Reversed-phase HPLC raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-05-11. Anything still debated is marked as such rather than presented as settled.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Contains one methionine sulfur atom |
| Molecular mass | Approximately 814 Da | Consistent with a seven-residue peptide |
| Appearance | White to off-white powder | Typical lyophilized form |
| Solubility | Freely soluble in water | Also soluble in dimethyl sulfoxide |
| Typical storage | -20 °C, desiccated | Limits methionine oxidation |
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
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.
Many of the key psychoactive compounds in M. speciosa are indole alkaloids related to mitragynine, which is a tetracyclic relative of the pentacyclic indole alkaloids, yohimbine and voacangine. In particular, mitragynine and 7-hydroxymitragynine (7-HMG) compose significant proportions of the natural products isolable from M. speciosa; e.g., in one study, mitragynine was 12% by weight from Malaysian leaf sources, versus 66% from Thai sources, and 7-hydroxymitragynine constituted ~2% by weight. At least 40 other compounds have been isolated from M. speciosa leaves, including ~25 additional alkaloids, including raubasine/ajmalicine (originally isolated from Rauvolfia serpentina), corynantheidine (also found in Corynanthe johimbe), as well as mitraphylline, mitragynine pseudoindoxyl, and rhynchophylline. In addition to alkaloids, M. speciosa produces many other secondary metabolites. These include various saponins, iridoids and other monoterpenoids, triterpenoids such as ursolic acid and oleanic acid, as well as various polyphenols including the flavonoids apigenin and quercetin. Although some of these compounds possess antinociceptive, anti-inflammatory, gastrointestinal, antidepressant, antioxidant, and antibacterial effects in cells and non-human animals, there is no sufficient evidence to support the clinical use of kratom in humans.
The cyclol fabric was shown to be implausible for several reasons. Hans Neurath and Henry Bull showed that the dense packing of side chains in the cyclol fabric was inconsistent with the experimental density observed in protein films. Maurice Huggins calculated that several non-bonded atoms of the cyclol fabric would approach more closely than allowed by their van der Waals radii; for example, the inner Hα and Cα atoms of the lacunae would be separated by only 1.68 Å (Figure 5). Haurowitz showed chemically that the outside of proteins could not have a large number of hydroxyl groups, a key prediction of the cyclol model, whereas Meyer and Hohenemser showed that cyclol condensations of amino acids did not exist even in minute quantities as a transition state. More general chemical arguments against the cyclol model were given by Bergmann and Niemann and by Neuberger. Infrared spectroscopic data showed that the number of carbonyl groups in a protein did not change upon hydrolysis, and that intact, folded proteins have a full complement of amide carbonyl groups; both observations contradict the cyclol hypothesis that such carbonyls are converted to hydroxyl groups in folded proteins. Finally, proteins were known to contain proline in significant quantities (typically 5%); since proline lacks the amide hydrogen and its nitrogen already forms three covalent bonds, proline seems incapable of the cyclol reaction and of being incorporated into a cyclol fabric. An encyclopedic summary of the chemical and structural evidence against the cyclol model was given by Pauling and Niemann.
In 1961, Vsevolod Klechkovsky derived the first part of the Madelung rule (that orbitals fill in order of increasing n + ℓ) from the Thomas–Fermi model; the complete rule was derived from a similar potential in 1971 by Yury N. Demkov and Valentin N. Ostrovsky.
==== Race ==== Mental health impacts individuals of all ethnic and racial backgrounds across the world. Asian Americans often experience extreme levels of self-stigma, created from the intersection of cultural and societal factors. Cultural pressures lead to self-isolation and shame surrounding the inability to exceed expectations and maintain high achievement. Latino Americans face societal discrimination and report heightened levels of shame when speaking about mental health struggles. Latino communities face structural barriers such as documentation, low rates of English proficiency, and difficulties understanding the steps needed to navigate the healthcare system, ultimately limiting accessibility to mental health services. Latino men often face deep-rooted shame regarding mental health issues due to the cultural expectation of leading communities or a household. Immigration status, language barriers, or cultural beliefs cause many Latino Americans to avoid seeking professional care. The stigma surrounding mental health results in delayed professional care, embarrassment, and social rejection.
