The short version of RP-HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-08-06 and is reviewed periodically as new material appears.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Reversed-phase high-performance liquid chromatography is widely used to assess purity and to separate the parent peptide from related substances. Mass spectrometry confirms identity and can resolve modifications that differ by a few daltons. Size-exclusion chromatography detects dimers and higher aggregates, which are relevant to both stability and immunogenicity questions. Peptide mapping with enzymatic digestion locates specific modifications along the sequence. Circular dichroism provides a secondary-structure profile, although it gives limited information about local conformational changes.
Quality control for peptide material focuses on identity, purity, content and the profile of impurities. Common degradants include deamidated and oxidised forms, plus aggregates formed during storage or handling. Forced degradation studies under heat, light, acid and peroxide help define which conditions accelerate change and which analytical methods detect it. Limits for individual impurities are set by pharmacopoeial monographs or manufacturer specifications. How much a given impurity affects biological activity is often uncertain, and conclusions may depend on the assay used.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.
Semaglutide dissolves readily in water and in aqueous buffers near neutral pH. Solubility decreases near the isoelectric point, where net charge is minimal. Common laboratory solvents include phosphate-buffered saline and dilute ammonium bicarbonate. Strongly acidic or basic conditions may accelerate hydrolysis. Working concentrations are usually prepared by diluting a concentrated stock. Vial surfaces can adsorb small amounts of peptide at low concentrations, so carrier proteins or low-binding tubes are sometimes used.
Quality control for research material typically involves reversed-phase HPLC for purity and identity, mass spectrometry for molecular weight confirmation, and Karl Fischer titration for residual water content. Peptide content is often reported as the mass of actual peptide rather than total powder mass, since counterions and water contribute to the latter. A certificate of analysis should list the method used for each specification. Limits and acceptance criteria vary by supplier and by intended application.
Handling practices center on minimizing contamination and adsorption. Lyophilized peptide tends to accumulate static charge, so weighing is done with antistatic measures and calibrated balances. Reconstitution with appropriate solvent should be gentle, avoiding vigorous vortexing that generates foam and shear. Solutions are typically aliquoted before freezing to reduce repeated temperature cycling. Personal protective equipment and a fume hood are standard for powder handling.
Reconstituted solutions are less stable than the dry powder, and stability depends on concentration, pH, buffer composition, and container material. Low-protein-binding tubes reduce loss of peptide to plastic surfaces. Some researchers add a carrier protein to limit adsorption at low concentrations. The exact shelf life of a given solution is best determined empirically through a stability study rather than assumed from general guidance, because published data cover only a limited set of conditions.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
Semaglutide is a synthetic peptide of thirty-one amino acids that shares roughly ninety-four percent sequence identity with human glucagon-like peptide-1. Two substitutions resist enzymatic cleavage by dipeptidyl peptidase-4, and a fatty diacid side chain attached through a linker promotes binding to serum albumin. That albumin binding slows renal clearance and extends the circulating half-life from minutes to approximately one week. The structural changes are well established in the published literature. Whether the same modifications affect receptor signalling bias in ways that matter clinically remains an open question.
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
Lyophilised semaglutide is generally held at -20 °C or below, protected from light and moisture. Reconstituted solutions are typically kept at 2-8 °C and used within a defined window because degradation accumulates over time. Repeated freeze-thaw cycles are discouraged, since each cycle can promote aggregation and reduce monomeric content. Room-temperature stability of the solid has been examined in some studies but remains incompletely characterised for long durations, so cold storage is the conservative default for research material.
Degradation proceeds along several parallel routes. Deamidation of asparagine and glutamine residues generates charged variants that shift retention time in chromatographic analysis. Oxidation targets methionine and can be accelerated by trace metals or dissolved oxygen. Non-covalent aggregation produces dimers, oligomers, and larger species that are difficult to reverse. Isomerisation at aspartate residues is slower but measurable under thermal stress. The distribution among these pathways depends on pH, buffer composition, ionic strength, and the presence of excipients such as sugars or surfactants.
The three-member tribunal was unanimous in its decision. The tribunal repeated prior criticisms of the governance of the Essendon's supplements program, which had been seen in the ASADA interim report and the Switkowski report. As a result of the verdict, the provisional suspensions on the players were lifted, and all affected players were eligible to play in Round 1. ASADA and the AFL were given a window of 21 days to appeal the decision. The verdict was handed down in private, and few other details about the reasons for the decision were released.
