Xanthine is a purine base found in most human body tissues and fluids, as well as in other organisms. Several stimulants are derived from xanthine, including caffeine, theophylline, and theobromine.
The adenosine receptors (or P1 receptors) are a class of purinergic G protein-coupled receptors with adenosine as the endogenous ligand. There are four known types of adenosine receptors in humans: A1, A2A, A2B and A3; each is encoded by a different gene.
A heteromer is something that consists of different parts; the antonym of homomeric. Examples are:
The adenosine A2A receptor, also known as ADORA2A, is an adenosine receptor, and also denotes the human gene encoding it.
Monoamine oxidase B, also known as MAO-B, is an enzyme that in humans is encoded by the MAOB gene.
SCH-58261 is a drug which acts as a potent and selective antagonist for the adenosine receptor A2A, with more than 50x selectivity for A2A over other adenosine receptors. It has been used to investigate the mechanism of action of caffeine, which is a mixed A1 / A2A antagonist, and has shown that the A2A receptor is primarily responsible for the stimulant and ergogenic effects of caffeine, but blockade of both A1 and A2A receptors is required to accurately replicate caffeine's effects in animals. SCH-58261 has also shown antidepressant, nootropic and neuroprotective effects in a variety of animal models, and has been investigated as a possible treatment for Parkinson's disease.
Istradefylline, sold under the brand name Nourianz, is a medication used as an add-on treatment to levodopa/carbidopa in adults with Parkinson's disease (PD) experiencing "off" episodes. Istradefylline reduces "off" periods resulting from long-term treatment with the antiparkinson drug levodopa. An "off" episode is a time when a patient's medications are not working well, causing an increase in PD symptoms, such as tremor and difficulty walking.
ZM-241,385 is a high affinity antagonist ligand selective for the adenosine A2A receptor.
PSB-10 is a drug which acts as a selective antagonist for the adenosine A3 receptor (ki value at human A3 receptor is 0.44 nM), with high selectivity over the other three adenosine receptor subtypes (ki values at human A1, A2A and A2B receptors are 4.1, 3.3 and 30 μM). Further pharmacological experiments in a [35S]GTPγS binding assay using hA3-CHO-cells indicated that PSB-10 acts as an inverse agonist (IC50 = 4 nM). It has been shown to produce antiinflammatory effects in animal studies. Simple xanthine derivatives such as caffeine and DPCPX have generally low affinity for the A3 subtype and must be extended by expanding the ring system and adding an aromatic group to give high A3 affinity and selectivity. The affinity towards adenosine A3 subtype was measured against the radioligand PSB-11.
Preladenant is a drug that was developed by Schering-Plough which acted as a potent and selective antagonist of the adenosine A2A receptor. It was being researched as a potential treatment for Parkinson's disease. Positive results were reported in Phase II clinical trials in humans, but it did not prove itself to be more effective than a placebo during Phase III trials, and so was discontinued in May 2013.
Theacrine, also known as 1,3,7,9-tetramethyluric acid, is a purine alkaloid found in Cupuaçu and in a Chinese tea known as kucha. It shows anti-inflammatory and analgesic effects and appears to affect adenosine signalling in a manner similar to caffeine. In kucha leaves, theacrine is synthesized from caffeine in what is thought to be a three-step pathway. Theacrine and caffeine are structurally similar.
Caffeine-induced anxiety disorder is a subclass of the DSM-5 diagnosis of substance/medication-induced anxiety disorder.
Adenosine A2A receptor antagonists are a class of drugs that blocks adenosine at the adenosine A2A receptor. Notable adenosine A2A receptor antagonists include caffeine, theophylline and istradefylline.
A pro-motivational agent is a drug which increases motivation. They can be used in the treatment of motivational deficits, for instance in depression, schizophrenia, and attention deficit hyperactivity disorder (ADHD), as well as in the treatment of disorders of diminished motivation (DDMs), including apathy, abulia, and akinetic mutism, for instance due to stroke, traumatic brain injury, or neurodegenerative diseases. They are also used non-medically by healthy people to increase motivation and productivity, for instance in educational contexts.
Lu AA47070 is a selective adenosine A2A receptor antagonist that was under development for the treatment of Parkinson's disease but was never marketed. It has been found to reverse some of the effects of dopamine D2 receptor antagonists like pimozide and haloperidol, for instance tremulous jaw movements, catalepsy, locomotor suppression, and other anti-motivational effects, in animals. The drug is a prodrug of Lu AA41063. It was discontinued in phase 1 clinical trials because it lacked the intended pharmacological properties in humans. Lu AA47070 was first described by 2008.
MSX-3 is a selective adenosine A2A receptor antagonist used in scientific research. Similarly to MSX-4, it is a water-soluble ester prodrug of MSX-2.
MSX-4 is a selective adenosine A2A receptor antagonist used in scientific research. It is a water-soluble amino acid ester prodrug of MSX-2, the active metabolite of the drug. MSX-4 reverses the motivational deficits induced by the dopamine D2 receptor antagonist eticlopride in animals and hence has the capacity to produce pro-motivational effects. MSX-4 was first described in the scientific literature by 2008.
MSX-2 is a selective adenosine A2A receptor antagonist used in scientific research. It is a xanthine and a derivative of the non-selective adenosine receptor antagonist caffeine.
Lu AA41063 is a selective adenosine A2A receptor antagonist. Structurally, it is a non-xanthine.
