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Rauwolscine hydrochloride

Alias: Rauwolscine hydrochloride; 6211-32-1; alpha-Yohimbine hydrochloride; Rauwolscine HCl; PQ323MIB24; Fauwolscine, hydrochloride; Methyl (16beta,17alpha,20alpha)-17-hydroxyyohimban-16-carboxylate hydrochloride; Rauwolscine (hydrochloride);
Cat No.:V5725 Purity: ≥98%
Rauwolscine HCl is a potent and specific α2 adrenergic receptor blocker (antagonist) with Ki of 12 nM.
Rauwolscine hydrochloride
Rauwolscine hydrochloride Chemical Structure CAS No.: 6211-32-1
Product category: New1
This product is for research use only, not for human use. We do not sell to patients.
Size Price Stock Qty
50mg
100mg
Other Sizes

Other Forms of Rauwolscine hydrochloride:

  • Yohimbine HCl
  • Rauwolscine (α-Yohimbine; Corynanthidine; Isoyohimbine)
Official Supplier of:
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Product Description
Rauwolscine HCl is a potent and specific α2 adrenergic receptor blocker (antagonist) with Ki of 12 nM.
Biological Activity I Assay Protocols (From Reference)
Targets
α2-adrenoceptor
ln Vitro
[3H]Rauwolscine binds reversibly, stereospecifically, and saturably to α2-adrenergic receptors. In the meninges, tauwolscine [3H] selectively identifies the high-affinity and low-affinity states of α2-adrenergic receptors [1]. In accordance with previous functional investigations demonstrating that yohimbine and rauwolscine have agonistic qualities at the 5-HT autoreceptor level, [3H]rauwolscine also functions as a 5-HT1A receptor agonist [2]. Raufulin was found to have a reasonably high affinity for human receptors (Ki human = 14.3nM, Ki rat = 35.8nM) when [3H]5-HT was used as the radioligand [3]. The affinity of [3H]Rauwolscine is comparable in mice, rats, rabbits, and dogs (2.33-3.03 nM), according to saturation experiments, but it is noticeably higher in humans (0.98 nM) [4].
ln Vivo
Binding of the alpha 2-adrenoceptor antagonist [3H]-rauwolscine was characterized in membrane preparations from the kidneys of mouse, rat, rabbit, dog, and man. In all species, binding reached equilibrium within 45 min and dissociated at a single exponential rate after addition of phentolamine 10 microM. Saturation studies showed that the affinity of [3H]-rauwolscine was similar in all species (2.33-3.03 nM) except man where it was significantly higher (0.98 nM). Marked differences were seen in the density of binding sites, increasing in the order: man less than dog less than rabbit less than rat less than mouse. In all cases, Hill coefficients were not significantly different from unity. [3H]-rauwolscine binds with low affinity (KD greater than 15 nM) to membranes prepared from guinea-pig kidney. The low affinity binding is not due to the absence of particular ions in the incubation medium or to receptor occupation by endogenous agonist. The binding in all species was found to be stereoselective with respect to the isomers of noradrenaline. However, differences were seen in the characteristics of agonist interactions with the binding site both between isomers and between species. Marked differences in affinity of particular alpha-adrenoceptor antagonists were observed for alpha 2-adrenoceptors labelled by [3H]-rauwolscine. These differences were most evident with the alpha 1-adrenoceptor selective antagonist prazosin which displayed inhibition constants (Ki values) of 33.2, 39.5, 261, 570 and 595 nM in rat, mouse, dog, man and rabbit, respectively. Differences are apparent in the characteristics of alpha 2-adrenoceptors labelled by [3H]-rauwolscine between species and it is suggested that the differences observed for alpha 1-selective antagonists such as prazosin may be related to binding to additional sites in the vicinity of the alpha 2-adrenoceptor[4].
Enzyme Assay
[3H]Rauwolscine, a specific and potent alpha 2-antagonist radioligand, was used to characterize alpha 2-receptor binding in bovine cerebral cortex. [3H]Rauwolscine binding was reversible, stereospecific, and saturable. Association, dissociation, and saturation studies revealed one site interactions (k -1/k+1 = 1.2 nM, KD = 2.5 nM, Bmax = 160 fmol/mg protein) and competition studies indicated that [3H]rauwolscine labeled the alpha 2-receptor. Agonists inhibited [3H]rauwolscine binding in a shallow, GTP-sensitive manner. These results suggest that [3H]rauwolscine specifically labels both the high and low affinity states of the alpha 2-receptor in brain membranes[1].
In previous reports, [3H]5-HT has been used to characterize the pharmacology of the rat and human 5-HT2B receptors. 