Sources: en.wikipedia.org
== Notable alumni == Anoop Malhotra (Lt. General, Indian Army) Cyrus Addie Pithawalla (Maj. General, Indian Army), (Recipient of Ashok Chakra) Ashok Malhotra (Professor, University of British Columbia) Diptendu Choudhury (Air Marshal, Indian Air Force) Nikesh Arora (CEO, Palo Alto Networks, previously, President & COO of SoftBank Corp and SVP and Chief Business Officer, Google) Pawanexh Kohli (CEO, National Centre for Cold-chain Development cum Chief Advisor, Department of Agriculture & Farmers Welfare, GOI) Rakesh Sharma (film director, made Final Solution in 2003) Rini Simon Khanna (News Anchor) Vijay Shankar (Retd.) (Vice Admiral, Indian Navy) Mohana Singh Jitarwal (One of the first female fighter pilots of India.) Kavery Nambisan (Surgeon and writer) Subrahmanyam Jaishankar (Minister of External Affairs) Parvez Dewan (Indian Administrative Service J&K Cadre. Secretary, India Tourism) Kabir Sadanand (Movie Director and Producer) Ramon Chibb (Filmmaker) Mohammad Jawed (Member of Parliament, Kishanganj) Kabir Khan (film director) Aparna Sharma (model, actress)
=== Oxidant === In organic synthesis, DMSO is used as a mild oxidant. It forms the basis of several selective sulfonium-based oxidation reactions including the Pfitzner–Moffatt oxidation, Corey–Kim oxidation and the Swern oxidation. The Kornblum oxidation is conceptually similar. These methods all involve formation of an intermediate sulfonium species (R2S+OX) where X is a heteroatom attached to oxygen).
Onset of type 2 diabetes can be delayed or prevented through proper nutrition and regular exercise. Intensive lifestyle measures may reduce the risk by over half. The benefit of exercise occurs regardless of the person's initial weight or subsequent weight loss. High levels of physical activity reduce the risk of diabetes by about 28%. Evidence for the benefit of dietary changes alone, however, is limited, with some evidence for a diet high in green leafy vegetables and some for limiting the intake of sugary drinks. There is an association between higher intake of sugar-sweetened fruit juice and diabetes, but no evidence of an association with 100% fruit juice. A 2019 review found evidence of benefit from dietary fiber. A 2017 review found that, long term, lifestyle changes decreased the risk by 28%, while medication does not reduce risk after withdrawal. While low vitamin D levels are associated with an increased risk of diabetes, correcting the levels by supplementing vitamin D3 does not improve that risk. In those with prediabetes, diet in combination with physical activity delays or reduces the risk of type 2 diabetes, according to a 2017 Cochrane review. In those with prediabetes, metformin may delay or reduce the risk of developing type 2 diabetes compared to diet and exercise or a placebo intervention, but not compared to intensive diet and exercise, and there was not enough data on outcomes such as mortality and diabetic complications and health-related quality of life, according to a 2019 Cochrane review.
Cooking in water causes the loss of some of the water-soluble elements, in particular vitamin C, especially when the tubers are peeled. Thus, in the case of a cooking of 25 to 30 minutes in boiling water, peeled potatoes can lose up to 40% of their vitamin C, 10% if they are cooked with the skin (in this last case, there remains 13 mg of vitamin C for 100 g of vegetable). These losses are added to those induced by the storage time, about 50% after three months. Other preparation methods are even more aggressive for vitamin C, but also for B vitamins; for example, pureeing causes up to 80% loss in vitamin C, and frying 60%. Nevertheless, a 100 g serving of processed potato products can provide 10–50% of the recommended daily allowance of vitamin C for an adult. Cooking with fat, especially frying, can lead to the formation of acrylamide, a substance that is probably carcinogenic to humans, especially if cooked for too long at high temperatures. This reaction occurs when potatoes contain too many reducing sugars (glucose and fructose); their rate, which should not exceed 0.4 to 0.6% of the fresh weight, depends on the variety, the maturity of the tubers and the storage conditions, low temperatures, below 8 °C, favoring the retrogradation of the starch into reducing sugars. The potatoes known as "for consumption", i.e. which were harvested with complete maturity, can be preserved several weeks, provided that they are stored in a room that is ventilated, fresh (between 8 and 9 °C) but sheltered from the frost, and obscure because the light makes them green.
