Aib substitution raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-09-13 and is reviewed periodically as new material appears.
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nm is the standard purity method, reported as area percent. Mass spectrometry, usually with electrospray ionisation, confirms identity and reveals covalent modifications. Size-exclusion chromatography quantifies aggregates and fragments. Peptide mapping after enzymatic digestion localises changes to specific sequence regions. Circular dichroism and infrared spectroscopy report on secondary structure, while light scattering tracks particle formation in liquid formulations. No single technique captures every quality attribute.
Quality control relies on pharmacopoeial monographs where they exist, combined with in-house specifications for identity, purity, water content, and counter-ion composition. Reference standards allow calibration across laboratories, although certified materials for every analogue are not universally obtainable. Batch records, chromatograms, and mass spectra form the documentation trail. Regulatory classification varies by jurisdiction and intended use, and research-grade material differs from pharmaceutical-grade material in testing scope. Analytical uncertainty is often expressed as relative standard deviation across replicate injections.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | Parent peptide; salt forms also reported |
| Molecular mass | about 4113.6 Da | Average mass of the free peptide |
| Peptide length | 31 amino acids | Backbone related to GLP-1(7-37) |
| Key substitution | Aib at position 8 | Blocks DPP-4 cleavage |
| Albumin binding | Via C-18 diacid side chain | Prolongs circulation time |
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.
Reversed-phase high-performance liquid chromatography with ultraviolet detection is the dominant approach for peptide purity assessment, usually paired with mass spectrometry to confirm molecular mass and sequence. Peptide mapping by enzymatic digestion and tandem mass spectrometry locates modifications such as deamidation and oxidation. Quantitation in plasma matrices can be performed by LC-MS/MS after solid-phase extraction. Method validation follows general guidance on accuracy, precision, linearity, and limits of detection. Comparability of results between laboratories, when no shared reference standard is available, remains an open question.
Stability studies focus on deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation into higher-order species. The fatty acid side chain adds susceptibility to oxidative change and can promote self-association at high concentration. Lyophilised material is comparatively robust when kept cold and dry, while aqueous solutions require refrigeration and protection from light. Forced degradation experiments under heat, acid, base, and peroxide conditions establish the specificity of each analytical method. Which degradation route dominates under real storage conditions depends on the formulation and stays formulation-specific.
Handling guidance for research quantities calls for single-use aliquots, an inert atmosphere where practical, and avoidance of repeated freeze-thaw cycles that accelerate aggregation. Certificates of analysis typically report purity by peak area, water content, counter-ion identity, and residual solvent levels. In the scientific literature the compound is usually described by its full amino acid sequence, its registry number, or its structural class rather than by any proprietary label. Reporting standards vary between journals, and reviewers increasingly request raw chromatograms alongside tabulated purity figures. Whether current purity thresholds are adequate for every experimental context is debated.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
The sequence incorporates alpha-aminoisobutyric acid at position 8, replacing the alanine found in the natural hormone. This substitution blocks the primary DPP-4 recognition site and contributes most of the enzymatic stability. Albumin binding further protects the peptide and reduces the frequency of administration required to maintain active plasma levels. Because the fatty acid chain increases lipophilicity, the compound is formulated as a solution rather than a simple aqueous buffer. Researchers describe the design as an incremental optimization of earlier GLP-1 analogs rather than a wholly new scaffold.
Some historians assert that as many as 17 million people were sold into slavery on the coast of the Indian Ocean, the Middle East, and North Africa, and approximately 5 million African slaves were bought by Muslim slave traders and taken from Africa across the Red Sea, Indian Ocean, and Sahara Desert between 1500 and 1900. The captives were sold throughout the Middle East. This trade accelerated as superior ships led to more trade and greater demand for labour on plantations in the region. Eventually, tens of thousands of captives were being taken every year. The Indian Ocean slave trade was multi-directional and changed over time. To meet the demand for menial labour, Bantu slaves bought by east African slave traders from southeastern Africa were sold in cumulatively large numbers over the centuries to customers in Egypt, Arabia, the Persian Gulf, India, European colonies in the Far East, the Indian Ocean islands, Ethiopia, Sudan and Somalia. According to the Encyclopedia of African History, "It is estimated that by the 1890s the largest slave population of the world, about 2 million people, was concentrated in the territories of the Sokoto Caliphate. The use of slave labour was extensive, especially in agriculture." The Anti-Slavery Society estimated there were 2 million slaves in Ethiopia in the early 1930s out of an estimated population of 8 to 16 million. Slave labour in East Africa was drawn from the Zanj, Bantu peoples that lived along the East African coast.
