Sincalide | CAS 25126-32-3 | CCK-A Receptor Agonist (Research Use Only) | Knowlux

Product Description

Sincalide, CAS 25126-32-3, is a synthetic sulfated octapeptide corresponding to the C-terminal sequence of cholecystokinin (CCK-8), supplied by Knowlux for laboratory research use. The peptide carries a sulfated tyrosine at position 2 and an amidated C-terminal phenylalanine. The molecular formula is C49H62N10O16S3 and the molecular weight is 1143.27 g/mol on the free-peptide basis. Each lot is released with a lot-specific COA, MSDS and analytical traceability.

Salt-Form Distinction: Sincalide circulates in commercial catalogues as two operationally distinct forms, and the distinction governs solubility and mass balance. CAS 25126-32-3 is the free sulfated peptide (C49H62N10O16S3, MW 1143.27). The ammonium salt carries a separate registry, CAS 70706-98-8, with formula C49H65N11O16S3 and MW 1160.3. The 17 g/mol mass difference corresponds to the ammonium counter-ion, and the ammonium form generally exhibits better aqueous handling characteristics than the free acid. Some catalogues also list an ammonium acetate salt under CAS 25126-32-3 without clarifying which counter-ion basis applies. Knowlux declares the salt form, counter-ion identity, and peptide content per lot on the COA. Buyers should confirm whether the quoted material is the free peptide, the ammonium salt, or a mixed ammonium/acetate form before procurement, and should reconcile the declared molecular weight against the salt basis.

Structural Note: The sulfated tyrosine is the defining structural feature of Sincalide relative to unsulfated CCK fragments. Sulfation is required for full CCK-A receptor potency; desulfated CCK-8 is substantially weaker at the CCK-A subtype. The sequence contains two methionine residues (Met3 and Met6), which are the principal oxidation liabilities, and a single tryptophan (Trp5), which provides the main UV chromophore. The C-terminus is phenylalaninamide (Phe-NH2), amidated against carboxypeptidase attack. The peptide is linear with no cysteine or disulfide bonds.

Product Parameters

Product Details

1. Overview

Sincalide is the synthetic sulfated C-terminal octapeptide of cholecystokinin, the principal hormonal regulator of gallbladder contraction and pancreatic enzyme secretion. It is used as a research tool for CCK receptor pharmacology and as a diagnostic cholecystokinetic agent in gallbladder and pancreatic function testing. The peptide was first approved in 1976 and remains the reference CCK-8 standard for in vitro and in vivo studies of CCK-A receptor function. The material supplied under this specification is research-grade and is not intended for human administration.

2. Receptor Pharmacology and Functional Selectivity

Sincalide is a potent agonist at both CCK receptor subtypes but is functionally CCK-A selective. Binding affinities compiled across radioligand displacement assays place Sincalide at approximately 0.6 to 2 nM at the human CCK-A receptor and approximately 0.3 to 7.3 nM at CCK-B, with the affinity ranges overlapping at the lower end but the functional potency diverging sharply. In calcium mobilization assays, Sincalide activates CCK-A with an EC50 of approximately 0.417 nM, whereas its functional potency at CCK-B is significantly lower and not consistently reported as a discrete EC50. A separate tissue-based study in guinea pig isolated ileum reports an EC50 of 207 pM for Sincalide-evoked contraction, a value consistent with the sub-nanomolar functional potency at CCK-A. An orthogonal screening assay reports an EC50 of 92 nM for CCK-1 (CCK-A) agonism, which is two orders of magnitude weaker than the calcium-mobilization and ileum-contraction values; this divergence likely reflects the specific assay format, receptor reserve, or cell background rather than a substantive disagreement about Sincalide potency. The consensus reading is that Sincalide is a sub-nanomolar to low-nanomolar CCK-A agonist with substantially weaker functional engagement of CCK-B, and researchers should establish potency in their own assay system rather than extrapolating across formats.

The signaling cascade downstream of CCK-A activation is Gq/11-mediated: receptor engagement activates phospholipase C, generates IP3 and DAG, mobilizes intracellular calcium, and activates protein kinase C, culminating in gallbladder smooth muscle contraction and pancreatic acinar enzyme secretion.

