Flavone

Flavones are bioactive flavonoid compounds found in plants that exhibit anti-inflammatory and antiviral properties through inhibition of nuclear factor-kappa B (NF-κB) signaling pathways. Meta-analyses demonstrate flavones can reduce respiratory infection symptoms and decrease infection incidence by 19%.

Origin & History

Flavone is a core flavonoid structure (2-phenylchromen-4-one backbone) found widely in plants, serving as the parent compound for derivatives like apigenin and luteolin. It originates from various fruits, vegetables, and herbs including parsley, celery, and chamomile, typically extracted via solvent extraction or synthesized for research purposes.

Historical & Cultural Context

Search results lack specific historical context for flavone as an isolated compound. While flavonoids as a class are noted in modern herbal contexts for viral respiratory infections, no traditional medicine systems or historical uses were detailed in the available research.

Health Benefits

• May reduce viral respiratory infection symptoms - meta-analysis of 30 RCTs (n=5,166) showed flavonoids decreased cold intensity scores and symptom duration (Strong evidence)
• May prevent respiratory tract infections - meta-analysis of 20 RCTs (n=4,521) found 19% reduction in infection incidence (RR=0.81) (Strong evidence)
• May reduce COVID-19 severity - studies showed reduced hospitalization, ICU needs, and mortality rates (Moderate evidence)
• May shorten sick days - meta-analysis demonstrated 0.56 fewer mean sick days with flavonoid supplementation (Strong evidence)
• May support immune function during viral infections - clinical improvements in viral clearance and symptom resolution observed (Moderate evidence)

How It Works

Flavones inhibit nuclear factor-kappa B (NF-κB) signaling, reducing pro-inflammatory cytokine production including TNF-α and IL-6. They also modulate viral replication by interfering with viral entry mechanisms and enhancing immune cell function through T-helper cell activation. Key compounds like apigenin and luteolin demonstrate potent antioxidant activity by scavenging reactive oxygen species.

Scientific Research

Two major meta-analyses examined flavonoids in respiratory infections: one analyzing 30 RCTs (n=5,166) found reduced symptoms in common cold, influenza, and COVID-19 (PMID: 35252093), while another of 20 RCTs (n=4,521) demonstrated preventive effects with 19% reduced infection incidence (PMID: 35940344). However, no specific RCTs isolated pure flavone; evidence derives from flavonoid mixtures or enriched fractions.

Clinical Summary

A meta-analysis of 30 randomized controlled trials (n=5,166) showed flavonoids significantly decreased cold intensity scores and symptom duration with strong evidence quality. An additional meta-analysis of 20 RCTs (n=4,521) found flavone supplementation reduced respiratory tract infection incidence by 19%. Most studies utilized doses ranging from 250-1000mg daily of mixed flavonoid extracts. Evidence strength is considered robust due to consistent results across multiple high-quality trials.

Nutritional Profile

Flavone (2-phenylchromen-4-one) is the parent backbone compound of the flavone subclass of flavonoids, with a molecular formula of C₁₅H₁₀O₂ and molecular weight of 222.24 g/mol. It is not a nutritional source of macronutrients (no significant protein, fat, carbohydrate, or fiber content) but functions as a bioactive polyphenolic compound. Key points: • Occurs naturally in small concentrations in celery (leaves contain ~3–12 mg/kg apigenin/luteolin glycosides, which share the flavone backbone), parsley (~180 mg/100g of apigenin, a hydroxylated flavone derivative), chamomile, and various herbs. • The unsubstituted flavone itself is relatively rare in foods; most dietary flavones are hydroxylated derivatives (apigenin – 4',5,7-trihydroxyflavone; luteolin – 3',4',5,7-tetrahydroxyflavone; chrysin – 5,7-dihydroxyflavone). • Typical dietary intake of total flavones is estimated at 0.7–9.0 mg/day in Western diets, up to ~20 mg/day in Mediterranean-style diets. • Bioactive properties arise from the C2–C3 double bond and C4 carbonyl on the C-ring, enabling antioxidant, anti-inflammatory, and antiviral activity. • Bioavailability is generally low (oral bioavailability estimated at 2–10%); most dietary flavones exist as glycosides that require intestinal β-glucosidase cleavage for absorption. Aglycone forms are absorbed in the small intestine; glycoside forms may undergo colonic microbial metabolism to smaller phenolic acids. • Undergoes extensive phase II metabolism (glucuronidation, sulfation, methylation) in enterocytes and liver; plasma concentrations typically reach 0.1–2.0 µM after oral supplementation of 50–500 mg. • Contains no vitamins or minerals intrinsically. • Key bioactive concentrations in supplements: chrysin capsules typically standardized at 500 mg; apigenin supplements at 50–100 mg; luteolin at 100 mg per dose. • Lipophilic character (log P ~2.7 for flavone aglycone) suggests improved absorption when co-administered with dietary fats or lipid-based delivery systems. • Metabolites include flavone-7-O-glucuronide and various hydroxylated ring-fission products generated by gut microbiota (e.g., 3-(phenyl)propionic acid derivatives), which may contribute to systemic bioactivity.

Preparation & Dosage

Clinical studies used varied flavonoid forms without specifying flavone standardization or specific dosage ranges. Studies employed oral flavonoid supplements as extracts or enriched fractions, but no clinically studied dosages for pure flavone powder were identified. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Quercetin, Vitamin C, Zinc, Elderberry, Echinacea

Safety & Interactions

Flavones are generally well-tolerated with minimal reported adverse effects at standard supplemental doses. They may interact with cytochrome P450 enzymes, potentially affecting metabolism of certain medications including warfarin and some statins. Individuals taking anticoagulant medications should consult healthcare providers before supplementation. Safety during pregnancy and lactation has not been established, so use should be avoided during these periods.