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Drug class | Trace amine-associated receptor 1 (TAAR1) antagonist |
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Formula | C19H11ClF3N5OS |
Molar mass | 449.84 g·mol−1 |
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RTI-7470-44 is a potent and selective antagonist of the human trace amine-associated receptor 1 (TAAR1) which is used in scientific research. [1] [2] [3] [4] It was discovered in 2022 and is the first potent antagonist of the human TAAR1 to be identified, following the potent mouse TAAR1 inverse agonist EPPTB in 2009. [3] [4] [5]
The affinity (Ki) of RTI-7470-44 for the human TAAR1 is 0.3 nM and its inhibitory potency (IC50 ) at the receptor is 8.4 nM in vitro . [2] [4] It is about 90-fold less potent at the rat TAAR1 (IC50 = 748 nM) and 140-fold less potent at the mouse TAAR1 (IC50 = 1,190 nM) compared to the human TAAR1. [2] [4] Surprisingly, RTI-7470-44 was found to be a competitive antagonist of the human and mouse TAAR1 but a non-competitive antagonist of the rat TAAR1. [4]
Species | Affinity (Ki, nM) | IC50 (nM) | Imax (%) |
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Mouse | 139 | 1,190 | ND |
Rat | ND | 748 | ND |
Human | 0.3 | 8.4 | 101% |
The compound has favorable in vivo drug-like properties, including good blood–brain barrier permeability, moderate metabolic stability, and a favorable preliminary profile of off-target activity (≥1–10 μM at 42 other targets). [1] [3] [4] It is far more potent (893-fold) as an antagonist of the human TAAR1 than the earlier TAAR1 inverse agonist EPPTB in vitro, which has dramatically lower potency (165–272-fold) at the human TAAR1 and rat TAAR1 compared to the mouse TAAR1. [4]
RTI-7470-44 has been found to increase the spontaneous firing rate of dopaminergic neurons in mouse ventral tegmental area (VTA) slices ex vivo and to block the effects of the high-efficacy TAAR1 partial agonist RO5166017 in this system. [1] [3] [4]
RTI-7470-44 was first described in the scientific literature in 2022. [2] [4] It was identified via high throughput screening followed by structure–activity optimization. [1] [4]
Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon. The structure of tryptamine is a shared feature of certain aminergic neuromodulators including melatonin, serotonin, bufotenin and psychedelic derivatives such as dimethyltryptamine (DMT), psilocybin, psilocin and others.
3,4-Methylenedioxyamphetamine (MDA), sometimes referred to as “sass,” is an empathogen-entactogen, stimulant, and psychedelic drug of the amphetamine family that is encountered mainly as a recreational drug. In its pharmacology, MDA is a serotonin–norepinephrine–dopamine releasing agent (SNDRA). In most countries, the drug is a controlled substance and its possession and sale are illegal.
Synephrine, or, more specifically, p-synephrine, is an alkaloid, occurring naturally in some plants and animals, and also in approved drugs products as its m-substituted analog known as neo-synephrine. p-Synephrine and m-synephrine are known for their longer acting adrenergic effects compared to epinephrine and norepinephrine. This substance is present at very low concentrations in common foodstuffs such as orange juice and other orange products, both of the "sweet" and "bitter" variety. The preparations used in traditional Chinese medicine (TCM), also known as Zhi Shi (枳实), are the immature and dried whole oranges from Citrus aurantium. Extracts of the same material or purified synephrine are also marketed in the US, sometimes in combination with caffeine, as a weight-loss-promoting dietary supplement for oral consumption. While the traditional preparations have been in use for millennia as a component of TCM-formulas, synephrine itself is not an approved over the counter drug. As a pharmaceutical, m-synephrine (phenylephrine) is still used as a sympathomimetic, mostly by injection for the treatment of emergencies such as shock, and rarely orally for the treatment of bronchial problems associated with asthma and hay-fever.
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(–)-Benzofuranylpropylaminopentane is an experimental drug related to selegiline which acts as a monoaminergic activity enhancer (MAE). It is orally active in animals.
Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the TAAR1 gene.
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o-Phenyl-3-iodotyramine (o-PIT) is a drug which acts as a selective agonist for the trace amine-associated receptor 1 (TAAR1). It has reasonable selectivity for TAAR1 but relatively low potency, and is rapidly metabolised in vivo, making it less useful for research than newer ligands such as RO5166017. Its EC50Tooltip half-maximal effective concentration values have been reported to be 35 nM for the mouse TAAR1, 2.4 nM at the rat TAAR1, and 9.5 nM at the human TAAR1.
