This is a working overview of LC-MS/MS, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-26 and is reviewed periodically as new material appears.
GW501516 acts as a selective agonist at PPARδ, a nuclear receptor that regulates transcription of genes involved in lipid handling and energy metabolism. Activation of PPARδ in preclinical models increases fatty acid oxidation, mitochondrial biogenesis, and exercise endurance in rodents. These effects have made the compound a subject of metabolic research and also a target for sport anti-doping rules. In humans, however, controlled studies are limited, and whether similar endurance or metabolic changes occur at tolerated exposures remains an open question. The receptor’s broad tissue distribution also means downstream effects may vary by organ and condition.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
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.
Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Visual description for typical solid reference material. |
| Solubility | Poorly soluble in water; soluble in DMSO | Solubility depends on solvent, purity, and form. |
| Storage | Cool, dry, protected from light | Long-term storage often uses low temperature and desiccant. |
| Common analytical method | LC-MS/MS | Used for detection and quantification in biological matrices. |
| Common synonyms | GW-501516; GW501516; endurobol | Naming varies among literature, vendors, and databases. |
== As vaccine or adjuvant == Peptidoglycan is immunologically active, which can stimulate immune cells to increase the expression of cytokines and enhance antibody-dependent specific response when combined with vaccine or as adjuvant alone. MDP, which is the basic unit of peptidoglycan, was initially used as the active component of Freund's adjuvant. Peptidoglycan from Staphylococcus aureus was used as a vaccine to protect mice, showing that after vaccine injection for 40 weeks, the mice survived from S. aureus challenge at an increased lethal dose.
Risk factors for opioid overdose include opioid dependence, injecting opioids, using high doses of opioids, and use together with alcohol, benzodiazepines, or cocaine. The risk is particularly high following detoxification. Dependence on prescription opioids can occur from their use to treat chronic pain. In young children, an overdose is usually due to opioids that are intended for their parents, older siblings, or grandparents. In mothers who take codeine during breastfeeding, opioid overdoses have occurred in their baby. Codeine is, therefore, not recommended for those who are breastfeeding.
=== Neurodegenerative disorders === As suppression of autophagy has been indicated as a contributing factor in a variety of neurodegenerative disorders, including Alzheimer's disease, rapamycin has been proposed as a potential treatment for these conditions, although results suggest it may not be effective in all cases.
Hormone replacement therapy (HRT) is primarily concerned with alleviating gender dysphoria in transgender people. Hormone therapy targets the secondary sex characteristics. Trans women typically use feminizing therapy, the goal of which is to develop female characteristics while suppressing male characteristics. Trans men typically use masculinizing therapy, which has the opposite goal – to develop male characteristics while suppressing female characteristics. Trans women are usually treated with estrogen and complementary anti-androgenic therapy. According to UCSF Transgender Care, "The primary class of estrogen used for feminizing therapy is 17-beta estradiol, which is a 'bioidentical' hormone in that it is chemically identical to that from a human ovary." The anti-adrogenic medications include spironolactone and the 5-alpha reductase inhibitors, finasteride and dutasteride. This therapy induces breast formation, reduces male hair pattern growth, and changes fat distribution, also leading to a decreased testicular size and erectile function. Trans men are normally treated with exogenous testosterone. Several formulations of testosterone exist, and in the U.S., all formulations are "bioidentical" to endogenous testosterone of testicular origin. Masculinizing therapy is expected to cease menses, to increase facial and body hair, to cause changes in skin and in fat distribution, and to increase muscle mass and libido.
Sources: en.wikipedia.org
== Clinical significance == Guanine nucleotide synthesis is essential for maintaining normal cell function and growth, and is also important for the maintenance of cell proliferation and immune responses. IMPDH expression is found to be upregulated in some tumor tissues and cell lines. B and T lymphocytes display a dependence on IMPDH for normal activation and function, and demonstrate upregulated IMPDH expression. Therefore, IMPDH has been addressed as a drug target for immunosuppressive and cancer chemotherapy. Mycophenolate is an immunosuppressant that is used to prevent transplant rejection and acts through inhibition of IMPDH. Mycophenolate mofetil has been shown to inhibit completely both vaccinia and monkeypox viruses. Mutations in the Bateman domain of IMPDH1 are associated with the RP10 form of autosomal dominant retinitis pigmentosa and dominant Leber's congenital amaurosis.