== Career == Using the profits from his construction business on Long Island, Kimmel and his friend, Milton Cooper, moved to Florida and founded the Kimco Realty Corporation in 1958. Kimco derives its name from the surnames of the two founders. They correctly presaged that Florida was in the midst of transitioning from a vacation destination to a retirement haven. Their first investment was a small strip mall with two stores attached to a Zayre's. Sticking to the same formula - focusing on strip developments in new subdivisions (often following utility trucks out to find new developments - they were wildly successful and over the next thirty years, Kimco's portfolio grew to over 1,900 properties of which 1,100 were strip shopping centers. Their business expanded internationally and included properties in Canada, Mexico, Chile and Brazil. The company went public in 1991 raising $128 million becoming the first Real Estate Investment Trust (REIT) IPO in history. Kimmel retired in 1991 to focus on philanthropic activities.
J. Lyons & Co. was a British restaurant chain store, food manufacturing, and hotel conglomerate founded in 1884 by Joseph Lyons and his brothers in law, Isidore and Montague Gluckstein. Lyons' first teashop opened in Piccadilly, London in 1894, and from 1909 they developed into a chain of teashops, with the firm becoming a staple of the High Street in the UK. At its peak the chain numbered around 200 cafes. The teashops provided for tea and coffee, with food choices consisting of hot dishes and sweets, cold dishes and sweets, and buns, cakes and rolls. Making their first cakes and pastries in 1894, several Lyons cake products are still available on grocers' shelves, including Lyons' treacle tart, Lyons' Bakewell tart, Lyons' Battenberg, and Lyons' trifle sponges, which are sold by Premier Foods. The company is also known for its pioneering use of computers in the office.
In 2009, the first to obtain FDA approval for topical DMSO usage was PENNSAID, which contains diclofenac in a carrier with 45.5% DMSO Each 1 mL of TDiclo contains 16.05 mg diclofenac sodium. TDiclo solution also contains 45.5% dimethyl sulfoxide (DMSO) vehicle, which can result in enhanced penetration of active drug through the skin. The most common adverse event reported was dry skin at the application site (25.3% of patients), followed by contact dermatitis (13.0%)In interventional radiology, DMSO is used as a solvent for ethylene vinyl alcohol in the Onyx liquid embolic agent, which is used in embolization, the therapeutic occlusion of blood vessels. In cryobiology DMSO has been used as a cryoprotectant and is still an important constituent of cryoprotectant vitrification mixtures used to preserve organs, tissues, and cell suspensions. Without it, up to 90% of frozen cells will become inactive. It is particularly important in the freezing and long-term storage of embryonic stem cells and hematopoietic stem cells, which are often frozen in a mixture of 10% DMSO, a freezing medium, and 30% fetal bovine serum. In the cryogenic freezing of heteroploid cell lines (MDCK, VERO, etc.) a mixture of 10% DMSO with 90% EMEM (70% EMEM + 30% fetal bovine serum + antibiotic mixture) is used. As part of an autologous bone marrow transplant the DMSO is re-infused along with the patient's own hematopoietic stem cells. DMSO is metabolized by disproportionation to dimethyl sulfide and dimethyl sulfone. It is subject to renal and pulmonary excretion.
Sources: en.wikipedia.org
On 5 February the Essendon Football Club asked the Australian Sports Anti-Doping Authority (ASADA) to investigate the concerns over the clubs possible use of un-approved supplements during the 2012 season. An internal independent review conducted by Dr. Ziggy Switkowski regarding the Essendon Football Club governance processes was released to the public on 6 May. While ASADA investigated the legality of the supplements, the AFL separately investigated the administration of the club's supplements program, and charged the club and senior staff with bringing the game into disrepute. The charges focussed on the poor business practices within the program, including allowing "a culture of frequent, uninformed and unregulated use of the injection of supplements" at the club, incomplete record keeping which had made it impossible to determine with certainty whether or not players had been administered banned supplements, and for failing to guarantee the health and safety of its players in its program. On 27 August, five days before round 23 and after two days of discussions between the club and the league, the following penalties were imposed relating to these charges:
=== Sexual dysfunction === Bupropion is less likely than other antidepressants to cause sexual dysfunction. A range of studies indicate that bupropion not only produces fewer sexual side effects than other antidepressants but can actually help to alleviate sexual dysfunction including sexual dysfunction induced by SSRI antidepressants. There have also been small studies suggesting that bupropion or a bupropion/trazodone combination may improve some measures of sexual function in women who have hypoactive sexual desire disorder (HSDD) and are not depressed. According to an expert consensus recommendation from the International Society for the Study of Women's Sexual Health, bupropion can be considered as an off-label treatment for HSDD despite limited safety and efficacy data. Likewise, a 2022 systematic review and meta-analysis of bupropion for sexual desire disorder in women reported that although data were limited, bupropion appeared to be dose-dependently effective for the condition.
