PPARδ agonist raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
GW501516 binds and activates PPARδ, a nuclear receptor that influences transcription of genes involved in fatty acid oxidation and energy use. Activation shifts some metabolic pathways in preclinical models, which is why the compound has been studied for lipid disorders and exercise-related endpoints. The exact downstream effects in humans are incompletely mapped. PPARδ is expressed in many tissues, including skeletal muscle, liver, and adipose tissue, so broad activation may have varied consequences. Researchers continue to examine how selective or partial activation might alter the balance between benefits and risks.
Published human data are sparse and mostly come from early-phase trials. Those studies examined short-term changes in lipids, glucose, and exercise capacity, but they were not large enough to establish efficacy or long-term safety. Some animal experiments reported increased running endurance, yet such findings do not prove a performance benefit in people. Anti-doping laboratories detect GW501516 and its metabolites in urine or blood using liquid chromatography-tandem mass spectrometry. Detection windows depend on dose, sample type, and individual metabolism. The method is sensitive enough to identify trace residues in tested samples.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | GW501516, GW-501516, GW 501516, endurobol | Names vary in research and anti-doping documents. |
| Chemical class | Synthetic PPARδ agonist | Small-molecule nuclear receptor ligand. |
| CAS Registry Number | 317318-70-0 | Identifier commonly associated with GW501516. |
| Appearance | White to off-white powder | Typical for purified research material. |
| Solubility | Low in water; soluble in DMSO and ethanol | Organic solvents are common for laboratory stock solutions. |
Cardarine is a common name for GW501516, also GW-1516, a synthetic compound developed as a peroxisome proliferator-activated receptor delta (PPARδ) agonist. It belongs to a class of agents that modulate gene transcription related to lipid and energy metabolism. The compound was studied in preclinical and early clinical research for metabolic and cardiovascular conditions, but it did not progress to approved therapeutic use. Its name appears in fitness and sports contexts despite not being approved as a drug.
PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.
Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.
Anti-doping laboratories identify GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the usual matrix, and detection can occur after the parent compound has cleared from blood. The exact detection window depends on dose, formulation, individual metabolism, and assay sensitivity. Because the compound is prohibited at all times, athletes are subject to testing in and out of competition. Analytical methods continue to improve as new metabolites and designer analogs are characterized.
== Further reading == Zolkepli, Farik (September 26, 2007). "Johor home to world's first bitubale packaging plant - Business News". The Star. Retrieved August 2, 2016. Zolkepli, Farik (September 3, 2007). "Bitumen Bale sets up first bitubale packaging plant - Business News". The Star. Retrieved August 2, 2016.
== Biology / Functions == Efficient presentation of antigenic peptides by MHC class I molecules provides the key signal for adaptive immune responses by cytotoxic (CD8+) T lymphocytes. In the "endogenous" antigen presentation pathway, proteins synthesized by cells undergo cytosolic degradation and some of their peptide fragments are transported to the ER, where suitable-length peptides are loaded onto MHC class I molecules. In the ER, ERAP1 shortens longer peptides to the optimal length for stable binding onto MHC class I molecules (Figure 1). ERAP1, like other APP components, is induced by interferon gamma, a cytokine inducing antigen presentation. ERAP1 preferentially trims N-extended substrates of 9-16 residues to optimally sized 8-10 residue peptides. This "molecular ruler" mechanism is unique to ERAP1. ERAP1 also functions in the presentation of extracellular antigens in the cross-presentation pathway. ERAP1 "trimming" modulates the peptide repertoire presented by MHC class I molecules and thereby shapes the adaptive immune response. In murine models, ERAAP (the murine homologue of human ERAP1) deficiency results in a strong alteration and increased immunogenicity of the peptide repertoire presented by MHC-I. Murine models with genetic deficiency for ERAAP have been instrumental for understanding the role of peptide trimming in the ER. Besides peptide trimming in the ER, ERAP1 has been proposed to perform additional functions depending on its location.
