Preparation and Characterization of Antarctic Krill Peptides with Multiple Bioactivities

Bioactive peptides have been widely used in food, medicine, healthcare products and other fields due to their diverse bioactivities. Antarctic krill (Euphausia superba) is a huge Antarctic biological resource with high nutritional value, which is now commonly used for krill oil production. However, its potential as a high-quality protein source remains underexploited. This study established a technological process for preparing AKPs based on the optimization of hydrolysis parameters and determined their physicochemical properties and biological activities. Additionally, multiple bioactive peptides in AKPs were identified. The prepared AKPs are rich in low-molecular-weight peptides, and contain 20 amino acids including 9 human essentials. The AKPs have high antioxidant activity, with scavenging rates for free radicals ABTS+, DPPH· and ·OH reaching 93.33% (at 10 mg/mL), 99.58% (at 30 mg/mL) and 92.33% (at 40 mg/mL), respectively. The AKPs exhibited significant inhibition of angiotensin-converting enzyme (ACE), evidenced by an IC50 value of 0.27 mg/mL, suggesting antihypertensive potential. Furthermore, at a concentration of 40 mg/mL, the AKPs also suppressed the activities of α-glucosidase and dipeptidyl peptidase IV (DPP-IV) by 12.15% and 16.89%, respectively, demonstrating hypoglycemic effects. The antibacterial activity of the AKPs against Escherichia coli was also observed. Further analysis revealed that the AKPs contain a spectrum of bioactive peptides, comprising 39 distinct sequences with functions in antioxidant, antihypertensive, and hypoglycemic activities. These included 11 antioxidants, 19 ACE inhibitors, 2 α-glucosidase inhibitors, and 7 DPP-IV inhibitors. The prepared AKPs have multiple bioactivities, and may have wide applications. This research presents a viable strategy for the valorization of defatted Antarctic krill powder, enhancing its commercial value and paving the way for high-value applications.