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3-Methylphenethylamine (3MPEA) is an organic compound with the chemical formula of C9H13N. 3MPEA is a human trace amine associated receptor 1 (TAAR1) agonist, a property which it shares with its monomethylated phenethylamine isomers, such as amphetamine (α-methylphenethylamine), β-methylphenethylamine, and N-methylphenethylamine.
4-Methylphenethylamine (4MPEA), also known as para-methylphenethylamine, is an organic compound with the chemical formula of C9H13N. 4MPEA is a human trace amine associated receptor 1 (TAAR1) agonist, a property which it shares with its monomethylated phenethylamine isomers, such as amphetamine (α-methylphenethylamine), β-methylphenethylamine, and N-methylphenethylamine. 4MPEA also appears to inhibit the human cytochrome P450 enzymes CYP1A2 and CYP2A6, based upon the published literature.
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RO5256390 or RO-5256390 is a drug developed by Hoffmann-La Roche which acts as an agonist for the trace amine associated receptor 1 (TAAR1). It is a full agonist of the rat, cynomolgus monkey, and human TAAR1, but a partial agonist of the mouse TAAR1.
RO5263397, or RO-5263397, is a trace amine-associated receptor 1 (TAAR1) partial or full agonist which is used in scientific research. It is the most well-studied of all of the synthetic TAAR1 ligands. In addition to its use in research, RO5263397 is or was under development for potential clinical use as a medication.
RO5203648 is a trace amine-associated receptor 1 (TAAR1) partial agonist. It is a potent and highly selective partial agonist of both rodent and primate TAAR1. The drug suppresses the effects of psychostimulants like cocaine and methamphetamine. It also produces a variety of other behavioral effects, such as antidepressant-like, antipsychotic-like, and antiaddictive effects. Research with RO5203648 has led to interest in TAAR1 agonists for potential treatment of drug addiction. RO5203648 itself was not developed for potential medical use due to poor expected human pharmacokinetics.
RO5073012 is a selective low-efficacy partial agonist of the trace amine-associated receptor 1 (TAAR1) which has been used in scientific research. TAAR1 partial agonists like RO5073012 can have agonist- or antagonist-like effects at the TAAR1 depending on the context and level of TAAR1 signaling.
On the other hand, HTS approaches [100] followed by structure-activity optimization allowed for the discovery of the hTAAR1 antagonist RTI-7470-44, endowed with a species-specificity preference over mTAAR1 (Figure 11A) [99]. RTI-7470-44 displayed good blood–brain barrier permeability, moderate metabolic stability, and a favorable preliminary off-target profile. In addition, RTI-7470-44 increased the spontaneous firing rate of mouse ventral tegmental area (VTA) dopaminergic neurons and blocked the effects of the known TAAR1 agonist RO5166017. [...] Figure 11. (A) Chemical structures of the available hTAAR1 agonists: EPPTB [98], RTI-7470-44 [99], and 4c [33], [...] RTI-7470-44: hTAAR1 IC50 = 0.0084 μM, mTAAR1 IC50 = 1.190 μM.
Studies have shown that there are considerable functional and pharmacological differences between hTA1 and TA1 in rats (rTA1) or mice (mTA1)12, with key implications for translating findings from preclinical models into human therapies. For instance, TYR has been reported to be ~30 times more potent at rTA1 than hTA1, and the antagonist EPPTB was shown to have an affinity of ~1 nM at mTA1 but does not appear to bind hTA132. Inversely, the recently reported TA1 antagonist RTI-7470-44 has an IC50 of about 8 nM at hTA1 but shows ~90-fold and ~140-fold reduced potencies at rTA1 and mTA1, respectively33.
Similar to EPPTB, RTI-7470-44 could increase the spontaneous firing rate of dopaminergic neurons in mice VTA slices and prevent the effects of TAAR1 agonist RO5166017 (Decker et [...] Furthermore, RTI-7470-44 has appropriate properties for in vivo use, including favorable preliminary off-target profile, moderate metabolic stability, and good blood-brain barrier permeability [...] However, currently there is no behavioral study that investigated the effects of RTI-7470-44. Compared to the limited literature on TAAR1 antagonists, many TAAR1 agonists have been [...]