Reserpine is a naturally occurring indole alkaloid obtained historically from Rauwolfia species and used as an antihypertensive and adrenergic-neuron-blocking pharmaceutical ingredient. It is chemically classified as a yohimban alkaloid and is identified by CAS No. 50-55-5. PubChem and NIST confirm its molecular formula as C33H40N2O9 and molecular weight as approximately 608.69 g/mol.
Reserpine is a crystalline alkaloid that appears as a white to light-yellow crystalline powder. It is sensitive to light and should be handled under controlled storage conditions. Current commercial analytical material is available at HPLC purity above 98%.
Reserpine is a centrally and peripherally acting adrenergic uptake inhibitor. Its pharmacological activity is associated with depletion of catecholamines and other monoamines from storage vesicles in sympathetic nerve endings.
The substance has a complex stereochemically defined pentacyclic structure and is chemically represented by the molecular formula C33H40N2O9.
| Parameter | Value |
|---|---|
| Chemical Name | Reserpine |
| CAS Number | 50-55-5 |
| Molecular Formula | C33H40N2O9 |
| Molecular Weight | 608.69 g/mol |
| Chemical Class | Indole / yohimban alkaloid |
| Physical Form | Crystalline powder |
| Appearance | White to light-yellow to light-orange powder/crystal |
| Pharmacological Class | Adrenergic uptake inhibitor |
| Chiral Nature | Stereochemically defined |
| Specific Rotation | −172° to −182° (c=1, DMF) |
| Water Solubility | Very slightly soluble / practically insoluble |
| Storage | Cool, dark conditions; protect from light |
PubChem describes Reserpine as white or cream to slightly yellow crystals/crystalline powder, while TCI specifies a white to light-yellow to light-orange powder/crystal and a specific rotation of −172° to −182° under its stated conditions.
Reserpine has historically been used as an antihypertensive and sympatholytic pharmaceutical ingredient. Its mechanism involves inhibition of vesicular monoamine storage, resulting in depletion of norepinephrine and other monoamines from sympathetic nerve terminals.
It has also historically been used in combination antihypertensive preparations. Because its clinical use has declined substantially in favor of newer antihypertensive therapies, its regulatory and commercial status should be considered when positioning the API.
Reserpine has an established USP identity and analytical framework. The USP monograph includes UV identification, loss on drying and residue-on-ignition testing. The USP identification procedure compares the UV spectrum with USP Reserpine Reference Standard and specifies the absorptivity difference at approximately 268 nm.
Important analytical controls include:
Current TCI analytical material specifies minimum 98.0 area% HPLC purity and minimum 98.0% by nonaqueous titration.
Reserpine API manufacturing requires careful control of alkaloid identity, chromatographic purity, moisture, inorganic residue and stereochemical integrity. Because Reserpine is a complex natural-product-derived alkaloid, analytical characterization should combine chromatographic and spectroscopic techniques.
The USP monograph provides established numerical controls for loss on drying and residue on ignition, while commercial analytical specifications provide additional purity and physical-property information.
Reserpine should be packaged in well-closed, light-protective pharmaceutical containers. TCI recommends storage at room temperature in a cool, dark location below 15°C and under inert gas.
Typical Reserpine API documentation may include:
Reserpine is a well-characterized pharmaceutical alkaloid with established analytical identification and quality-control requirements. A suitable API quality program should control assay/purity, moisture, inorganic residue, stereochemical characteristics and chromatographic impurities.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | NLT 98.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Heavy Metals | NMT 20 ppm |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |
| Specific Rotation | −172° to −182° (c=1, DMF) — commercial reference specification |
| Melting Point | 150°C – 154°C |