Monoamine transporters (MATs) are proteins that function as integral plasma-membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. The three major classes are serotonin transporters (SERTs), dopamine transporters (DATs), and norepinephrine transporters (NETs) and are responsible for the reuptake of their associated amine neurotransmitters. MATs are located just outside the synaptic cleft (peri-synaptically), transporting monoamine transmitter overflow from the synaptic cleft back to the cytoplasm of the pre-synaptic neuron. MAT regulation generally occurs through protein phosphorylation and post-translational modification. Due to their significance in neuronal signaling, MATs are commonly associated with drugs used to treat mental disorders as well as recreational drugs. Compounds targeting MATs range from medications such as the wide variety of tricyclic antidepressants, selective serotonin reuptake inhibitors such as fluoxetine (Prozac) to stimulant medications such as methylphenidate (Ritalin) and amphetamine in its many forms and derivatives methamphetamine (Desoxyn) and lisdexamfetamine (Vyvanse). Furthermore, drugs such as MDMA and natural alkaloids such as cocaine exert their effects in part by their interaction with MATs, by blocking the transporters from mopping up dopamine, serotonin, and other neurotransmitters from the synapse.
Butyrophenone is an organic compound with the formula C6H5C(O)C3H7. It is a colorless liquid.
(–)-2-β-Carbomethoxy-3-β-(4-fluorophenyl)tropane is a stimulant drug used in scientific research. CFT is a phenyltropane based dopamine reuptake inhibitor and is structurally derived from cocaine. It is around 3-10x more potent than cocaine and lasts around 7 times longer based on animal studies. While the naphthalenedisulfonate salt is the most commonly used form in scientific research due to its high solubility in water, the free base and hydrochloride salts are known compounds and can also be produced. The tartrate is another salt form that is reported.
Phenyltropanes (PTs) were originally developed to reduce cocaine addiction and dependency. In general these compounds act as inhibitors of the plasmalemmal monoamine reuptake transporters. This research has spanned beyond the last couple decades, and has picked up its pace in recent times, creating numerous phenyltropanes as research into cocaine analogues garners interest to treat addiction.
(+)-CPCA is a stimulant drug similar in structure to pethidine and to RTI-31, but nocaine is lacking the two-carbon bridge of RTI-31's tropane skeleton. This compound was first developed as a substitute agent for cocaine.
A serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), also known as a triple reuptake inhibitor (TRI), is a type of drug that acts as a combined reuptake inhibitor of the monoamine neurotransmitters serotonin, norepinephrine, and dopamine. It does this by concomitantly inhibiting the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT), respectively. Inhibition of the reuptake of these neurotransmitters increases their extracellular concentrations and, therefore, results in an increase in serotonergic, adrenergic, and dopaminergic neurotransmission. The naturally-occurring and potent SNDRI cocaine is widely used recreationally and often illegally for the euphoric effects it produces.
Metabotropic glutamate receptor 3 (mGluR3) is an inhibitory Gi/G0-coupled G-protein coupled receptor (GPCR) generally localized to presynaptic sites of neurons in classical circuits. However, in higher cortical circuits in primates, mGluR3 are localized post-synaptically, where they strengthen rather than weaken synaptic connectivity. In humans, mGluR3 is encoded by the GRM3 gene. Deficits in mGluR3 signaling have been linked to impaired cognition in humans, and to increased risk of schizophrenia, consistent with their expanding role in cortical evolution.
Difluoropine (O-620) is a stimulant drug synthesised from tropinone, which acts as a potent and selective dopamine reuptake inhibitor. Difluoropine is unique among the tropane-derived dopamine reuptake inhibitors in that the active stereoisomer is the (S) enantiomer rather than the (R) enantiomer, the opposite way round compared to natural cocaine. It is structurally related to benztropine and has similar anticholinergic and antihistamine effects in addition to its dopamine reuptake inhibitory action.
1-Amino-5-phosphonoindan-1-carboxylic acid (APICA) is a drug that is used in neuroscience research. It is a selective antagonist for the group II metabotropic glutamate receptors (mGluR2/3), and has been useful in the study of this receptor subfamily.
