Purification and identification of novel antioxidant peptides derived from Bombyx mori pupae hydrolysates

The biological importance of antioxidant peptides was the focus of new natural sources of food preservatives. Bombyx mori pupae are considered a valuable by-product of the silk-reeling industry due to their high-quality protein content. This study aimed to purify and identify the antioxidant peptides obtained from enzymatically hydrolyzed B. mori pupae, which could be used as new sources of natural food preservatives. Among the prepared hydrolysates, pepsin hydrolysate with the highest antioxidant activities was purified sequentially using ultrafiltration and reversed-phase high-performance liquid chromatography (RP-HPLC). The DPPH radical scavenging and ferrous ion chelating activity were used to evaluate antioxidant activity. Fractions with high activity were further analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Three peptides were identified as Glu-Asn-Ile-Ile-Leu-Phe-Arg (ENIILFR), Leu-Asn-Lys-Asp-Leu-Met-Arg (LNKDLMR), and Met-Leu-Ile-Ile-Ile-Met-Arg (MLIIIMR), respectively. All three novel identified peptides exhibited significantly stronger antioxidant capacity than synthetic antioxidants used in the food industry, including butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT). ENIILFR showed the best antioxidant activity. These findings indicate that the three peptides have potential applications as natural antioxidants in the food industry.