For research use only.

Catalog No.S2698 Synonyms: MT500

2 publications

RS-127445 Chemical Structure

Molecular Weight(MW): 281.33

RS-127445 is a selective 5-HT2B receptor antagonist with pKi of 9.5 and pIC50 of 10.4, exhibits >1000-fold selectivity against other 5-HT receptors.

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Biological Activity

Description RS-127445 is a selective 5-HT2B receptor antagonist with pKi of 9.5 and pIC50 of 10.4, exhibits >1000-fold selectivity against other 5-HT receptors.
5-HT2B [1] 5-HT2B [1]
10.4(pIC50) 9.5(pKi)
In vitro

RS-127445 is a novel high affinity, selective 5-HT2B receptor antagonist devoid of detectable intrinsic activity. RS-127445 is found to have nM affinity and 1000 fold selectivity for the 5-HT2B receptor. RS-127445 is thus among the highest affinity, most selective 5- HT2B receptor ligands. RS-127445 potently blocks the 5-HT evoked increase in inositol phosphate formation and blocks the 5-HT evoked increases in intracellular calcium concentrations with a potency 1000 times greater than that of yohimbine. [1]

In vivo RS-127445 is readily absorbed with no obvious dose or route-dependent limitations and rapidly absorbed following both oral and intraperitoneal administration with peak plasma concentrations being achieved within 15 min of dosing. RS-127445 concentration in the plasma are proportional to the administered dose. RS-127445 administrated at dose of 5 mg/kg with approximately 60% of an intraperitoneal dose and 14% of the oral dose is bioavailable. RS-127445 concentration in the plasma is predicted to fully saturate accessible 5-HT2B receptors can be readily achieved and maintained in the rat. RS-127445 administered at 1 to 10 mg/kg with oral significantly inhibits visceral hypersensitivity up to 35 to 74% provoked by restraint stress. Oral RS-127445 produces a significant suppression of TNBS-induced visceral hypersensitivity (15 to 62% inhibition at 3 to 30 mg/ kg), although RS-127445 has no significant effect on the visceral nociceptive threshold of native rats. RS-127445 administrated orally with 1 to 30 mg/kg also dose -dependently reduce the restraint stress-induced defecation in native and TNBS-treated rats. [2]. RS-127445 inhibits colonic motility and defecation. [3]


Kinase Assay:


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Radioligand binding:

The selectivity of RS-127445 for 5-HT2B receptors is examined by testing the compound for affinity at over 100 additional ion channel or receptor binding sites. CHO-K1 cells expressing human 5-HT2A, 5-HT2B or 5-HT2C receptors are harvested using 2 mM EDTA in phosphate buffered saline. Cell membranes are prepared by four cycles of homogenization and centrifugation (48,000×g for 15 min). Each assay is established so as to achieve steady state conditions and to optimize specific binding. For the 5-HT2A receptor, membranes from 1×106 cells are incubated with 0.2 nM [3 H]-ketanserin at 32 °C for 60 min. Nonspecific binding is determined using 10 μM methysergide. For the 5-HT2B receptor, membranes from 1.5×106 cells are incubated with 0.2 nM [3 H]-5-HT at 48 °C for 120 min. Nonspecific binding is determined using 10 μM 5-HT. For the 5-HT2Creceptor, membranes from 3×10 5 cells are incubated with 0.5 nM [3 H]-mesuler -gine at 32 °C for 60 min. Nonspecific binding is determined using 10μM methysergide. Assays are terminated by vacuum filtration through glass fibre filters(GF/B) which has been pretreated with 0.1% polyethyleneimine. Total and bound radioactivity is determined by liquid scintillation counting. Greater than 90% specific binding is achieved in each of these assays.
Cell Research:


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  • Cell lines: HEK-293 cells expressing the human 5-HT2B receptor
  • Concentrations: 10 μM
  • Incubation Time: 20 min
  • Method:

    RS-127445, vehicle or other antagonists are pre-incubated with 240 μl of HEK-293 cells expressing the human 5-HT2B receptor suspension at 37 °C for 20 min. HEK-293 cells are incubated with[3H]-myoinositol (1.67 μCi/ml) in 162 cm2 flasks overnight at 37 °C in an inositol free Ham's F12 medium containing 10% dialyzed foetal bovine serum. The cells are harvested, washed five times with phosphate bufffered saline and resuspended in inositol free Ham's F12 media at density of approximately 3×103 cells/ml. The reactions are initiated by addition of 5-HT. Sixty minutes later, the reactions are terminated by adding 50 μl of ice-cold 20% perchloric acid, chilled in an ice-water bath for 10 min and then neutralized with 160μl of 1 N KOH. Each sample is diluted with 2 ml of 50 mM Tris-HCl, pH 7.4 at room temperature. The aqueous portion (2.2 ml) is transferred onto Dowex AG1X8 columns (1 ml, 1 : 1, w/v) which has been washed with 5 ml of distilled water. The columns are then washed with 18 ml of distilled water and the inositol phosphates are eluted with 3 ml of 1 N HCl. The eluted radioactivity is determined by liquid scintillation spectroscopy using a Packard 1900CA analyzer. [1]

    (Only for Reference)
Animal Research:


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  • Animal Models: rats
  • Dosages: 5 mg/kg
  • Administration: Oral for 2.5 h ,intraperitoneal and intravenousroutes for 0.08 h
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 56 mg/mL (199.05 mM)
Ethanol 8 mg/mL (28.43 mM)
Water Insoluble

* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 281.33


CAS No. 199864-87-4
Storage powder
in solvent
Synonyms MT500
Smiles CC(C)C1=NC(=NC(=C1)C2=C3C=CC=CC3=C(F)C=C2)N

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID