Antioxidant and cytotoxic properties of protein hydrolysates obtained from enzymatic hydrolysis of Klunzinger’s mullet (Liza klunzingeri) muscle

Today, consumers are looking for functional foods that promote health and prevent certain diseases in addition to provide nutritional requirements. This study aimed to evaluate the antioxidant and cytotoxic properties of Liza klunzingeri protein hydrolysates. Fish protein hydrolysates (FPHs) were prepared from L. klunzingeri muscle using enzymatic hydrolysis with papain at enzyme/substrate ratios of 1:25 and 1:50 for 45, 90 and 180 min. The antioxidant activities of the FPHs were investigated through five antioxidant assays. The cytotoxic effects on 4T1 carcinoma cell line were also evaluated. The amino acid composition and molecular weight distribution of the hydrolysate with the highest antioxidant activity were determined by HPLC. All six FPHs exhibited good scavenging activity on ABTS (IC50=0.60-0.12 mg/mL), DPPH (IC50= 3.18-2.08 mg/mL), and hydroxyl (IC50=4.13-2.07 mg/mL) radicals. They also showed moderate Fe+2 chelating capacity (IC50=2.12-12.60 mg/mL) and relatively poor ferric reducing activity (absorbance at 70 nm= 0.01-0.15, 5 mg/mL). In addition, all hydrolysates showed cytotoxic activities against the 4T1 cells (IC50=1.62-2.61 mg/mL). 94.6% of peptide in hydrolysate with the highest antioxidant activity had molecular weight less than 1,000 Da. L. klunzingeri protein hydrolysates show significant antioxidant and anticancer activities in vitro and are suggested to be used in animal studies.

当前，消费者在寻求满足营养需求的同时，也愈发青睐兼具健康促进与疾病预防功效的功能性食品。本研究旨在评估昆氏棱鲻（Liza klunzingeri）蛋白水解物的抗氧化与细胞毒性特性。研究以木瓜蛋白酶（papain）为水解用酶，按酶与底物比1:25及1:50的比例，对昆氏棱鲻肌肉进行酶解，分别制备得到酶解时长为45、90、180分钟的鱼蛋白水解物（fish protein hydrolysates, FPHs）。通过五项抗氧化实验对鱼蛋白水解物的抗氧化活性进行检测，并评估其对4T1癌细胞系的细胞毒性作用。采用高效液相色谱（HPLC）测定抗氧化活性最优的水解物的氨基酸组成与分子量分布情况。全部六组鱼蛋白水解物均对ABTS自由基、DPPH自由基及羟基自由基表现出良好的清除活性，其半数抑制浓度（IC50）分别为0.60~0.12 mg/mL、3.18~2.08 mg/mL与4.13~2.07 mg/mL。同时，此类水解物还展现出中等强度的Fe²+螯合能力（IC50=2.12~12.60 mg/mL），以及相对较弱的铁还原活性（5 mg/mL浓度下70 nm处吸光度为0.01~0.15）。此外，所有水解物对4T1细胞均表现出细胞毒性活性，其IC50值介于1.62~2.61 mg/mL之间。抗氧化活性最优的水解物中，94.6%的肽段分子量低于1000 Da。综上，昆氏棱鲻蛋白水解物在体外具备显著的抗氧化与抗肿瘤活性，建议开展相关动物实验进行后续验证。