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the sci-wiki/effects/Acetylcholine

Acetylcholine

Every compound in the sci-wiki that affects acetylcholine; the ones you can source are floated to the front, then the reference-only entries. Tap any for the full entry, mechanism, and outlets.

41 sourced · 67 reference

←acetylcholine108/108filter this drawer by compound name

Noopept

Noopept is one of the most extensively researched dipeptide nootropics, a proline-containing compound designed as a peptide analog of piracetam with far greater potency by weight. Its standout quality is neuroprotection; in cellular models it guarded neurons against oxidative and amyloid-related damage more effectively than piracetam or classic antioxidants, while attenuating tau hyperphosphorylation [1][3]. Studied for memory restoration and neuroprotection, it also raises endogenous NGF and BDNF and activates adaptive stress-response pathways.

Phenylpiracetam

Phenylpiracetam (phenotropil, carphedon) is a phenylated derivative of piracetam, developed in Russia and used clinically as a nootropic, with reported effects on focus, physical endurance, and tolerance to cold and fatigue. The added phenyl group makes it considerably more potent than the parent racetam and confers a distinct mechanism, selective inhibition of the dopamine transporter, which is thought to underlie its stimulant-like, motivating properties. It was among the first cognitive enhancers prohibited in competitive sport, having been banned by anti-doping authorities in 1998.

Acetyl-L-Carnitine

Acetyl-L-carnitine (ALCAR), also known as levacecarnine, is the acetylated form of the amino-acid derivative L-carnitine. It occurs naturally in the body, where it participates in mitochondrial energy metabolism by helping transport fatty acids for breakdown and by supplying acetyl groups. Sold widely as a dietary supplement and used as a medicine in some countries, it has been studied for depression, nerve pain, and age-related cognitive decline.

Alpha-GPC

Alpha-GPC (L-alpha glycerylphosphorylcholine) is a highly bioavailable choline source that readily crosses the blood-brain barrier to supply the raw material for acetylcholine, the neurotransmitter central to memory, focus, and muscular power. Clinical and meta-analytic evidence supports its use for cognitive performance, making it one of the most reliable cholinergic nootropics available [1][2]. It additionally potentiates growth hormone release and is widely used across both cognitive and athletic supplementation [4][5].

Aniracetam

Aniracetam is a fat-soluble member of the racetam family and one of the original ampakines, a positive allosteric modulator of AMPA-type glutamate receptors used as a cognition enhancer. By slowing the desensitization of these excitatory receptors it strengthens the synaptic transmission tied to learning and memory, and it has been used clinically abroad for cognitive symptoms after stroke and in dementia. Its principal metabolite, 2-pyrrolidinone, has been reported to produce a longer-lasting enhancement of AMPA-receptor function through a CaMKII-dependent pathway. It is also noted for anxiolytic and mood effects in animal models.

Bacopa Monnieri

Bacopa monnieri is a creeping wetland herb of the family Plantaginaceae, known in Ayurvedic tradition as brahmi and used for centuries as a remedy for memory and mental clarity. Its characteristic compounds are a group of triterpenoid saponins called bacosides, and standardized extracts are marketed as dietary supplements aimed at cognition. Clinical trials suggest it may modestly aid memory in some settings, though the overall evidence is mixed and it is not an approved medicine.

Choline

Choline is an essential nutrient that the body needs for building cell membranes, making the neurotransmitter acetylcholine, and supplying methyl groups used in metabolism [1][2]. Chemically it is a small water-soluble molecule, a quaternary ammonium compound, found in foods such as eggs, liver, meat, fish, and soybeans [1][2]. The body can make a little choline in the liver, but most people must obtain it from the diet, and it was formally recognized as an essential nutrient in 1998 [1][2]. Adequate choline is especially important during pregnancy for fetal brain development [3].

Coluracetam

Coluracetam has the most distinctive proposed mechanism in the racetam family. Rather than acting at a receptor, it was designed to raise the rate at which neurons take up choline, the raw material the brain uses to build acetylcholine. Mitsubishi developed it in Japan in the 1990s as an Alzheimer's candidate, and it was later carried into depression research and through a completed 115-person trial. Readers who use it describe sharper focus and, unusually for a nootropic, changes in visual vividness. The evidence for the mechanism is narrower than the reputation: the choline-uptake effect was shown in animals whose cholinergic neurons had been deliberately lesioned first and not in normal tissue, and an independent group at Pfizer testing the same transporter across four separate methods found no effect at all. That lesion-dependence is itself worth understanding, because it would predict a quieter effect in a healthy brain rather than none. No human trial has yet reported a cognitive result; the 2009 study completed without publishing its outcomes.

Galantamine

Galantamine is a plant-derived alkaloid, isolated from snowdrops and related plants of the Amaryllidaceae family, used to treat the memory and thinking difficulties of mild-to-moderate Alzheimer's disease. It has an unusual dual action on the cholinergic system: it inhibits the enzyme acetylcholinesterase, and it separately acts as an allosteric potentiating ligand that binds a site distinct from the neurotransmitter's on nicotinic acetylcholine receptors, making them respond more strongly to acetylcholine. Marketed under names such as Razadyne and Reminyl, it has also been studied as a nerve-agent countermeasure and, more curiously, as an aid to lucid dreaming.

Huperzine A

Huperzine A is a naturally occurring alkaloid isolated from the Chinese club moss Huperzia serrata, a plant long used in traditional Chinese medicine. It is a potent, selective, and long-acting reversible inhibitor of acetylcholinesterase, and it additionally acts as a non-competitive antagonist of the NMDA glutamate receptor at one of the polyamine binding sites, a combination that has made it of interest for memory, dementia, and neuroprotection. In China it is used as an approved drug, whereas in the United States it is sold as a dietary supplement.

Lemairamin

Lemairamin, sold as WGX-50 or gx-50, is a small molecule found naturally in Sichuan pepper (Zanthoxylum bungeanum and related species); chemically it is a simple cinnamamide, not an alkaloid and not a stimulant. Laboratory work suggests it switches on the alpha-7 nicotinic acetylcholine receptor, quiets inflammatory activity in the immune cells of the brain and gut, and can break apart the amyloid clumps associated with Alzheimer's disease. Every one of those findings comes from cells, worms, zebrafish, rats or mice; no person has been given this compound in any published study, and no clinical trial of it has ever been registered. The honest position is that WGX-50 is an interesting preclinical candidate with no evidence whatsoever that it does anything in humans.

Memantine

Memantine (brand names Namenda and Ebixa) is an NMDA receptor antagonist approved for moderate to severe Alzheimer's disease; it calms excess glutamate signaling to protect neurons while leaving the normal signaling needed for memory and learning intact [1][2]. What makes it unusual is its voltage-dependent, fast-off-rate binding; it blocks the constant, low-level 'noise' of glutamate but steps aside when a real learning signal arrives, so it doesn't cloud cognition the way stronger blockers (like ketamine) do. It is also more than a pure NMDA blocker; at or near therapeutic brain concentrations it reaches a spread of remote targets, agonizing the high-affinity state of the dopamine D2 receptor, antagonizing 5-HT3 serotonin receptors and several nicotinic acetylcholine receptors (alpha-7, alpha-4/beta-2, alpha-3/beta-4 and alpha-9/alpha-10), and weakly engaging sigma-1 receptors; see the affinity table below for the full fingerprint. Beyond Alzheimer's it is being investigated for a range of conditions; it shows the most promise for the negative symptoms of schizophrenia (social withdrawal, apathy, blunted motivation) and as a mood stabilizer in bipolar disorder, with earlier signals in ADHD (often as an adjunct to a stimulant), anxiety and OCD, and autism.