RTI(-4229)-113 is a stimulant drug which acts as a potent and fully selective dopamine reuptake inhibitor (DRI). It has been suggested as a possible substitute drug for the treatment of cocaine addiction. "RTI-113 has properties that make it an ideal medication for cocaine abusers, such as an equivalent efficacy, a higher potency, and a longer duration of action as compared to cocaine." Replacing the methyl ester in RTI-31 with a phenyl ester makes the resultant RTI-113 fully DAT specific. RTI-113 is a particularly relevant phenyltropane cocaine analog that has been tested on squirrel monkeys. RTI-113 has also been tested against cocaine in self-administration studies for DAT occupancy by PET on awake rhesus monkeys. The efficacy of cocaine analogs to elicit self-administration is closely related to the rate at which they are administered. Slower onset of action analogs are less likely to function as positive reinforcers than analogues that have a faster rate of onset.
(–)-2β-Carbomethoxy-3β-(4'-chlorophenyl)tropane (RTI-4229-31) is a synthetic analog of cocaine that acts as a stimulant. Semi-synthesis of this compound is dependent upon the availability of cocaine starting material. According to the article, RTI-31 is 64 times the strength of cocaine in terms of its potency to elicit self-administration in monkeys. WIN 35428 was 6 times weaker than RTI-31, whereas RTI-51 was 2.6 times weaker than RTI-31.
(–)-2β-Carbomethoxy-3β-(4-bromophenyl)tropane is a semi-synthetic alkaloid in the phenyltropane group of psychostimulant compounds. First publicized in the 1990s, it has not been used enough to have gained a fully established profile. RTI-51 can be expected to have properties lying somewhere in between RTI-31 and RTI-55. Importantly it has a ratio of monoamine reuptake inhibition of D > S > N which is an unusual balance of effects not produced by other commonly used compounds. It has been used in its 76Br radiolabelled form to map the distribution of dopamine transporters in the brain.
JZ-IV-10 is a piperidine derivative related to cocaine which acts as a highly potent serotonin–norepinephrine–dopamine reuptake inhibitor. The eugeroic modafinil was used as a lead to fuel this compound's discovery.
4-Fluoromethylphenidate is a stimulant drug that acts as a higher potency dopamine reuptake inhibitor than the closely related methylphenidate.
1-Methyl-3-propyl-4-(p-chlorophenyl)piperidine is a drug developed by a team led by Alan Kozikowski, which acts as a potent dopamine reuptake inhibitor, and was developed as a potential therapeutic agent for the treatment of cocaine addiction. As with related compounds such as nocaine, it is a structurally simplified derivative of related phenyltropane compounds. Its activity at the serotonin and noradrenaline transporters has not been published, though most related 4-phenylpiperidine derivatives are relatively selective for inhibiting dopamine reuptake over the other monoamine neurotransmitters. While several of its isomers are active, the (3S,4S)-enantiomer is by far the most potent. The rearranged structural isomer 2-[1-(4-chlorophenyl)butyl]piperidine is also a potent inhibitor of dopamine reuptake.
Willardiine (correctly spelled with two successive i's) or (S)-1-(2-amino-2-carboxyethyl)pyrimidine-2,4-dione is a chemical compound that occurs naturally in the seeds of Mariosousa willardiana and Acacia sensu lato. The seedlings of these plants contain enzymes capable of complex chemical substitutions that result in the formation of free amino acids (See: #Synthesis). Willardiine is frequently studied for its function in higher level plants. Additionally, many derivates of willardiine are researched for their potential in pharmaceutical development. Willardiine was first discovered in 1959 by R. Gmelin, when he isolated several free, non-protein amino acids from Acacia willardiana (another name for Mariosousa willardiana) when he was studying how these families of plants synthesize uracilyalanines. A related compound, Isowillardiine, was concurrently isolated by a different group, and it was discovered that the two compounds had different structural and functional properties. Subsequent research on willardiine has focused on the functional significance of different substitutions at the nitrogen group and the development of analogs of willardiine with different pharmacokinetic properties. In general, Willardiine is the one of the first compounds studied in which slight changes to molecular structure result in compounds with significantly different pharmacokinetic properties.
David E. Olson is an American chemist and neuroscientist. He is an associate professor of chemistry, biochemistry and molecular medicine at the University of California, Davis.
Delix Therapeutics is an American biotech company based in Boston, Massachusetts. The company develops novel neuroplasticity-promoting therapeutics for central nervous system (CNS) diseases such as depression and post-traumatic stress disorder (PTSD). It was co-founded in 2019 by David E. Olson and Nick Haft.
