Antioxidant and anti-inflammatory activity of peptides from foxtail millet (Setaria italica) prolamins in HaCaT cells and RAW264.7 murine macrophages

Peptides from natural plant proteins have been observed to show various bioactivities in many studies. In this paper, oxidation resistance and anti-inflammatory effect of three millet prolamins peptides (MPP) was evaluated, including peptides with molecular weight below 1kDa obtained from hydrolysate by alcalase and two other peptides: Pro-Phe-Leu-Phe (PFLF) and Ile-Ala-Leu-Leu-Ile-Pro-Phe (IALLIPF), in human keratinocyte HaCaT cells and RAW264.7 murine macrophages. As a result, MPP effectively reduced the production of reactive oxygen species (ROS) as well as malondialdehyde (MDA) but increased the level of glutathione (GSH) in H2O2-induced HaCaT cells, showing anti - oxidant bioactivity in cells. To be specific, IALLIPF could more effectively both de-crease the ROS and increase GSH than the other two peptides. And PFLF had better activity to reduce MDA production. In addition, MPP were able to significantly alleviate inflammation by inhibiting the yield of nitric oxide (NO) and pro-inflammatory cytokines (TNF-alpha, interleukin IL-6 and IL-1 beta) in (lipopolysaccharide) LPS-stimulated RAW264.7 murine macrophages. Moreover, these findings suggested that MPP pre-treatment lowered the level of p-I kappa B and p65 by suppressing the translocation of NF-kB to cell nucleus. Besides, this effect might be related to the inhibition of MAPK pathway as well. Therefore, this study suggested that MPP could be a possible anti-inflammatory alternative for the therapy of inflammatory related illness.