Oxiracetam

Oxiracetam is a synthetic compound from the racetam family and a close chemical relative of piracetam; it was developed in Italy in the 1980s as a prescription drug for memory and attention problems in dementia. Older European trials in dementia patients generally reported small improvements on cognitive test scores, but the modern evidence is split: a 590-patient Chinese trial in traumatic brain injury found a real benefit, while a 500-patient Korean trial found none for preventing cognitive decline after stroke, and South Korea then withdrew the drug. Nobody has established how it works; a standard 19-target receptor screen found no measurable binding at concentrations up to 30 micromolar, and no binding constant for oxiracetam at any brain receptor exists in the published literature. It remains in clinical use in China and is sold elsewhere as an unapproved powder, with a mild side-effect record but no trial evidence at all that it improves cognition in healthy people.

Sulbutiamine

Sulbutiamine is a synthetic derivative of thiamine, or vitamin B1, formed by joining two modified thiamine molecules into a fat-soluble disulfide. This lipophilic structure lets it cross the blood-brain barrier and raise thiamine levels in the brain more readily than thiamine itself, which distinguishes it from benfotiamine, a related derivative that raises thiamine chiefly in peripheral tissues. Developed in Japan and marketed under names such as Arcalion, it is used to treat asthenia, a state of persistent weakness and fatigue, and is also taken off-label as a nootropic; more recent work implicates its disulfide group in cellular thiol-redox regulation.

Nefiracetam

Nefiracetam is a fat-soluble pyrrolidinone racetam that modulates cholinergic, glutamatergic, and calcium signaling. It potentiates neuronal nicotinic acetylcholine receptor currents at sub-nanomolar concentrations and enhances NMDA-receptor function and long-term potentiation through protein kinase C and CaMKII, giving it a pronounced pro-cognitive and neuroprotective profile in preclinical research; it has also been reported to reverse signaling deficits in a laboratory model of Rett syndrome. It has been studied for memory impairment, dementia, and post-stroke apathy and depression.

Fasoracetam

Fasoracetam is a racetam-class nootropic that acts on the glutamatergic and GABAergic systems; with repeated administration it up-regulates GABA-B and metabotropic glutamate (mGluR) receptors. It is one of relatively few racetams to have reached controlled human trials, having been evaluated in adolescents with attention-deficit hyperactivity disorder who carry variants in genes governing mGluR signaling. It remains an investigational compound and is not an approved medicine.

Piracetam

Piracetam is the original nootropic, the very compound for which the word 'nootropic' was coined, developed by Corneliu Giurgea in the late 1960s to enhance learning and memory [1]. A cyclic derivative of the neurotransmitter GABA, it has become the foundational template of the entire racetam family and remains one of the most widely studied cognitive enhancers in the world [1][4]. Prized for a remarkable safety record and effects that are most pronounced when brain function is impaired, piracetam supports memory, learning, and cerebral circulation, and is used clinically for cognitive decline, myoclonus, and stroke recovery [2][4][5].

CDP-Choline

CDP-choline (citicoline, cytidine diphosphate-choline) is a naturally occurring compound that the body uses as an intermediate in making phosphatidylcholine, a major building block of cell membranes. Taken as a drug or dietary supplement, it supplies choline and cytidine to the brain and is studied for cognition, stroke recovery, and certain eye conditions. It is sold as a prescription medicine in some countries and as an over-the-counter supplement in others.

Donepezil

Donepezil is a medication used to treat the symptoms of dementia in Alzheimer's disease. It belongs to a class of drugs called cholinesterase inhibitors, which work by boosting levels of the signaling chemical acetylcholine in the brain. Developed by the Japanese company Eisai and approved in the United States in 1996 under the brand name Aricept, it is one of the most widely prescribed treatments for Alzheimer's dementia. Donepezil eases symptoms modestly but does not stop or reverse the underlying disease.

PRL-8-53

PRL-8-53 is a classic research nootropic famous for a single striking human study in which low oral doses significantly improved the retention of newly learned verbal information [1]. Chemically a methyl benzoate compound developed in the 1970s, it was reported to sharpen memory while potentiating the brain's dopaminergic and stimulant signaling [1][2]. Its reputation rests almost entirely on that early double-blind trial, as PRL-8-53 has never been independently replicated or brought to market, and it remains an obscure but intriguing research chemical [1][2].

Tropisetron

Tropisetron is a prescription anti-nausea drug that blocks the serotonin 5-HT3 receptor, and it is used to stop the vomiting caused by chemotherapy or by surgery; it has been sold for that purpose since 1992 in Europe, Japan, Australia and much of Asia, but it was never approved in the United States. What sets it apart from the other drugs in its class is that it also binds tightly to a brain receptor called the alpha-7 nicotinic acetylcholine receptor, which is why researchers have tested it for fibromyalgia pain, for thinking problems in schizophrenia, and in animal models of Alzheimer's and Huntington's disease. The anti-nausea use is solidly established; every other use rests on small short trials, mostly fewer than 45 people and under two weeks long, or on animal work, and no regulator anywhere has approved it for any of them. Anyone reading the older literature should also know that a large slice of the post-surgical anti-nausea evidence base was fabricated and later retracted, so individual old trials in that area carry very little weight on their own.

MNT (pmp)

MNT (PMP) is a combination injectable and pre-workout formula that pairs nitric oxide precursors with a focused cognitive stack in a single shot. Arginine, citrulline, and the arginase inhibitor norvaline drive vasodilation and blood flow for a stronger pump, while citicoline, N-acetyl-L-tyrosine, and trimethylglycine sharpen focus and support drive under load. It is engineered as a two-in-one performance blend that delivers physical pump and mental clarity together.

RGPU-95

RGPU-95 is an experimental compound studied in Russian pharmacological research as a structural analog of fenotropil, better known as phenylpiracetam, a nootropic of the racetam family. In animal experiments it has shown anxiety-reducing and antidepressant-like effects, in some measures exceeding those of its parent compound. It is an obscure investigational substance with essentially no human data, and it is not an approved medicine or recognized supplement ingredient anywhere.

Atropine

Atropine is a tropane alkaloid obtained from belladonna and related nightshades, existing chemically as the racemate dl-hyoscyamine and acting as a competitive antagonist at muscarinic acetylcholine receptors. Its parasympatholytic action supports several essential clinical uses: reversing symptomatic bradycardia, dilating the pupil for ophthalmic examination, reducing secretions before anesthesia, and serving with an oxime reactivator as the cornerstone antidote for organophosphate insecticide and nerve-agent poisoning. Its historical isolation in the 1830s was instrumental in the discovery of acetylcholine as a neurotransmitter and in the characterization of autonomic signaling. Because it blocks muscarinic transmission throughout the body, atropine can itself precipitate an anticholinergic delirium at excessive doses, which is why nonmedical use is discouraged. It remains on the World Health Organization list of essential medicines and continues to anchor research into improved antidotal formulations.

Choline Bitartrate

Choline bitartrate is a salt of the essential nutrient choline combined with tartaric acid, widely used as an inexpensive dietary supplement to boost choline intake [1][2]. Because choline supports cell membranes, the neurotransmitter acetylcholine, and methyl-group metabolism, the bitartrate form is taken to help meet the body's need for the nutrient [1][3]. It is a common choice in supplements, valued for being stable and absorbing little moisture, and it delivers choline for the same functions as choline from food [1]. As with choline generally, very high intakes can cause side effects such as a fishy body odor [1].

