Taxifolin

Natural occurrences

It can be found in conifers like the Siberian larch, Larix sibirica, in Russia, in Pinus roxburghii, in Cedrus deodara and in the Chinese yew, Taxus chinensis var. mairei.

It is also found in the silymarin extract from the milk thistle seeds.

Taxifolin is present in vinegars aged in cherry wood.

Pharmacology

Taxifolin is not mutagenic and less toxic than the related compound quercetin. It acts as a potential chemopreventive agent by regulating genes via an ARE-dependent mechanism. Taxifolin has shown to inhibit the ovarian cancer cell growth in a dose-dependent manner. There is also a strong correlation (with a correlation coefficient of 0.93) between the antiproliferative effects of dihydroquercetin (DHQ, Taxifolin) derivatives on murine skin fibroblasts and human breast cancer cells.

The capacity of taxifolin to stimulate fibril formation and promote stabilization of fibrillar forms of collagen can be used in medicine. Also taxifolin inhibited the cellular melanogenesis as effectively as arbutin, one of the most widely used hypopigmenting agents in cosmetics. However, arbutin acts as quercetin extremely mutagenic, carcinogenic and toxic.

Taxifolin enhanced also the efficacy of conventional antibiotics like levofloxacin and ceftazidime in vitro, which have potential for combinatory therapy of patients infected with methicillin-resistant Staphylococcus aureus (MRSA).

Taxifolin, as well as many other flavonoids, has been found to act as a non-selective antagonist of the opioid receptors, albeit with somewhat weak affinity.

Taxifolin has been found to act as an agonist of the adiponectin receptor 2 (AdipoR2).

Metabolism

The enzyme taxifolin 8-monooxygenase uses taxifolin, NADH, NADPH, H⁺, and O₂ to produce 2,3-dihydrogossypetin, NAD⁺, NADP⁺, and H₂O.

The enzyme leucocyanidin oxygenase uses leucocyanidin, 2-oxoglutarate, and O₂ to produce cis-dihydroquercetin, taxifolin, succinate, CO₂, and H₂O.

Glycosides

Astilbin is the 3-O-rhamnoside of taxifolin. Taxifolin deoxyhexose can be found in açai fruits.

Taxifolin 3-O-glucoside isomers have been separated from Chamaecyparis obtusa.

(-)-2,3-trans-Dihydroquercetin-3'-O-β-D-glucopyranoside, a taxifolin glucoside has been extracted from the inner bark of Pinus densiflora and can act as an oviposition stimulant in the cerambycid beetle Monochamus alternatus.

(2S,3S)-(-)-Taxifolin-3-O-β-D-glucopyranoside has been isolated from the root-sprouts of Agrimonia pilosa.

(2R,3R)-Taxifolin-3'-O-β-D-pyranoglucoside has been isolated from the rhizome of Smilax glabra.

Minor amount of taxifolin 4′-O-β-glucopyranoiside can be found in red onions.

(2R,3R)-Taxifolin 3-O-arabinoside and (2S,3S)-taxifolin 3-O-arabinoside have been isolated from the leaves of Trachelospermum jasminoides (star jasmine).

Chemistry

(+)-Leucocyanidin can be synthesized from taxifolin by sodium borohydride reduction.