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Other names | 3-(2,4-dimethoxy-benzylidene)anabaseine |
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Formula | C19H20N2O2 |
Molar mass | 308.374 g·mol−1 |
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This article needs to be updated.(April 2015) |
GTS-21 (DMXBA or DMBX-anabaseine) is a drug that has been shown to enhance memory and cognitive function. It has been studied for its potential therapeutic uses, particularly in the treatment of neurodegenerative diseases and psychiatric disorders.
It is a derivative of the natural product anabaseine that acts as a partial agonist at neural nicotinic acetylcholine receptors (nAChRs). It binds to both the α4β2 and α7 subtypes, but activates only the α7 to any significant extent. [1] [2] Activation of the α7 nAChR has been shown to have neuroprotective effects and to improve cognitive function, making it an attractive target for drug development.
Both GTS-21 itself and its demethylated active metabolite 4-OH-GTS-21 [3] display nootropic [4] and neuroprotective effects, [5] [6] [7] [8] and GTS-21 is being investigated for the treatment of Alzheimer's disease, [9] [10] nicotine dependence, [11] and, most significantly, for schizophrenia. [12] [13] [14] [15] [16]
Several studies have investigated the effects of GTS-21 in various animal models of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. In these studies, GTS-21 has been shown to have anti-inflammatory and neuroprotective effects, and to improve cognitive function.
A recent study investigated the cholinergic anti-inflammatory pathway (CAP) in rheumatoid arthritis (RA). They used the α7 nicotinic acetylcholine receptor (α7nAChR) agonist GTS-21 to study its role in reducing synovial inflammation in a mice model of collagen-induced arthritis (CIA). GTS-21 lessened inflammation and reduced monocyte infiltration into the synovium. This study highlights a new mechanism by which cholinergic signaling can mitigate synovial inflammation in RA. [17]
Phase one of a clinical trial using DXMBA as a potential treatment for schizophrenia was completed in January of 2005. 12 non-smoking subjects diagnosed with schizophrenia each received 3 daily treatments. The treatments consisted of 150mg of DMXBA, with another dose of 75mg administered 2 hours later, 75mg of DXMBA, with another dose of 37.5mg administered 2 hours later, and a placebo treatment. The order of the doses was randomized over the 3-day course of the treatments. A P50 auditory-evoked test measured a significant effect on sensory gating, and a Repeatable Battery for Assessment of Neuropsychological Status test measured a significant effect on neurocognition. The subjects did not report any symptoms or side effects, however the leukocyte count of one subject decreased from slightly above normal on the placebo, to slightly below normal when administered the higher dose of DXMBA. After receiving no exposure to the drug, the subject's leukocyte count returned to normal 2 days later. [18] This clinical trial untimely was discontinued during phase II. [18] Several other trials focusing on a range of health issues including Alzheimer's, schizophrenia, autism, ADHD, and nicotine use were either discontinued or withdrawn. [19] [20] [21] [22] [23]
Another study of GTS-21 in healthy volunteers found that the drug improved attention and memory performance. [4]
Overall, the available evidence suggests that GTS-21 has potential as a therapeutic agent for neurodegenerative diseases and psychiatric disorders. However, more research is needed to fully understand its safety and efficacy, and to determine the optimal dosing and administration regimens.
The laboratory name GTS-21 means that it is the 21st chemical compound created by Gainesville (University of Florida in Gainesville) and Tokushima (Taiho Pharmaceutical) Scientists. [24] DMXBA – 3-2,4-dimethoxybenzylidene anabaseine.
Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral nervous system, muscle, and many other tissues of many organisms. At the neuromuscular junction they are the primary receptor in muscle for motor nerve-muscle communication that controls muscle contraction. In the peripheral nervous system: (1) they transmit outgoing signals from the presynaptic to the postsynaptic cells within the sympathetic and parasympathetic nervous system, and (2) they are the receptors found on skeletal muscle that receive acetylcholine released to signal for muscular contraction. In the immune system, nAChRs regulate inflammatory processes and signal through distinct intracellular pathways. In insects, the cholinergic system is limited to the central nervous system.
Memantine is a medication used to slow the progression of moderate-to-severe Alzheimer's disease. It is taken by mouth.
Kynurenic acid is a product of the normal metabolism of amino acid L-tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an antagonist at excitatory amino acid receptors. Because of this activity, it may influence important neurophysiological and neuropathological processes. As a result, kynurenic acid has been considered for use in therapy in certain neurobiological disorders. Conversely, increased levels of kynurenic acid have also been linked to certain pathological conditions.
Tropisetron is a serotonin 5-HT3 receptor antagonist used mainly as an antiemetic to treat nausea and vomiting following chemotherapy, although it has been used experimentally as an analgesic in cases of fibromyalgia.
A nicotinic agonist is a drug that mimics the action of acetylcholine (ACh) at nicotinic acetylcholine receptors (nAChRs). The nAChR is named for its affinity for nicotine.
The alpha-7 nicotinic receptor, also known as the α7 receptor, is a type of nicotinic acetylcholine receptor implicated in long-term memory, consisting entirely of α7 subunits. As with other nicotinic acetylcholine receptors, functional α7 receptors are pentameric [i.e., (α7)5 stoichiometry].