Commenting on a report released by The Asthma Foundation, Turner said it confirmed concerns that poverty and deprivation impacted greatly on respiratory disease in New Zealand children, and the underlying causes needed to be addressed to ensure that children and families had adequate income, good housing and easy access to health care. In 2015 after the Children's Commissioner released data showing that at the time, there were 305,000 children living in poverty in New Zealand – an increase of 45,000 from the previous year – Turner said that child poverty was now a national issue, not just for individual parents, and there appeared to be an unwillingness to resource a solution to the problem.
Sources: en.wikipedia.org
=== Disease === Neon tetras are occasionally afflicted by the so-called "neon tetra disease" (NTD) or pleistophora disease, a sporozoan disease caused by Pleistophora hyphessobryconis. Despite being a well-known condition, it is generally incurable and often fatal to the fish. However this disease is also generally preventable. The disease cycle begins when microsporidian parasite spores enter the fish after it consumes infected material, such as the bodies of a dead fish, or live food such as tubifex, which may serve as intermediate hosts. The disease is most likely passed by newly acquired fish that have not been quarantined. Symptoms include restlessness, loss of coloration, lumps on the body as cysts develop, difficulty swimming, curved spines as the disease progresses, and secondary infections, such as fin rot and bloating. A so-called "false neon disease", which is bacterial, shows very similar symptoms. It is impossible for the home aquarist to determine for certain the difference between NTD and false NTD on the basis of visible symptoms alone, without laboratory backup. This disease has also been confused with columnaris (mouth rot, mouth fungus, 'flex'). Generally the best 'treatment' is the immediate removal of diseased fish to preserve the remaining fish, although some occasional successful treatments have been performed that include fish baths and a "medication cocktail". The use of a diatom filter, which can reduce the number of free parasites in the water, may help.
=== Diminished sensitivity, associated with diabetes risk === Although many factors influence insulin secretion, the most important control is the amount of glucose moving from the blood into the beta cells of the pancreas. In healthy people, even small rises in blood glucose result in increased insulin secretion. As long as the pancreatic beta cells are able to sense the glucose level and produce insulin, the amount of insulin secreted is usually the amount required to maintain a fasting blood glucose between 70 and 100 mg/dL (3.9–5.6 mmol/L) and a non-fasting glucose level below 140 mg/dL (<7.8 mmol/L). When liver cells and other cells that remove glucose from the blood become less sensitive (more resistant) to the insulin, the pancreas increases secretion and the level of insulin in the blood rises. This increased secretion can compensate for reduced sensitivity for many years, with maintenance of normal glucose levels. However, if insulin resistance worsens or insulin secretion ability declines, the glucose levels will begin to rise. Persistent elevation of glucose levels is termed diabetes mellitus. Typical fasting insulin levels found in this type of hyperinsulinism are above 20 μU/mL. When resistance is severe, levels can exceed 100 μU/mL. In addition to being a risk factor for type 2 diabetes, hyperinsulinism due to insulin resistance may increase blood pressure and contribute to hypertension by direct action on vascular endothelial cells (the cells lining blood vessels).
Osteocalcin, also known as bone gamma-carboxyglutamic acid-containing protein (BGLAP), is a small (49-amino-acid) noncollagenous protein hormone found in bone and dentin, first identified as a calcium-binding protein. Because osteocalcin has gla domains, its synthesis is vitamin K2–dependent. In humans, osteocalcin is encoded by the BGLAP gene. Its receptors include GPRC6A, GPR158, and possibly a third, yet-to-be-identified receptor. There is evidence that GPR37 might be the third osteocalcin receptor.
== Developments == A water-soluble prodrug, fospropofol, has been developed and tested with positive results. Fospropofol is rapidly broken down by the enzyme alkaline phosphatase to form propofol. Marketed as Lusedra, this formulation may not produce the pain at the injection site that often occurs with the conventional form of the drug. The U.S. Food and Drug Administration (FDA) approved the product in 2008. By incorporation of an azobenzene unit, a photoswitchable version of propofol (AP2) was developed in 2012 that allows for optical control of GABAA receptors with light. In 2013, a propofol binding site on mammalian GABAA receptors has been identified by photolabeling using a diazirine derivative. Additionally, it was shown that the hyaluronan polymer present in the synovia can be protected from free-radical depolymerization by propofol. Ciprofol is another derivative of propofol that is 4–6 times more potent than propofol. As of 2022 it is undergoing Phase III trials. Ciprofol appears to have a lower incidence of injection site pain and respiratory depression than propofol. Propofol has also been studied for treatment resistant depression.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
Lower temperatures slow hydrolysis, oxidation and aggregation reactions that degrade the molecule over time. Lyophilised powder is more tolerant than solution, but both benefit from controlled conditions.