials.
Peptides such as ipamorelin are subject to chemical and physical degradation. Hydrolysis of peptide bonds, oxidation of susceptible residues, and aggregation are common pathways that reduce purity over time. The rate of these processes depends on temperature, moisture, pH, and the number of freeze-thaw cycles a sample undergoes. Because the compound is typically handled as a lyophilized powder, controlling moisture during storage is a central concern. Degradation products can be detected with separation techniques that resolve the parent peptide from related impurities.
| 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 |
Ipamorelin is a synthetic pentapeptide that acts on the growth hormone secretagogue receptor, also known as the ghrelin receptor. Its sequence contains five amino acid residues, including a non-natural residue that increases stability against enzymatic breakdown. The compound was developed in the 1990s as part of research into small peptides that stimulate pituitary hormone release. Unlike larger protein hormones, it can be produced by solid-phase peptide synthesis and characterized by standard analytical methods.
At the receptor level, ipamorelin binds GHS-R1a and triggers signaling through Gq-coupled pathways. Activation leads to calcium release and downstream effects in pituitary somatotroph cells. These events promote the release of growth hormone into circulation. The response depends on the presence of the receptor and on the physiological state of the animal or tissue studied. Because the receptor is also found in other tissues, effects beyond the pituitary have been examined in laboratory models, though the extent of those effects remains an area of ongoing study.
One distinguishing feature reported in animal studies is selectivity. Ipamorelin stimulated growth hormone release with limited elevation of adrenocorticotropic hormone or cortisol compared with earlier secretagogues such as GHRP-6. This pattern has been described as more selective for the growth hormone axis. The finding comes mainly from preclinical work, and the degree to which it holds across species and doses is not fully settled. Reports also describe effects on gastric motility in animal models, suggesting activity outside the pituitary, though the clinical relevance of this observation is uncertain.
Purity assessment for this peptide relies mainly on reversed-phase high-performance liquid chromatography. A C18 column with a water-acetonitrile gradient containing trifluoroacetic acid separates the target from truncated sequences and oxidation products. Detection near 214 nm exploits the amide backbone, while the aromatic side chains allow additional monitoring close to 280 nm. Reported purity values depend on the method, so a certificate of analysis carries weight only when gradient, column and integration parameters are given.
Mass spectrometry confirms identity and reveals structural deviations that chromatography alone can miss. Positive-mode electrospray ionisation generally yields multiply charged ions whose deconvoluted mass is checked against the theoretical value. Amino acid analysis, and enzymatic digestion with subsequent fragment mapping, provide independent confirmation of sequence and of the terminal amide. Analysts take care to separate the target from deletion sequences, which may differ by one residue and therefore by only a small mass increment.
The lyophilised solid is normally held at -20 °C or colder, shielded from light and moisture. Stability in that state is measured in years, although shelf life depends on residual water content and the container seal. Once dissolved, the peptide is more fragile: aqueous solutions are commonly kept at 2-8 °C and used within days to weeks, and repeated freeze-thaw cycling is avoided. Strongly acidic or basic conditions accelerate hydrolysis, and prolonged exposure to them can strip the terminal amide.
in [a black bear] chase there is much excitement, and occasionally a slight spice of danger, just enough to render it attractive; so it has always been eagerly followed. He wrote that black bears were difficult to hunt by stalking, due to their habitat preferences, though they were easy to trap. Roosevelt described how, in the southern states, planters regularly hunted bears on horseback with hounds. General Wade Hampton was known to have been present at 500 successful bear hunts, two-thirds of which he killed personally. He killed 30 or 40 bears with only a knife, which he would use to stab the bears between the shoulder blades while they were distracted by his hounds. Unless well trained, horses were often useless in bear hunts, as they often bolted when the bears stood their ground. In 1799, 192,000 American black bear skins were exported from Quebec. In 1822, 3,000 skins were exported from the Hudson's Bay Company. In 1992, untanned, fleshed and salted hides were sold for an average of $165. In Canada, black bears are considered as both a big game and furbearer species in all provinces, save for New Brunswick and the Northwest Territories, where they are only classed as a big game species. There are around 80,900 licensed bear hunters in Canada. Canadian black bear hunts take place in the fall and spring, and both male and female bears can be legally taken, though some provinces prohibit the hunting of females with cubs, or yearlings. Currently, 28 of the U.S. states have American black bear hunting seasons.
== Function == CENPA is a protein which epigenetically defines the position of the centromere on each chromosome, determining the position of kinetochore assembly and the final site of sister chromatid cohesion during mitosis. This proteins is frequently accompanied by "centrochromatin"-associated changes to canonical histones and is constitutively present in centromeres. The CENPA protein is a histone H3 variant which replaces one or both canonical H3 histones in a subset of nucleosomes within centromeric chromatin. CENPA has the greatest sequence divergence of the histone H3 variants, with just 48% similarity to canonical histone H3, and has a highly diverged N-terminal tail that lacks many well characterised histone modification sites including H3K4, H3K9 and H3K27. Unusually for a histone, CENPA nucleosomes are not loaded together with DNA replication and are loaded at different cell cycle stages in different organisms: G1 phase in human, M phase in drosophila, G2 in S. pombe. To orchestrate this specialised loading there are CENPA-specific histone chaperones: HJURP in human, CAL1 in drosophila, nefr-1 in C. elegans and Scm3 in S. pombe. In most eukaryotes CENPA is loaded into large domains of highly repetitive satellite DNA. The position of CENPA within satellite DNA are heritable at the protein level through a purely epigenetic mechanism. This means that the position of CENPA protein binding to the genome is copied upon cell division to the two daughter cells independent of the underlying DNA sequence.
