Chemopreventive potential of dietary bioflavonoids against 20-methylcholanthrene-induced tumorigenesis

Area of Science:

• Biochemistry
• Pharmacology
• Oncology

Background:

• Flavonoids are plant-derived polyphenolic compounds with known antioxidant and anti-inflammatory properties.
• Dietary supplementation is explored for cancer chemoprevention, but specific mechanisms require elucidation.

Purpose of the Study:

• To investigate the chemopreventive effects of dietary flavonoids (quercetin, rutin, luteolin, (+)-catechin) against 20-methylcholanthrene (20-MC)-induced fibrosarcoma in mice.
• To explore the impact of these flavonoids on tumor incidence, expression, and key biochemical markers associated with carcinogenesis.

Main Methods:

• Male Swiss albino mice were administered 20-methylcholanthrene (20-MC) to induce fibrosarcoma.
• Mice received dietary supplementation with quercetin, rutin, luteolin, or (+)-catechin.
• Tumor incidence, onset, and expression were monitored.
• Levels of lipid peroxides, cytochrome P450, and glutathione-S-transferase (GST) activity were assessed in tumor-bearing and treated animals.
• In vitro DNA synthesis inhibition was measured using [3H]thymidine incorporation.

Main Results:

• 20-MC induced 100% fibrosarcoma incidence within 7 weeks.
• Dietary quercetin (52% incidence) and luteolin (60% incidence) significantly reduced tumor incidence and delayed onset (9th week).
• Rutin and (+)-catechin did not affect tumor expression.
• Flavonoid treatment reduced lipid peroxides and cytochrome P450, while increasing GST activity (P < 0.001).
• In vitro studies demonstrated flavonoid inhibition of DNA synthesis in fibrosarcoma cells.

Conclusions:

• Quercetin and luteolin exhibit significant chemopreventive effects against 20-MC-induced fibrosarcoma.
• These flavonoids may act by inhibiting tumor initiation/promotion and enhancing detoxification pathways.
• Flavonoids show potential as dietary agents for cancer prevention through modulation of key carcinogenic processes.