Antioxidant, pancreatic lipase, and α-amylase inhibitory properties of oat bran hydrolyzed proteins and peptides

Abstract

This work aimed to determine the antioxidant properties of identified hydrolyzed oat proteins and peptides, and their capacity to inhibit lipase and α-amylase. The protein hydrolysates retarded the oxidation of peanut oil by reducing peroxide values (up to 2.5-fold), relative to the control oil. Of the five tested peptides, P1 (YFDEQNEQFR), P3 (SPFWNINAH), and P4 (NINAHSVVY) significantly reduced the oxidation of linoleic acid. In the enzyme assays, P3 was the best lipase inhibitor (IC₅₀ 85.4 ± 3 µM) while P1 was the most potent inhibitor of α-amylase (IC₅₀ 37.5 ± 1.1 µM). The structure-activity relationship assessed using the CABS-dock computational model predicted that interactions between peptides and pancreatic lipase residues of Ser¹⁵³ , His²⁶⁴ , and Asp¹⁷⁷ were important for the inhibition. In the case of α-amylase, interactions with residues of the active sites (Asp¹⁹⁷ , Glu²³³ , and Asp³⁰⁰ ), but not those of calcium- or chloride-binding domains, were important for the inhibition. PRACTICAL APPLICATIONS: In recent years, there have been many studies focussing on isolating multifunctional peptides from food and food waste with antioxidant and bioactivity potential to promote human health. Some of these antioxidant peptides have been found to be effective to prevent diseases and complications such as hypertension, cardiovascular disease, cancer, diabetes, and obesity. The peptides studied in this work showed a great potential to prevent oxidation in a lipid system and demonstrated a significant ability to reduce the enzymatic activity of lipase and α-amylase. These enzymes contribute to the digestion of fat and carbohydrate, and their inhibition can reduce the absorption of these macronutrients and make them a great target for designing antioxidant and anti-obesity compounds. With the multifunctional activity of oat bran-derived peptides, it is proposed that these peptides can be used in food formulations due to their antioxidant and potential anti-obesity properties.

Keywords: antioxidant; enzyme inhibitory activity; lipase; lipid peroxidation; peptides; α-amylase.