Ornipressin Acetate | CAS 3397-23-7 / 914453-98-8 | Vasopressin V1 Receptor Agonist (Research Use Only) | Knowlux

Product Description

Ornipressin Acetate, CAS 3397-23-7 (free peptide basis) / 914453-98-8 (acetate salt), is a synthetic cyclic nonapeptide analogue of vasopressin in which the arginine residue at position 8 is replaced by ornithine, supplied by Knowlux for laboratory research use. The sequence is H-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Orn-Gly-NH2, with a disulfide bridge between Cys1 and Cys6. The molecular formula is C45H63N13O12S2 and the molecular weight is 1042.19 g/mol (free peptide basis). Each lot is released with a lot-specific COA, MSDS and analytical traceability.

CAS and Salt Form Clarification: CAS 3397-23-7 is the identifier most widely applied to Ornipressin across ChemicalBook, MedChemExpress, GLPBIO, and Biorbyt, and is frequently used for both the free peptide and the acetate salt in supplier catalogues. The acetate salt is separately registered under CAS 914453-98-8, and this registry is the more precise identifier when the counter-ion basis must be documented explicitly. A Biosynth Certificate of Analysis for CAS 914453-98-8 lists the chemical formula as C46H63N13O12S2.xC2H4O2 with a molecular weight of 1042.19 on a free-acid basis, consistent with the free peptide assignment. Some supplier listings under CAS 914453-98-8 show molecular weights in the 1100 range (e.g., TargetMol lists 1102.25 with formula C47H67N13O12S2); this apparent discrepancy reflects the inclusion of acetate counter-ions and possibly hydration, and should be reconciled against the lot-specific COA rather than treated as a conflicting structural assignment. Knowlux declares the salt stoichiometry, acetate content, and water content per lot on the COA. Buyers should confirm whether the quoted material is reported on a free-peptide or acetate-salt basis before procurement.

Sequence and Structural Verification: The 9-residue sequence H-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Orn-Gly-NH2 with a disulfide bridge between Cys1 and Cys6 is confirmed by ChemicalBook, MedChemExpress, GLPBIO, Biorbyt, and Proteogenix. The C-terminus is glycinamide (Gly-NH2), amidated against carboxypeptidase degradation. The ornithine (Orn) residue at position 8 distinguishes Ornipressin from argipressin (Arg8) and lypressin (Lys8); the shorter, non-guanidinium side chain of ornithine is the structural basis for the analogue's pharmacological profile. Ornipressin is sometimes referred to by the research code POR-8.

Product Parameters

Product Details

1. Overview

Ornipressin is a synthetic nonapeptide vasopressin analogue in which the arginine residue at position 8 of the native hormone is replaced by ornithine. This substitution shortens the C-terminal basic side chain and removes the guanidinium group, producing a pharmacological profile that is characterized by potent V1 receptor-mediated vasoconstriction with comparatively modest antidiuretic (V2-mediated) activity. Ornipressin is described in the pharmacological literature as a vasopressin V1 receptor agonist, a potent vasoconstrictor, haemostatic and renal agent, and a local vasoconstrictor used as an alternative to sympathomimetic agents in regional anaesthesia and haemostasis protocols. In clinical practice, Ornipressin has been used under the trade name POR-8 as a local vasoconstrictor in surgical and dental settings. The material supplied under this specification is research-grade and is not intended for human administration. Knowlux supplies this compound strictly for laboratory investigation of V1 receptor pharmacology, vasoconstrictor mechanisms, and structure-activity relationships within the vasopressin analogue series.

2. Receptor Pharmacology and Selectivity

Ornipressin acts as a vasopressin V1 receptor agonist, with selectivity for the V1 subtype over V2 relative to argipressin. The Orn8 substitution is the structural determinant of this selectivity: the ornithine side chain is shorter than arginine and lacks the terminal guanidinium group that contributes to high-affinity V2 binding in the native hormone. As a result, Ornipressin produces vasoconstriction through V1-mediated Gq/11 signaling and calcium mobilization in vascular smooth muscle, while its antidiuretic activity is comparatively limited. Published pharmacological descriptions characterize Ornipressin as a V1 receptor-specific agonist and a potent vasoconstrictor, consistent with its use as a local haemostatic agent. Quantitative receptor binding constants (Ki) for Ornipressin at V1a, V1b, and V2 are less extensively tabulated in public supplier databases than for argipressin; researchers characterizing receptor selectivity in their own systems should establish potency ratios empirically rather than relying on catalogue values. The pharmacological position of Ornipressin within the vasopressin analogue family is best appreciated by comparison with its nearest analogues: Arg8 (argipressin, non-selective V1a/V2), Lys8 (lypressin, V1a-preferring but with retained V2 activity), Phe2 (felypressin, V1a-preferring via a different substitution), and Orn8 (ornipressin, the most V1-selective of the group).

3. Research Applications

Published pharmacological characterizations and documented protocols describe the following research applications:

• Vasopressin V1 receptor binding and functional assays (calcium mobilization, vascular smooth muscle contraction)

• Structure-activity relationship studies of position-8 substitutions across vasopressin analogues

• Local vasoconstrictor and haemostatic mechanism research in anaesthesia and surgical models

• Renal and antidiuretic activity profiling in comparative pharmacology studies

• Reference standard development for HPLC and LC-MS analytical methods

These descriptions are derived from published research and are provided for scientific reference only. They do not constitute clinical guidance or dosing recommendations.

