Muscarine, L-(+)-muscarine, or muscarin is a natural product found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly C. dealbata. Mushrooms in the genera Entoloma and Mycena have also been found to contain levels of muscarine which can be dangerous if ingested. Muscarine has been found in harmless trace amounts in Boletus, Hygrocybe, Lactarius and Russula. Trace concentrations of muscarine are also found in Amanita muscaria, though the pharmacologically more relevant compound from this mushroom is the Z-drug-like alkaloid muscimol. A. muscaria fruitbodies contain a variable dose of muscarine, usually around 0.0003% fresh weight. This is very low and toxicity symptoms occur very rarely. Inocybe and Clitocybe contain muscarine concentrations up to 1.6%.
Chlorphenamine, also known as chlorpheniramine, is an antihistamine used to treat the symptoms of allergic conditions such as allergic rhinitis. It is taken by mouth. The medication takes effect within 6 hours and lasts for about a day.
Donepezil, sold as the trade name Aricept among others, is a medication used to treat Alzheimer's disease. It appears to result in a small benefit in mental function and ability to function. Use, however, has not been shown to change the progression of the disease. Treatment should be stopped if no benefit is seen. It is taken by mouth.
A parasympathomimetic drug, sometimes called a cholinomimetic drug or cholinergic receptor stimulating agent, is a substance that stimulates the parasympathetic nervous system (PSNS). These chemicals are also called cholinergic drugs because acetylcholine (ACh) is the neurotransmitter used by the PSNS. Chemicals in this family can act either directly by stimulating the nicotinic or muscarinic receptors, or indirectly by inhibiting cholinesterase, promoting acetylcholine release, or other mechanisms.
Tacrine is a centrally acting acetylcholinesterase inhibitor and indirect cholinergic agonist (parasympathomimetic). It was the first centrally acting cholinesterase inhibitor approved for the treatment of Alzheimer's disease, and was marketed under the trade name Cognex. Tacrine was first synthesised by Adrien Albert at the University of Sydney in 1949. It also acts as a histamine N-methyltransferase inhibitor.
Galantamine is used for the treatment of cognitive decline in mild to moderate Alzheimer's disease and various other memory impairments. It is an alkaloid that has been isolated from the bulbs and flowers of Galanthus nivalis, Galanthus caucasicus, Galanthus woronowii, and some other members of the family Amaryllidaceae, such as Narcissus (daffodil), Leucojum aestivum (snowflake), and Lycoris including Lycoris radiata. It can also be produced synthetically.
Huperzine A is a naturally occurring sesquiterpene alkaloid compound found in the firmoss Huperzia serrata and in varying quantities in other food Huperzia species, including H. elmeri, H. carinat, and H. aqualupian. Huperzine A has been investigated as a treatment for neurological conditions such as Alzheimer's disease, but a meta-analysis of those studies concluded that they were of poor methodological quality and the findings should be interpreted with caution. Huperzine A inhibits the breakdown of the neurotransmitter acetylcholine by the enzyme acetylcholinesterase. It is commonly available over the counter as a nutrient supplement, and is marketed as a cognitive enhancer for improving memory and concentration.
WIN 55,212-2 is a chemical described as an aminoalkylindole derivative, which produces effects similar to those of cannabinoids such as tetrahydrocannabinol (THC) but has an entirely different chemical structure.
The muscarinic acetylcholine receptor M2, also known as the cholinergic receptor, muscarinic 2, is a muscarinic acetylcholine receptor that in humans is encoded by the CHRM2 gene. Multiple alternatively spliced transcript variants have been described for this gene.
Etazolate (SQ-20,009, EHT-0202) is an anxiolytic drug which is a pyrazolopyridine derivative and has unique pharmacological properties. It acts as a positive allosteric modulator of the GABAA receptor at the barbiturate binding site, as an adenosine antagonist of the A1 and A2 subtypes, and as a phosphodiesterase inhibitor selective for the PDE4 isoform. It is currently in clinical trials for the treatment of Alzheimer's disease.
Eseroline is a drug which acts as an opioid agonist. It is a metabolite of the acetylcholinesterase inhibitor physostigmine but unlike physostigmine, the acetylcholinesterase inhibition produced by eseroline is weak and easily reversible, and it produces fairly potent analgesic effects mediated through the μ-opioid receptor. This mixture of activities gives eseroline an unusual pharmacological profile, although its uses are limited by side effects such as respiratory depression and neurotoxicity.