3. Research Applications

Documented applications include:

• CCK-A and CCK-B receptor binding and functional agonist assays (radioligand displacement, calcium mobilization, tissue contraction)

• Gallbladder contractility and biliary physiology studies

• Pancreatic exocrine secretion and enzyme output research

• Gastrointestinal motility and transit studies (gastric emptying, intestinal transit)

• Sphincter of Oddi function and bile flow research

• CCK receptor selectivity profiling (Sincalide as the CCK-A-preferring reference agonist, contrasted with CCK-B-preferring ligands such as gastrin-17 and CCK-4)

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

These descriptions are derived from published research and are provided for scientific reference only.

Quality Control

Solubility and Handling

Solubility: Sincalide solubility is the parameter with the greatest divergence across sources, and the divergence is largely resolvable by salt form and pH. The free peptide (CAS 25126-32-3) is described in the FDA drug substance review as soluble in 1M ammonium hydroxide, and a ChemicalBook supplier listing specifies 1 mg/mL in 0.05 M ammonium hydroxide as a clear, colorless solution. In neutral aqueous media, the free peptide is poorly soluble: Selleck lists water as insoluble for its free-peptide catalogue item. The ammonium salt (CAS 70706-98-8), by contrast, is reported by AbMole and MyBioSource as soluble in water at 12.5 mg/mL (10.77 mM) with ultrasonic assistance. MedChemExpress lists water solubility of 50 mg/mL (43.73 mM) for its Sincalide material, but this value is conditional on ultrasonic treatment and adjustment to pH 11 with NH3.H2O; DMF solubility is also 50 mg/mL with sonication. Selleck reports DMSO solubility of 100 mg/mL (87.46 mM) for the free peptide at 25C, and MedChemExpress/AbMole report DMSO at 25 mg/mL with sonication. The chemically coherent reading is that the free peptide requires alkaline pH (ammonium hydroxide or pH 11 adjustment) or DMSO/DMF for dissolution, whereas the ammonium salt offers meaningful neutral-pH aqueous solubility at 12.5 mg/mL. Aqueous stock preparation should therefore specify the salt form and pH; researchers should not assume that a water-solubility figure reported for one form applies to the other.

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 two methionine residues are the principal oxidation liabilities; protect from prolonged exposure to air and light, and handle under an inert atmosphere where practical. The sulfated tyrosine is stable under standard handling conditions but should not be exposed to strongly acidic conditions that could hydrolyze the sulfate ester. The FDA review characterizes the drug substance as non-hygroscopic, which simplifies weighing but does not eliminate the need for standard moisture protection during storage.

Storage and Stability

Documentation Support

Per lot: COA, MSDS, HPLC chromatogram, and mass spectrometry data. Where available, NMR and specific rotation data are provided. Salt-form identity, counter-ion content, and peptide content 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. Sincalide is an approved diagnostic agent (Kinevac) in certain jurisdictions for gallbladder and pancreatic function testing; 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 C49H62N10O16S3 and molecular weight 1143.27-1143.29 are confirmed across KEGG DRUG, ChEMBL, BOC Sciences, Sigma-Aldrich, Selleck, MedChemExpress, and the FDA drug substance review. The sequence H-Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2 is confirmed by KEGG DRUG, ChinaPeptides, BenchChem, and the FDA review. The ammonium salt CAS 70706-98-8, formula C49H65N11O16S3, and MW 1160.3 are confirmed by BenchChem, MedChemExpress, AbMole, and MyBioSource. The CCK-A affinity range of approximately 0.6-2 nM and CCK-B range of approximately 0.3-7.3 nM are from BenchChem compiled binding table. The CCK-A functional EC50 of approximately 0.417 nM is from BenchChem calcium mobilization compilation, and the ileum EC50 of 207 pM is from Ambeed. The orthogonal 92 nM CCK-1 EC50 is from Eurofins DiscoverX and is reported as a divergent value rather than reconciled. The FDA drug substance review confirms the non-hygroscopic powder appearance, solubility in 1M ammonium hydroxide, specific rotation of approximately -21 deg, and the quality control panel including IR, HPLC, GC residual solvents, water content, and specific rotation. Solubility values are reported with their salt-form and pH conditions rather than reconciled into a single figure because the free peptide requires alkaline pH or organic solvent while the ammonium salt offers neutral-pH aqueous solubility. Storage guidance is reported with the distinction between lyophilized powder and reconstituted solution, and the clinical 12-hour saline stability window is presented alongside the longer research-stock frozen stability windows.

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