Cytisine

cytisine (tabex, cytisinicline) is a natural plant-alkaloid nicotinic partial agonist and the structural parent of varenicline; a high-affinity alpha4beta2 partial agonist, high-efficacy alpha3beta4 agonist, and only a weak partial agonist at the alpha6beta2* dopamine-terminal receptors that gate nicotine reward; a cheap, trial-validated smoking-cessation drug rather than a nootropic.

DMAE

Dimethylaminoethanol (DMAE), also known as deanol or dimethylethanolamine, is an organic amino alcohol with the formula (CH3)2NCH2CH2OH. Structurally it resembles the nutrient choline, differing by one methyl group on its nitrogen atom, and it is chemically related to the neurotransmitter acetylcholine. Alongside a range of industrial uses, DMAE is sold as a dietary supplement promoted for cognition and mood and is used as an ingredient in skin-firming cosmetics, although the evidence for many of its claimed effects is limited.

Hopantenic Acid

Hopantenic acid, best known by the Russian brand Pantogam and as its calcium salt calcium hopantenate, is a naturally occurring homologue of pantothenic acid in which the beta-alanine unit is replaced by GABA [1]. It is used in Russia and formerly in Japan as a gentle nootropic and mild anxiolytic-anticonvulsant, particularly in children with cognitive, behavioral and hyperkinetic problems [1][2]. Its effects are attributed to weak GABA-B-like modulation combined with support of neuronal metabolism, and the bulk of its clinical evidence is Russian rather than from large Western trials [1].

Lemon Balm

Lemon balm, known botanically as Melissa officinalis, is a lemon-scented perennial herb in the mint family, Lamiaceae. Native to the eastern Mediterranean and western Asia, it has been grown for over two thousand years and used traditionally to ease tension, lift mood, and aid digestion and sleep. Its leaves are rich in the polyphenol rosmarinic acid and in fragrant terpenes such as citronellal, geranial, and neral. Modern controlled studies have examined it for anxiety, mood, cognition, sleep, and palpitations, with its calming effect attributed largely to rosmarinic acid inhibiting GABA transaminase and to extract binding at cholinergic receptors.

Magnesium Acetate

Magnesium acetate is the magnesium salt of acetic acid, with the formula Mg(CH3COO)2. It forms white, water-soluble, moisture-absorbing crystals and is used as a food additive, a laboratory buffer, and a source of magnesium. As a dietary ingredient its role is simply to deliver magnesium, an essential mineral, in a soluble form.

Nicergoline

nicergoline (sermion) is a semisynthetic ergoline nootropic-vasodilator; a potent alpha-1 blocker that also boosts cholinergic/neurotrophic tone, with modest but real cochrane-backed benefit in age-related and vascular cognitive decline, tempered by ergot-class fibrosis risk on long timelines.

Phosphatidylcholine

Phosphatidylcholine is a class of phospholipids that form a major part of the membranes surrounding living cells and are the principal component of lecithin. Each molecule is built from a glycerol backbone, two fatty acids, and a phosphate group linked to choline, and the compound is abundant in foods such as egg yolk and soybeans. Beyond its structural role, phosphatidylcholine is the body's main store of the essential nutrient choline and has been studied as a dietary supplement and in conditions ranging from liver disease to ulcerative colitis.

Phosphatidylserine

Phosphatidylserine is a phospholipid that is a normal building block of cell membranes, where it is concentrated on the inner surface and is especially abundant in the membranes of nerve cells. It takes part in cell signaling and blood clotting, and its externalization onto the cell surface serves as the principal signal that flags dying cells for removal, a signal that some tumors and pathogens exploit to evade immune clearance. As a dietary supplement, usually derived from soy or sunflower, it is marketed chiefly for memory and age-related cognitive decline and has been reported to blunt the cortisol response to stress, although the supporting evidence for cognitive benefit is regarded as limited.

Piritinol

Piritinol, also spelled pyritinol and known as pyrithioxine, is a semisynthetic derivative of vitamin B6 (pyridoxine) that has been used as a nootropic and cerebral-function agent since the 1960s. It is built from two pyridoxine molecules linked by a disulfide bridge, a change that alters how the molecule behaves compared with the parent vitamin. In several European countries it is prescribed for chronic cognitive impairment and as supportive care after head trauma, and it has also been sold as a dietary supplement in some markets.

Unifiram

Unifiram (DM232) is an exceptionally potent synthetic nootropic developed by Italian medicinal chemists as a next-generation cognition enhancer. Structurally related to the ampakines and to piracetam, it was reported in preclinical studies to be roughly four orders of magnitude more potent than piracetam at reversing memory impairment. This remarkable potency, paired with an ampakine-like boost to learning circuitry, has made unifiram a headline compound in the research-chemical nootropic scene.

Uridine

Uridine is a nucleoside, one of the building blocks of ribonucleic acid (RNA), formed from the base uracil joined to the sugar ribose. It occurs naturally in the body, where it can be made from scratch, and in foods, and it takes part in RNA synthesis, sugar metabolism and the production of cell-membrane phospholipids. As a supplement, usually in the form of uridine monophosphate, it has been studied for effects on brain phospholipids, memory and mood [1][3].

Uridine Monophosphate

Uridine monophosphate (UMP) is the nucleotide form of uridine and the most common way uridine is sold as a nootropic. It feeds the pathway that builds neuronal membranes and supports acetylcholine and dopamine signaling; it is the uridine in the popular Mr Happy stack alongside omega-3s and a choline source.

Uridine Triacetate

Uridine triacetate is a prodrug of uridine; three acetate groups make it far more orally bioavailable than plain uridine, so it delivers much more uridine to the body and brain. It is used both clinically (as Vistogard/Xuriden) and popularly in nootropic uridine stacks for memory and mood.

Pramiracetam

Pramiracetam is a laboratory-made compound in the piracetam ("racetam") family, developed by Parke-Davis as CI-879 and later sold in a few European countries as a prescription memory drug under the brand name Pramistar. It is meant to improve memory and attention; in animals it reliably increases the rate at which brain cells take up choline, a building block of the memory-related signalling chemical acetylcholine, but no receptor that it binds to has ever been identified. Human evidence is thin: a small placebo-controlled trial in men with head injuries reported better delayed recall, and a study in healthy volunteers found it partly blunted drug-induced forgetting, while a trial in Alzheimer's disease found no benefit even at high doses. The entire published literature is roughly 40 papers, most of them small, decades old, or done in rodents, so confident claims that it strongly enhances cognition in healthy people are not supported by what has actually been measured.

Sunifiram

Sunifiram (DM-235) is a synthetic nootropic structurally related to piracetam but dramatically more potent, active at very low doses. It enhances learning and memory by acting on the glycine site of the NMDA receptor and strengthening AMPA-mediated signaling through the CaMKII and PKC pathways, the molecular basis of long-term potentiation. In animal studies it improves cognition and reverses drug-induced amnesia at doses roughly a thousandfold lower than classic racetams, making it one of the most potent research nootropics of its kind.

Citicoline + Piracetam

Citicoline with piracetam is a combination of two nootropic compounds sometimes taken together for cognitive support. Citicoline, also called cytidine diphosphate choline, is a naturally occurring precursor used to build brain cell membranes and the neurotransmitter acetylcholine, while piracetam is a synthetic derivative of GABA and the original member of the racetam family. The pairing is popular in nootropic circles, although the two ingredients have been studied mainly on their own rather than as a fixed combination.

reference shelf; no outlet carries these yet

522-054

522-054 is a laboratory research compound built in Kelvin Gee's group at the University of California, Irvine to do two opposite things to the hippocampus at once: strengthen α7 nicotinic acetylcholine receptors and block the α5-subunit-containing GABA-A receptors that hold pyramidal cells under constant inhibition. In rats the combination potentiated synapses, lowered the threshold for long-term potentiation, and restored learning and attention that had been disrupted either by scopolamine or by a traumatic brain injury months earlier. The whole published record is two primary papers, both in rats and rat tissue, plus one review that summarises them. No human has been given it and no clinical trial exists.