== Mechanism of action == Gliotoxin is suspected to be an important virulence factor (aka pathogenicity factor) in Aspergillus fungus. Gliotoxin possesses immunosuppressive properties that may suppress and cause apoptosis in certain cells of the immune system, including neutrophils, eosinophils, granulocytes, macrophages, and thymocytes. Specifically, neutrophils exposed to gliotoxin release less reactive oxygen species (ROS) and complete fewer phagocytic activities. Gliotoxin is also believed to interfere with T-cell activation. Additionally, gliotoxin acts as an inhibitor of farnesyl transferase. It noncompetitively inhibits the chymotrypsin-like activity of the 20S proteasome. In vivo gliotoxin displays anti-inflammatory activity. It was investigated as an antibiotic and antifungal in the 1940s and as an antiviral agent. Gliotoxin inactivates many different enzymes, including nuclear factor-κB (NF-κB), NADPH oxidase, and glutaredoxin. The inhibition of NF-κB leads prevents cytokine release and induction of the inflammatory response. The immunosuppressive properties of gliotoxin are due to the disulfide bridge within its structure. Interactions occur between sulfur molecules that make up the disulfide bridge and thiol groups contained in cysteine residues. Gliotoxin acts by blocking thiol residues in the cell membrane. Gliotoxin also activates a member of the Bcl-2 family called Bak in order to mediate cell apoptosis. Activated Bak then causes the release of ROS, which form pores within the mitochondrial membrane.
Sources: en.wikipedia.org
== Mechanism == The Bergmann degradation begins with benzoylation at the alpha-group of a peptide and subsequent conversion to an acyl azide. As in the Curtius rearrangement, the acyl azide, in the presence of benzyl alcohol and heat, rearranges to a highly reactive isocyanate intermediate, releasing nitrogen gas in the process. The isocyanate in turn reacts with benzyl alcohol to form a benzylurethane (also referred to as carboxybenzyl), a compound possessing a carbamate amine protecting group. Subsequent removal of the carbamate protecting group is carried out by catalytic hydrogenation in the presence of hydrochloric acid followed by addition to boiling water, yielding an unstable intermediate that rapidly rearranges to release carbon dioxide, driving the reaction forward. This leads to further rearrangement and subsequent hydrolysis, ultimately resulting in the formation of an aldehyde bearing the next amino acid residue in the sequencing series and the expulsion of the residual peptide in amide form.
== Pharmacokinetics == Butyrfentanyl binds to the opioid receptor. During the studies of in vitro inhibition of specific [3H] fentanyl binding to the opioid receptor, the order of analogues was: (±)-cis-3-methylfentanyl > fentanyl = alpha-methylfentanyl > butyrylfentanyl > benzylfentanyl. The studies in inhibition studies on binding affinity achieved the same order of analogues. It means that butyrfentantyl is a less potent opioid-agonist than fentanyl. On the other side, during in vitro studies of cross-reactivity with the fentanyl antibody between fentanyl and the fentanyl analogs examined, revealed order: fentanyl = butyrylfentanyl > (±)-cis-3-methylfentanyl > benzylfentanyl > alpha-methylfentanyl. High cross-reactivity may be the effect of the shape of the molecule — the shape of butyrfentanyl is closest to the original fentanyl molecule, which makes it easy to bind by fentanyl antibodies. The opioid receptor affinity of fentanyl and its analogs was determined from their inhibitory potency in a binding assay with [3H] fentanyl as the radioligand. The Ki value for butyrfentanyl was 32 ± 4.1 nM. Comparing to fentanyl's Ki (1.06 ± 0.15 nM), butyrfentanyl's ability to displace [3H] fentanyl is low and it requires high concentrations of the drug. Studies on urinary excretion revealed that almost all of the injected butyrfentanyl was excreted or metabolized within the first 3 hours after injection, and only very low concentrations were still detectable after 3 hours. Urinary concentrations of butyrylfentanyl from animals injected with 15 μg/kg and 45 μg/kg i.v.
== Further reading == Anie KA, Massaglia P (March 2014). "Psychological therapies for thalassaemia". The Cochrane Database of Systematic Reviews. 2014 (3) CD002890. doi:10.1002/14651858.cd002890.pub2. PMC 7138048. PMID 24604627. Galanello R, Cao A (February 2011). "Gene test review. Alpha-thalassemia". Genetics in Medicine. 13 (2): 83–8. doi:10.1097/GIM.0b013e3181fcb468. PMID 21381239. S2CID 209070781.
