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Inhibition of nitric oxide (NO.) production in murine macrophages by flavones
W Król1, Z P Czuba, M D Threadgill
1Department of Microbiology and Immunology, Silesian School of Medicine, Zabrze-Rokitnica, Poland.
Abstract:
The effect of flavone (2-phenylbenzopyran-4-one) and three amino-substituted flavones on the production of nitrite by murine activated peritoneal macrophages was studied in vitro. Activated peritoneal macrophages obtained from mice pre-treated with concanavalin A (Con A) (in vivo), after exposure in vitro to lipopolysaccharide (LPS) at a concentration of 100 ng/ml, produced nitrite (20.3 +/- 2.5 nmol/10(6) cells), as measured after 24 hr by the Griess reaction. Stimulation of production of nitrite was inhibited by NG-monomethyl-L-arginine, suggesting that nitrite was formed via nitric oxide (NO.) as a product of metabolism of arginine. Stimulation was inhibited by flavone and the aminoflavones (20-100 microM). 3'-amino-4'-hydroxyflavone was the most potent inhibitor of nitrite production. Genistein (5,7-dihydroxy- 3-(4-hydroxy-phenyl)-4H-1-benzopyran-4-one) also inhibited production of nitrite, by a mechanism that appears not to involve protein tyrosine kinases. These results suggest that the flavones can modulate the immune responses and the inflammatory reactions by controlling production of nitric oxide.
Insights
Flavones, including 3'-amino-4'-hydroxyflavone, inhibit nitric oxide production in activated macrophages. This suggests flavones can modulate immune and inflammatory responses by controlling nitric oxide generation.
Area of Science:
- Immunology
- Pharmacology
- Biochemistry
Background:
- Nitric oxide (NO) plays a crucial role in immune and inflammatory responses.
- Macrophages are key immune cells involved in these processes.
- Flavonoids are plant-derived compounds with potential biological activities.
Purpose of the Study:
- To investigate the in vitro effect of flavone and amino-substituted flavones on nitrite production by activated murine macrophages.
- To determine the inhibitory potential of specific flavone derivatives on nitric oxide synthesis.
Main Methods:
- Murine peritoneal macrophages were activated in vitro with lipopolysaccharide (LPS).
- Nitrite production was measured using the Griess reaction.
- The effects of flavone, aminoflavones, and genistein on nitrite production were assessed.
Main Results:
- Activated macrophages produced significant amounts of nitrite, indicating nitric oxide synthesis.
- Flavone and aminoflavones, particularly 3 -amino-4 -hydroxyflavone, potently inhibited nitrite production.
- Genistein also inhibited nitrite production through a mechanism independent of protein tyrosine kinases.
Conclusions:
- Flavones can effectively modulate immune responses by inhibiting nitric oxide production in macrophages.
- These findings suggest potential therapeutic applications for flavones in managing inflammatory conditions.