Aloracetam

Aloracetam is an experimental nootropic compound that was investigated as a potential treatment for cognitive impairment, most notably Alzheimer's disease. It is often grouped with the racetam family of cognition agents, though its structure departs from the classic 2-pyrrolidinone racetams. The compound was never brought to market and holds no regulatory approval in any major jurisdiction [1][2].

Alpha-Conotoxin MII

alpha-conotoxin mii is a cone-snail peptide toxin and the foundational research probe for alpha6-containing nicotinic receptors; native mii blocks both alpha3beta2 and alpha6* subtypes, but engineered analogs (mii[h9a;l15a], mii[s4a,e11a,l15a]) reach ~590-1000-fold alpha6 selectivity at low-nanomolar potency; a lab tool, not a drug, but the one that unlocked alpha6* dopamine-terminal pharmacology.

Alpha-Conotoxin PIA

alpha-conotoxin pia is a cone-snail (conus purpurascens) peptide toxin and the first ligand able to cleanly discriminate alpha6- from alpha3-containing nicotinic receptors; a highly alpha6beta2*-selective research probe that sharpened the interpretation of 'mii-sensitive' dopamine and gaba experiments; a lab reagent, not a drug.

Alpha-Conotoxin TxIB

alpha-conotoxin txib is a conus textile peptide toxin and one of the most selective alpha6/alpha3beta2beta3 nicotinic antagonists known (rat ic50 ~28 nm, sparing other rat subtypes), with a human alpha6/alpha3beta4 off-target as a species-difference caveat; a clean research probe and drug-design lead for addiction and parkinson's, not a therapeutic in itself.

Alpha-Pinene

Alpha-pinene is a bicyclic monoterpene and one of the most widely distributed terpene compounds in nature. It is a principal constituent of the resin and essential oils of conifers such as pine and spruce and is also present in rosemary, many culinary herbs, and cannabis, lending these plants their characteristic fresh, piney aroma. Alongside its role as a fragrance material and industrial feedstock, alpha-pinene has been studied for a range of biological activities, including anti-inflammatory, antimicrobial, and nervous-system effects [1][2].

AN6001

an6001 is an experimental (saniona) positive allosteric modulator that is selective for alpha6beta2-containing nicotinic receptors; it boosts nicotine's potency and efficacy at alpha6/alpha3beta2beta3 (ec50 ~0.58 uM) without touching alpha4beta2/alpha3beta4/alpha7/muscle, augments striatal dopamine release and nigral neuron activity, and potentiates nicotine's neuroprotection in a parkinson's model; a preclinical tool and proof that alpha6-selective small molecules exist, not a medicine.

Atropa belladonna

Atropa belladonna, commonly called deadly nightshade, is a Solanaceous plant that produces the tropane alkaloids atropine, scopolamine, and hyoscyamine throughout its roots, leaves, and berries. These alkaloids are potent competitive antagonists at muscarinic acetylcholine receptors, which accounts for the plant's dual identity as both a historic poison and a deliriant, and which historically made it a key pharmacological tool in mapping the autonomic nervous system. Ingestion produces a classic central and peripheral anticholinergic toxidrome, including mydriasis, tachycardia, hyperthermia, agitation, and delirium, with physostigmine reserved as an antidote in severe cases. Its danger is compounded by highly variable alkaloid content between plants and plant parts, and its sweet-looking dark berries are a frequent cause of accidental pediatric poisoning. Modern case reports also document intoxication from belladonna-contaminated herbal products and remedies.

AVL-3288

AVL-3288 (also known as UCI-4083) is an experimental compound that acts as a type I positive allosteric modulator of the α7 nicotinic acetylcholine receptor. Rather than activating the receptor directly, it strengthens the receptor's response to the brain's own acetylcholine, and it has been investigated as a way to improve cognition, particularly in schizophrenia.

Benztropine

Benztropine (marketed as Cogentin) is a synthetic tropane used medically for parkinsonism and for the drug-induced extrapyramidal symptoms produced by antipsychotics. It acts principally as a muscarinic acetylcholine receptor antagonist, but it is pharmacologically unusual within its class because it also inhibits dopamine reuptake at the dopamine transporter, doing so by preferentially binding an inward-facing transporter conformation; this "atypical" binding mode is associated with markedly reduced cocaine-like subjective and locomotor effects and has made benztropine a template for candidate cocaine-dependence medications. Research has further highlighted its antagonism of M1 and M3 muscarinic receptors as a driver of oligodendrocyte differentiation and remyelination, prompting interest in multiple sclerosis and in protection against chemotherapy-induced peripheral neuropathy. Like other members of the deliriant anticholinergic family it produces a dangerous and unpleasant anticholinergic delirium at high doses rather than euphoria, so recreational use is discouraged.

Bifemelane

Bifemelane (brand names Alnert and Celeport; development code MCI-2016) is a Japanese cerebral activator and antidepressant that acted mainly as a reversible, competitive inhibitor of monoamine oxidase type A, with weaker noncompetitive inhibition of MAO-B [1]. It was prescribed in Japan from the late 1980s for the emotional and cognitive disturbances that follow cerebral infarction [6], and was also trialed in glaucoma [9]. Most of its evidence comes from small Japanese studies from the 1980s and 1990s; it was pulled from the market in 1998 after a national re-evaluation judged the effectiveness of that whole class of cerebral metabolic enhancers to be unproven.

Biperiden

Biperiden (marketed as Akineton) is an anticholinergic agent used to treat parkinsonism and the extrapyramidal side effects caused by antipsychotic drugs. Compared with older nonselective anticholinergics it shows relative selectivity for the M1 muscarinic acetylcholine receptor subtype, a property that has made it a widely used pharmacological probe for dissecting cholinergic contributions to memory, cognition, and antidepressant response in animal and human studies. Experimental work has employed it to model muscarinic cognitive impairment, to examine M1-mediated modulation of reward and cocaine-related behaviors, and to probe brain choline metabolism and functional connectivity in psychosis. Although it is a legitimate prescription medicine, biperiden is a dangerous deliriant at high doses, producing a distressing anticholinergic delirium rather than pleasurable effects.

Brilaroxazine

Brilaroxazine (developmental code RP5063, sometimes called oxaripiprazole) is an investigational oral multimodal dopamine and serotonin receptor modulator being developed by Reviva Pharmaceuticals, primarily for schizophrenia. It is a close structural analogue of aripiprazole that acts as a partial agonist at dopamine D2, D3 and D4 and serotonin 5-HT1A receptors, and an antagonist at 5-HT2A, 5-HT2B and 5-HT7, with moderate affinity for the serotonin transporter [1]. A 234-patient phase 2 trial reported a significant reduction in total PANSS score versus placebo [1], and a phase 3 programme (RECOVER, NCT05184335) is ongoing. It is not approved by any regulator and is not an available nootropic or prescription medicine.

Brompheniramine

Brompheniramine is a first-generation alkylamine H1 antihistamine structurally almost identical to chlorpheniramine, differing only by a bromine atom in place of chlorine. It relieves allergic symptoms by antagonizing histamine H1 receptors, and its ready central nervous system penetration produces the characteristic sedation of this drug class. In vitro binding studies show that it also blocks all five human muscarinic acetylcholine receptor subtypes with affinity comparable to chlorpheniramine, which underlies its anticholinergic side effects and places it among the deliriants. Because sedation and impaired psychomotor performance can occur even at therapeutic doses, brompheniramine has been repeatedly detected in forensic toxicology of transportation fatalities; large overdoses can precipitate a dangerous anticholinergic delirium.