Vedaclidine (INN, codenamed LY-297,802, NNC 11-1053) is an experimental analgesic drug which acts as a mixed agonist–antagonist at muscarinic acetylcholine receptors, being a potent and selective agonist for the M1 and M4 subtypes, yet an antagonist at the M2, M3 and M5 subtypes. It is orally active and an effective analgesic over 3× the potency of morphine, with side effects such as salivation and tremor only occurring at many times the effective analgesic dose. Human trials showed little potential for development of dependence or abuse, and research is continuing into possible clinical application in the treatment of neuropathic pain and cancer pain relief.
SB-357134 is a drug which is used in scientific research. It acts as a potent, selective and orally active 5-HT6 receptor antagonist. SB-357134 and other 5-HT6 antagonists show nootropic effects in animal studies, and have been proposed as potential novel treatments for cognitive disorders such as schizophrenia and Alzheimer's disease.
Oxaprotiline, also known as hydroxymaprotiline, is a norepinephrine reuptake inhibitor of the tetracyclic antidepressant (TeCA) family that is related to maprotiline. Though investigated as an antidepressant, it was never marketed.
Acetylcholinesterase inhibitors (AChEIs) also often called cholinesterase inhibitors, inhibit the enzyme acetylcholinesterase from breaking down the neurotransmitter acetylcholine into choline and acetate, thereby increasing both the level and duration of action of acetylcholine in the central nervous system, autonomic ganglia and neuromuscular junctions, which are rich in acetylcholine receptors. Acetylcholinesterase inhibitors are one of two types of cholinesterase inhibitors; the other being butyryl-cholinesterase inhibitors. Acetylcholinesterase is the primary member of the cholinesterase enzyme family.
Cholinesterase inhibitors (ChEIs), also known as anti-cholinesterase, are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine. This increases the amount of the acetylcholine or butyrylcholine in the synaptic cleft that can bind to muscarinic receptors, nicotinic receptors and others. This group of inhibitors is divided into two subgroups, acetylcholinesterase inhibitors (AChEIs) and butyrylcholinesterase inhibitors (BChEIs).
Dextrallorphan (DXA) is an opioid derivative chemical of the morphinan class that is used in scientific research. It acts as a σ1 receptor agonist and NMDA receptor antagonist. It has no significant affinity for the σ2, μ-opioid, or δ-opioid receptor, or for the serotonin or norepinephrine transporter. As an NMDA receptor antagonist, in vivo, it is approximately twice as potent as dextromethorphan, and five-fold less potent than dextrorphan.
Rivastigmine is a cholinesterase inhibitor used for the treatment of mild to moderate Alzheimer's disease and Parkinson's. The drug can be administered orally or via a transdermal patch; the latter form reduces the prevalence of side effects, which typically include nausea and vomiting.
Cymserine is a drug related to physostigmine, which acts as a reversible cholinesterase inhibitor, with moderate selectivity (15×) for the plasma cholinesterase enzyme butyrylcholinesterase, and relatively weaker inhibition of the better-known acetylcholinesterase enzyme. This gives it a much more specific profile of effects that may be useful for treating Alzheimer's disease without producing side effects such as tremors, lacrimation, and salivation that are seen with the older nonselective cholinesterase inhibitors currently used for this application, such as donepezil. A number of cymserine derivatives have been developed with much greater selectivity for butyrylcholinesterase, and both cymserine and several of its analogues have been tested in animals, and found to increase brain acetylcholine levels and produce nootropic effects, as well as reducing levels of amyloid precursor protein and amyloid beta, which are commonly used biomarkers for the development of Alzheimer's disease.
Methylfluorophosphonylcholine (MFPCh) is an extremely toxic chemical compound related to the G-series nerve agents. It is an extremely potent acetylcholinesterase inhibitor which is around 100 times more potent than sarin at inhibiting acetylcholinesterase in vitro, and around 10 times more potent in vivo, depending on route of administration and animal species tested. MFPCh is resistant to oxime reactivators, meaning the acetylcholinesterase inhibited by MFPCh can't be reactivated by oxime reactivators. MFPCh also acts directly on the acetylcholine receptors. However, despite its high toxicity, methylfluorophosphonylcholine is a relatively unstable compound and degrades rapidly in storage, so it was not deemed suitable to be weaponised for military use.
