MT1 (EC50 = 19 nM); MT2 (EC50 = 4.6 nM)
S22153 targets the melatonin MT1 and MT2 receptors, which are G protein-coupled receptors that mediate the effects of the pineal hormone melatonin. These receptors are involved in the regulation of circadian rhythms, sleep-wake cycles, and various neuroendocrine functions. S22153 is a potent antagonist at both receptor subtypes, with slightly higher potency at MT2 (EC50 = 4.6 nM) compared to MT1 (EC50 = 19 nM). By blocking these receptors, S22153 inhibits melatonin-induced signaling, making it a valuable tool for studying the physiological roles of melatonin and its receptors.

S22153 is a specific ligand of MT1 and MT2 melatonin receptor subtypes, which displayed both in vitro and in vivo antagonistic properties in rodents. S22153 antagonized the in vitro melatonin-induced potentiation of electrically evoked contractions of isolated rat tail arteries[1].

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In vitro, S22153 acts as a potent antagonist at melatonin receptors. It competes with melatonin for binding to MT1 and MT2 receptors, effectively blocking melatonin-induced activation of these receptors. In cell-based assays, S22153 can inhibit melatonin-mediated inhibition of adenylyl cyclase, a common downstream signaling pathway for MT1 and MT2 receptors. The compound's high potency (EC50 in the low nanomolar range) makes it a highly effective tool for studying melatonin receptor function in vitro. It has Ki values of 8.6 nM for MT1 and 8.0 nM for MT2.

S-22153 increases the circadian amplitude of both rhythms in mice exposed to continuous light, and it sets the temperature and activity cycles to roughly 24 hours [1].

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The ability of daily melatonin and the melatonin receptor antagonist, S22153, to entrain circadian system function was investigated in mice with atypical melatonin rhythm. B6D2F(1) mice were first synchronized to a LD 12:12 for approximately 2 wk, then exposed to continuous light (LL) until study completion. After 10-18 days of LL exposure, mice received daily subcutaneous (s.c.) melatonin at a dose of 0.1, 1 or 10 mg/kg/day (exp. 1) or daily intraperitoneal (i.p.) S22153 (20 mg/kg/day) with or without melatonin (1 mg/kg/day, exp. 2) at subjective zeitgeber time (ZT) 10 for 19 days. Then all the mice were exposed to LL for another 10 days. Spectral analysis showed that initial LL lengthened the period of both rhythms by approximately 1.5 hr as compared with LD 12:12. No entrainment of either rhythm was found in controls. Conversely, daily melatonin-only, S22153-only or their combination set the temperature and activity periods to approximately 24 hr and produced a significant increase of the circadian amplitude of both rhythms as compared with controls. However, after treatment withdrawal, the dominant period lengthened to approximately 25.5 hr in mice receiving either melatonin or S22153. On the contrary, the period remained close to 24 hr for the 10 days following withdrawal of combined S22153 and melatonin. Such sustained pharmacological resetting of circadian function could display therapeutic potential against external resynchronization resulting from defective photoperiodic entrainment[1].

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In vivo, S22153 has been used to investigate the role of melatonin receptors in circadian rhythm regulation. By blocking melatonin signaling, S22153 can disrupt the entrainment of circadian rhythms to light-dark cycles. In animal models, it has been shown to affect sleep-wake patterns and other melatonin-dependent physiological processes. The compound is a valuable tool for studying the chronobiological effects of melatonin and for understanding the mechanisms underlying circadian rhythm disorders. Its effects on circadian rhythm entrainment have been studied in mice exposed to constant light.

Non-cellular in vitro assays for S22153 involve receptor binding studies. A standard protocol uses membrane preparations from cells expressing recombinant human MT1 or MT2 receptors. The membranes are incubated with a radiolabeled ligand, such as [¹²⁵I]melatonin or [³H]melatonin, and varying concentrations of S22153. Non-specific binding is determined in the presence of an excess of unlabeled melatonin. After incubation, the reaction is terminated by rapid filtration, and the radioactivity bound to the membranes is measured. The Ki values are calculated from the competition curves using the Cheng-Prusoff equation.

Cellular assays for S22153 are performed using cell lines expressing melatonin receptors, such as CHO cells or HEK293 cells stably transfected with MT1 or MT2. Cells are pre-treated with S22153 at various concentrations and then stimulated with melatonin. The inhibition of melatonin-induced signaling is measured. For example, the inhibition of adenylyl cyclase can be assessed by measuring the levels of cAMP using a competitive ELISA or a homogeneous time-resolved fluorescence (HTRF) assay. The EC50 for antagonism is determined from the concentration-response curve.

