Preparation of Oligopeptides from Holothuria leucospilota and Analysis of Their Antioxidant Activity in Vitro

Abstract:

[Objective] This study aims to analyze the nutritional components of Holothuria leucospilota body wall, optimize the preparation process of Holothuria leucospilota oligopeptides, and evaluate their antioxidant activity in vitro. [Method] The basic nutritional components and amino acid composition were determined via national standard methods. Through protease screening and single-factor experiments combined with orthogonal design, the conditions for enzymatic hydrolysis were optimized, with the polypeptide yield and relative molecular weight distribution serving as evaluation indicators. Antioxidant activity in vitro of the obtained oligopeptides was assessed based on the free radical scavenging rates and Fe²⁺-chelating ability. [Result] The body wall of Holothuria leucospilota (on a dry basis) exhibited the highest crude protein mass fraction of (64.59±9.45)%. The conditions for enzymatic hydrolysis were optimized as follows: hydrolysis with 3 000 U/g alkaline protease and a solid-to-liquid ratio of 1 g∶11 mL at 70 ℃ and pH 9.5 for 3 h. Under these conditions, the polypeptide yield reached 75.75%, with over 98.00% of components having the relative molecular mass below 2 000. The IC₅₀ of the obtained oligopeptides for scavenging ABTS⁺ free radicals, scavenging hydroxyl free radicals, scavenging superoxide anion free radicals, and chelating Fe²⁺ were 0.93, 0.51, 8.97, and 0.40 mg/mL, respectively. [Conclusion] The body wall of Holothuria leucospilota is rich in high-quality protein. The established enzymatic hydrolysis process is efficient and feasible, with a high polypeptide yield. The obtained oligopeptides of Holothuria leucospilota demonstrate strong antioxidant activity, serving as a potential raw material for the development of functional foods.