Cebaracetam

Cebaracetam is an experimental nootropic drug of the racetam family that was studied during the 1990s as a candidate treatment for cognitive and memory disorders [1]. In chemical terms it is a chlorinated, piperazinone-bearing analogue of phenylpiracetam, with the molecular formula C16H18ClN3O3 [2]. The compound advanced into phase II clinical trials, but its development was discontinued in 1995 and it was never marketed [1]. Its mechanism of action was never clearly defined.

Chlorpheniramine

Chlorpheniramine (chlorphenamine) is a first-generation alkylamine H1 antihistamine ubiquitous in cold and allergy preparations, providing symptom relief through histamine H1 receptor blockade while causing sedation and, via muscarinic acetylcholine antagonism at all five subtypes, anticholinergic effects that classify it among the deliriants. A distinctive and less appreciated property is that it is a comparatively potent serotonin reuptake inhibitor; rodent studies show it raises prefrontal extracellular serotonin and produces anxiolytic-like effects independent of H1 blockade, and its in vitro profile resembles that of antidepressants. This serotonergic action carries clinical risk, since chlorpheniramine has contributed to serotonin toxicity in overdose, particularly when combined with dextromethorphan. High doses otherwise produce the anticholinergic delirium typical of the class.

Corallocin A

Corallocin A is an isoindolinone natural product first isolated from the coral tooth mushroom Hericium coralloides and subsequently found in Hericium erinaceus fruiting bodies. It induces both nerve growth factor and brain-derived neurotrophic factor expression in human astrocytes, making it one of the dual-neurotrophin inducers of the Hericium genus. Its ability to raise BDNF as well as NGF distinguishes it from the classic NGF-focused hericenones and links it to memory-relevant signaling.

Cytidine

Cytidine is a pyrimidine nucleoside made up of the base cytosine joined to a ribose sugar. It is one of the fundamental building blocks of RNA, where its phosphorylated forms act as nucleotides, and it also feeds into the synthesis of cell membrane phospholipids. In humans, dietary and supplemental cytidine is largely converted to the related nucleoside uridine, and it is closely tied to the choline donor CDP-choline (citicoline); it has additionally been studied in a small way for mood disorders.

Datura

Datura is a genus of Solanaceae plants, most notably Datura stramonium (jimsonweed or thornapple), whose seeds and foliage contain the tropane alkaloids scopolamine, atropine (hyoscyamine), and related compounds. These alkaloids are potent competitive antagonists of muscarinic acetylcholine receptors, so the plant acts as a deliriant, producing peripheral anticholinergic signs such as mydriasis and tachycardia alongside central confusion, agitation, and vivid hallucinations. Datura is regarded as especially hazardous because alkaloid content varies widely between plants, plant parts, and seasons, so that the toxic and lethal thresholds lie close to the doses that produce delirium; forensic and clinical reports document severe poisonings and deaths, including from accidental exposure and from contamination of food crops. Analytical methods based on liquid chromatography-mass spectrometry and rapid immunoassays are used to confirm atropine and scopolamine exposure.

Dimenhydrinate

Dimenhydrinate is a salt combining diphenhydramine with 8-chlorotheophylline, marketed as an antiemetic and antivertigo antihistamine for motion sickness. Its pharmacologically active moiety is diphenhydramine, a first-generation H1 antihistamine with strong antimuscarinic (anticholinergic) activity, while the 8-chlorotheophylline component contributes mild central stimulation intended to offset sedation. At therapeutic doses effects are chiefly sedation and typical anticholinergic signs, but at high doses dimenhydrinate behaves as a deliriant equivalent to the diphenhydramine it releases, producing confusion, hallucinations, and anticholinergic toxidrome. Systematic reviews document a distinct pattern of tolerance, dependence, and neuropsychiatric sequelae with heavy or chronic use, and management of severe intoxication parallels that of diphenhydramine overdose.

Diphenhydramine

Diphenhydramine is a first-generation H1 antihistamine sold over the counter for allergies and as a sleep aid, sedating at ordinary doses through histamine H1 blockade. It is also a potent muscarinic acetylcholine receptor antagonist, and at the high doses taken recreationally this antimuscarinic action produces a deliriant state of confusion, agitation, and frightening hallucinations characteristic of the anticholinergic toxidrome rather than euphoria. Toxicity is dose-dependent, with the risk of delirium, seizures, and coma rising sharply above roughly one gram, and diphenhydramine additionally blocks cardiac sodium channels, causing QRS prolongation and conduction abnormalities that may respond to sodium bicarbonate. Severe anticholinergic delirium can be reversed with centrally acting cholinesterase inhibitors such as physostigmine or, where unavailable, rivastigmine.

Doliracetam

Doliracetam is an obscure synthetic compound of the racetam family, a group of acetamide-based substances studied for possible effects on cognition. Unlike the classic racetams built on a pyrrolidinone ring, it is chemically an oxindole derivative carrying an acetamide group. It was patented by the German pharmaceutical company Hoechst in the early 1980s as one of a series of compounds described as having neuroanabolic properties. Doliracetam never became an established medicine, and very little published research on it exists.

Doxylamine

Doxylamine is a first-generation H1 antihistamine marketed over the counter as a hypnotic and combined into nighttime cold and flu preparations. It produces sedation through histamine H1 receptor blockade and, like related ethanolamine antihistamines, is strongly anticholinergic, so that supratherapeutic doses can cause an unpleasant deliriant state with somnolence, agitation, hallucinations, mydriasis, and tachycardia. A characteristic and clinically important feature of doxylamine overdose is a comparatively high incidence of rhabdomyolysis, which can lead to acute kidney injury requiring haemodialysis; the amount ingested is the principal predictor, with risk rising steeply above roughly 20 mg per kilogram. Management centres on aggressive hydration, electrolyte monitoring, and support for renal and, less commonly, hepatic and pancreatic complications.

Dupracetam

Dupracetam is an experimental nootropic of the racetam (pyrrolidinone) family, structurally related to piracetam. It was investigated in the late twentieth century for possible effects on learning and cognition, yet it was never developed into an approved medicine and remains an obscure research compound with only a sparse scientific literature.

Ecklonia Cava

Ecklonia cava is an edible brown alga (seaweed) found in the coastal waters of East Asia, especially around Korea and Japan. It is a rich source of polyphenols called phlorotannins, including the marker compound dieckol, which have been studied for antioxidant, anti-inflammatory, and other biological activities. Extracts of the seaweed are used in foods, dietary supplements, and cosmetics.

Encenicline

Encenicline (EVP-6124) is an investigational, orally active, selective partial agonist of the alpha7 nicotinic acetylcholine receptor developed for cognitive impairment in schizophrenia and Alzheimer disease. Late-stage clinical development was halted after serious gastrointestinal adverse events, and it is not approved for any use.

Erinacine A

Erinacine A is the flagship cyathane diterpenoid produced by the mycelium of the culinary-medicinal mushroom Hericium erinaceus (Lion's Mane). It is the single most pharmacologically characterized Lion's Mane metabolite in the central nervous system, acting as a potent low-molecular-weight inducer of nerve growth factor (NGF) synthesis. Unlike the larger hericenones of the fruiting body, erinacine A is small and lipophilic enough to cross the blood brain barrier, giving it central activity after oral dosing in rodents. Preclinical work reports benefit across Alzheimer-type pathology, Parkinsonian models, ischemic stroke, metabolic-driven cognitive decline, and colorectal cancer models.

