Felypressin Acetate | CAS 56-59-7 / 914453-97-7 | Vasopressin V1a Receptor Agonist (Research Use Only) | Knowlux

Product Description

Felypressin Acetate, CAS 56-59-7 (free peptide) / 914453-97-7 (acetate salt), is a synthetic cyclic nonapeptide analogue of lysine vasopressin, supplied by Knowlux for laboratory research use. The sequence is H-Cys-Phe-Phe-Gln-Asn-Cys-Pro-Lys-Gly-NH2, with a disulfide bridge between Cys1 and Cys6. The molecular formula is C46H65N13O11S2 and the molecular weight is 1040.22 g/mol (free peptide basis). Each lot is released with a lot-specific COA, MSDS and analytical traceability.

CAS and Salt Form Clarification: CAS 56-59-7 is the established registry for the Felypressin free peptide and is the identifier most consistently used across KEGG, PubChem, NCI Thesaurus, Selleck, and ChemicalBook. The acetate salt form is assigned CAS 914453-97-7. A frequently encountered point of confusion concerns the molecular weight of the acetate salt: some supplier certificates (LGC Standards, Santa Cruz Biotechnology) list 1040.22 for the acetate salt, which is in fact the free peptide molecular weight; others (InvivoChem, BenchChem, MyBioSource, EvitaChem) list approximately 1100.28 g/mol for the diacetate form (C48H69N13O13S2). The 1100.28 assignment is consistent with the addition of two acetate counter-ions to the free peptide. Knowlux declares the salt stoichiometry, acetate content, and water content per lot on the COA. Buyers should confirm whether the quoted material is free peptide, monoacetate, or diacetate before procurement, as the counter-ion load shifts the mass balance by approximately 60 g/mol per acetate.

Sequence and Structural Verification: The 9-residue sequence H-Cys-Phe-Phe-Gln-Asn-Cys-Pro-Lys-Gly-NH2 with a disulfide bridge between Cys1 and Cys6 is confirmed by KEGG, PubChem, Selleck, and ChemicalBook. The C-terminus is glycinamide (Gly-NH2), amidated against carboxypeptidase degradation. Felypressin is derived from lysine vasopressin (lypressin) by substitution of tyrosine at position 2 with phenylalanine, a modification that enhances vasoconstrictor activity while reducing antidiuretic effects relative to vasopressin.

Product Parameters

Product Details

1. Overview

Felypressin is a synthetic nonapeptide vasopressin analogue developed as a derivative of lysine vasopressin (lypressin), with phenylalanine substituted for tyrosine at position 2. This single substitution shifts the pharmacological profile toward potent V1a receptor-mediated vasoconstriction while attenuating the antidiuretic (V2-mediated) activity that characterizes native vasopressin. Felypressin is classified as a non-catecholamine vasoconstrictor, a property that has made it a research alternative to adrenaline in local anaesthetic formulations, particularly in experimental models examining sympathomimetic-sparing haemostasis. In clinical practice, felypressin has been used as a vasoconstrictor component in dental local anaesthetic preparations (e.g., Citanest octapressin) and in certain regional haemostasis protocols. 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 V1a receptor pharmacology, vasoconstrictor mechanisms, and peptide analogue structure-activity relationships.

2. Receptor Pharmacology and Selectivity

Felypressin acts primarily as an agonist at the vasopressin V1a receptor (AVPR1A), a Gq/11-coupled GPCR that triggers intracellular calcium mobilization and smooth muscle contraction. KEGG records Felypressin's primary target as AVPR1A and classifies it within the vasopressin analogue drug group, with pathway annotations in neuroactive ligand-receptor interaction and vascular smooth muscle contraction. The Phe2 substitution is the structural determinant of the analogue's altered selectivity: by replacing the phenolic hydroxyl of tyrosine with the unsubstituted phenyl ring of phenylalanine, the analogue loses a key hydrogen-bonding interaction that contributes to V2 receptor affinity, thereby favoring V1a-mediated vasoconstriction over V2-mediated water retention. This selectivity profile distinguishes Felypressin from argipressin (non-selective across V1a, V1b, and V2) and from desmopressin (V2-preferring). Quantitative receptor binding data for Felypressin at V1a versus V2 are less extensively reported in public supplier databases than for argipressin; researchers characterizing selectivity in their own assay systems should establish V1a/V2 potency ratios empirically rather than relying on catalogue values.

