This is a working overview of reversed-phase HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-10-08. Anything still debated is marked as such rather than presented as settled.
Semax binds to melanocortin receptors and is thought to influence neuronal survival and plasticity rather than to act through the adrenal axis. Laboratory work has shown increased expression of brain-derived neurotrophic factor and nerve growth factor in treated tissue. Changes in c-Fos, a marker of neuronal activation, have also been reported. Because the peptide is rapidly degraded by peptidases, its effects are generally attributed to downstream signaling cascades rather than to sustained receptor occupancy.
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
| Property | Value | Notes |
|---|---|---|
| Appearance | White lyophilized powder | Typical for synthetic peptides |
| Solubility | Freely soluble in water | Also soluble in saline |
| Storage temperature | -20 C or below | Protect from repeated freeze-thaw |
| Analytical method | Reverse-phase HPLC | Confirms purity and identity |
| Common synonym | ACTH(4-10) analog | Reflects structural origin |
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
=== Data modelling === Much of Aarons' work focuses on building an understanding of how the effects of drugs or toxic agents are managed in humans. In 2009 he co-authored a paper that aimed to explore an approach to the modelling of effects on people by drugs and toxic agents "based on the underlying physiology and pathology of the biological processes,...[ and to review]...the current status of pharmacodynamic and pharmacokinetic modelling, and outline a conceptual framework that may be helpful in advancing the field." A model was proposed that included the kinetics of the substance as a part of the process. To some extent, this was a challenge to the widely accepted dose/effect concept in pharmacology and toxicology at the time which assumed that the exposure/dose of a drug or a toxin is related to the effects on the patient, beneficial or toxic. The paper explained the purposes of data modelling as being to describe complex data, test hypotheses and make predictions, and noted when a drug interacts with a patient, there is a "chain of events at the molecular level, cellular level, organ/physiological system level, and whole-body level...[and ]... in principle, modelling may be performed at each of these levels." The effect on a patient could be therapeutic or possibly result in adverse outcomes. The authors concluded that including the systems biology model they discussed in the paper into conventional PKPD modelling would require further collaboration to make it robust but able to be clearly defined.
== Awards and honors == Edwin A. Bierman Award for Excellence in Prevention and Treatment of Macrovascular Disease (2024) – American Diabetes Association Luminary in Cardiometabolic Medicine Award (2025) – awarded at the Heart in Diabetes Conference for contributions to research innovation, clinical management, and treatment development in cardiometabolic disease Recognition as an Outstanding Reviewer for Circulation (American Heart Association journal) Fellow of the American Heart Association, the American College of Cardiology, and the European Society of Cardiology Excellence in Teaching Award, UT Southwestern Internal Medicine Residency Program Odyssey Distinguished Alumni Award in Research, Hendrix College Dallas Heart Ball Chair for Research on Heart Disease in Women Outstanding Research Mentor Award L. David Hillis Award for Excellence in Teaching Stanford Citation of Top 2% of Scientists Clarivate Highly Cited Researcher
Ba(Cl2C=C(Cl)COO)2 → BaCl2 + ClC≡CCl + 2CO2 Dichloroacetylene was discovered as an intermediate in the synthesis of diphenylacetylene with calcium carbide, chlorine and benzene in 1918. It was first synthesized from trichloroethylene by Erwin Ott, W. Ottemeyer and K. Packendorff in 1930.
The AAS that have been used most commonly in medicine are testosterone and its many esters (but most typically testosterone undecanoate, testosterone enanthate, testosterone cypionate, and testosterone propionate), nandrolone esters (typically nandrolone decanoate and nandrolone phenylpropionate), stanozolol, and metandienone (methandrostenolone). Others that have also been available and used commonly but to a lesser extent include methyltestosterone, oxandrolone, mesterolone, and oxymetholone, as well as drostanolone propionate (dromostanolone propionate), metenolone (methylandrostenolone) esters (specifically metenolone acetate and metenolone enanthate), and fluoxymesterone. Dihydrotestosterone (DHT), known as androstanolone or stanolone when used medically, and its esters are also notable, although they are not widely used in medicine. Boldenone undecylenate and trenbolone acetate are used in veterinary medicine. Designer steroids are AAS that have not been approved and marketed for medical use but have been distributed through the black market. Examples of notable designer steroids include 1-testosterone (dihydroboldenone), methasterone, trenbolone enanthate, desoxymethyltestosterone, tetrahydrogestrinone, and methylstenbolone.
Sources: en.wikipedia.org
== Side effects == Side effects of dextromethorphan/bupropion include dizziness, nausea, headache, diarrhea, somnolence, dry mouth, sexual dysfunction (including abnormal orgasm, erectile dysfunction, decreased libido, and anorgasmia), hyperhidrosis, anxiety, constipation, decreased appetite, insomnia, arthralgia, fatigue, paresthesia, and blurred vision. These side effects occurred at rates ≥2% and to a greater extent than with placebo in clinical trials.
