This is a working overview of purity, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-21 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.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
GLP-1 receptors are expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises cyclic AMP, enhances glucose-dependent insulin secretion, and suppresses glucagon release when blood glucose is high. Effects on gastric emptying and on hypothalamic appetite circuits reduce energy intake. Because insulin release remains glucose-dependent, the risk of hypoglycemia is low when the drug is used alone. The precise contribution of each pathway to body weight change in humans remains an area of active investigation.
Clinical studies of semaglutide generally measure glycated hemoglobin, fasting plasma glucose, body weight, and composite cardiovascular endpoints. The SUSTAIN program enrolled adults with type 2 diabetes, while the STEP program focused on obesity without diabetes. Administration follows a stepwise escalation schedule designed to limit gastrointestinal effects during the first weeks. Reported outcomes include mean percentage weight change, the proportion of participants reaching defined weight-loss thresholds, and rates of nausea, vomiting, and diarrhea. Long-term data on durability after treatment stops are still limited and remain a topic of ongoing research.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, developed by Novo Nordisk and first approved in 2017 for type 2 diabetes. It belongs to the incretin mimetic class, a group of agents that reproduce the glucose-dependent actions of endogenous GLP-1. The molecule was engineered to resist degradation by dipeptidyl peptidase-4 and to bind serum albumin, extending its half-life from minutes to roughly one week. Approval for chronic weight management followed in 2021, based on large cardiovascular and obesity outcome trials.
| 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 |
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
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.
Solid peptide material is generally kept at reduced temperature to limit degradation. Short-term storage at 2 to 8 degrees Celsius is common, while longer archival storage at minus 20 degrees Celsius or below is typical for lyophilised powder. Vials should remain sealed and protected from light, because ultraviolet exposure can oxidise susceptible residues. Repeated freeze-thaw cycles are avoided, as they promote aggregation and loss of soluble material. Solutions are less stable than solids and are usually prepared close to the time of use.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilized peptide material is typically stored at or below -20 °C, with -80 °C used for longer-term archives. Vials should remain sealed and desiccated because moisture promotes aggregation and hydrolysis. Repeated freeze-thaw cycles are avoided since they can alter peptide conformation and reduce recovery. Once reconstituted, solutions are generally kept at 2-8 °C and used within a defined window. Stability beyond those windows depends on buffer composition and concentration, and exact limits are product-specific rather than universal.
Identity and purity are assessed with reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities by hydrophobicity. Mass spectrometry confirms molecular weight and detects truncation or modification products. Peptide mapping after enzymatic digestion verifies the amino acid sequence. Quantitation is often performed by LC-MS/MS or by immunoassay, and the two approaches can give different values because they measure different things. Method validation parameters such as accuracy, precision, and limit of quantitation are reported alongside results.
Certificate of analysis documents from suppliers typically report purity by chromatographic area, water content, and counter-ion identity. Independent verification is advisable because reported values can be generated under differing conditions. Impurity profiles matter for research use, where aggregates, deamidation products, and residual solvents may influence experimental results. Container, lot, and chain-of-custody records support traceability. Analytical results are method-dependent, so comparisons between laboratories require the same procedure and reference standards.
=== Disease association === Genetic variants and haplotypes (i.e., allotypes) of ERAP1 have been associated with a wide variety of inflammatory conditions, infectious diseases, and cancer. In particular, ERAP1 is a major risk gene identified in genome-wide association studies of MHC-I associated inflammatory conditions (or "MHC-I-opathies"), including Ankylosing Spondylitis, Bechet's disease, Birdshot Uveitis, and Psoriasis. In these conditions, ERAP1 is often in epistasis with the primary risk MHC-I allele. Other disease associations include insulin dependent Diabetes Mellitus and Multiple Sclerosis. Historically, ERAP1 gene associations were first reported in Hypertension. Emerging evidence links ERAP1 SNVs to cancer development, and susceptibility to infectious disease, such as ERAP1 SNVs that modify the resistance to influenza virus infection.