5-HT, the native agonist for the 5-HT2B receptor, has a limitation in its usefulness as a radioligand since it is difficult to study the agonist low-affinity state of a G protein-coupled receptor using an agonist radioligand. When using [3H]5-HT as a radioligand, rauwolscine was determined to have relatively high affinity for the human receptor (Ki human = 14.3+/-1.2 nM, compared to Ki rat = 35.8+/-3.8 nM). Since no known high affinity antagonist was available as a radioligand, these studies were performed to characterize [3H]rauwolscine as a radioligand for the cloned human 5-HT2B receptor expressed in AV12 cells. When [3H]rauwolscine was initially tested for its usefulness as a radioligand, complex competition curves were obtained. After testing several alpha2-adrenergic ligands, it was determined that there was a component of [3H]rauwolscine binding in the AV12 cell that was due to the presence of an endogenous alpha2-adrenergic receptor. The alpha2-adrenergic ligand efaroxan was found to block [3H]rauwolscine binding to the alpha2-adrenergic receptor without significantly affecting binding to the 5-HT2B receptor and was therefore included in all subsequent studies. In saturation studies at 37 degrees C, [3H]rauwolscine labeled a single population of binding sites, Kd = 3.75+/-0.23 nM. In simultaneous experiments using identical tissue samples, [3H]rauwolscine labeled 783+/-10 fmol of 5-HT2B receptors/mg of protein, as compared to 733+/-14 fmol of 5-HT2B receptors/mg of protein for [3H]5-HT binding. At 0 degrees C, where the conditions for [3H]5-HT binding should label mostly the agonist high affinity state of the human 5-HT2B receptor, [3H]rauwolscine (Bmax = 951+/-136 fmol/mg), again labeled significantly more receptors than [3H]5-HT (Bmax = 615+/-34 fmol/mg). The affinity of [3H]rauwolscine for the human 5-HT2B receptor at 0 degrees C did not change, Kd = 4.93+/-1.27 nM, while that for [3H]5-HT increased greatly (Kd at 37 degrees C = 7.76+/-1.06 nM; Kd at 0 degrees C = 0.0735+/-0.0081 nM). When using [3H]rauwolscine as the radioligand, competition curves for antagonist structures modeled to a single binding site, while agonist competition typically resulted in curves that best fit a two site binding model. In addition, many of the compounds with antagonist structures displayed higher affinity for the 5-HT2B receptor when [3H]rauwolscine was the radioligand. Typically, approximately 85% of [3H]rauwolscine binding was specific binding. These studies display the usefulness of [3H]rauwolscine as an antagonist radioligand for the cloned human 5-HT2B receptor. This should provide a good tool for the study of both the agonist high- and low-affinity states of the human cloned 5-HT2B receptor[2].
Cell Assay
The alpha 2 adrenergic antagonist [3H]rauwolscine binds with comparable nanomolar affinity to alpha 2 adrenoceptors and the nonadrenergic 5-HT1A receptors sites in human frontal cortex membranes. Addition of 0.5 mM GTP into the incubation medium produces a significant decrease in the amount of [3H]rauwolscine binding sites (Bmax = 230 +/- 16 and 115 +/- 11 fmol/mg protein in the absence and presence of GTP, respectively). The affinity for [3H]rauwolscine remains unchanged (i.e. KD = 40 +/- 0.9 nM and 4.1 +/- 1 nM). This effect of GTP can be attributed to decreased binding of the radioligand to the 5-HT1A receptors. GTP decreases binding of [3H]rauwolscine to nearly the same level as the one corresponding to the alpha 2 adrenoceptors in membranes from both the human frontal cortex and hippocampus. The venom of the marine cone snail, Conus tessulatus, preferentially inhibits [3H]rauwolscine binding to 5-HT1A receptors as compared with the alpha 2 adrenoceptors. Following complete masking of the 5-HT1A receptors by this venom. GTP no longer affects the saturation binding characteristics of [3H]rauwolscine for the remaining alpha 2 adrenoceptors. Nucleotides decrease the binding of [3H]rauwolscine to the 5-HT1A receptors with an order of potencies (i.e. GTP gamma S greater than GPP(NH)P much greater than GDP greater than GTP much greater than ATP) that is typical for nucleotide-mediated receptor-G protein dissociation. This suggests that [3H]rauwolscine is a 5-HT1A receptor agonist and this conclusion is compatible with earlier functional studies, indicating that rauwolscine (as well as yohimbine) has agonistic properties at the level of 5-HT autoreceptors[2].
Animal Protocol
The alpha 2 agonist clonidine has been shown to be anxiolytic in a number of preclinical anxiety models. Interestingly, intravenous infusion of the alpha 2 antagonists idazoxan at 10 mg/kg and rauwolscine at 2.24 mg/kg significantly disinhibited lick-shock conflict responding in rats similar to the alpha 2 agonist clonidine (0.022 mg/kg) and the benzodiazepine diazepam (0.5 mg/kg). However, the alpha 2 antagonists yohimbine and piperoxan, the alpha 2 agonists medetomidine, guanfacine, and guanabenz, the non-specific alpha antagonist phentolamine, and the alpha 1 antagonist prazosin did not disinhibit conflict responding in the Vogel lick-shock paradigm. In fact, yohimbine has been shown to be anxiogenic in both animals and man. This may be due to yohimbine's lack of specificity and its ability to inhibit GABAergic release. In addition, all of these agents, except idazoxan, did not increase water consumption in water deprived rats. Idazoxan (10 mg/kg) significantly decreased water consumption by 45%. Therefore, idazoxan increased conflict responding for water reward at a dose (10 mg/kg) which also decreased water consumption in a non-conflict paradigm. These data suggest that agents with selective antagonism at the alpha 2 receptor site may be anxiolytic while agents with less specificity at this site such as yohimbine, piperoxan, and phentolamine are not anxiolytic.Life Sci . 1994;54(10):PL179-84. doi: 10.1016/0024-3205(94)00556-7.
Toxicity/Toxicokinetics
mouse LDLo oral 125 mg/kg
References

