Influence of sericin in alleviating the hydrogen peroxide induced oxidative stress in silkworm Bombyx mori: role of the amino acids

Abstract

Sericin is an important peptide derived from silk fibre spun by the silkworm Bombyx mori and has various biological activities. The aim of the present study was to characterize the major constituents of sericin that are providing cytoprotective effect against hydrogen peroxide-induced cell damage in midgut epithelial cells and hemocytes of silkworm. Extracted sericin was subjected to LCMS analysis for amino acid composition. Isolated cells of midgut and hemocytes were incubated with sericin or with mixture of serine and aspartic acid prior to suboptimal concentration of hydrogen peroxide treatment. Sericin as well as amino acid mixture reduced the activity of antioxidant enzymes triggered by hydrogen peroxide, inhibited oxidative derivatives such as protein carbonyl and malondialdehyde and increased antioxidant capacity in both the cells studied. Furthermore, sericin and amino acid mixture significantly decreased intracellular reactive oxygen species as assessed by fluorescent detection. These results suggest that major constituent amino acids of sericin defend midgut epithelial cells and hemocytes against oxidative damage by scavenging reactive oxygen species rather than activating antioxidant enzyme system thereby inhibiting cell damage.