Some prohormones contain structures other than inactive peptide hormones for the purpose of keeping hormone expression suppressed. For example, proinsulin contains an extra non-hormonal chain called C-peptide that binds two insulin peptide chains together, designed to keep both chains inactive by binding to their ends, specifically, their C-domain junctions, which have been proposed to be their site of binding to hormone-expression receptors in the cell. Despite the restrictions it enables, the C-peptide folds the proinsulin chains to make their junction ends accessible to be cleaved by prohormone convertases later, making the folding of the proinsulin chain containing C-peptide essential for the proper cleavage of proinsulin to successfully produce insulin.
At the outbreak of the Second World War, the Indian Army numbered 205,000 men and, as the war continued, this would rise to 2.5 million men to become the largest all–volunteer force in history. During this process, six corps would be raised; which consisted of the Indian III Corps, Indian IV Corps, Indian XV Corps, Indian XXI Corps (served with Tenth Army in the Middle East in 1942), Indian XXXIII Corps and Indian XXXIV Corps. Furthermore, the 2nd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 14th, 17th, 19th, 20th, 21st, 23rd, 25th, 26th, 34th, 36th (later converted to an all-British formation), and 39th Indian Divisions were formed, as well as other forces. Additionally there were at one time or another four armoured divisions formed (the 31st, 32nd, 43rd, and 44th), and one airborne division, also designated the 44th. In matters of administration, weapons, training, and equipment, the Indian Army had considerable independence; for example, prior to the war the Indian Army adopted the Vickers–Berthier (VB) light machine gun instead of the Bren gun of the British Army, while continuing to manufacture and issue the older SMLE No. 1 Mk III rifle during the Second World War, instead of the Lee–Enfield No.4 Mk I issued to the British Army from the middle of the war. Particularly notable contributions of the Indian Army during that conflict were the:
Drosophila melanogaster is a species of fly (an insect of the order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly", or "banana fly". D. melanogaster is attracted to rotting fruit and fermenting beverages and is often found in orchards, kitchens, and pubs. Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, D. melanogaster continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. In 1946 D. melanogaster was the first animal to be launched into space. As of 2017, six Nobel Prizes have been awarded to drosophilists for their work using the insect. Drosophila melanogaster is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. D. melanogaster is a common pest in homes, restaurants, and other places where food is served. Flies belonging to the family Tephritidae are also called "fruit flies". This can cause confusion, especially in the Mediterranean, Australia, and South Africa, where the Mediterranean fruit fly Ceratitis capitata is an economic pest.
Sources: en.wikipedia.org
=== Teleost fish interferons === Like tetrapods, teleost (ray-finned) fish, including the zebrafish and salmons, belong to the group of bony fish. However, the teleosts have experienced their own whole genome duplication which produced many more genes. Unlike the amniotes which lost the original copy of their type I IFN, the teleost fish generally have two possible locations for their type I IFN, both corresponding to the ancestral location between SCN4A and ARHGAP27. The teleost interferons are:
costmary, 1–66 grams sweet flag, 20 grams hypericum, 8 grams Natural gum, 8 grams sagapenum, 8 grams acacia juice, 8 grams Illyrian iris (probably I. germanica), 8 grams cardamom, 8 grams anise, 12 grams Gallic nard (Valeriana italica), 16 grams gentian root, 16 grams dried rose leaves, 16 grams poppy-tears (Papaver rhoeas, a wild poppy with low opiate content), 17 grams parsley, 17 grams cassia, 20–66 grams saxifrage, 20–66 grams darnel, 20–66 grams long pepper, 20–66 grams storax, 21 grams castoreum, 24 grams frankincense, 24 grams hypocistis juice, 24 grams myrrh, 24 grams opopanax, 24 grams malabathrum leaves, 24 grams flower of round rush, 24–66 grams turpentine-resin, 24–66 grams galbanum, 24–66 grams Cretan carrot seeds, 24–66 grams nard, 25 grams opobalsam, 25 grams shepherd's purse, 25 grams rhubarb root, 28 grams saffron, 29 grams ginger, 29 grams cinnamon, 29 grams The ingredients are then "pounded and taken up in honey. Against poisoning, a piece the size of an almond is given in wine. In other affections an amount corresponding in size to an Egyptian bean is sufficient." Of these ingredients, Illyrian iris, darnel, and rhubarb were not commonly found in other versions of the antidote. However, Celsus' formulation, written 100 years after the death of Mithridates, was one of the first published. Galen called the antidote "theriac" and presented versions by Aelius (used by Julius Caesar), Andromachus (physician to Nero), Antipater, Nicostratus, and Damocratis. The Andromachus formulation closely resembles that of Celsus.
