The anti-inflammatory effects of apigenin and genistein on the rat intestinal epithelial (IEC-6) cells with TNF-? stimulation in response to heat treatment

The aims of the present study were to investigate the anti-inflammatory function of two flavonoids apigenin and genistein in rat intestinal epithelial (IEC-6) cells stimulated by tumor necrosis factor-alpha (TNF-alpha) and to clarify whether the heat treatment of the flavonoids might affect flavonoid activity. The flavonoids at lower dosage (e.g. 5 mu mol/L) had no toxic effect but growth promotion on the cells. Meanwhile, the flavonoid pretreatment of the cells before TNF-alpha stimulation could maintain cellular morphology, decrease the production of prostaglandin E2 and two pro-inflammatory cytokines interleukin-1 beta (IL-1 beta) and IL-6, but increase the production of two antiinflammatory cytokines IL-10 and transforming growth factor-beta. Additionally, the flavonoids could block off the nuclear translocation of nuclear factor-kappaB (NF-kappa B) p65, and suppress the expression of phosphorylated I kappa B alpha and p65 induced by TNF-alpha. Meanwhile, the NF-kappa B inhibitor BAY 11-7082 shared a similar function with the flavonoids to mediate the production of IL-6/IL-10. Furthermore, in silico analysis also declared that the flavonoids could interact with the I kappa B alpha-NF-kappa B complex at the binding pockets to yield the binding energies ranging from -31.7 to -34.0 kJ/mol. However, the heated flavonoids were consistently less effective than the unheated counterparts to perform these anti-inflammatory effects. It is thus proposed that both apigenin and genistein have anti-inflammatory potential to the TNF-alpha-stimulated IEC-6 cells by inactivating the NF-kappa B pathway, while heat treatment of the flavonoids caused a negative impact on these assessed anti-inflammatory effects.