Quercetin & Dihydroquercetin

Dihydroquercetin (taxifolin) is a potent flavonoid found in onions, French tamarisk bark, milk thistle, and tamarind seeds. Many reviews focus on the therapeutic promise of dihydroquercetin in major disease states such as cancer, cardiovascular disease and liver disease, by examining its proposed mechanisms of action, including activation of the antioxidant response element and detoxification of phase II enzymes, inhibition of cytochrome P(450) and fatty acid synthase in carcinogenesis. TNF-alpha and NF-ĸB-dependent transcription in hepatitis C infection, the effect of scavenging reactive nitrogen species derived from myeloperoxidase and the consequent effects on cholesterol biosynthesis, as well as effects on apob/apoA-I, HMG-CoA reductase, and apoptosis are reviewed. The stereochemistry and pro-oxidant effects of dihydroquercetin are also discussed. Although most of the research on dihydroquercetin to date has focused on the identification of molecular targets in vitro, there are reviews that have summarized the evidence on the potency and mode of action of dihydroquercetin and suggested a role for the therapeutic potential of flavonoid antioxidants.

Taxifolin (dihydroquercetin) has shown promising pharmacological activities in the treatment of inflammation, tumors, microbial infections, oxidative stress, cardiovascular and liver disorders. The anticancer activity was more pronounced than other activities assessed using various in vitro and in vivo models.

Dihydroquercetin and liver diseases: The investigation of the therapeutic properties of dihydroquercetin in hepatological disorders is probably the most intuitive on the one hand, and the least explored on the other. Dihydroquercetin is the only flavonoid found in the licensed hepatoprotective drug silymarin (Legalon®) for the treatment of toxic liver damage and adjunctive treatment of chronic inflammatory liver disease and liver cirrhosis.

Dihydroquercetin in cardiovascular disease: As in cancer pathology, the synthesis of long-chain fatty acids is essential for maintaining a functional cardiovascular system through membrane repair and energy production. One of the main risk factors for the development of coronary heart disease is elevated levels of low-density lipoprotein (LDL) cholesterol. This plays a key role in the development of atherosclerosis, and dihydroquercetin reduces the activity of an enzyme that is important in the synthesis of LDL-cholesterol.

Dihydroquercetin – molecular targets for cancer therapy: By far the largest number of citations for dihydroquercetin in recent years has been related to its effect on cancer cell models and the prevention of effects associated with drug toxicity. Proliferative changes in cells, differentiation, apoptosis, as well as altered expression of transcription factors and proteins important for cell cycle regulation, result in the development of abnormal cells. So according to all studies to date, dihydroquercetin is recommended as an additional supplementation in cancer patients, due to the known mechanism of action on cancer cells.

Use of dihydroquercetin in the treatment of COVID-19 infections: Dihydroquercetin (DHQ) is a bioflavonoid with high antioxidant, capillary-protective and anti-inflammatory activity. DHQ has previously been used to treat Middle East respiratory syndrome coronavirus (MERS-CoV) infection and is currently considered a potential regulator of oxidative stress as part of a multi-purpose therapy for COVID-19.