Apigenin modulates the expression levels of pro-inflammatory mediators to reduce the human insulin amyloid-induced oxidant damages in SK-N-MC cells.

Amyloid depositions of proteins play crucial roles in a wide variety of degenerative disorders called amyloidosis. Although the exact mechanisms involved in amyloid-mediated cytotoxicity remain unknown, increased formation of reactive oxygen species (ROS) and nitrogen species and overproduction of pro-inflammatory cytokines are believed to play key roles in the process. In that regard, we investigated the effect of apigenin, a common dietary flavonoid with high antioxidant and anti-inflammatory properties on potential factors involved in cytotoxicity of human insulin amyloids. Pretreatment of SK-N-MC neuroblastoma cells with apigenin increased cell viability and reduced the apoptosis induced by insulin fibrils. In addition, apigenin attenuated insulin fibril-induced ROS production and lipid peroxidation. Our result also demonstrated that pretreatment of the fibril-affected cells with apigenin caused an increase in catalase activity and the intracellular glutathione content along with reduction in nitric oxide production and nuclear factor κB, tumor necrosis factor α, and interleukin 6 gene expression based on real-time polymerase chain reaction evaluation. In accordance with these results, apigenin could be a promising candidate in the design of natural-based drugs for treatment or prevention of amyloid-related disorders.