Corn Silk Extract and Its Bioactive Peptide Ameliorated Lipopolysaccharide-Induced Inflammation in Mice via the Nuclear Factor-κB Signaling Pathway

Bioactive peptides derived from foods have shown beneficial anti-inflammatory potential. Inhibitory kappa B kinase-beta (IKK beta) plays a crucial role in the activation of nuclear factor-kappa B (NF-kappa B), a transcription factor involved in inflammation. Here we applied proteomic and bioinformatics approaches to identify anti-inflammatory peptides that target IKK beta, from corn silk. Corn silk extract significantly suppressed lipopolysaccharide (LPS)-induced NF-kappa B activities [(1.7 +/- 0.2)-fold vs (3.0 +/- 0.6)-fold, p < 0.05] in cells. Trypsin hydrolysate of corn silk also suppressed LPS-induced NF-kappa B activities [(1.1 +/- 0.3)-fold vs 3.3 +/- 0.5 fold, p < 0.01]. In addition, both corn silk extract and trypsin hydrolysate significantly inhibited LPS-induced interleukin-1 beta (IL-1 beta) production by 58.3 +/- 4.5 and 55.1 +/- 7.4%, respectively. A novel peptide, FK2, docked into the ATP-binding pocket of IKK beta, was further identified from trypsin hydrolysis of corn silk. FK2 inhibited IKK beta activities, I kappa B phosphorylation, and subsequent NF-kappa B activation [(2.3 +/- 0.4)-fold vs (5.5 +/- 0.4)-fold, p < 0.001]. Moreover, FK2 significantly reduced NF-kappa B-driven luminescent signals in organs by 5-11-fold and suppressed LPS-induced NF-kappa B activities and IL-beta production in tissues. In conclusion, our findings indicated that corn silk displayed anti-inflammatory abilities. In addition, we first identified an anti-inflammatory peptide FK2 from corn silk. Moreover, the anti-inflammatory effect of FK2 might be through IKK beta-NF-kappa beta signaling pathways.