Quercetin | CAS 117-39-5 | Flavonol Polyphenol (Research Use Only) | Knowlux

Product Summary

Knowlux supplies quercetin as a plant-derived flavonol reference material for laboratory research, analytical method development and formulation pre-studies. The molecule is a pentahydroxyflavone built on a flavone core bearing five hydroxyl groups, and is one of the most widely distributed flavonoids in the plant kingdom, found in onions, tea, apples and Sophora flower buds. It presents as a yellow crystalline powder, practically insoluble in water but soluble in ethanol and alkaline solutions. Each consignment ships with a batch-tied analytical file (COA, SDS, chromatograms and origin documentation) so the material can be traced from container to bench.

Specification Sheet

Structural and Stability Notes

Quercetin belongs to the flavonol subclass of flavonoids: a flavone core with a 3-hydroxyl group and four additional hydroxyls at positions 5, 7, 3' and 4'. The catechol pattern on the B-ring and the 3-hydroxyl on the C-ring are the principal sites of antioxidant activity, but they are also the sites most vulnerable to oxidation and metal-catalysed degradation.

Three practical consequences follow:

Air and light sensitivity. Quercetin is sensitive to exposure to air and light, with oxidation driving a shift toward brown discolouration. Amber glass, nitrogen headspace where possible, and protection from direct light are functional requirements.

Aqueous insolubility governs handling. The compound is practically insoluble in water, so in vitro work typically requires ethanol or DMSO stock solutions. Alkaline solutions dissolve quercetin but also accelerate its oxidation; stock solutions should be kept neutral to mildly acidic and prepared fresh.

Metal chelation. Quercetin is a strong metal chelator, which is central to its antioxidant mechanism but also means trace transition metals in buffers can catalyse degradation and colour change. Use chelator-free or metal-free buffer systems where assay reproducibility matters.

Analytical Release

Each batch is released with the chromatogram set generated for that lot, not a generic specification sheet.

Handling and Storage

Keep containers tightly closed, protected from light, and stored cold under dry conditions. Working solutions in ethanol or DMSO should be prepared fresh and protected from light; alkaline aqueous solutions should be avoided for stock storage because they accelerate oxidation. Discolouration toward brown indicates oxidative degradation. Sealed, light-protected storage at -20 C supports the retest period stated on the COA.

Research Applications

• Certified reference material for quercetin quantification in plant extracts and biological matrices

• Antioxidant capacity assay calibration (DPPH, ABTS, FRAP)

• Metal chelation and flavonoid-metal interaction studies

• Kinase inhibition and cell signalling research models

• Formulation stability screening for flavonol actives

• Analytical method validation for HPLC and LC-MS platforms

Documentation and Traceability

Each lot is released against its own file: certificate of analysis with raw chromatograms, safety data sheet, certificate of origin, residual-solvent statement (on request), and a stability/retest note. Method-transfer packages and supplier audit support are available project by project.

Packing and Dispatch

Primary containment: amber glass vial or high-barrier aluminium pouch with tamper-evident seal. Secondary containment: light-blocking carton with desiccant. Shipments leave Hubei within the quoted lead time, ambient by default, with cold packs where route or season requires. Export documents (invoice, packing list, COA, SDS, origin certificate) are prepared before dispatch.

About Knowlux

Knowlux Biotechnology operates from Hubei, China, as a GMP-oriented supplier of peptides, active substances and fine-chemical research compounds. Customers include academic laboratories, CDMOs, formulation developers and distributors in more than 40 countries. Beyond catalogue supply, we handle custom synthesis, bespoke pack sizes and documentation packages built to a client's audit template.

Compliance and Use Restriction

This material is released strictly for laboratory research use. It must not be administered to humans or animals, must not be used in diagnosis or therapy, and is not offered for retail, personal or household use.

Quercetin is sold as a dietary supplement ingredient in many jurisdictions and has been studied clinically, but the US FDA has stated that quercetin is not a recognised nutrient and cannot be used as a drug on the basis of current evidence. Those regulatory positions attach to compliant supplement-grade supply chains and do not apply to, and are not represented by, this research-grade lot.

Statements describing published research are scientific background only. They are not medical advice, not a health claim, and not dosing or therapeutic guidance.