Erinacine C

Erinacine C is a cyathane diterpenoid from Hericium erinaceus mycelium and one of the more potent members of the erinacine series for inducing nerve growth factor synthesis. Beyond neurotrophic activity, it is distinguished by a well-characterized anti-neuroinflammatory profile: in microglial models it suppresses nitric oxide and pro-inflammatory cytokine production while activating the cytoprotective Nrf2/HO-1 pathway. It is investigated as a natural neuroprotective lead for conditions driven by microglial activation and oxidative stress.

Erinacine P

Erinacine P is a cyathane diterpenoid isolated from liquid cultures of Hericium erinaceus and is best understood as a biosynthetic precursor within the erinacine pathway that leads to erinacine A and erinacine C. Despite its precursor role it is itself neuroactive, promoting neurite outgrowth in PC12 cells at low micromolar concentrations. It is of particular interest to metabolic engineers seeking to raise erinacine A yields, since the pathway flows through erinacine P.

GTS-21

GTS-21, also known as DMXB-A, is an investigational drug that acts as a selective partial agonist at the alpha-7 subtype of nicotinic acetylcholine receptors. It is a synthetic derivative of anabaseine, a natural compound found in certain marine worms, and was developed as a candidate treatment for the cognitive problems of conditions such as schizophrenia and Alzheimer's disease [1][2]. Despite encouraging early laboratory results, it has not shown clear clinical benefit and has not advanced beyond mid-stage trials [2].

Hericene A

Hericene A is a hydrophobic hericerin-derived isoindoline compound from Hericium erinaceus that activates a pan-neurotrophic signaling pathway distinct from the classic NGF mechanism. In cultured hippocampal neurons it and its precursor N-de-phenylethyl isohericerin promoted extensive axon outgrowth and neurite branching even without serum, acting partly through a TrkB-independent route that converges on ERK1/2. Mice fed Hericium extract and hericene A showed increased neurotrophin signaling and significantly enhanced hippocampal memory, making hericene A a standout modern discovery in Lion's Mane neurobiology.

Hericenone C

Hericenone C is an aromatic fatty-acid ester isolated from the fruiting body of Hericium erinaceus and one of the classic small-molecule inducers of nerve growth factor synthesis identified from Lion's Mane. Together with hericenones D and E it helped establish the scientific basis for the mushroom's traditional reputation as a nerve tonic. Unlike the mycelial erinacines, hericenones are relatively large and lipophilic and are thought to act largely peripherally rather than crossing the blood brain barrier efficiently.

Hericenone D

Hericenone D is an aromatic fatty-acid ester from the fruiting body of Hericium erinaceus, one of the original nerve growth factor-inducing hericenones described from Lion's Mane. It is closely related to hericenones C and E and contributes to the neurotrophic activity attributed to fruiting-body extracts. Like its congeners it is considered to act predominantly in the peripheral nervous system rather than crossing the blood brain barrier.

Hyoscyamine

Hyoscyamine is the levorotatory (S) enantiomer of atropine and a tropane alkaloid found in belladonna, henbane, jimsonweed, and related nightshades; atropine itself is the racemate, and the l-hyoscyamine form carries essentially all of the mixture's antimuscarinic potency. It acts as a competitive, non-selective antagonist at muscarinic acetylcholine receptors, and is used medically as a gastrointestinal and genitourinary antispasmodic to relieve smooth-muscle cramping. As a classical anticholinergic it dose-dependently reduces secretions and raises heart rate, and its systemic absorption even from ophthalmic use can produce peripheral antimuscarinic effects. At high doses it can precipitate the full anticholinergic toxidrome, with agitation, delirium, and vivid hallucinations, a state reversible with the cholinesterase inhibitor physostigmine and responsible for the deliriant reputation of the nightshade alkaloids.

Idalopirdine

Idalopirdine is a potent, selective serotonin 5-HT6 receptor antagonist developed by H. Lundbeck (as Lu AE58054) as an adjunctive symptomatic treatment for Alzheimer's disease. By blocking 5-HT6 receptors, which are expressed almost exclusively in the central nervous system and concentrated in the hippocampus and cortex, it disinhibits cholinergic, glutamatergic and monoaminergic transmission relevant to memory. A phase 2 trial (LADDER) in donepezil-treated moderate Alzheimer's disease showed a significant cognitive benefit, but the larger phase 3 STARSHINE, STARBEAM and STARBRIGHT programme failed to replicate it. Idalopirdine is discontinued for cognition and is now referenced primarily as a pharmacological tool and cautionary case study.

Indeloxazine

Indeloxazine was developed and marketed in Japan from the late 1980s, under brand names including Elen and Noin, as a dual serotonin/norepinephrine reuptake inhibitor aimed at a use case Western antidepressants of the era largely ignored: the depression, apathy and cognitive slowing that follow a stroke. It stayed almost entirely confined to the Japanese market and pharmacology literature, mechanistically an early dual-reuptake antidepressant that never secured a Western indication despite predating some Western SNRIs. More recently its resolved (+)-isomer, given the separate code AS1069562, has been revisited in Japanese pain research as a serotonin-transporter-mediated analgesic for neuropathic and myalgic pain, giving this obscure Japanese post-stroke drug an unexpected second research life decades later.

Intepirdine

Intepirdine is a selective serotonin 5-HT6 receptor antagonist originally discovered at GlaxoSmithKline as SB-742457 and later licensed to Axovant Sciences as RVT-101 for Alzheimer's disease and dementia with Lewy bodies. Like other compounds in its class it was intended to enhance cognition by disinhibiting cholinergic and glutamatergic signaling in cortex and hippocampus. A phase 2 study suggested a modest global and cognitive benefit, but the pivotal phase 3 MINDSET trial in mild-to-moderate Alzheimer's disease was clearly negative. Its high-profile failure in 2017 effectively ended enthusiasm for 5-HT6 antagonism as a standalone dementia strategy.

Irdabisant

Irdabisant (CEP-26401) is a potent, highly selective histamine H3 receptor antagonist and inverse agonist developed by Cephalon. Because the H3 receptor is largely an inhibitory autoreceptor and heteroreceptor that restrains release of histamine and other arousal-related neurotransmitters, blocking it disinhibits wake-promoting signaling; in preclinical models irdabisant showed robust wake-promoting activity and improved short-term memory at low doses, alongside favorable central nervous system drug-like properties and high selectivity over other histamine receptor subtypes. It was studied as a candidate cognition-enhancing and wakefulness-promoting agent for conditions such as cognitive impairment and schizophrenia. Early human studies characterized its pharmacokinetics and pharmacodynamics, including dose-dependent effects on sleep, but the compound advanced only into early clinical trials and was never brought to market.

L-Clausenamide

L-Clausenamide, or (-)-clausenamide, is a pyrrolidinone alkaloid isolated from the leaves of Clausena lansium (wampee) and studied in China as a nootropic and neuroprotective anti-dementia drug candidate [1]. It is the eutomer of the clausenamide enantiomers, improving learning and memory through multi-target actions including modulation of intracellular calcium, cholinergic support, enhancement of synaptic plasticity and long-term potentiation, and antioxidant protection [1]. In cellular and animal models it protects neurons against beta-amyloid, okadaic-acid and ischemic injury and inhibits ferroptosis in dopaminergic neurons [2][3][4].

Latrepirdine

Latrepirdine, better known by its Soviet-era trade name Dimebon, is a multi-target small molecule originally marketed in Russia as a non-selective antihistamine and later repurposed as a candidate cognition enhancer. Among its many actions it is a moderate-affinity 5-HT6 receptor antagonist, and this activity is thought to contribute to its acute pro-cognitive effects in animal models. After an early positive Russian trial in Alzheimer's disease generated intense interest, large international phase 3 studies in both Alzheimer's disease and Huntington's disease were negative. It is now studied mainly as a promiscuous pharmacological tool and a lesson in multi-target drug development.

