Semaglutide is a synthetic peptide engineered from human glucagon-like peptide-1 (GLP-1) that binds and activates the GLP-1 receptor. It was designed by Novo Nordisk and is the active molecule in three FDA-approved prescription medicines: Ozempic, Wegovy, and Rybelsus. In research settings, semaglutide and related GLP-1 receptor agonists are studied for receptor pharmacology, incretin signaling, and metabolic biology; the research-grade peptide described on this page is a laboratory reagent, not a copy of an approved drug, and is not for human or animal use.
| Attribute | Detail |
|---|---|
| Class | Acylated GLP-1 receptor agonist (GLP-1 analog) |
| Backbone | 31-amino-acid peptide based on human GLP-1(7-37), with 94% sequence homology to native GLP-1 |
| Key modifications | Aib8 (DPP-4 resistance), Arg34, and a C18 fatty diacid linked at Lys26 via a hydrophilic spacer |
| Molecular formula / weight | C187H291N45O59, 4113.58 g/mol |
| Origin | Designed by Novo Nordisk; peptide backbone produced by yeast fermentation |
| Approved medicines built on it | Ozempic, Wegovy, Rybelsus (all prescription-only) |
| What studies examine | Receptor binding and activation, albumin-binding pharmacokinetics, and glycemic and body-weight endpoints in randomized clinical trials of the approved drug |
| Research form supplied | Lyophilized powder, for reconstitution at the bench |
Where does semaglutide come from?
Semaglutide is derived from human GLP-1(7-37), the 31-amino-acid active fragment of the incretin hormone glucagon-like peptide-1. Novo Nordisk researchers built semaglutide by modifying that native sequence at two positions and attaching a fatty-acid side chain, with the goal of producing a molecule that resists the enzyme that normally inactivates GLP-1 within minutes and that stays in circulation far longer than the native hormone (Lau et al., 2015).
The design substitutes the native alanine at position 8 with aminoisobutyric acid (Aib8), which blocks cleavage by dipeptidyl peptidase-4 (DPP-4), the enzyme responsible for the very short half-life of native GLP-1. A second substitution, Arg34, replaces the native lysine at that position so that the free lysine at position 26 is left as a single, defined attachment site. A C18 fatty diacid is then conjugated to that Lys26 through a hydrophilic spacer, giving the finished molecule a hydrophobic tail it did not start with (Lau et al., 2015; FDA Ozempic label, 2017).
Why does the C18 diacid extend the half-life?
The fatty diacid does not change what the peptide binds to at the receptor. Its role is to give the molecule a second, non-covalent binding partner: albumin, the most abundant protein in blood plasma. According to the FDA label, this albumin binding is the principal protraction mechanism behind semaglutide's long half-life, reducing renal clearance and protecting the peptide from metabolic degradation while it is bound. The combined effect of DPP-4 resistance and reversible albumin binding gives semaglutide a terminal half-life of approximately one week, long enough that the approved subcutaneous product is dosed on a weekly rather than daily interval (FDA Ozempic label, 2017). This is the same general acylation strategy used in liraglutide, an earlier GLP-1 analog, but semaglutide's fatty-diacid chain length and linker chemistry were selected specifically to push the half-life further (Lau et al., 2015).
How does the GLP-1 receptor work?
GLP-1 is an incretin hormone released from intestinal L-cells after a meal. It acts on the GLP-1 receptor, a class B G protein-coupled receptor expressed in the pancreas, stomach, and central nervous system, among other tissues (UniProt, GLP1R entry P43220). Per the FDA label's mechanism-of-action description, GLP-1 receptor activation stimulates insulin secretion and lowers glucagon secretion, both in a glucose-dependent manner, and is associated with a delay in gastric emptying in the early postprandial phase (FDA Ozempic label, 2017).
A broader literature review of once-weekly GLP-1 receptor agonists describes additional pathways studied for this receptor class: activation of hypothalamic satiety centers in the central nervous system, effects on brain circuits linked to food reward and motivation, and slowed gastrointestinal motility, all reported as contributors to the appetite-related effects observed with GLP-1 receptor agonists in the literature (Cornell, 2020). These are receptor and systems-biology findings reported in the cited sources about GLP-1 receptor agonists generally; they describe what has been studied and published for the receptor and for approved drugs, not instructions or outcomes for use of the research-grade peptide sold here.
Ozempic, Wegovy, and Rybelsus: what is actually approved?
Ozempic, Wegovy, and Rybelsus are FDA-approved prescription medicines that all contain semaglutide as the active ingredient, but they differ in formulation, route, and approved indication. The research-grade semaglutide peptide sold for laboratory use is not any of these medicines, is not formulated, dosed, or tested to their standards, and is not for human or animal use.
| Brand | Formulation | Route | FDA approval |
|---|---|---|---|
| Ozempic | Semaglutide injection | Subcutaneous | 2017 |
| Rybelsus | Semaglutide tablet | Oral | 2019 |
| Wegovy | Semaglutide injection (higher-dose formulation) | Subcutaneous | 2021 |
Approval years and formulations are taken from the FDA prescribing information for each product (FDA Ozempic label, 2017; FDA Rybelsus label, 2019; FDA Wegovy label, 2021).
What have preclinical and clinical studies examined?