=== Available forms === Suvorexant is available in the form of 5, 10, 15, and 20 mg oral film-coated tablets. It is provided as 10- and 30-tablet blister packs as well as 3-tablet starter packs. The availability of these different packs varies by country.
== Procedure == Dried blood spot specimens are collected by applying a few drops of capillary blood, drawn by lancet from the finger, heel or toe, onto specially manufactured absorbent filter paper. The blood is allowed to thoroughly saturate the paper. It is air dried for several hours. Specimens are stored in low gas-permeability plastic bags with desiccant added to reduce humidity, and may be kept at ambient temperature, even in tropical climates. Once in the laboratory, technicians separate a small disc of saturated paper from the sheet using an automated or manual hole punch, dropping the disc into a flat bottomed microtitre plate. The blood is eluted out in phosphate buffered saline containing 0.05% Tween 80 and 0.005% sodium azide, overnight at 4 °C. The resultant plate containing the eluates forms the "master" from which dilutions can be made for subsequent testing. As an alternative to punching out a paper disc, recent automation solutions extract the sample by flushing an eluent through the filter without punching it out. An automation including the application of an internal standard prior extraction was developed by the Swiss company CAMAG.
Sources: en.wikipedia.org
Similar patterns in other Xanthoria species suggest that, despite limited variation within local populations, long-distance dispersal and genetic drift contribute to regional differentiation and ecological adaptation. At broader spatial scales, X. parietina populations show a pattern of isolation by distance—genetic differences increase with geographic separation. A global genetic study using RAPD-PCR fingerprinting identified just two major genetic clusters worldwide: one in southwestern Europe (Iberian Peninsula, Balearic and Canary Islands) and another spanning Europe, North America, Australia, and New Zealand. The high similarity between Australian/New Zealand samples and those from Europe indicates the species was introduced by humans to the Southern Hemisphere, possibly via grapevine transport or ship ballast stones. A similar human introduction has been suggested for the lichen in the populated Willamette Valley of the western United States, and in Ontario, where it may have arrived on nursery trees. The high genetic diversity observed in X. parietina has several practical implications for its ecology and conservation. This diversity likely supports the species' adaptability to different environments—from coastal rocks to urban trees and polluted areas. High genetic variation within local populations provides material for natural selection, enabling adaptation to changing conditions including pollution levels and climate shifts. The different genetic structures between the fungal and algal partners suggest that X.
== History == Pseudoephedrine, along with ephedrine, occurs naturally in ephedra. This herb has been used for thousands of years in traditional Chinese medicine. Pseudoephedrine was first isolated and characterized in 1889 by the German chemists Ladenburg and Oelschlägel, who used a sample that had been isolated from Ephedra vulgaris by the Merck pharmaceutical corporation of Darmstadt, Germany. It was first synthesized in the 1920s in Japan. Subsequently, pseudoephedrine was introduced for medical use as a decongestant.
Calculations using a quantum-tunneling model predict the existence of several heavier isotopes of oganesson with alpha-decay half-lives close to 1 ms. Theoretical calculations done on the synthetic pathways for, and the half-life of, other isotopes have shown that some could be slightly more stable than the synthesized isotope 294Og, most likely 293Og, 295Og, 296Og, 297Og, 298Og, 300Og and 302Og (the last reaching the N = 184 shell closure). Of these, 297Og might provide the best chances for obtaining longer-lived nuclei, and thus might become the focus of future work with this element. Some isotopes with many more neutrons, such as some located around 313Og, could also provide longer-lived nuclei. The isotopes from 291Og to 295Og might be produced as daughters of element 120 isotopes that can be reached in the reactions 249–251Cf+50Ti, 245Cm+48Ca, and 248Cm+48Ca. In a quantum-tunneling model, the alpha decay half-life of 294Og was predicted to be 0.66+0.23−0.18 ms with the experimental Q-value published in 2004. Calculation with theoretical Q-values from the macroscopic-microscopic model of Muntian–Hofman–Patyk–Sobiczewski gives somewhat lower but comparable results.
=== Gender dysphoria === Many international guidelines and institutions require persistent, well-documented gender dysphoria as a pre-requisite to starting gender-affirmation therapy. Gender dysphoria refers to the psychological discomfort or distress that an individual can experience if their sex assigned at birth is incongruent with that person's gender identity. Signs of gender dysphoria can include comorbid mental health stressors such as depression, anxiety, low self-esteem, and social isolation. Not all gender nonconforming individuals experience gender dysphoria, and measuring a person's gender dysphoria is critical when considering medical intervention for gender nonconformity.
Sources: en.wikipedia.org
It is associated with the melanocortin receptor family, particularly subtypes found in the central nervous system. This interaction is separate from the adrenal pathway activated by full-length ACTH.
Peptidases degrade the compound within minutes in circulation. This short half-life is one reason nasal delivery is used, placing the substance close to the olfactory and trigeminal pathways.
No large multicenter trials have been published in English-language journals. The existing human evidence consists mainly of smaller studies conducted in Russia, which limits generalization.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.