[1]. [3H]rauwolscine (alpha-yohimbine): a specific antagonist radioligand for brain alpha 2-adrenergic receptors. Eur J Pharmacol. 1981 Dec 17;76(4):461-4.

[2]. [3H]rauwolscine behaves as an agonist for the 5-HT1A receptors in human frontal cortex membranes. Eur J Pharmacol. 1991 May 25;207(1):1-8.

[3]. [3H]Rauwolscine: an antagonist radioligand for the cloned human 5-hydroxytryptamine2b (5-HT2B) receptor. Naunyn Schmiedebergs Arch Pharmacol. 1998 Jan;357(1):17-24.

[4]. [3H]-rauwolscine binding to alpha 2-adrenoceptors in the mammalian kidney: apparent receptor heterogeneity between species. Br J Pharmacol. 1985 Jun;85(2):349-59.

These protocols are for reference only. InvivoChem does not independently validate these methods.
Physicochemical Properties
Molecular Formula
C21H26N2O3.CLH
Molecular Weight
390.90400
Exact Mass
390.171
Elemental Analysis
C, 64.52; H, 6.96; Cl, 9.07; N, 7.17; O, 12.28
CAS #
6211-32-1
Related CAS #
Yohimbine Hydrochloride;65-19-0;Rauwolscine;131-03-3; 6211-32-1 (HCl); 28834-05-1 (phosphate)
PubChem CID
197067
Appearance
White to off-white solid powder
Density
1.31 g/cm3
Boiling Point
543ºC at 760 mmHg
Melting Point
270-280ºC
Flash Point
282.2ºC
LogP
3.387
Hydrogen Bond Donor Count
3
Hydrogen Bond Acceptor Count
4
Rotatable Bond Count
2
Heavy Atom Count
27
Complexity
555
Defined Atom Stereocenter Count
5
InChi Key
PIPZGJSEDRMUAW-ZKKXXTDSSA-N
InChi Code
InChI=1S/C21H26N2O3.ClH/c1-26-21(25)19-15-10-17-20-14(13-4-2-3-5-16(13)22-20)8-9-23(17)11-12(15)6-7-18(19)24;/h2-5,12,15,17-19,22,24H,6-11H2,1H3;1H/t12-,15+,17+,18+,19+;/m1./s1
Chemical Name
methyl (1S,15S,18S,19S,20S)-18-hydroxy-1,3,11,12,14,15,16,17,18,19,20,21-dodecahydroyohimban-19-carboxylate;hydrochloride
Synonyms
Rauwolscine hydrochloride; 6211-32-1; alpha-Yohimbine hydrochloride; Rauwolscine HCl; PQ323MIB24; Fauwolscine, hydrochloride; Methyl (16beta,17alpha,20alpha)-17-hydroxyyohimban-16-carboxylate hydrochloride; Rauwolscine (hydrochloride);
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

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.
Shipping Condition
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
Solubility Data
Solubility (In Vitro)
DMSO : ~12.5 mg/mL (~31.98 mM)
H2O : ~5 mg/mL (~12.79 mM)
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 : PEG300Tween 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 : PEG300Tween 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).
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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


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.)
Preparing Stock Solutions 1 mg 5 mg 10 mg
1 mM 2.5582 mL 12.7910 mL 25.5820 mL
5 mM 0.5116 mL 2.5582 mL 5.1164 mL
10 mM 0.2558 mL 1.2791 mL 2.5582 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.

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In vivo Formulation Calculator (Clear solution)
Step 1: Enter information below (Recommended: An additional animal to make allowance for loss during the experiment)
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Working concentration mg/mL;

Method for preparing DMSO stock solution mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.

Method for preparing in vivo formulation:Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O,mix and clarify.

(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
             (2) Be sure to add the solvent(s) in order.

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