Isoquercetin (also known as isoquercitrin or isotrifoliin) is a flavonoid, a type of chemical compound. It is the 3-O-glucoside of quercetin. Isoquercitrin can be isolated from various plant species including Mangifera indica (mango) and Rheum nobile (the Noble rhubarb). It is also present in the leaves of Annona squamosa, Camellia sinensis (tea), and Vestia foetida.

Spectral data

The lambda-max for isoquercetin is 254.8 and 352.6 nm.

Biosynthesis and metabolism

Isoquercetin if formed from quercetin by action of the enzyme flavonol 3-O-glucosyltransferase in plants such as the tulip.

The enzyme flavonol-3-O-glucoside L-rhamnosyltransferase in tulips converts isoquercetin to rutin by adding an L-rhamnose sugar unit from UDP-L-rhamnose, with uridine diphosphate (UDP) as byproduct.

Potential clinical uses

Isoquercetin is presently being investigated for prevention of thromboembolism in selected cancer patients and as an anti-fatigue agent in kidney cancer patients treated with sunitinib.

There is a single case report of its use in the successful treatment of prurigo nodularis, a difficult to treat pruritic eruption of the skin.

Isoquercetin belongs to the class of chemical compounds known as pan-assay interference compounds (PAINS), which frequently give false positive results in assays for pharmacological activities.

See also