Ispronicline is an experimental drug which acts as a partial agonist at neural nicotinic acetylcholine receptors. It progressed to phase II clinical trials for the treatment of dementia and Alzheimer's disease, but is no longer under development.
ABT-418 is a drug developed by Abbott, that has nootropic, neuroprotective and anxiolytic effects, and has been researched for treatment of both Alzheimer's disease and ADHD. It acts as an agonist at neural nicotinic acetylcholine receptors, subtype-selective binding with high affinity to the α4β2, α7/5-HT3, and α2β2 nicotinic acetylcholine receptors but not α3β4 receptors ABT-418 was reasonably effective for both applications and fairly well tolerated, but produced some side effects, principally nausea, and it is unclear whether ABT-418 itself will proceed to clinical development or if another similar drug will be used instead.
Pozanicline is a drug developed by Abbott, that has nootropic and neuroprotective effects. Animal studies suggested it useful for the treatment of ADHD and subsequent human trials have shown ABT-089 to be effective for this application. It binds with high affinity subtype-selective to the α4β2 nicotinic acetylcholine receptors and has partial agonism to the α6β2 subtype, but not the α7 and α3β4 subtypes familiar to nicotine. It has particularly low tendency to cause side effects compared to other drugs in the class.
Xanomeline is a small molecule muscarinic acetylcholine receptor agonist that was first synthesized in a collaboration between Eli Lilly and Novo Nordisk as an investigational therapeutic being studied for the treatment of central nervous system disorders.
Neramexane is a drug related to memantine, which acts as an NMDA antagonist and has neuroprotective effects. It is being developed for various possible applications, including treatment of tinnitus, Alzheimer's disease, drug addiction and as an analgesic. Animal studies have also suggested antidepressant and nootropic actions, so there are a wide range of potential applications this drug may be used for. It also acts as a nicotinic acetylcholine receptor antagonist.
PNU-282,987 is a drug that acts as a potent and selective agonist for the α7 subtype of neural nicotinic acetylcholine receptors. In animal studies, it shows nootropic effects, and derivatives may be useful in the treatment of schizophrenia, although PNU-282,987 is not suitable for use in humans because of excessive inhibition of the hERG antitarget. PNU-282987 has been shown to initiate signaling that leads to adult neurogeneis in mammals.
PHA-543,613 is a drug that acts as a potent and selective agonist for the α7 subtype of neural nicotinic acetylcholine receptors, with a high level of brain penetration and good oral bioavailability. It is under development as a possible treatment for cognitive deficits in schizophrenia. It reduces excitotoxicity and protects striatal dopaminergic neurons in rat models. It also potentiates cognitive enhancement from memantine, decreases dynorphin release and inhibits GSK-B3.
SSR180711 is a drug that acts as a potent and selective partial agonist for the α7 subtype of neural nicotinic acetylcholine receptors. In animal studies, it shows nootropic effects and may be useful in the treatment of schizophrenia.
TC-1698 is a drug developed by Targacept which acts as a partial agonist for the α7 subtype of neural nicotinic acetylcholine receptors. It has neuroprotective effects in animal studies, and has been used as a lead compound to find further potent derivatives.
WAY-317538 (SEN-12333) is a drug that acts as a potent and selective full agonist for the α7 subtype of neural nicotinic acetylcholine receptors. It was not the most potent compound in the series, but was selected for further development on the basis of its high selectivity over related receptors, ease of synthesis, and good in vivo properties including high oral bioavailability and good brain penetration. It has nootropic and neuroprotective effects in animal studies, and is being investigated as a potential treatment for neurodegenerative and neurocognitive conditions including Alzheimer's disease and schizophrenia.
Encenicline is a selective partial agonist of the α7 nicotinic receptor. It was in phase III clinical trials for the treatment of cognitive impairment in schizophrenia, but failed to meet the study endpoints in 2016.
Anabaseine (3,4,5,6-tetrahydro-2,3′-bipyridine) is an alkaloid toxin produced by Nemertines and Aphaenogaster ants. It is structurally similar to nicotine and anabasine. Similarly, it has been shown to act as an agonist on most nicotinic acetylcholine receptors in the central nervous system and peripheral nervous system.
JNJ-39393406 is an experimental medication which is under development by Janssen Pharmaceutica, a division of Johnson & Johnson, for the treatment of depressive disorders and smoking withdrawal. It acts as a selective positive allosteric modulator of the α7 nicotinic acetylcholine receptor (nAChR). It does not act on the α4β2 or α3β4 nAChRs or the serotonin 5-HT3 receptor, and does not interact with a panel of 62 other receptors and enzymes. The drug has been found to lower the agonist and nicotine threshold for activation of the α7 nAChR by 10- to 20-fold and to increase the maximum agonist response of the α7 nAChR by 17- to 20-fold.
KarXT is an investigational oral dual-drug fixed-dose combination of xanomeline and trospium. It is undergoing a phase 3 clinical trial for the treatment of schizophrenia. Xanomeline is a functionally preferring muscarinic M4 and M1 receptor agonist that readily passes into the central nervous system (CNS) to stimulate these receptors in key areas of the brain. Trospium is a non-selective muscarinic antagonist that does not cross into the CNS and reduces peripheral cholinergic side effects associated with xanomeline.