Animal/Disease Models: 7weeks old male B6D2F1 mice, continuous light exposure for 10-18 days [1]
Doses: 20 mg/kg
Route of Administration: daily intraperitonealfor 19 days
Experimental Results: Temperature and activity cycles were set to approximately 24 hrs (hrs (hours)) and increased the circadian amplitude of both rhythms in mice exposed to continuous light.

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In vivo animal studies for S22153 are conducted in rodent models to study circadian rhythms. A typical protocol involves housing mice under a specific light-dark cycle (e.g., 12:12 h LD). S22153 is administered either orally (p.o.) or intraperitoneally (i.p.) at doses such as 10-50 mg/kg. The administration is typically given at a specific time relative to the light-dark cycle (e.g., at the onset of darkness). Locomotor activity is recorded using running wheels or infrared sensors to assess the circadian rhythm of activity. The phase shifts in the activity rhythm are analyzed to determine the effects of S22153 on circadian entrainment.

S22153 is a small molecule with a molecular weight of 247.36. It has a predicted density of 1.400 g/cm³. For in vivo studies, it is typically formulated in vehicles such as 10% DMSO, 40% PEG300, 5% Tween-80, and 45% saline, or similar aqueous solutions. Detailed pharmacokinetic parameters for S22153, such as half-life, bioavailability, and clearance, have not been fully reported in the available literature. However, its use in animal models suggests that it has sufficient bioavailability to exert its effects.

Detailed toxicological data for S22153 have not been extensively reported. As a research chemical, it is not intended for human use and is strictly for preclinical research purposes. Standard safety precautions should be followed when handling this compound, including the use of personal protective equipment. No specific toxicity data, such as LD50 values, are available in the provided literature.

[1]. Circadian rhythm entrainment with melatonin, melatonin receptor antagonist S22153 or their combination in mice exposed to constant light. J Pineal Res. 2004;37(3):176-184.

[2]. New selective ligands of human cloned melatonin MT1 and MT2 receptors. Naunyn Schmiedebergs Arch Pharmacol. 2003;367(6):553-561.

Melatonin plays a crucial role in the circadian rhythm of signal transmission to peripheral organs. It exerts its diverse functions primarily through two seven-transmembrane G protein-coupled receptors (MT1 and MT2 receptors). This study pharmacologically characterized human cloned melatonin hMT1 and hMT2 receptors stably expressed in HEK-293 or CHO cells using the 2-[125I]-iodine-melatonin binding assay and the [35S]-GTPγS functional assay. Reference compounds and novel ligands with diverse chemical structures were evaluated. Results showed that the binding affinity of each receptor was comparable on the HEK-293 or CHO cell membrane. Novel non-selective or selective hMT1 and hMT2 ligands were described. The [35S]-GTPγS functional assay was used to determine the functional activities of these compounds, including partial agonist, full agonist, and/or antagonist activities. None of the compounds exhibited inverse agonist activity. We report novel selective antagonists, such as S 25567 and S 26131 for the MT1 receptor and S 24601 for the MT2 receptor. These studies also lead to other new molecular tools, such as the selective MT1 receptor agonist S 24268 and the non-selective antagonist S 22153. Finally, we also discovered S 25150, the most potent melatonin receptor agonist reported to date. [2]

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S22153 is a valuable pharmacological tool for studying the role of melatonin receptors in circadian rhythm regulation and sleep biology. It has been used in research to investigate the physiological roles of melatonin in neuroendocrine regulation, sleep biology, and mood disorders. The compound's activity provides insights into receptor-mediated chronobiology and the therapeutic potential of targeting melatonin receptors. S22153 is not a clinically approved drug and has not entered clinical trials. Its primary application is in academic and pharmaceutical research.

C14H17NOS

247.35588

247.103

C, 67.98; H, 6.93; N, 5.66; O, 6.47; S, 12.96

180304-07-8

9816339

White to off-white solid powder

3.982

1

2

4

17

269

0

CCC1=CC2=C(C=C1)SC=C2CCNC(=O)C

PICRXJDULXLJCZ-UHFFFAOYSA-N

InChI=1S/C14H17NOS/c1-3-11-4-5-14-13(8-11)12(9-17-14)6-7-15-10(2)16/h4-5,8-9H,3,6-7H2,1-2H3,(H,15,16)

N-[2-(5-ethyl-1-benzothiophen-3-yl)ethyl]acetamide

N-[2-(5-ethyl-1-benzothiophen-3-yl)ethyl]acetamide; S-22153; N-(2-(5-ethylbenzo[b]thiophen-3-yl)ethyl)acetamide; starbld0003449;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)