AMP Kinase Activation and Inhibition of Nuclear Factor-Kappa B (NF-κB) Translocation Contribute to the Anti-Inflammatory Effect of Tricin

Tricin is a methylated flavone widely distributed in cereal crops. The mechanism underlying the anti-inflammatory effects of tricin was examined using RAW 264.7 macrophages. Tricin up to 50 μg/mL showed no cytotoxic effects and significantly decreased the levels of nitric oxide (NO) and prostaglandin E2 (PGE2). The inhibition of inducible NO synthase (iNOS) and cyclooxygenase (COX-2) expression were determined by western blotting. The level of iNOS expression was decreased by 80% with tricin concentration as low as 3 μg/mL. Moreover, treatment with tricin significantly decreased the production of pro-inflammatory cytokines, including tumor necrosis factor α (TNF-α), interlukin 1β (IL-1β), and IL-6. These effects were mediated by inhibition of the nuclear factor-kappa B (NF-κB) translocation through stimulation of adenosine monophosphate-activated protein kinase (AMPK) in macrophages. Practical Applications Tricin is a flavonoid found in the outer layer of cereal crops including cereal byproducts. This study demonstrated that anti-inflammatory activity mediated by tricin was related to AMPK activation that inhibits NF-κB translocation. Since AMPK activation is a promising target to modulate lipid and glucose metabolism, tricin has great potential as anti-diabetic and anti-obesity agent. Cereal bran fraction containing high tricin content can be a practical source to deliver valuable bioactive compounds.