Abstract
In this report, protein of hairtail (Trichiurus japonicas) muscle was separately hydrolyzed using five kinds of proteases (alcalase, trypsin, neutrase, pepsin, and papain), and the papain- and alcalase-hydrolysates showed higher 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) and hydroxyl radical (HO•) scavenging activity than other three protease hydrolysates. Therefore, the protein hydrolysate of hairtail muscle (HTP) was prepared using binary-enzymes hydrolysis process (papain + alcalase). Subsequently, eight antioxidant peptides were purified from HTP using membrane ultrafiltration and chromatography technology, and their amino acid sequences were identified as Gln-Asn-Asp-Glu-Arg (TJP1), Lys-Ser (TJP2), Lys-Ala (TJP3), Ala-Lys-Gly (TJP4), Thr-Lys-Ala (TJP5), Val-Lys (TJP6), Met-Lys (TJP7), and Ile-Tyr-Gly (TJP8) with molecular weights of 660.3, 233.0, 217.1, 274.1, 318.0, 245.1, 277.0, and 351.0 Da, respectively. TJP3, TJP4, and TJP8 exhibited strong scavenging activities on DPPH• (EC50 0.902, 0.626, and 0.663 mg/mL, respectively), HO• (EC50 1.740, 2.378, and 2.498 mg/mL, respectively), superoxide anion radical (EC50 2.082, 2.538, and 1.355 mg/mL, respectively), and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical (EC50 1.652, 0.831, and 0.586 mg/mL, respectively). Moreover, TJP3, TJP4, and TJP8 showed higher reducing power and inhibiting ability on lipid peroxidation in a linoleic acid model system. These results suggested that eight isolated peptides (TJP1 to TJP8), especially TJP3, TJP4, and TJP8 might serve as potential antioxidants applied in the pharmaceutical and health food industries.
Highlights
Reactive oxygen species (ROS) such as superoxide anion radical (O2− ), hydrogen peroxide (H2 O2 ), hydroxyl radical (HO), and singlet oxygen (1 O2 ), are formed in aerobic organisms as a natural by-product of oxygen metabolism and play vital roles in the physiological processes involved in signal transduction and homeostasis [1,2]
Enzymatic hydrolysis, and microbial fermentation of food proteins can be used for bioactive peptides production
The enzymatic hydrolysis method is preferred in the food and pharmaceutical industries because the other methods may leave residual organic solvents or toxic chemicals in the final products [7]
Summary
Reactive oxygen species (ROS) such as superoxide anion radical (O2− ), hydrogen peroxide (H2 O2 ), hydroxyl radical (HO), and singlet oxygen (1 O2 ), are formed in aerobic organisms as a natural by-product of oxygen metabolism and play vital roles in the physiological processes involved in signal transduction and homeostasis [1,2]. An imbalance in pro-oxidant/antioxidant can induce oxidative stress, trigger accumulated ROS production, and result in cell damage and many health disorders, such as diabetes mellitus, coronary heart diseases, cancer, Mar. Drugs 2019, 17, 23; doi:10.3390/md17010023 www.mdpi.com/journal/marinedrugs. Oxidation is believed to the major course of food deterioration because ROS-mediated oxidation can react with lipids, proteins, amino acids, vitamins, and cholesterol to produce undesirable off-flavors, and potentially toxicity during food processing, transportation, and storage [3,6]. It is very important for pharmaceutical, health food, and food processing and preservation industries to develop efficient antioxidants [7]. Some artificial antioxidants including butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and tertiary butylhydroquinone (TBHQ) show stronger antioxidant activities and have been widely used in medicine and food industry for retarding oxidation in organisms and food [4,7]
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