Masupirdine

Masupirdine is a potent, selective serotonin 5-HT6 receptor antagonist developed by Suven Life Sciences as SUVN-502 for cognitive deficits in Alzheimer's disease. It was distinctive as the first compound in its class tested on a background of both donepezil and memantine, reflecting real-world moderate Alzheimer's disease management. The pivotal phase 2 proof-of-concept study did not meet its prespecified cognitive endpoint, although exploratory post hoc analyses suggested that concurrent memantine may have masked a benefit. Suven has since pivoted masupirdine toward agitation in dementia rather than core cognition.

Meclizine

Meclizine (also spelled meclozine; brand names Bonine and Antivert) is a long-acting first-generation piperazine antihistamine used chiefly for motion sickness and vertigo. It blocks histamine H1 receptors and central muscarinic acetylcholine receptors, dampening vestibular and emetic signaling; this same anticholinergic activity allows it to produce a deliriant, confusional state at high doses, alongside sedation from H1 blockade. It is metabolized largely by CYP2D6, giving wide interindividual variation in exposure and onset. Beyond its antihistamine role, meclizine has drawn research interest for an unusual metabolic action, partially inhibiting mitochondrial oxidative phosphorylation and redirecting energy production toward glycolysis, an effect studied for neuroprotection and cytoprotection.

Meclofenoxate

Meclofenoxate, also known as centrophenoxine, is a nootropic compound classified as a cholinergic agent, made by combining dimethylethanolamine (DMAE) with para-chlorophenoxyacetic acid. Developed in the late 1950s, it has been used, mainly in Europe and Asia, as a prescription drug for age-related cognitive decline and dementia, and it is sold elsewhere as an unapproved dietary supplement marketed for memory and mental alertness [1][4]. Research, much of it older or preclinical, has examined its effects on memory, brain aging, and the accumulation of the cellular waste pigment lipofuscin [2].

Methylphenylpiracetam

Methylphenylpiracetam (MPP) is a methylated analogue of phenylpiracetam developed at the Latvian Institute of Organic Synthesis, and its most studied stereoisomer, E1R, is a positive allosteric modulator of the sigma-1 receptor [1]. In mice, E1R enhances memory retention and reverses scopolamine-induced cognitive impairment without altering locomotor activity, effects abolished by the selective sigma-1 antagonist NE-100 [1]. Unlike its parent phenylpiracetam, which is primarily a dopaminergic psychostimulant, MPP is characterized as a non-stimulant cognition enhancer acting through sigma-1 chaperone signaling [1].

Muscarinic Toxin 2

One of the two original green mamba muscarinic toxins; it binds M1 and M4 near-irreversibly and acts as a slow muscarinic agonist, but it is markedly less selective than its early reputation suggested.

Muscarinic Toxin 3

A 65 residue green mamba toxin used as the standard M4-preferring muscarinic antagonist, with the significant caveat that it binds several alpha adrenoceptors just as tightly.

Muscarinic Toxin 7

A 65 residue three-finger protein from green mamba venom that blocks the M1 muscarinic receptor from an allosteric site; it is the most subtype-selective muscarinic ligand anyone has found.

Nebracetam

Nebracetam (development code WEB 1881 FU) is an investigational nootropic of the racetam family that was studied mainly in Japan as a potential cognition enhancer. Chemically a pyrrolidinone related to piracetam, it is distinguished from most racetams by acting as a direct agonist at the M1 muscarinic acetylcholine receptor, alongside pronounced cholinergic and neuroprotective effects in preclinical models of memory impairment and cerebral ischemia. It was explored in such models but did not become an approved medicine.

Nicotine

nicotine is a genuinely nootropic nicotinic agonist with a small, real, meta-analysis-backed edge on attention and psychomotor speed (bigger in cholinergic-deficit brains than in healthy young ones), delivered through α4β2, α6 and α7 receptors; the honest catch is that it's an addictive drug whose habit-forming power scales with how fast you take it, so the entire case for using it rests on non-combusted low-dose delivery and clear eyes about dependence.

Nutmeg

Nutmeg is the culinary spice obtained from the seed of Myristica fragrans, the same tree whose seed covering yields mace. Culinary quantities are inert, but very large ingestions of the ground seed can cause a slow-onset, long-lasting intoxication attributed chiefly to the aromatic constituents myristicin, elemicin, and safrole, often accompanied by anticholinergic-like features such as tachycardia and agitation. Myristicin is additionally reported to possess weak monoamine oxidase inhibitory activity, and its structural resemblance to amphetamine precursors has prompted speculation about amphetamine- or MDMA-like metabolites, though such conversion in humans remains unproven. Case series and poisoning reports characterize the experience as unpredictable and generally unpleasant; documented exposures have required medical evaluation but have not typically been life-threatening, and toxicokinetic analysis of the psychoactive constituents in serum has been performed in overdose cases.

Orphenadrine

Orphenadrine is an anticholinergic agent used as a skeletal muscle relaxant and, historically, in the management of Parkinsonism. A close structural analog of the antihistamine diphenhydramine, it combines first-generation antihistaminic and muscarinic-blocking activity with additional pharmacology that has been well characterized in vitro: binding and patch-clamp studies established it as an uncompetitive, voltage-dependent open-channel NMDA-receptor antagonist, and later work demonstrated concentration-dependent blockade of voltage-gated sodium channels implicated in its analgesic action. Despite this NMDA activity, its low channel affinity means it does not substitute for phencyclidine in drug-discrimination models, so overtly dissociative effects are minimal at therapeutic doses. In overdose the drug becomes a dangerous deliriant, with reported toxicity encompassing agitation, delirium, seizures, and, through sodium-channel effects, cardiac conduction disturbances.

PF-04995274

PF-04995274 is a selective, brain-penetrant 5-HT4 receptor partial agonist originally developed by Pfizer that has become the leading clinical probe for pro-cognitive and antidepressant effects of central 5-HT4 activation in humans. It advanced into experimental medicine studies in major depressive disorder, where short courses altered emotional and memory-related brain circuitry in ways distinct from a conventional selective serotonin reuptake inhibitor. In the RESTAND programme it increased hippocampal and parietal activity during memory encoding and produced early signals of mood improvement without the classic negative-bias shift seen with citalopram. It remains an investigational compound and is not approved for any indication.

PNU-120596

PNU-120596 is a selective type II positive allosteric modulator of the alpha7 nicotinic acetylcholine receptor; it raises channel open probability and destabilizes receptor desensitization to amplify cholinergic signaling without directly activating the receptor. It is an investigational research tool used to probe alpha7 mechanisms in cognition, schizophrenia and inflammation, and is not approved for human use.

Pregnenolone Sulfate

Pregnenolone sulfate (PregS) is an endogenous excitatory neurosteroid (a steroid synthesized in and acting upon the nervous system) formed by sulfation of pregnenolone at its 3beta-hydroxyl group. It is among the most intensively studied neurosteroids in ion-channel pharmacology, acting simultaneously as a positive allosteric modulator of N-methyl-D-aspartate (NMDA) receptors that contain GluN2A or GluN2B subunits (the principal glutamate-gated channels underlying synaptic plasticity), a negative allosteric modulator of GABA-A receptors (the brain's main inhibitory chloride channels), a low-affinity agonist of the sigma-1 receptor (an intracellular chaperone protein) and the prototypical agonist of the TRPM3 cation channel. Through these convergent actions it enhances glutamatergic transmission, hippocampal acetylcholine release, long-term potentiation and memory consolidation in animal models, which underlies its reputation as a pro-cognitive neurosteroid. Its physiological concentrations, and even its unambiguous presence in mammalian brain, remain debated, so much of the evidence base derives from experimental administration rather than demonstrated endogenous signaling.