== Inhibition == The main inhibitor of tissue plasminogen activator and urokinase is plasminogen activator inhibitor-1 (PAI-1). Plasminogen activator inhibitor-1 is a serine protease, synthesized by endothelial cells, that specifically inhibits tissue plasminogen activator (tPA) and urokinase (uPA). Tissue plasminogen activator and urokinase are the activators of plasminogen and result in the breakdown of blood clots (fibrinolysis). PAI-1 levels have also been studied in patients and how they influence certain diseases. Elevated serum levels of PAI-1 have been found in obese individuals. Elevated levels of PAI-1 also seem to increase the risk of atherothrombotic events and may also promote vascular disease. Plasminogen activator inhibitor-2 (PAI-2) is a serine protease that inactivates tPA and uPA. PAI-2 is produced by the placenta and only found in high quantities in the blood during pregnancy.
Sources: en.wikipedia.org
=== N05AH Diazepines, oxazepines, thiazepines and oxepines === N05AH01 Loxapine N05AH02 Clozapine N05AH03 Olanzapine N05AH04 Quetiapine N05AH05 Asenapine N05AH06 Clotiapine N05AH53 Olanzapine and samidorphan
== Research == Lasofoxifene is under development by Sermonix Pharmaceuticals for the treatment of metastatic breast cancer and dyspareunia associated with vaginal atrophy in the United States and Europe. It is also being researched for the potential treatment of ovarian cancer. As of December 2017, lasofoxifene is in phase III clinical trials for breast cancer and phase II clinical studies for dyspareunia.
Both these levels are raised to be close in energy to the 7s ones, high enough to possibly be chemically active. This would allow for the possibility of exotic nihonium compounds without lighter group 13 analogues. Periodic trends would predict nihonium to have an atomic radius larger than that of thallium due to it being one period further down the periodic table, but calculations suggest nihonium has an atomic radius of about 170 pm, the same as that of thallium, due to the relativistic stabilisation and contraction of its 7s and 7p1/2 orbitals. Thus, nihonium is expected to be much denser than thallium, with a predicted density of about 16 to 18 g/cm3 compared to thallium's 11.85 g/cm3, since nihonium atoms are heavier than thallium atoms but have the same volume. Bulk nihonium is expected to have a hexagonal close-packed crystal structure, like thallium. The melting and boiling points of nihonium have been predicted to be 430 °C and 1100 °C respectively, exceeding the values for indium and thallium, following periodic trends. Nihonium should have a bulk modulus of 20.8 GPa, about half that of thallium (43 GPa).
== Thoracic and Respiratory == Adenocarcinoma of the lung Basaloid squamous cell lung carcinoma Bronchial adenomas/carcinoids Giant-cell carcinoma of the lung Large-cell lung carcinoma Large cell lung carcinoma with rhabdoid phenotype Laryngeal cancer Mesothelioma Non-small cell lung cancer Non-small cell lung carcinoma Pleuropulmonary blastoma Sarcomatoid carcinoma of the lung Small cell lung cancer Squamous-cell carcinoma of the lung Thymoma and thymic carcinoma
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.
It is given either as a once-weekly subcutaneous injection or as an oral tablet taken once daily. The two forms use different absorption strategies, so they are not interchangeable on a milligram-for-milligram basis.