Quality Control

Supplier specifications for Ornipressin Acetate are consistent across the principal research-grade listings. ChemicalBook and CPhI supplier entries specify HPLC purity >=98.0%, single impurity <=1.0%, acetate content <12%, water content <=10.0%, and peptide content >=80.0%. A MedChemExpress Certificate of Analysis (batch 96386) reports LC-MS purity of 98.38%, peptide content of 83.2%, acetic acid content of 9.3%, and water content of 4.2% by Karl Fischer, with nitrogen and carbon content consistent with the assigned structure. Biorbyt lists a lower-purity grade at >95% for a bulk catalogue item, and GL Biochem specifies >=98.0% by HPLC with a single impurity maximum of 1.0%. The principal quality consideration for Ornipressin Acetate, as with the other vasopressin analogues in this series, is the distinction between HPLC area-percent purity and peptide content on an anhydrous, acetate-free basis. A lot with 98.4% LC-MS purity and 83.2% peptide content (as in the MedChemExpress batch above) is analytically consistent, but researchers preparing molar solutions should use the peptide content value rather than the HPLC purity figure for accurate concentration calculations. Full COA, MSDS, and lot-specific chromatograms are issued with each shipment.

Solubility and Handling

Solubility: Ornipressin Acetate is freely soluble in water. GLPBIO, TargetMol, and Molnova report water solubility of >=100 mg/mL (95.95 mM) with sonication assistance. Biorbyt lists DMSO solubility of approximately 10 mM for the free peptide catalogue item. The high aqueous solubility reflects the peptide's basic character and distinguishes it from the more lipophilic, DMSO-favoring peptides such as Pentagastrin. For stock solutions, water or buffered saline is the preferred solvent; DMSO is feasible at approximately 10 mM for applications requiring anhydrous conditions. Prepare solutions fresh and aliquot to avoid repeated freeze-thaw cycles.

Handling Precautions: Use powder-handling containment (glove box or fume hood with particulate control). Avoid inhalation of fine powder. Wear nitrile gloves, lab coat, and eye protection. The disulfide bridge is sensitive to reducing agents; avoid contact with dithiothreitol (DTT) or mercaptoethanol during handling. Follow institutional chemical hygiene plans for research peptides.

Storage and Stability

Storage guidance varies across suppliers in a pattern consistent with the vasopressin analogue series. MedChemExpress specifies 2 years at -80C and 1 year at -20C for powder, with solutions stable for 6 months at -80C or 1 month at -20C. TargetMol specifies 3 years at -20C for powder and 1 year at -80C for solutions. Biorbyt lists -20C for one year, and GLPBIO recommends -20C for stock solutions stored for several months. The -80C condition is the more conservative choice for long-term archival storage of the powder, while -20C is adequate for routine working inventories within the supplier-specified window. The lyophilized powder is hygroscopic; equilibrate vials to room temperature before opening to prevent condensation. Protect from light and moisture.

Documentation Support

Per lot: COA, MSDS, certificate of origin, HPLC chromatogram, and mass spectrometry data. Acetate content, water content, and peptide content data available on request. Custom specifications and third-party inspection can be arranged on a project basis.

About Knowlux

Knowlux Biotechnology is a GMP-oriented manufacturer and supplier of peptides, APIs and fine-chemical research compounds, operating from Hubei, China. We serve research groups, CDMOs and distributors in more than 40 countries, and support contract synthesis, custom packaging and technical documentation requests.

Compliance Statement

FOR RESEARCH USE ONLY. NOT FOR HUMAN USE. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE.

This product is supplied for laboratory research use only. It is not for human or animal administration, not for diagnostic or therapeutic use, not for retail sale, and not for personal use. Ornipressin has been used clinically as a local vasoconstrictor in certain jurisdictions; however, the material offered under this specification is research-grade and is not intended for clinical use. The purchaser is responsible for verifying product specifications against their specific research requirements and for compliance with all applicable institutional, local, and national regulations governing research chemical acquisition, storage, and use. Research context statements are for scientific reference only and do not constitute medical advice, promotional claims, or dosing guidance.

Data Verification Notes: The molecular formula C45H63N13O12S2 and molecular weight 1042.19 g/mol (free peptide basis) are confirmed by ChemicalBook, MedChemExpress, GLPBIO, Biorbyt, Proteogenix, and GL Biochem. The sequence H-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Orn-Gly-NH2 with disulfide bridge Cys1-Cys6 is consistent across ChemicalBook, MedChemExpress, GLPBIO, and Proteogenix. The CAS mapping is as follows: 3397-23-7 is the free-peptide registry most widely used in supplier catalogues; 914453-98-8 is the acetate-salt registry, confirmed by Biosynth, MedChemExpress, PeptideDB, Creative Peptides, and Sigma-Aldrich. The molecular weight discrepancy under CAS 914453-98-8 (TargetMol listing 1102.25 with formula C47H67N13O12S2) is noted and treated as an acetate-inclusive or hydrated-form value rather than a conflicting structural assignment; the free-peptide-based 1042.19 value is adopted for the structural table. The Quality Control specifications (purity >=98.0%, single impurity <=1.0%, acetate <12%, water <=10.0%, peptide content >=80.0%) are drawn from ChemicalBook/CPhI supplier listings and are corroborated by the MedChemExpress batch 96386 COA data (LC-MS purity 98.38%, peptide content 83.2%, acetic acid 9.3%, water 4.2%). Storage shelf-life divergence across suppliers (-20C versus -80C for powder) is reported as-is; the -80C condition is presented as the conservative archival option.

Formatting Note: All formulas, sequences, and comparison operators use plain ASCII notation to prevent character corruption on the platform. Section headings, table alignment, and spacing follow the approved product detail pattern. No trailing spaces or non-breaking characters are used; tables use consistent pipe alignment.