Clean-in-place systems are typically used to remove fouling from membranes after extensive use. The CIP process may use detergents, reactive agents such as sodium hypochlorite and acids and alkalis such as citric acid and sodium hydroxide (NaOH). Sodium hypochlorite (bleach) must be removed from the feed in some membrane plants. Bleach oxidizes thin-film membranes. Oxidation will degrade the membranes to a point where they will no longer perform at rated rejection levels and have to be replaced. Bleach can be added to a sodium hydroxide CIP during an initial system start-up before spirally-wound membranes are loaded into the plant to help disinfect the system. Bleach is also used to CIP perforated stainless steel (Graver) membranes, as their tolerance for sodium hypochlorite is much higher than a spirally-wound membrane. Caustics and acids are most often used as primary CIP chemicals. Caustic removes organic fouling and acid removes minerals. Enzyme solutions are also used in some systems for helping remove organic fouling material from the membrane plant. The pH and temperature are important to a CIP program. If pH and temperature are too high the membrane will degrade and flux performance will suffer. If pH and temperature are too low, the system simply will not be cleaned properly. Every application has different CIP requirements. e.g. a dairy reverse osmosis (RO) plant most likely will require a more rigorous CIP program than a water purification RO plant. Each membrane manufacturer has their own guidelines for CIP procedures for their product.
== Biological origin == Isoprenoid GDGTs originate as archaeal membrane lipids, whose fatty acids are converted to glycerol via esterification (ether lipid). They were first recognized as being associated with extremophilic archaea, but research in recent decades has discovered the compounds in a wide range of mesophilic environments as well, including soils, lake sediment, and marine deposits. Archaeal phylogenetic classes Nitrososphaerota (formerly Thaumarchaeota), Thermoproteota (formerly Crenarchaeota), "Euryarchaeota", and "Korarchaeota" produce GDGTs. Branched GDGTs are most commonly detected in peats and soils and are most associated with terrestrial settings. To date, no direct evidence for an unequivocal source organism has been reported, but the structural similarity of acidobacterial lipid to brGDGT alkyl chains strongly suggests that acidobacteriota synthesize brGDGT. The stereochemistry strongly hints at a non-archaeal origin.
== Structure == In humans, granzyme B is encoded by GZMB on chromosome 14q11.2, which is 3.2kb long and consists of 5 exons. It is one of the most abundant granzymes of which there are 5 in humans and 10 in mice. Granzyme B is thought to have evolved from a granzyme H related precursor and is more effective at lower concentrations than the other granzymes. The enzyme is initially in an inactive precursor zymogen form, with an additional amino terminal peptide sequence. This sequence can be cleaved by cathepsin C, removing 2 amino acids. Cathepsin H has also been reported to activate granzyme B. Granzyme B's structure consists of two six-stranded β sheets with three trans domain segments. In the granules of cytotoxic lymphocytes the enzyme can exist in two glycosylated forms. The high mannose form weighs 32kDa and the complex form, 35kDa. Granzyme B contains the catalytic triad histidine-aspartic acid-serine in its active site and preferentially cleaves after an aspartic acid residue situated in the P1 position. The aspartic acid residue to be cleaved associates with an arginine residue in the enzyme's binding pocket. Granzyme B is active at a neutral pH and is therefore inactive in the acidic CTL granules. The enzyme is also rendered inactive when bound by serglycin in the granules to avoid apoptosis triggering inside the cytotoxic T cells themselves.
The xanthophyll cycle involves the enzymatic removal of epoxy groups from xanthophylls (e.g. violaxanthin, antheraxanthin, diadinoxanthin) to create so-called de-epoxidised xanthophylls (e.g. diatoxanthin, zeaxanthin). These enzymatic cycles were found to play a key role in stimulating energy dissipation within light-harvesting antenna proteins by non-photochemical quenching- a mechanism to reduce the amount of energy that reaches the photosynthetic reaction centers. Non-photochemical quenching is one of the main ways of protecting against photoinhibition. In higher plants, there are three carotenoid pigments that are active in the xanthophyll cycle: violaxanthin, antheraxanthin, and zeaxanthin. During light stress, violaxanthin is converted, i.e. reduced, to zeaxanthin via the intermediate antheraxanthin, which plays a direct photoprotective role acting as a lipid-protective anti-oxidant and by stimulating non-photochemical quenching within light-harvesting proteins. This conversion of violaxanthin to zeaxanthin is done by the enzyme violaxanthin de-epoxidase (EC 1.23.5.1), while the reverse reaction, i.e. oxidation, is performed by zeaxanthin epoxidase (EC 1.14.15.21). In diatoms and dinoflagellates, the xanthophyll cycle consists of the pigment diadinoxanthin, which is transformed into diatoxanthin (diatoms) or dinoxanthin (dinoflagellates) under high-light conditions. Wright et al.
Sources: en.wikipedia.org
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.
Most methods use liquid chromatography with tandem mass spectrometry. Urine is common in anti-doping testing, and blood or plasma may be used in research.
Typical guidance is cool, dry, dark storage, often at low temperature and with desiccant. Stability data are limited, so storage conditions should be verified for each batch or supplier.
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.