=== Animals === In cats (and some dogs and ferrets) vaccine-associated sarcoma (VAS) or feline injection-site sarcoma (FISS) occurs at a rate of 1–10 per 10,000 injections. In 1993, a causal relationship between VAS and administration of aluminium-adjuvated rabies and FeLV vaccines was established through epidemiologic methods, and in 1996 the Vaccine-Associated Feline Sarcoma Task Force was formed to address the problem. FISS is characterized by an unintentionally prolonged inflammation at the injection site and an imappropriate respose by the other cells to the inflammation. However, evidence conflicts on whether types of vaccines, manufacturers or factors have been associated with sarcomas. It is unknown why humans do not have this reaction.
The acetylcholinesterase inhibitor chemical class includes neostigmine and rivastigmine, both of which have a chemical structure based on the natural alkaloid physostigmine. The tranquilizer, sedative-hypnotic, and muscle relaxant, meprobamate (branded Miltown) was commonly prescribed from the 1950s through the 1970s. Soma (carisoprodol) is a CNS depressant and a prodrug of meprobamate; initially acting primarily as a mildy-sedating muscle relaxant and muscle pain reliever; after 2-3 hours, 20-30% of initial dose converts into active metabolite meprobamate, synergistically working together to potentiate, or add on to/increase, the existing sedation and muscle relaxation and analgesia. Valmid or Valamin was a carbamate derivative chemically named ethinamate. It was withdrawn from the market in the U.S. and Netherlands around 1990. The protease inhibitor darunavir for HIV treatment also contains a carbamate functional group. Ephedroxane, an aminorex analogue used as a stimulant, also falls into the carbamate category. Felbamate is an anticonvulsant used in the treatment of epilepsy, with high risk of potentially fatal aplastic anemia and/or liver failure limiting the drug's usage to severe refractory epilepsy.
== Partnerships == Towards fulfilling its mandate, RCB is collaborating with various national and international institutions of repute. The partnerships are meant for exchange of ideas, information sharing, training, networking, conducting scientific colloquia, workshops, academic exchange programmes and student study visits within (and outside) India and for students of the Asia-Pacific region. RCB and National Institute of Advanced Industrial Science and Technology (AIST), Japan announced a partnership to further capacity building initiatives in bio-imaging and biotechnology. The agreement offers an excellent opportunity for both the institutions in capacity building, training and research collaborations, benefitting young scientists not only in India and Japan, but also from the UNESCO member countries in the Asia-Pacific and SAARC regions. In its continuing effort to fulfill the core mandate, RCB is actively engaged in a range of research and related activities in partnership with other academic institutions, which form part of the NCR Biotech Science Cluster, Faridabad. Shared facilities such as Advanced Technology Platform Centre (ATPC), and Bioincubators (supported by Biotechnology Industry Research Assistance Council (BIRAC)), which is meant to support the budding biotechnology entrepreneurs, are being established.
Sources: en.wikipedia.org
This change from an irregular cavalry force that fought against the enemies of Russia, such as the Ottoman Empire and France, to a repressive gendarmerie deployed against the subjects of the Empire caused much disquiet within the various Hosts, as it was contrary to the heroic ethos of frontier warfare that the Cossacks cherished. In 1879, the Shah of Iran, Nasir al-Din, who had been impressed with the equestrian skills and distinctive uniforms of the Cossacks while on a visit to Russia the previous year, requested that the Emperor Alexander II sent some Cossacks to train a Cossack force for himself. Alexander granted his request and later in 1879 a group of 9 Cossacks led by Kuban Cossack Colonel Aleksey Domantovich arrived in Tehran to train the Persian Cossack Brigade. The shah very much liked the colorful uniforms of the Cossacks and Domantovich devised uniforms for one regiment of the brigade based on the uniforms of the Kuban Cossack Host and another regiment had its uniform based on the Terek Cossack Host. The uniforms of the Cossacks were based on the flamboyant costumes of the peoples of the Caucasus, and what in Russia were viewed as exotic and colorful uniforms were viewed in Iran as a symbol of Russianness. Nasir al-Din, who was widely regarded as a deeply superficial and shallow man, was not interested in having his Cossack Brigade be an effective military force, and for him merely seeing his brigade ride before him while dressed in their brightly colored uniforms was quite enough.