3. Research Applications

Published pharmacological characterizations describe the following research applications:

• V1a receptor binding and functional assays (calcium mobilization, smooth muscle contraction)

• Structure-activity relationship studies of position-2 substitutions in vasopressin analogues

• Non-catecholamine vasoconstrictor mechanism research in local anaesthesia and haemostasis models

• Renin-angiotensin system interaction studies (Felypressin as a V1a-selective tool)

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

One application note describes Felypressin as a tool for studying renin-angiotensin system crosstalk, leveraging its V1a-selective agonism to isolate V1a-mediated effects from V2-mediated confounds. 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

Selleck's released specification for Felypressin Acetate (catalogue P1047, batch P104706) reports purity of 99.75% by HPLC, peptide content >=80% by nitrogen analysis, water content <=5.0% by Karl Fischer, acetate content <=15.0% by HPLC, single impurity <=1.0%, amino acid composition within +/-10% of theoretical, assay (anhydrous, acetic acid-free basis) 95.0%-105.0%, and bacterial endotoxins <=1 EU/mg. ChemicalBook supplier listings offer a lower-cost research grade at >=98.0% HPLC purity with single impurity <=2%, peptide content >=75.0%, and endotoxin <=50 EU/mg; buyers selecting this grade should recognize the wider impurity and endotoxin windows relative to the Selleck specification. The assay window of 95.0%-105.0% on an anhydrous, acetic acid-free basis is a useful orthogonal check against HPLC area-percent purity, because it accounts for counter-ion and water content. Buyers should request lot-specific HPLC chromatograms, mass spectra, and acetate content data, and verify that the reported molecular weight reconciles to the declared salt stoichiometry: 1040.22 for free peptide versus approximately 1100.28 for the diacetate. Full COA, MSDS, and lot-specific chromatograms are issued with each shipment.

Solubility and Handling

Solubility: Felypressin Acetate is freely soluble in water. Selleck reports water solubility of 100 mg/mL (96.13 mM) for its batch, and MedChemExpress lists water solubility of >=100 mg/mL (96.13 mM) alongside DMSO solubility of >=10.4 mg/mL (10.00 mM). ChemicalBook notes that water dissolution may require ultrasonic assistance. The lower DMSO solubility relative to water reflects the peptide's highly polar, basic character and distinguishes its handling profile from the more lipophilic, DMSO-favoring peptides such as Pentagastrin. For most assay formats, water or buffered saline is the preferred solvent; DMSO stock solutions are feasible at >=10 mg/mL 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 diverges across suppliers in a pattern consistent with the peptide's stability profile: Selleck and AbMole specify 3 years at -20C for powder and 2 years at 4C, while MedChemExpress, BenchChem, and PeptideDB specify 2 years at -80C and 1 year at -20C for powder. This discrepancy does not necessarily indicate a stability failure at -20C over 3 years; it more likely reflects differences in the stability-indicating methods and batch histories used to support each shelf-life claim. For long-term archival storage, -80C is the more conservative choice. Reconstituted solutions are less stable: Selleck lists 1 year at -80C and 1 month at -20C, whereas MedChemExpress and PeptideDB list 6 months at -80C and 1 month at -20C. Selleck ships at room temperature, noting that stability testing supports shipment without cooling measures. 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, amino acid composition, and endotoxin 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. Felypressin has been used clinically as a vasoconstrictor component in certain local anaesthetic preparations; 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 C46H65N13O11S2 and molecular weight 1040.22 g/mol for the free peptide are confirmed across KEGG, PubChem, NCI Thesaurus, Selleck, and ChemicalBook. The sequence Cys-Phe-Phe-Gln-Asn-Cys-Pro-Lys-Gly-NH2 with disulfide bridge Cys1-Cys6 is consistent across KEGG, PubChem, Selleck, and ChemicalBook. The acetate salt CAS 914453-97-7 is confirmed by ChemicalBook, InvivoChem, LGC Standards, and Santa Cruz Biotechnology. The molecular weight discrepancy for the acetate salt is explicitly addressed in the CAS Clarification section: LGC and SCBT list 1040.22 for the acetate salt, which is the free peptide value, while InvivoChem, BenchChem, MyBioSource, and EvitaChem list 1100.28 for the diacetate (C48H69N13O13S2). The 1100.28 assignment is adopted as the chemically consistent diacetate value; buyers should verify the declared stoichiometry on the COA. The Phe2 substitution relative to lysine vasopressin and its role in V1a selectivity is supported by BenchChem documentation. Storage shelf-life divergence across suppliers is reported as-is rather than reconciled, because the differing claims reflect distinct stability-indicating datasets rather than a single consensus value.

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