A biological target is anything within a living organism to which some other entity is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets are proteins and nucleic acids. The definition is context-dependent, and can refer to the biological target of a pharmacologically active drug compound, the receptor target of a hormone, or some other target of an external stimulus. Biological targets are most commonly proteins such as enzymes, ion channels, and receptors.
Histamine H3 receptors are expressed in the central nervous system and to a lesser extent the peripheral nervous system, where they act as autoreceptors in presynaptic histaminergic neurons and control histamine turnover by feedback inhibition of histamine synthesis and release. The H3 receptor has also been shown to presynaptically inhibit the release of a number of other neurotransmitters (i.e. it acts as an inhibitory heteroreceptor) including, but probably not limited to dopamine, GABA, acetylcholine, noradrenaline, histamine and serotonin.
Neurotensin receptors are transmembrane receptors that bind the neurotransmitter neurotensin. Two of the receptors encoded by the NTSR1 and NTSR2 genes contain seven transmembrane helices and are G protein coupled. Numerous crystal structures have been reported for the neurotensin receptor 1 (NTS1). The third receptor has a single transmembrane domain and is encoded by the SORT1 gene.
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 lacks the two-carbon bridge of RTI-31's tropane skeleton. This compound was first developed as a substitute agent for cocaine.
Angiopoietin 1 is a type of angiopoietin and is encoded by the gene ANGPT1.
RTI(-4229)-55, also called RTI-55 or iometopane, is a phenyltropane-based psychostimulant used in scientific research and in some medical applications. This drug was first cited in 1991. RTI-55 is a non-selective dopamine reuptake inhibitor derived from methylecgonidine. However, more selective analogs are derived by conversion to "pyrrolidinoamido" RTI-229, for instance. Due to the large bulbous nature of the weakly electron withdrawing iodo halogen atom, RTI-55 is the most strongly serotonergic of the simple para-substituted troparil based analogs. In rodents RTI-55 actually caused death at a dosage of 100 mg/kg, whereas RTI-51 and RTI-31 did not. Another notable observation is the strong propensity of RTI-55 to cause locomotor activity enhancements, although in an earlier study, RTI-51 was actually even stronger than RTI-55 in shifting baseline LMA. This observation serves to highlight the disparities that can arise between studies.
(–)-2β-Carboisopropoxy-3β-(4-iodophenyl)tropane is a stimulant drug used in scientific research, which was developed in the early 1990s. RTI-121 is a phenyltropane based, highly selective dopamine reuptake inhibitor and is derived from methylecgonidine. RTI-121 is a potent and long-lasting stimulant, producing stimulant effects for more than 10 hours after a single dose in mice which would limit its potential uses in humans, as it might have significant abuse potential if used outside a medical setting. However RTI-121 occupies the dopamine transporter more slowly than cocaine, and so might have lower abuse potential than cocaine itself.
Neurotensin receptor type 1 is a protein that in humans is encoded by the NTSR1 gene. For a crystal structure of NTS1, see pdb code 4GRV. In addition, high-resolution crystal structures have been determined in complex with the peptide full agonist NTS8-13, the non-peptide full agonist SRI-9829, the partial agonist RTI-3a, and the antagonists / inverse agonists SR48692 and SR142948A, as well as in the ligand-free apo state., see PDB codes 6YVR (NTSR1-H4X:NTS8–13), 6Z4V (NTSR1-H4bmX:NTS8–13), 6Z8N (NTSR1-H4X:SRI-9829), 6ZA8 (NTSR1-H4X:RTI-3a), 6Z4S (NTSR1-H4bmX:SR48692), 6ZIN (NTSR1-H4X:SR48692), 6Z4Q, and 6Z66.
Reuptake inhibitors (RIs) are a type of reuptake modulators. It is a drug that inhibits the plasmalemmal transporter-mediated reuptake of a neurotransmitter from the synapse into the pre-synaptic neuron. This leads to an increase in extracellular concentrations of the neurotransmitter and an increase in neurotransmission. Various drugs exert their psychological and physiological effects through reuptake inhibition, including many antidepressants and psychostimulants.
Dichloropane ((−)-2β-Carbomethoxy-3β-(3,4-dichlorophenyl)tropane, RTI-111, O-401) is a stimulant of the phenyltropane class that acts as a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) with IC50 values of 3.13, 18, and 0.79 nM, respectively. In animal studies, dichloropane had a slower onset and longer duration of action compared to cocaine.
S-15535 is a phenylpiperazine drug which is a potent and highly selective 5-HT1A receptor ligand that acts as an agonist and antagonist at the presynaptic and postsynaptic 5-HT1A receptors, respectively. It has anxiolytic properties.
(–)-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. It has a ratio of monoamine reuptake inhibition of dopamine > serotonin > norepinephrine 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.
RTI(-4229)-274, or 2β-( methyl)-3α-(4-fluorophenyl)nortropane is a phenyltropane homologue of paroxetine developed by the group led by F Ivy Carroll in the 1990s.
RTI-229, also known as (–)-3β-(4-iodophenyl)tropane-2β-pyrrolidine carboxamide and RTI-4229-229, is a potent and long-lasting stimulant drug which was developed in the 1990s as part of a large group of related analogues from the phenyltropane family. With the combination of two potent dopamine transporter (DAT) binding motifs attached to the tropane ring, the p-iodophenyl group at the 3β-position and a pyrrolidine carboxamide at 2β, RTI-229 has extremely high selectivity for the dopamine transporter and is one of the most DAT-selective compounds in the RTI series.
Iron tetracarbonyl dihydride is the organometallic compound with the formula H2Fe(CO)4. This compound was the first transition metal hydride discovered. The complex is stable at low temperatures but decomposes rapidly at temperatures above –20 °C.
(–)-2β-Carbophenoxy-3β-(p-tolyl)tropane (RTI-4229-120) is a phenyltropane derivative which acts as a reasonably selective dopamine reuptake inhibitor, along with weaker inhibition of noradrenaline and serotonin reuptake. It has a reasonably fast rate of occupancy of dopamine transporters in the brain, though slower than that of cocaine itself. RTI-120 has a short duration of action, along with other p-methyl substituted phenyltropanes such as RTI-150, RTI-171 and RTI-199, giving it a more similar pharmacological profile to cocaine compared to longer acting analogues like RTI-121 and RTI-177.
PCP site 2 is a binding site that was identified as a high-affinity target for phencyclidine (PCP), an anesthetic and dissociative hallucinogen that acts primarily as an NMDA receptor antagonist. The site is distinct from the PCP binding site on the NMDA receptor and the common/main sites on the monoamine transporters. It is associated with monoamine reuptake inhibition, and it has been suggested that the site may be an allosteric/regulatory site of the monoamine transporters.