== Clinical significance == Maleylacetoacetate isomerase deficiency is a disease caused by a mutation in the gene GSTZ1. This is an autosomal recessive inborn error of metabolism. It is caused by a mutation in the gene that codes for the synthesis of 4-maleylacetoacetate isomerase, GSTZ1. Mutations in 4-maleylacetoacetate isomerase resulted in accumulation of fumarylacetoacetate and succinylacetone in the urine, but individuals were otherwise healthy. It is likely that there exists an alternate nonenzymatic bypass that allows the catabolism of 4-maleylacetoacetate in the absence of 4-maleylacetoacetate isomerase. Because of this mechanism, a mutation in the gene encoding 4-Maleylacetoacetate isomerase is not considered dangerous. GSTZ1 is highly expressed in the liver, however mutations in this gene do not impair liver function or coagulation.
=== Drug-drug interactions === Typically, drug-drug interactions are formally quantified by comparing the observed combined effect of two co-administered drugs against a theoretical baseline of no interaction. This concept, commonly referred to as the additive effect, explains the synergistic interaction, or lack thereof, between drugs. In order to validly quantify the effect, two primary null models are used: loewe additivity and bliss independence. Loewe additivity (dosage additivity) postulates that if two drugs share the same mechanism of action, their combined effects should be identical to the effect achieved from taking a higher dose of either drug alone. Bliss independence (response additivity) postulates that if two drugs act independently of each other, their combined effect should be the product of their individual effects. Both models identify two combined effects that signal a true drug interaction, as they deviate from the additive baseline: a synergistic effect, where the observed combined effect is greater than predicted which results in higher efficacy or toxicity levels; and an antagonistic effect, where the observed combined effect is less than predicted which often results in drug therapy problems. The therapeutic index (TI) of a drug is the measurement of its efficacy, calculated as the ratio of the median toxic dose (TD50) to the median effective dose (ED50). Various Cytochrome P450 metabolic enzymes are inhibited or induced by many drugs.
Sources: en.wikipedia.org
== Overdose == Buspirone appears to be relatively benign in cases of single-drug overdose, although no definitive data on this subject appear to be available. In one clinical trial, buspirone was administered to healthy male volunteers at a dosage of 375 mg/day, and produced side effects including nausea, vomiting, dizziness, drowsiness, miosis, and gastric distress. In early clinical trials, buspirone was given at dosages even as high as 2,400 mg/day, with akathisia, tremor, and muscle rigidity observed. Deliberate overdoses with 250 mg and up to 300 mg buspirone have resulted in drowsiness in about 50% of individuals. One death has been reported in a co-ingestion of 450 mg buspirone with alprazolam, diltiazem, alcohol, and cocaine.
== Medical uses == Treatment of PCP caused by Pneumocystis jirovecii Prevention of PCP in adults with HIV who have one or both of the following: History of PCP CD4+ count ≤ 200mm³ Treatment of leishmaniasis Treatment of African trypanosomiasis caused by Trypanosoma brucei gambiense Balamuthia infections Pentamidine is classified as an orphan drug by the U.S. Food and Drug Administration
==== Reactions of tyrosines ==== Tyrosine residues are relatively unreactive; therefore they have not been a popular targets for bioconjugation. Recent development has shown that the tyrosine can be modified through electrophilic aromatic substitutions (EAS) reactions, and it is selective for the aromatic carbon adjacent to the phenolic hydroxyl group. This becomes particularly useful in the case that cysteine residues cannot be targeted. Specifically, diazonium effectively couples with tyrosine residues (diazonium salt shown as reagent in the first reaction in Figure 3 below), and an electron withdrawing substituent in the 4-position of diazonium salt can effectively increase the efficiency of the reaction. Cyclic diazodicarboxyamide derivative like 4-Phenyl-1,2,4-triazole-3,5-dione (PTAD) were reported for selective bioconjugation on tyrosine residues (the second reaction in Figure 3 below). A three-component Mannich-type reaction with aldehydes and anilines (the last reaction in Figure 3) was also described to be relatively tyrosine-selective under mild optimised reaction conditions.
Sources: en.wikipedia.org
It belongs to the incretin mimetic class and acts as a long-acting glucagon-like peptide-1 receptor agonist. The class includes several peptides with different half-lives and routes of administration.
The side chain enables reversible binding to albumin in the bloodstream, which protects the peptide from rapid renal clearance. This extends the interval between administrations compared with unmodified GLP-1.
No. It shares much of the native sequence but carries substitutions and an added side chain. These changes increase stability against enzymatic breakdown.
Reverse-phase high-performance liquid chromatography with ultraviolet detection is the usual choice, with results reported as area percent. Complementary methods such as size-exclusion chromatography and mass spectrometry are needed because a single separation cannot resolve every impurity class. Purity figures are therefore method dependent and should always be read alongside the technique used.