Sources: en.wikipedia.org
When venomous snakes bite a target, they secrete venom through their venom delivery system. The venom delivery system generally consists of two venom glands, a compressor muscle, venom ducts, a fang sheath, and fangs. The primary and accessory venom glands store the venom quantities required during envenomation. The compressor muscle contracts during bites to increase the pressure throughout the venom delivery system. The pressurized venom travels through the primary venom duct to the secondary venom duct that leads down through the fang sheath and fang. The venom is then expelled through the exit orifice of the fang. The total volume and flow rate of venom administered into a target varies widely, sometimes as much as an order of magnitude. One of the largest factors is snake species and size, larger snakes have been shown to administer larger quantities of venom.
Its Estey Hall was the first building constructed for the higher education of Black women, and Leonard Medical Center was the first four-year medical school in the country for African Americans. In 1867, Episcopal clergy founded St. Augustine's College for the education of freedmen. The biracial Reconstruction legislature created new welfare institutions: in 1869, it approved the United States' first school for blind and deaf Black people, to be located in Raleigh. In 1874, the federal government constructed the Federal Building in Raleigh, the first federal government project in the Southern U.S. following the Civil War. In 1880, the newspapers News and Observer combined to form The News & Observer. It continues to be Raleigh's primary daily newspaper. The North Carolina College of Agriculture and Mechanic Arts, now known as North Carolina State University, was founded as a land-grant college in 1887. The city's Rex Hospital opened in 1889 and included the state's first nursing school. The Baptist Women's College, now known as Meredith College, opened in 1891, and in 1898, The Academy of Music, a private music conservatory, was established. In the late nineteenth century, two Black Congressmen were elected from North Carolina's 2nd district, the last in 1898. George Henry White sought to promote civil rights for Black citizens and to challenge efforts by White Democrats to reduce Black voting by new discriminatory laws. He and his allies were unsuccessful.
== Interactions == Gelsolin is a cytoplasmic, calcium-regulated, actin-modulating protein that binds to the barbed ends of actin filaments, preventing monomer exchange (end-blocking or capping). It can promote nucleation (the assembly of monomers into filaments), as well as sever existing filaments. In addition, this protein binds with high affinity to fibronectin. Plasma gelsolin and cytoplasmic gelsolin are derived from a single gene by alternate initiation sites and differential splicing. Gelsolin has been shown to interact with:
Modern drug discovery is thus usually a capital-intensive process that involves large investments by pharmaceutical industry corporations as well as national governments (who provide grants and loan guarantees). Despite advances in technology and understanding of biological systems, drug discovery is still a lengthy, "expensive, difficult, and inefficient process" with low rate of new therapeutic discovery. In 2010, the research and development cost of each new molecular entity was about US$1.8 billion. In the 21st century, basic discovery research is funded primarily by governments and by philanthropic organizations, while late-stage development is funded primarily by pharmaceutical companies or venture capitalists. To be allowed to come to market, drugs must undergo several successful phases of clinical trials, and pass through a new drug approval process, called the New Drug Application in the United States. Discovering drugs that may be a commercial success, or a public health success, involves a complex interaction between investors, industry, academia, patent laws, regulatory exclusivity, marketing, and the need to balance secrecy with communication. Meanwhile, for disorders whose rarity means that no large commercial success or public health effect can be expected, the orphan drug funding process ensures that people who experience those disorders can have some hope of pharmacotherapeutic advances.
Sources: en.wikipedia.org
Cardarine is an investigational synthetic compound that acts as a PPARδ agonist. It is also known as GW501516 and has been studied mainly in preclinical research. It is not an approved medicine.
No. Cardarine is not a steroid hormone; it targets the nuclear receptor PPARδ. Its classification in anti-doping rules differs from anabolic steroids, though it remains prohibited in sport.
Early rodent studies reported tumor formation at multiple sites, which raised safety concerns. Sponsors stopped clinical development, and no approved human product exists.
Anti-doping and clinical laboratories commonly use liquid chromatography-tandem mass spectrometry. The method can identify GW501516 and its metabolites in urine or blood. Detection depends on sample timing and the amount present.