Procyclidine

Procyclidine (marketed as Kemadrin) is a synthetic antimuscarinic agent used to treat parkinsonism and antipsychotic-induced extrapyramidal symptoms such as acute dystonia and tardive movement disorders. Its principal action is competitive blockade of central muscarinic acetylcholine receptors, restoring the striatal dopamine-acetylcholine balance disrupted in these conditions. Beyond its anticholinergic profile, procyclidine also antagonizes NMDA glutamate receptors, a property that has drawn interest in combination pretreatment regimens against organophosphate nerve-agent poisoning, where it contributes anticonvulsant and neuroprotective effects. Although a legitimate prescription medicine, procyclidine is, like other brain-penetrant anticholinergics, capable of producing a dangerous deliriant and anticholinergic-toxidrome state in overdose.

RS-67333

RS-67333 is a selective, high-affinity partial agonist of the serotonin 5-HT4 receptor that has become the reference pharmacological tool for probing the pro-cognitive and disease-modifying potential of 5-HT4 activation in the central nervous system. Unlike the marketed gastrointestinal 5-HT4 agonists, RS-67333 crosses the blood-brain barrier readily and has been studied almost exclusively in preclinical models of learning, memory, and Alzheimer's disease. Its signature finding is that chronic 5-HT4 stimulation shifts amyloid precursor protein processing toward the non-amyloidogenic alpha-secretase pathway, increasing release of the neurotrophic sAPPalpha fragment while lowering amyloid-beta. RS-67333 is an investigational research compound with no human clinical development and no approved use.

Sabeluzole

Sabeluzole (R 58 735) is a benzothiazole derivative developed by Janssen Pharmaceutica as a neuroprotective memory enhancer. In controlled studies it improved learning and recall in healthy elderly volunteers and showed signs of stabilizing cognition in Alzheimer's disease over a year of treatment. Its actions are attributed to modulation of sodium channels, protection against glutamate excitotoxicity and anoxia, and effects on fast axonal transport. Development was ultimately discontinued, but it remains a notable historical cognition-focused neuroprotectant.

Sapunifiram

Sapunifiram (MN-19) is an investigational piperidine cognition-enhancer developed by the medicinal chemistry group at the University of Florence as a close structural relative of sunifiram (DM235). Like its parent scaffold, it produces potent antiamnesic and procognitive effects in rodent avoidance paradigms at very low doses, with reported potency exceeding that of piracetam. It is best understood as an ampakine-like glutamatergic and cholinergic facilitator rather than a classical racetam, and it has never advanced beyond preclinical characterization. It remains a purely research-grade compound of interest to structure-activity chemists and the nootropic community.

SB-271046

SB-271046 is one of the first potent and selective serotonin 5-HT6 receptor antagonists, developed at SmithKline Beecham as a research tool and early cognition-enhancer candidate. It is a benzothiophene sulfonamide with high 5-HT6 affinity and behaves as an antagonist or inverse agonist at the receptor. Widely used in preclinical neuroscience, it helped establish the link between 5-HT6 blockade and increased cortical glutamate and cognitive performance. It was never developed into a marketed drug and remains a benchmark reference antagonist for the receptor.

SB-399885

SB-399885 is a potent, selective and orally active serotonin 5-HT6 receptor antagonist developed at GlaxoSmithKline as a cognition-enhancer research compound. It has very high 5-HT6 affinity and more than 200-fold selectivity over other receptors, ion channels and enzymes, making it one of the cleaner pharmacological probes for the receptor. In rodent studies it reversed scopolamine- and dizocilpine-induced memory deficits, improved spatial learning in aged rats and raised cortical acetylcholine. It was never marketed but is a well-validated tool antagonist widely used to test the 5-HT6 cognition hypothesis.

Scopolamine

Scopolamine, also known as hyoscine, is a tropane alkaloid found in nightshade plants such as Datura and belladonna and is the prototypical deliriant; it is a potent, brain-penetrant antagonist of muscarinic acetylcholine receptors. At low doses it is used clinically, most familiarly as a transdermal patch for motion sickness and nausea, and it has attracted research interest as a rapid-acting antidepressant, with placebo-controlled trials showing benefit and preclinical work tracing the effect to blockade of M1 receptors on cortical somatostatin interneurons that in turn drives glutamatergic and GABAergic plasticity and BDNF-TrkB signaling. At higher doses scopolamine produces a compliant, amnesic, and confused anticholinergic state, the basis of its notoriety under the street name Devil's Breath and of the severe anticholinergic toxidrome seen in Datura poisoning.

SL65.0155

SL65.0155 is a selective 5-HT4 receptor partial agonist developed as a cognition-enhancing candidate, notable for producing robust improvements in learning, memory, and attention in rodents at very low doses. It reversed associative learning deficits after hippocampal damage and enhanced attentional performance comparable to nicotine in the five-choice serial reaction time task. Alongside RS-67333, it is one of the classic experimental 5-HT4 agonists used to establish the receptor as a pro-cognitive and potential anti-dementia target. SL65.0155 is an investigational research compound without approved use.

TAK-071

TAK-071 is Takeda's M1 muscarinic positive allosteric modulator, built around a deliberately low cooperativity value on the finding that cooperativity, not potency, is what decides whether an M1 drug causes diarrhoea; it reached a phase 2 crossover trial in Parkinson disease where it missed its gait endpoint and improved a secondary cognitive measure.

TC299423

tc299423 is an experimental (targacept) small-molecule nicotinic agonist with an alpha6-preferring profile; it activates alpha6beta2* receptors at ec50 ~30-60 nm (about 2.5-fold over alpha4beta2), is orally bioavailable with a clean off-target screen, produces alpha6*-mediated reward in place-preference tests, but did not block nicotine self-administration; a research tool showing small molecules can preferentially target alpha6*, not a medicine.

Trihexyphenidyl

Trihexyphenidyl (Artane) is a synthetic anticholinergic prescribed mainly for Parkinson's disease symptoms and for antipsychotic-induced extrapyramidal and dystonic reactions. It acts by antagonizing central muscarinic acetylcholine receptors, correcting the striatal cholinergic-dopaminergic imbalance that underlies these motor disorders. Although not a controlled substance, it is sometimes misused for its relaxing or euphoriant effects, particularly among psychiatric populations, and cases of dependence, diversion, and a distinct withdrawal syndrome have been documented. At high doses trihexyphenidyl produces the same dangerous, disorienting deliriant and anticholinergic-toxidrome state as other antimuscarinics, and recreational use is generally reported as unpleasant rather than pleasurable.

Varenicline

varenicline (chantix/champix) is a cytisine-derived nicotinic partial agonist and a first-line smoking-cessation drug; a high-affinity partial agonist at alpha4beta2 (its core mechanism), full agonist at alpha7, partial at alpha3beta4, and only a weak partial agonist at the alpha6beta2* dopamine-terminal receptors that gate nicotine reward; effective for quitting, with nausea as the main trade-off.

AF710B

AF710B, also known as ANAVEX 3-71 (later ANAVEX3-71), is an experimental small-molecule drug that acts as a selective allosteric agonist of the M1 muscarinic acetylcholine receptor and an agonist of the sigma-1 receptor. Originating from the medicinal-chemistry work of Abraham Fisher and developed by Anavex Life Sciences, it has been investigated as a potential disease-modifying treatment for Alzheimer's disease and related neurodegenerative and psychiatric conditions.