== Cancer == Grape seed extract has been incorrectly described as a cancer cure on social media websites. There is no clinical evidence that grape seed extract is effective to treat cancer. In 2017, the Food and Drug Administration listed grape seed extract as a fake cancer cure that consumers should avoid.
=== In U.S. drinking water === In 2000, perchlorate contamination beneath the former flare manufacturing plant Olin Corporation Flare Facility, Morgan Hill, California was first discovered several years after the plant had closed. The plant had used potassium perchlorate as one of the ingredients during its 40 years of operation. By late 2003, the State of California and the Santa Clara Valley Water District had confirmed a groundwater plume currently extending over nine miles through residential and agricultural communities. The California Regional Water Quality Control Board and the Santa Clara Valley Water District have engaged in a major outreach effort, a water well testing program has been underway for about 1,200 residential, municipal, and agricultural wells. Large ion exchange treatment units are operating in three public water supply systems which include seven municipal wells with perchlorate detection. The potentially responsible parties, Olin Corporation and Standard Fuse Incorporated, have been supplying bottled water to nearly 800 households with private wells, and the Regional Water Quality Control Board has been overseeing cleanup efforts. The source of perchlorate in California was mainly attributed to two manufacturers in the southeast portion of the Las Vegas Valley in Nevada, where perchlorate has been produced for industrial use.
Sources: en.wikipedia.org
=== Adults === The widely used rule calculating normal maximum ESR values in adults (98% confidence limit) is given by a formula devised in 1983 from a study of ≈1000 individuals over the age of 20: The normal values of ESR in men is age (in years) divided by 2; for women, the normal value is age (in years) plus 10, divided by 2.
==== Other drugs ==== Opipramol (Ensidon; G-33040; Insidon; Nisidana) – tricyclic antidepressant (TCA) (non-selective monoamine receptor modulator and other actions) [44] Pregabalin (CI-1008; isobutylgaba; Lyrica; PD-144723) – gabapentinoid (α2δ subunit-containing voltage-gated calcium channel ligand) [45]
== Adverse effects == Common side effects include infusion-related reactions, swelling caused by excess fluid in body tissue (edema), nausea, fatigue, headache, fever (pyrexia), constipation, anemia and diarrhea. The prescribing information for moxetumomab pasudotox includes a boxed warning about the risk of developing capillary leak syndrome, a condition in which fluid and proteins leak out of tiny blood vessels into surrounding tissues. Symptoms of capillary leak syndrome include difficulty breathing, weight gain, hypotension, or swelling of arms, legs and/or face. The boxed warning also notes the risk of hemolytic uremic syndrome, a condition caused by the abnormal destruction of red blood cells. Other serious warnings include: decreased renal function, infusion-related reactions and electrolyte abnormalities. Women who are breastfeeding should not be given moxetumomab pasudotox.
Sources: en.wikipedia.org
== Properties == The physical properties of organic compounds typically of interest include both quantitative and qualitative features. Quantitative information includes a melting point, boiling point, solubility, and index of refraction. Qualitative properties include odor, consistency, and color.
== Signs and symptoms == Children with autosomal dominant MED experience joint pain and fatigue after exercising. Their x-rays show small and irregular ossification centers, most apparent in the hips and knees. There are very small capital femoral epiphyses and hypoplastic, poorly formed acetabular roofs. A waddling gait may develop. Knees have metaphyseal widening and irregularity while hands have brachydactyly (short fingers) and proximal metacarpal rounding. Flat feet are very common. The spine is normal but may have a few irregularities, such as scoliosis. By adulthood, people with MED are of short stature or in the low range of normal and have short limbs relative to their trunks. Frequently, movement becomes limited at the major joints, especially at the elbows and hips. However, loose knee and finger joints can occur. Signs of osteoarthritis usually begin in early adulthood. Children with recessive MED experience joint pain, particularly of the hips and knees, and commonly have deformities of the hands, feet, knees, or vertebral column (like scoliosis). Approximately 50% of affected children have abnormal findings at birth (such as club foot or twisted metatarsals, cleft palate, inward curving fingers due to underdeveloped bones and brachydactyly, or ear swelling caused by injury during birth). Height is in the normal range before puberty. As adults, people with recessive MED are only slightly more diminished in stature, but within the normal range. Lateral knee radiography can show multi-layered patellae.
== Use as a biomarker == Although a number of surrogate biomarkers exist for measuring the metabolic products of bone resorption, the serum CTX marker was chosen because it is both highly correlated to bone turnover rate and already available for detection in a laboratory test carried out by a major lab testing corporation. The CTX test measures for the presence and concentration of a crosslink peptide sequence of type I collagen, found, among other tissues, in bone. This specific peptide sequence relates to bone turnover because it is the portion that is cleaved by osteoclasts during bone resorption, and its serum levels are therefore proportional to osteoclastic activity at the time the blood sample is drawn. Serum levels in healthy patients not taking bisphosphonates tends to hover above 300 pg/mL.
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。