Abstract
Agonism of the 5-HT2C receptor represents one of the most well-studied and clinically proven mechanisms for pharmacological weight reduction. Selectivity over the closely related 5-HT2A and 5-HT2B receptors is critical as their activation has been shown to lead to undesirable side effects and major safety concerns. In this communication, we report the development of a new screening paradigm that utilizes an active site mutant D134A (D3.32) 5-HT2C receptor to identify atypical agonist structures. We additionally report the discovery and optimization of a novel class of nonbasic heterocyclic amide agonists of 5-HT2C. SAR investigations around the screening hits provided a diverse set of potent agonists at 5-HT2C with high selectivity over the related 5-HT2A and 5-HT2B receptor subtypes. Further optimization through replacement of the amide with a variety of five- and six-membered heterocycles led to the identification of 6-(1-ethyl-3-(quinolin-8-yl)-1H-pyrazol-5-yl)pyridazin-3-amine (69). Oral administration of 69 to rats reduced food intake in an ad libitum feeding model, which could be completely reversed by a selective 5-HT2C antagonist.
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
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ATP Binding Cassette Transporter, Subfamily G, Member 2 / genetics
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Animals
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Arginine / analogs & derivatives*
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Arginine / chemical synthesis
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Arginine / chemistry
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Arginine / pharmacology
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Brain / metabolism
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Caco-2 Cells
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Cell Membrane Permeability
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Feeding Behavior / drug effects
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Flavones / chemical synthesis
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Flavones / chemistry*
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Flavones / pharmacology
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HEK293 Cells
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Humans
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Male
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Membranes, Artificial
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Mice, Knockout
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Microsomes, Liver / metabolism
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Mutation
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Rats, Sprague-Dawley
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Receptor, Serotonin, 5-HT2A / metabolism
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Receptor, Serotonin, 5-HT2B / metabolism
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Receptor, Serotonin, 5-HT2C / genetics
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Receptor, Serotonin, 5-HT2C / metabolism*
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Serotonin 5-HT2 Receptor Agonists / chemical synthesis
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Serotonin 5-HT2 Receptor Agonists / chemistry*
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Serotonin 5-HT2 Receptor Agonists / pharmacokinetics
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Serotonin 5-HT2 Receptor Agonists / pharmacology
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Structure-Activity Relationship
Substances
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ATP Binding Cassette Transporter, Subfamily B, Member 1
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ATP Binding Cassette Transporter, Subfamily G, Member 2
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Abcg2 protein, mouse
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Flavones
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Membranes, Artificial
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Receptor, Serotonin, 5-HT2A
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Receptor, Serotonin, 5-HT2B
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Receptor, Serotonin, 5-HT2C
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Serotonin 5-HT2 Receptor Agonists
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methyl (2-((7-((7-guanidino-4-(methoxyamino)-2,3-dioxoheptyl)oxy)-5-hydroxy-2-(4-methoxyphenyl)-8-(3-methylbut-2-en-1-yl)-4-oxo-4H-chromen-3-yl)oxy)acetyl)argininate
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Arginine