Silk peptide production from whole silkworm cocoon using ultrasound and enzymatic treatment and its suppression of solar ultraviolet-induced skin inflammation

Silk fibroin, which is derived from sericin through degumming, is mainly used as a biomaterial. However, interest in functional verification and industrial applications of sericin has been growing for several years. We used ultrasonication to simplify the extraction process of the silk peptide under low salt conditions at 20 °C, instead of using the conventional conditions of high salt and temperature. The concentration of the silk peptide was measured to determine the optimized extraction time and solvent, which were 4 h and 0.1 N NaOH, respectively. The molecular weight of the enzyme-treated silk peptide was measured using SDS-PAGE and GPC. Silk peptide treated with papain after ultrasound had a molecular weight of less than 5 kDa, and the papain treated-silk peptide reduced solar ultraviolet-induced COX-2 expression through inhibition of ERK phosphorylation. This is the first study investigating simultaneous extraction of fibroin and sericin, which can be used for mass production of food materials.