(R)-Butaprost (free acid) is the free acid form of Butaprost, which is a structural analog of prostaglandin E2 (PGE2) with good selectivity for the EP2 receptor subtype. Butaprost is frequently used pharmacologically to define EP receptor expression profiles in various human and animal tissues and cells. Gardiner caused serious confusion about the structure of butaprost in 1986 when he reported that the butaprost epimer showing this selective activity was the C-16 (R)-epimer ( See Reference 2 and notes). To increase the binding affinity of (R)-butaprost to prostaglandin receptors, we removed the methyl ester of (R)-butaprost and re-established the native C-1 carboxylic acid. Prostaglandin free acids typically bind to their cognate receptors with 10 to 100 times the affinity of the corresponding ester analogues. The pharmacology of (R)-butaprost has not been carefully studied, but it is generally believed to be the less active C-16 epimer. (Note: In the 1986 Gardiner paper in the British Journal of Pharmacology, butaprost appears on page 46 as TR 4979. The structure drawn is incorrect because the authors use and refer to the more active C - 16 epimer, actually 16(S). The structure on page 46 shows the structure as 16(R). It was not until the late 1990s that careful studies in the United States and Japan correctly determined the actual structure of C-16 The type is 16(S) in the compound called butaprost.)

Physicochemical Properties

Molecular Formula	C23H38O5
Exact Mass	394.271
CAS #	215168-33-5
Related CAS #	(S)-Butaprost free acid;433219-55-7
PubChem CID	35021645
Appearance	Typically exists as solid at room temperature
Density	1.1±0.1 g/cm3
Boiling Point	565.7±50.0 °C at 760 mmHg
Flash Point	310.0±26.6 °C
Vapour Pressure	0.0±3.5 mmHg at 25°C
Index of Refraction	1.558
LogP	3.04
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	13
Heavy Atom Count	28
Complexity	537
Defined Atom Stereocenter Count	4
SMILES	CCCC1(CCC1)[C@@H](C/C=C/[C@@H]2[C@@H](CCCCCCC(=O)O)C(=O)C[C@H]2O)O
InChi Key	PAYNQYXOKJDXAV-NMXQQJQMSA-N
InChi Code	InChI=1S/C23H38O5/c1-2-13-23(14-8-15-23)21(26)11-7-10-18-17(19(24)16-20(18)25)9-5-3-4-6-12-22(27)28/h7,10,17-18,20-21,25-26H,2-6,8-9,11-16H2,1H3,(H,27,28)/b10-7+/t17-,18-,20-,21-/m1/s1
Chemical Name	7-[(1R,2R,3R)-3-hydroxy-2-[(E,4R)-4-hydroxy-4-(1-propylcyclobutyl)but-1-enyl]-5-oxocyclopentyl]heptanoic acid
Synonyms	(R)-Butaprost (free acid); 215168-33-5; 7-[(1R,2R,3R)-3-hydroxy-2-[(E,4R)-4-hydroxy-4-(1-propylcyclobutyl)but-1-enyl]-5-oxocyclopentyl]heptanoic acid; Cyclopentaneheptanoic acid,3-hydroxy-2-[(1E,4R)-4-hydroxy-4-(1-propylcyclobutyl)-1-butenyl]-5-oxo-,(1R,2R,3R)-; (R)-Butaprost, free acid; (S)-Butaprost (free acid); Butaprost free acid; Butaprost,free acid;
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

Targets	EP2 (prostaglandin E receptor)
ln Vitro	1. Prostaglandin E2 (PGE2) relaxes circular smooth muscle of the rabbit isolated jugular vein at very low concentrations (mean pIC50 against histamine-induced contraction = 9.34). This effect is not blocked by the EP1-receptor antagonist, AH 6809 (2 microM). 2. From a group of prostaglandin E analogues examined, 16,16-dimethyl PGE2, misoprostol, 11-deoxy PGE2-1-alcohol and 11-deoxy PGE1 were highly potent relaxant agents, whereas 17-phenyl-omega-trinor PGE2, MB 28767 and butaprost had low potency and sulprostone and oxoprostol were virtually inactive. 3. Comparison of the jugular vein data with published data for inhibitory agonist potencies on the cat trachea (EP2 preparation) and the field-stimulated guinea-pig vas deferens (EP3) indicates that the EP-receptor in the rabbit jugular vein is closest to the EP2 subtype. However, the correlation is not entirely convincing. For example, butaprost, 16,16-dimethyl PGE2 and 11-deoxy PGE1 are of similar potency on the cat trachea, whereas butaprost is about 300 times less potent than the other two analogues on the jugular vein. The existence of more than one EP2-receptor appears possible. 4. It was felt that the activity of butaprost required further investigation in view of the claim that it is a specific EP2-receptor agonist. We have shown that butaprost has very low inhibitory activity on the guinea-pig vas deferens, a very sensitive EP3-receptor containing preparation. However, on the chick ileum, the original EP3 preparation, butaprost showed potent contractile activity (pEC25 approximately 8.0).In addition, its maximum response was lower than that of PGE2; lower maxima were also found for sulprostone, MB 28767 and oxoprostol, but not for ICI 80205, 16,16-dimethyl PGE2 and 17-phenyl-omega-trinor PGE2. The maximal response to a combination of either sulprostone and butaprost or sulprostone and PGE2 was similar to that achieved by PGE2 alone. Analysis of the interaction between sulprostone and PGE2 appears to exclude a partial agonist action for sulprostone. Furthermore neither sulprostone nor butaprost appear to have inhibitory activity on the ileum. AH 6809 at 2 pM produced only a small shift of the PGE2 log concentration-response curve.5. It is likely that contraction of the longitudinal smooth muscle of the chick ileum is mediated by (at least) two EP-receptor subtypes; activation of only one receptor system does not induce the maximum response (i.e. the acetylcholine maximum) of the preparation. One receptor could be an EP3 subtype, at which sulprostone exerts a selective agonist action. The other receptor is unlikely to be an EP, subtype, because of the high agonist potency of butaprost, the low agonist potency of iloprost, and the low antagonist potency of AH 6809. An alternative hypothesis is that the chick ileum contains a novel EP-receptor subtype in addition to an EP3-receptor[1].
References	[1]. Lawrence, R.A., and Jones, R.L. Investigation of the prostaglandin E (EP-) receptor subtype mediating relaxation of the rabbit jugular vein. Br. J. Pharmacol. 1992, 105(4), 817-824. [2]. Gardiner, P.J. Characterization of prostanoid relaxant/inhibitory receptors (XyX) using a highly selective agonist, TR4979. Br. J. Pharmacol. 1986, 87(1), 45-56. [3]. Regan, J.W., Bailey, T.J., Pepperl, D.J., et al. Cloning of a novel human prostaglandin receptor with characteristics of the pharmacologically defined EP2 subtype. Mol. Pharmacol.1994, 46(2), 213-220.
Additional Infomation	(r)-butaprost (free acid) is a prostanoid.

Solubility Data

Solubility (In Vitro)

DMF: 25 mg/ml DMSO: 25 mg/ml Ethanol: 50 mg/ml PBS (pH 7.2): 0.1 mg/ml

Solubility (In Vivo)

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. Injection Formulations (e.g. IP/IV/IM/SC) 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). 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) Oral Formulations 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). 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 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.  (Please use freshly prepared in vivo formulations for optimal results.)