Dihydroquercetin Encyclopedia — Scientific Background

What Is Dihydroquercetin?

Dihydroquercetin (DHQ), also known as taxifolin, distylin, or 3,3′,4′,5,7-pentahydroxyflavanone, is a naturally occurring flavanonol belonging to the flavonoid subclass of polyphenols. It is chemically characterized by the molecular formula C₁₅H₁₂O₇ and a molecular weight of 304.25 g/mol. Dihydroquercetin belongs to the subclass flavanonols in the flavonoids, which in turn is a class of polyphenols.

Botanical Source

Dihydroquercetin is primarily extracted from the wood and roots of Siberian larch (Larix sibirica Ledeb) and Dahurian larch (Larix gmelinii). The extraction process involves removing the bark, chopping and drying the wood at 40°C to a residual humidity of 15–17%, and extracting with an aqueous ethanol solution. The method provides the desired product with a yield of 1.5–2.5% of the mass of absolutely dry wood. Dihydroquercetin is also found in milk thistle and other plant sources.

Mechanisms of Action

Antioxidant Defense — Nrf2/ARE Pathway

Dihydroquercetin exerts its antioxidant effects through activation of the Nrf2-dependent antioxidant pathway. Research has demonstrated for the first time that DHQ stimulates the expression of phase II detoxifying enzymes through the Nrf2-dependent signaling pathway. DHQ upregulates the Nrf2-related antioxidant genes heme oxygenase-1 (HO-1) and NQO1, protecting cells against oxidative stress. Dihydroquercetin also enhances the antioxidant capacity of neuronal cells by activating antioxidant enzymes such as superoxide dismutase (SOD) and Glutathione peroxidase.

AMPK/Nrf2/HO-1 Signaling

Dihydroquercetin activates AMPK/Nrf2/HO-1 signaling in macrophages and attenuates inflammation in LPS-induced endotoxemic mice. Knockdown of heme oxygenase-1, one of the most important DHQ-induced antioxidant genes, cancelled the inhibition of DHQ treatment on LPS-induced TNF-α production.

Anti-Ferroptosis Activity

Dihydroquercetin ameliorates spinal cord injury in rats by modulating the AKT/Nrf2/GPX4 signaling pathway-mediated ferroptosis. It suppresses cigarette smoke-induced ferroptosis in the pathogenesis of chronic obstructive pulmonary disease by activating the Nrf2-mediated pathway.

Cardioprotective Effects

Dihydroquercetin has demonstrated cardioprotective effects against ischemia-reperfusion injury by inhibiting oxidative stress and endoplasmic reticulum stress-induced apoptosis via the PI3K/Akt pathway. It also reduces inflammatory reactions in wound zones after thermal burns.

The Bioavailability Challenge

Despite its potent antioxidant and therapeutic potential, dihydroquercetin presents significant formulation challenges. Dihydroquercetin has low solubility and limited bioavailability, which have stimulated the development of nanotechnology-based delivery systems. The widespread use of dihydroquercetin in medical practice is limited by the physicochemical properties of the compound and, in part, the related features of its pharmacokinetics: absorption, distribution, metabolism, and excretion.

A pharmacokinetic study in rats investigated DHQ isolated from Larix sibirica and identified its metabolites in blood plasma and urine after single intravenous and oral administration. The study established that DHQ is a short-living drug, with quantification performed by reverse-phase HPLC with UV- and MS-detection.

Liposomal dihydroquercetin

liposomal encapsulation of dihydroquercetin provides a fundamentally different delivery mechanism from conventional forms. The phospholipid bilayer surrounds the dihydroquercetin molecule, forming a shield that protects it from degradation and enhances absorption. This delivery system:

• Protects dihydroquercetin from oxidative and enzymatic degradation

• Enhances solubility and dispersibility in aqueous systems

• Improves intestinal absorption through lipid-mediated pathways

• Provides sustained release for prolonged antioxidant activity

A pharmacokinetic study comparing the oral administration of a parent compound and liposomal dihydroquercetin in rats demonstrated the pharmacokinetic advantages of the liposomal form. Nanometerizing dihydroquercetin into selenized liposomes achieved a relative bioavailability of 216.65%, significantly higher than dihydroquercetin suspensions and unmodified liposomes, with improved gastrointestinal drug absorption and sustained release characteristics.

Clinical Evidence

Idiopathic Male Infertility

A clinical study evaluated dihydroquercetin in men with idiopathic infertility. All participants received 60 mg of dihydroquercetin twice daily for 90 days. Semen parameters, including morphology assessed by Kruger's strict criteria, were evaluated before therapy and every 30 days during the 3-month treatment period. The study concluded that dihydroquercetin is a promising dietary supplement for the treatment of idiopathic male infertility.

Obesity and Prediabetes

Dihydroquercetin has been investigated as a treatment for patients with obesity and prediabetes requiring a moderate therapeutic effect. In a clinical case report of a 30-year-old Caucasian male, DHQ was administered as a dietary supplement at a dose of 100–200 mg/day during 3 months with treatment interruption for 1 month. The paper proposed a molecular mechanism of its anti-obesity effect.

Chronic Heart Failure

A clinical study evaluated dihydroquercetin at a dose of 240 mg per day as a single dose or combined with arabinogalactan in chronic heart failure patients. The study was designed based on the hypothesis that dihydroquercetin treatment would improve the clinical condition and functional status of CHF patients.

Hypertensive Patients with COVID-19

A pharmacoepidemiologic and clinical study evaluated the inclusion of L-arginine and dihydroquercetin in the combined pharmacotherapy of hypertensive patients with COVID-19. The study found that the inclusion of L-arginine and dihydroquercetin in antihypertensive pharmacotherapy was effective, with a more significant nightly decrease in blood pressure observed in the group receiving the combination.

Safety and Regulatory

Dihydroquercetin is generally well tolerated at commonly used doses. Clinical studies have used dihydroquercetin at doses of 100–240 mg/day for periods ranging from 3 to 6 months without serious adverse effects reported. Dihydroquercetin is widely commercialized as a dietary supplement ingredient and is used in pharmaceutical, food, and cosmetic applications. Testing protocols must adhere to international standards including USP, European Pharmacopoeia, and FAO/WHO Codex Alimentarius. Formulators should verify local regulatory requirements prior to market entry.

This product is intended for research, nutraceutical, and functional food applications. Not intended to diagnose, treat, cure, or prevent any disease.

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