The original medicinal chemistry paper describing semaglutide's design reported receptor-binding potency, plasma protein binding, and pharmacokinetic profiling used to select the final candidate from a series of acylated GLP-1 analogs (Lau et al., 2015). Clinical development of the approved drug included large randomized, placebo-controlled trials; one widely cited trial in the STEP program, published in the New England Journal of Medicine, examined once-weekly subcutaneous semaglutide in adults with overweight or obesity over a defined treatment period and reported body-weight outcomes compared with placebo, alongside lifestyle intervention in both arms (Wilding et al., 2021). A separate review traces semaglutide's regulatory path from first approval through subsequent indications, summarizing the clinical trial program supporting the approved drug (Dhillon, 2018).
These are findings reported for the approved pharmaceutical product studied in defined clinical trial populations under medical supervision. They describe what was measured and published in the cited sources, not a description of the research-grade peptide sold for laboratory use, and none of it is dosing or use guidance.
How does semaglutide differ from tirzepatide and retatrutide?
Semaglutide activates a single receptor, GLP-1R. Tirzepatide and retatrutide are engineered as multi-receptor agonists rather than GLP-1-selective molecules, which is the structural basis for comparing them in the research literature. A side-by-side breakdown of receptor targets, backbone differences, and the published data on each molecule is covered in Semaglutide vs Tirzepatide vs Retatrutide and in the blog comparison Retatrutide vs Tirzepatide vs Semaglutide: How the Three Incretin Peptides Differ in the Lab. Researchers working across this peptide family sometimes source research-grade tirzepatide alongside semaglutide to compare receptor-engagement data directly.
Analytical and handling notes for the bench
Research-grade semaglutide is supplied as a lyophilized (freeze-dried) powder. Lyophilization is used across the peptide industry because a dried peptide is markedly more stable in storage and transit than one already in solution, since hydrolysis and related degradation pathways are far slower in the solid state. Reconstitution, the process of returning a lyophilized peptide to solution with an appropriate diluent at the bench, is a standard laboratory technique with its own concentration math; the step-by-step calculations are covered separately in Reconstituting Lyophilized Peptides: The Math, Step by Step. Once reconstituted, a peptide solution should be handled and stored according to the analytical documentation supplied with the lot, since reconstituted peptides are generally less stable than the lyophilized form. Full specifications, certificate of analysis data, and lot documentation for this peptide are available on the research-grade semaglutide product page; a structural and literature summary is maintained separately in the semaglutide research library entry.
Frequently asked questions
Is semaglutide the same molecule as Ozempic?
Semaglutide is the active peptide ingredient in Ozempic, Wegovy, and Rybelsus, which are distinct, differently formulated FDA-approved prescription medicines. Research-grade semaglutide sold for laboratory use is not manufactured, formulated, or tested as any of these drugs and is not a substitute for them.
What is the difference between semaglutide, tirzepatide, and retatrutide?
Semaglutide is selective for the GLP-1 receptor. Tirzepatide and retatrutide are designed to engage additional receptors beyond GLP-1R. The structural and published-data comparison across all three is covered in Semaglutide vs Tirzepatide vs Retatrutide.
Why is a C18 fatty diacid attached to the peptide?
The fatty diacid gives the peptide a reversible binding site for serum albumin. According to the FDA label, that albumin binding is the mechanism behind semaglutide's extended, approximately one-week half-life in the approved drug, by reducing renal clearance and protecting the peptide from degradation while bound (FDA Ozempic label, 2017).
What does "GLP-1 receptor agonist" mean?
It means the molecule binds to and activates the GLP-1 receptor, the same receptor that native GLP-1 activates. The receptor is a class B G protein-coupled receptor studied in the pancreas, stomach, and central nervous system in the cited literature (UniProt P43220; Cornell, 2020).
Why does semaglutide ship as a lyophilized powder instead of a ready solution?
Lyophilization removes water from the peptide, which slows hydrolysis and other degradation pathways and improves stability during storage and transit. Reconstitution at the bench returns it to solution immediately before use in an assay or study, following standard laboratory technique.
Is the semaglutide sold by Homegrown Peptides approved for human use?
No. It is a research-use-only laboratory reagent intended for in vitro and preclinical research applications. It is not the same product as Ozempic, Wegovy, or Rybelsus, and it is not a drug, supplement, or article for human or animal use.
References
- Lau J, Bloch P, Schaffer L, et al. Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide. J Med Chem. 2015. https://pubmed.ncbi.nlm.nih.gov/26308095/
- Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021. https://pubmed.ncbi.nlm.nih.gov/33567185/
- Dhillon S. Semaglutide: First Global Approval. Drugs. 2018. https://pubmed.ncbi.nlm.nih.gov/29363040/
- U.S. Food and Drug Administration. OZEMPIC (semaglutide) injection, prescribing information. 2017. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/209637lbl.pdf
- U.S. Food and Drug Administration. RYBELSUS (semaglutide) tablets, prescribing information. 2019. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/213051s000lbl.pdf
- U.S. Food and Drug Administration. WEGOVY (semaglutide) injection, prescribing information. 2021. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/215256s000lbl.pdf
- UniProt Consortium. Glucagon-like peptide 1 receptor, Homo sapiens (P43220). https://www.uniprot.org/uniprotkb/P43220/entry
- Cornell S. A review of GLP-1 receptor agonists in type 2 diabetes: A focus on the mechanism of action of once-weekly agents. J Clin Pharm Ther. 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7540167/
Research use only. Homegrown Peptides products are for laboratory research and are not for human or animal use. Nothing in this article is medical advice.
