## 1 Introduction  
Reactive oxygen species (ROS) such as superoxide anion radical (O\({}_{2}^{-}\bullet\)), hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)), hydroxyl radical (HO\(\bullet\)), and singlet oxygen (\({}^{1}\)O\({}_{2}\)), 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]. Under normal conditions, superfluous ROS are effectively eliminated by antioxidant enzymes and non-enzymatic factors in organisms [3]. 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,hepatic diseases, and inflammatory diseases [4; 5]. Additionally, 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]. Therefore, it is very important for pharmaceutical, health food, and food processing and preservation industries to develop efficient antioxidants [7]. At present, 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]. However, the side effects of synthetic antioxidants such as liver damage and carcinogenesis causes consumer anxiety and significantly affect their application [7; 8]. Therefore, there has been a major interest in searching for efficient antioxidants from natural sources as alternatives to synthetic antioxidants for countering these adverse effects. At present, dietary antioxidant ingredients including vitamins, carotenoids, flavonoids, phenols, saccharides, and peptides, have been continually investigated for their health benefits in terms of their scavenging potential of free radicals and low toxicity [9]. Among them, bioactive peptides released from food proteins under controlled proteolysis have aroused wide public concern not only in their possibilities as natural alternatives to synthetic antioxidants, but also for their beneficial effects, lack of residual side effects, and functionality in food systems [10]. Antioxidant peptides from food resources are inactive in the amino acid sequence of their parent proteins and are produced by in vitro enzymatic hydrolysis [7]. These peptides with 2 to 20 amino acid residues are considered to be easy absorption and no hazardous immunoreactions. More importantly, antioxidant peptides can exert their activity as free radical scavengers, peroxide decomposers, metal inactivators and oxygen inhibitors to protect food and organisms from ROS [11; 12; 13]. In recent years, antioxidant peptides derived from seafood were more attractive and have been isolated and identified from diverse marine organisms, such as swim bladders of miuuy croaker (_Miichthys miuuy_) [6], bluefin leatherjacket (_Navodon septentronials_) heads and skin [8; 14], thornback ray skins [15], _Palmaria palmate_[16], viscera and carcass of Nile tilapia [17], _Pinctada fucata_[18], pectoral fin of salmon [19], and jellyfish gonad [20]. [PERSON] et al. isolated ten antioxidant peptides from swim bladders of miuuy croaker, and PYLRH and GIEWA exhibited stronger scavenging activities on 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH\(\bullet\)), hydroxyl radical (HO\(\bullet\)), and superoxide anion radical (O\({}_{2}^{-}\bullet\)) than other eight peptides. Furthermore, FPYLRH and GIEWA could effectively inhibit lipid peroxidation in the \(\beta\)-carotene linoleic acid and in the linoleic acid emulsion system [6]. [PERSON] et al.