== Early life == Elizabeth Evans Hughes was born August 19, 1907, in the New York State Executive Mansion in Albany, New York, to Antoinette (Carter) and Charles Evans Hughes, who was Governor of New York at the time. Elizabeth developed diabetes in 1918 at age 11. At the time, the life expectancy of a Type 1 diabetic without treatment was usually no more than a few months. Since it was unable to metabolize sugars, the diabetic body would instead begin to burn fats. The dependence on fat would eventually lead to acidosis, followed by coma and death. The only known treatment was a low-carbohydrate low-calorie diet at a level that the patient could tolerate without showing sugar in the urine. If the diet was carefully observed, diabetics could expect to live for a couple of years before eventually succumbing to starvation, organ damage, or an infectious disease in their malnourished state. In spring 1919, Elizabeth Hughes was brought to Dr. Frederick Madison Allen at his special clinic, the Physiatric Institute in Morristown, New Jersey. Allen put her on a strict diet and continued to monitor her condition over the next three years while she lived at home with a private nurse. She was 4 feet 11.5 inches (1.511 m) and 75 pounds (34 kg) when she developed diabetes. Under diets that averaged 800 calories per day, her weight fell to 45 pounds (20 kg) by August 1922.
Sources: en.wikipedia.org
=== PhD program === The Graduate Division of Biomedical Sciences hosts an "umbrella" PhD program that is not confined to a specific department. In 2023, the program had 39 matriculants. Students undertake three lab rotations before selecting a mentor. A concentration in clinical investigation is offered for both PhD and MD/PhD candidates. PhD students receive full tuition remission, a stipend, and subsidized housing.
=== Differential diagnosis === Seborrhoeic dermatitis can look similar to other skin conditions that share its characteristic dry, flaky, scaly, and inflamed appearance, but have different causes and treatments. Physicians use the history of the individual with the skin condition as well as other tests to identify which disorder is present. Other conditions that may be confused with seborrhoeic dermatitis based on appearance are listed below.
September 21: Malta becomes independent from the UK. September 24: The Mozambican War of Independence begins in Portuguese Mozambique. October 12: The first spaceflight to carry multiple crewman into orbit was conducted by Voskhod 1. October 14: Leonid Brezhnev succeeds Khrushchev to become General Secretary of the Communist Party of the Soviet Union, with Alexei Kosygin as his Premier. October 16: China tests its first atomic bomb. The test makes China the world's fifth nuclear power. October 24: Northern Rhodesia renamed Zambia becomes independent from the UK. November 28: Mariner 4 was launched.
== Polymorphs == Calcium carbonate crystallizes in three anhydrous polymorphs, of which calcite is the thermodynamically most stable at room temperature, aragonite is only slightly less so, and vaterite is the least stable.
Cardiology: angioplasty, cardioversion, cardiac ablation, intra-aortic balloon pump Critical care medicine: mechanical ventilation Gastroenterology: endoscopy and ERCP Nephrology: dialysis Pulmonology: bronchoscopy Other tests are ordered, and patients are also referred to specialists for further evaluation. The effectiveness and efficiency of the specialist referral process is an area of potential improvement.
Sources: en.wikipedia.org
It is registered as a pharmaceutical product in Russia, where it is typically supplied as a nasal solution. In most other countries it is not an approved drug and is traded as a research chemical instead. Approval status depends entirely on the jurisdiction involved.
Most published work uses intranasal administration, matching the route of the registered Russian formulation. Some animal experiments use intravenous or intraperitoneal injection. The route matters because the intact peptide is cleared rapidly from blood, so exposure differs between methods.
A purity value describes the share of the powder accounted for by the target peptide, usually by high-performance liquid chromatography. It does not confirm that the sequence is correct, which requires mass spectrometry or amino acid analysis. Purity and identity are separate checks.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.