ONO-2952 is a potent, selective, orally bioactive translocation protein 18 kDa (TSPO) antagonist (inhibitor) with Kis of 0.330-9.30 nM for rat and human TSPO. ONO-2952 is selective for TSPO compared to other receptors, transporters, ion channels and enzymes. ONO-2952 exerts its anti-stress effects by inhibiting excessive activation of the noradrenergic system in the brain without erasing memory. ONO-2952 is indicated for irritable bowel syndrome.

Physicochemical Properties

Molecular Formula	C22H20CLFN2O2
Molecular Weight	398.86
Exact Mass	398.119
CAS #	895169-20-7
Related CAS #	(R)-ONO-2952
PubChem CID	11524127
Appearance	White to off-white solid powder
Density	1.4±0.1 g/cm3
Boiling Point	609.4±55.0 °C at 760 mmHg
Flash Point	322.3±31.5 °C
Vapour Pressure	0.0±1.7 mmHg at 25°C
Index of Refraction	1.682
LogP	4.15
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	2
Heavy Atom Count	28
Complexity	630
Defined Atom Stereocenter Count	1
SMILES	CC(=O)N1CC2(CC2)C3=C([C@@H]1C4=C(C=C(C=C4)Cl)OC)NC5=C3C(=CC=C5)F
InChi Key	ZBQMTQGDBFZUBG-NRFANRHFSA-N
InChi Code	InChI=1S/C22H20ClFN2O2/c1-12(27)26-11-22(8-9-22)19-18-15(24)4-3-5-16(18)25-20(19)21(26)14-7-6-13(23)10-17(14)28-2/h3-7,10,21,25H,8-9,11H2,1-2H3/t21-/m0/s1
Chemical Name	1-[(1S)-1-(4-chloro-2-methoxyphenyl)-5-fluorospiro[3,9-dihydro-1H-pyrido[3,4-b]indole-4,1'-cyclopropane]-2-yl]ethanone
Synonyms	ONO 2952; ONO2952; ONO-2952
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	Regarding TSPO selectivity, ONO-2952 demonstrated high TSPO selectivity versus 98 off-targets (<50% inhibition) at a dose of 10 μM. Only three receptors (melatonin 2, progesterone B, and epinephrine α2C) exhibited Ki values less than 1 μM, according to the determination of ONO-2952 Ki or IC50 values (50% inhibition at 10 μM) for the remaining 35 targets. Compared to TSPO, ONO-2952's affinity for these receptors is at least 59 times lower. Compared to TSPO, the ONO-2952 GABAA receptor has a Ki value that is more than 600 times greater [1].
ln Vivo	In rats with more than 50% brain TSPO occupancy, treatment with ONO-2952 (0.03-3 mg/kg; oral; male Sprague Dawley rats) dose-dependently reduces the defecation produced by restraint stress. Additionally, ONO-2952 can prevent rats from freezing when they experience conditioned fear stress [1]. In the brains of acutely stressed rats, ONO-2952 blocks the release of norepinephrine and the buildup of neurosteroids [1].
Animal Protocol	Animal/Disease Models: Male Sprague Dawley rats (8 weeks old) conditioned fear stress test [1] Doses: 0.03 mg/kg, 0.1 mg/kg, 0.3 mg/kg, 1 mg/kg, 3 mg/kg Route of Administration: Orally Experimental Results:Dose-dependent inhibition of restraint stress-induced defecation in rats. And inhibits freezing behavior in rats induced by conditioned fear stress.
References	[1]. Anti-stress effects of ONO-2952, a novel translocator protein 18 kDa antagonist, in rats. Neuropharmacology. 2015 Dec;99:51-66. [2]. Randomised clinical trial: exploratory phase 2 study of ONO-2952 in diarrhoea-predominant irritable bowel syndrome. Aliment Pharmacol Ther. 2017 Jan;45(1):14-26.
Additional Infomation	ONO-2952 is under investigation in clinical trial NCT01887002 (Study to Evaluate the Effects of ONO-2952 on Pain Perception Produced by Rectal Distention in Female Subjects With Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)).

Solubility Data

Solubility (In Vitro)

DMSO : ~180 mg/mL (~451.29 mM)

Solubility (In Vivo)

Solubility in Formulation 1: 4.5 mg/mL (11.28 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 45.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 4.5 mg/mL (11.28 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 45.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.5071 mL	12.5357 mL	25.0715 mL
	5 mM	0.5014 mL	2.5071 mL	5.0143 mL
	10 mM	0.2507 mL	1.2536 mL	2.5071 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.