Paraxanthine-d6 is intended for use as an internal standard for the quantification of paraxanthine (Item No. 21068) by GC- or LC-MS. Paraxanthine is an active metabolite of caffeine (Item No. 14118).{58128} It is formed via N3-demethylation of caffeine by the cytochrome P450 (CYP) isoform CYP1A2. Paraxanthine is an adenosine A1 and A2 receptor antagonist (Kis = 35 and 22 µM, respectively).{38151} In vivo, paraxanthine (30 mg/kg) increases striatal cGMP and extracellular striatal dopamine levels and locomotor activity, as well as inhibits motor depression induced by the adenosine A1 agonist CPA (N6-cyclopentyladenosine; Item No. 21448) or the adenosine A2 receptor agonist CGS 21680 (Item No. 17126) in rats not habituated to caffeine.{38150} It also promotes wakefulness and increases locomotor activity and core temperature in narcoleptic transgenic mice without increasing behavioral anxiety.{38152}
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An internal standard for the quantification of paraxanthine by GC- or LC-MS
Formal name: 3,7-dihydro-1,7-di(methyl-d3)-1H-purine-2,6-dione
Synonyms: 1,7-Dimethylxanthine-d6
Molecular weight: 186.2
CAS: 117490-41-2
Purity: ≥99% deuterated forms (d1-d6); ≤1% d0
Formulation: A crystalline solid
The maintenance of embryonic stem cells in culture typically requires feeder cells and various exogenous factors found in serum. Murine embryonic stem (mES) cells can be maintained in the absence of feeder cells and serum but require the leukemia inhibitor factor (LIF) and bone morphogenic protein (BMP) to prevent differentiation and promote self-renewal. SC-1 is a small molecule activator of stem cell renewal that allows the propagation of OG2 mES cells for at least 10 passages in an undifferentiated state.{14533} The activity of SC-1 is mediated by the combined inhibition of RasGAP and ERK1 with Kd values of 98 and 212 nM, respectively.{14533} Inhibition of RasGAP increases Ras signaling via the PI3-kinase pathway which promotes self-renewal, whereas inhibition of ERK blocks differentiation.
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Cyclin-dependent kinases (CDKs) are key regulators of cell cycle progression and are therefore promising targets for cancer therapy. (R)-Roscovitine is a potent inhibitor of Cdk2/cyclin E with an IC50 value of 0.1 µM.{14988} It also inhibits Cdk7/cyclin H, Cdk5/p35, and cell division cycle (cdc)/cyclin B with IC50 values of 0.49, 0.16, and 0.65 µM, respectively.{14987,14988,14991} (R)-Roscovitine inhibits the growth of rapidly proliferating cells with an average IC50 value of 15.2 µM against a panel of 19 human tumor cell lines.{14988} In murine models of polycystic kidney disease, (R)-roscovitine effectively inhibited disease progression at doses of 50-100 mg/kg.{14564}
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The PtdIn phosphates play an important role in the generation and transduction of intracellular signals.{8344,4096,14518} PtdIns-(3,4,5)-P3-biotin is an affinity probe which allows the PIP3 to be detected through an interaction with the biotin ligand. This design allows PtdIns-(3,4,5)-P3-biotin to serve as a general probe for any protein with a high affinity binding interaction with inositol-(3,4,5)-triphosphate phospholipids, such as phosphatidylinositol 3-kinase, PTEN, or PH-domain-containing proteins.
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Cyclin-dependent kinases (CDKs) are key regulators of cell cycle progression and are therefore promising targets for cancer therapy. (R)-Roscovitine is a potent inhibitor of Cdk2/cyclin E with an IC50 value of 0.1 µM.{14988} It also inhibits Cdk7/cyclin H, Cdk5/p35, and cell division cycle (cdc)/cyclin B with IC50 values of 0.49, 0.16, and 0.65 µM, respectively.{14987,14988,14991} (R)-Roscovitine inhibits the growth of rapidly proliferating cells with an average IC50 value of 15.2 µM against a panel of 19 human tumor cell lines.{14988} In murine models of polycystic kidney disease, (R)-roscovitine effectively inhibited disease progression at doses of 50-100 mg/kg.{14564}
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