Yohimbine is a naturally occurring indole alkaloid belonging to the yohimbine alkaloid family. It is chemically identified as a stereochemically defined pentacyclic indole alkaloid and is associated with alpha-2 adrenergic receptor antagonist activity. Yohimbine has been studied and used in pharmaceutical and pharmacological applications, particularly in areas involving adrenergic receptor modulation.
Yohimbine is chemically distinct from Yohimbine Hydrochloride. The free-base compound has CAS Number 146-48-5, molecular formula C21H26N2O3, and molecular weight 354.44 g/mol. Yohimbine Hydrochloride, in comparison, has CAS Number 65-19-0 and molecular weight approximately 390.90 g/mol. These substances should therefore be specified and documented separately during API procurement and quality control.
Yohimbine is an indole alkaloid with a complex polycyclic molecular structure containing nitrogen atoms, an ester group and a hydroxyl group. PubChem identifies the compound as an indole alkaloid and provides the molecular formula C21H26N2O3 and molecular weight 354.4 g/mol. NIST reports a molecular weight of 354.4427 and CAS Registry Number 146-48-5.
The compound is also known by several historical and chemical synonyms, including Yohimbin, Quebrachine, Corynine, Aphrodine and Yohimbic acid methyl ester. The IUPAC name listed by PubChem is methyl (1S,15R,18S,19R,20S)-18-hydroxy-1,3,11,12,14,15,16,17,18,19,20,21-dodecahydroyohimban-19-carboxylate.
Yohimbine is primarily recognized as an alpha-2 adrenergic receptor antagonist. By antagonizing alpha-2 adrenergic receptors, it can influence noradrenergic signaling. PubChem and ChEBI also record additional receptor-related activities, including alpha-adrenergic antagonist, dopamine D2 antagonist and serotonergic antagonist activity.
Its pharmacological profile has resulted in research and therapeutic interest in several areas involving adrenergic function. Yohimbine has historically been associated with the management of erectile dysfunction and has also been investigated as a pharmacological research compound for studying adrenergic receptor mechanisms.
Yohimbine is a naturally occurring alkaloid associated with plants of the genus Pausinystalia, particularly Pausinystalia johimbe, commonly known as the yohimbe tree. It has also been reported in other plant sources, including species of Rauwolfia. PubChem identifies Yohimbine as an indole alkaloid produced by Corynanthe johimbe and Rauwolfia serpentina.
Because naturally derived material can contain multiple alkaloids and related constituents, pharmaceutical-grade Yohimbine requires appropriate purification and analytical characterization to establish chemical identity and control related substances.
Yohimbine has been used historically in pharmaceutical preparations and has significant importance as a pharmacological research compound. Its alpha-2 adrenergic receptor antagonism makes it useful for studying adrenergic signaling and receptor-mediated physiological responses.
Yohimbine has been associated with pharmaceutical applications involving erectile dysfunction and has historically been used as a mydriatic. NCBI's LiverTox identifies Yohimbine as a generic drug substance and lists its chemical identity as CAS 146-48-5 with molecular formula C21H26N2O3.
For API manufacturers and pharmaceutical developers, Yohimbine can therefore be considered a specialized natural-product-derived active ingredient with applications dependent on the applicable regulatory framework and intended formulation.
Quality control of Yohimbine API requires confirmation of identity, assay, purity, stereochemical characteristics and control of related substances. Because Yohimbine is a structurally complex natural alkaloid, analytical characterization is particularly important for distinguishing the desired compound from structurally related yohimbine-type alkaloids.
Potential analytical approaches for Yohimbine may include chromatographic purity testing, spectroscopic identification, optical rotation and other validated analytical procedures. The precise acceptance criteria should be established according to the applicable product specification, regulatory filing and intended pharmaceutical use.
A key point for API documentation is that Yohimbine free base and Yohimbine Hydrochloride should not be treated as interchangeable specifications. Public pharmacopoeial material identified during research specifically covers Yohimbine Hydrochloride, including USP and Ph. Eur. monograph information. The free base has CAS 146-48-5, while the hydrochloride salt has CAS 65-19-0.
For the free-base Yohimbine API, a universal current BP/Ph. Eur. numerical assay specification was not identified in the public sources reviewed. Therefore, an invented 98%, 99% or 99.5% pharmacopoeial assay range should not be presented as an official universal specification for Yohimbine free base.
Commercial analytical materials can report high-purity Yohimbine, but these values are product-specific. For example, supplier specifications for Yohimbine Hydrochloride report HPLC purity values above 99%, but these results apply to the hydrochloride salt rather than free-base Yohimbine.
For a pharmaceutical API page, the appropriate approach is therefore to identify the substance correctly and state Product-Specific Specification where a universally applicable numerical release limit could not be verified.
Related-substance control is particularly relevant for Yohimbine because naturally occurring yohimbine-type alkaloids can have closely related structures. The pharmacopoeial Yohimbine Hydrochloride monograph identifies several specified and other detectable impurities, including alpha-yohimbine, beta-yohimbine, corynantheine and pseudo-yohimbine. These impurity requirements should not automatically be transferred to the free-base API without confirmation that the same monograph and specification apply.
For Yohimbine free base, chromatographic methods such as HPLC may be used to establish identity and purity, with method parameters and acceptance criteria defined in the applicable validated specification.
Yohimbine is a stereochemically defined natural alkaloid, making optical rotation a potentially useful characterization parameter. However, the well-established numerical value +100° to +105° found in the USP and Ph. Eur. material applies to Yohimbine Hydrochloride, measured as a specified test solution.
Because the requested product is Yohimbine free base, that hydrochloride-specific numerical range is not inserted into the free-base API specification table.
Yohimbine is a crystalline alkaloid and is normally handled as a solid chemical substance. Its physicochemical behavior differs from its hydrochloride salt because salt formation changes molecular weight, ionization and aqueous solubility.
For this reason, solubility data should be stated against the exact form of the API being supplied. Yohimbine Hydrochloride is reported as soluble in hot water by several commercial specifications, but this should not be represented as a free-base Yohimbine solubility specification.
Yohimbine API requires controlled sourcing, identification and analytical testing before incorporation into pharmaceutical products. Important quality attributes include chemical identity, assay, chromatographic purity, related substances, moisture or loss on drying where applicable, elemental impurities and physical characteristics.
For pharmaceutical manufacturing, the certificate of analysis should correspond specifically to Yohimbine free base, CAS 146-48-5, rather than Yohimbine Hydrochloride. This distinction is important for accurate material identification, specification management and regulatory documentation.
Storage conditions should be established according to the manufacturer's validated stability data and applicable product specification. Pharmaceutical-grade material should be protected from inappropriate environmental exposure and maintained in suitable, controlled packaging.
The exact storage condition should be confirmed against the supplier's current certificate of analysis, technical specification and stability documentation rather than applying hydrochloride-specific storage information to the free base.
Yohimbine is a specialized indole alkaloid API with established pharmacological relevance and a well-defined chemical identity. With CAS Number 146-48-5, molecular formula C21H26N2O3 and molecular weight 354.44 g/mol, it can be characterized using appropriate chromatographic, spectroscopic and physicochemical analytical techniques.
For pharmaceutical companies, formulation developers and API procurement teams, Yohimbine should be evaluated according to the exact chemical form, analytical purity, impurity profile, documentation and regulatory requirements applicable to the intended market.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |