不同分子质量虾源壳寡糖的抗菌抗氧化活性差异研究

Antibacterial and antioxidant activities of shrimp-derived chitosan oligosaccharides with different molecular weights

为明确虾源壳寡糖的抗菌抗氧化活性与其数均分子质量之间的相关性,该研究采用乙醇分级沉淀法分离虾源壳聚糖酶解物,得到4种不同分子质量的壳寡糖产品(COS50、COS60、COS70、COS70 s),数均分子质量分别为2365、2807、3105、1390 Da。比较4种壳寡糖产品的抑菌抗氧化活性,发现COS50(数均分子质量为2362 Da)对大肠杆菌、枯草杆菌、金黄色葡萄球菌、假单胞菌和希瓦氏菌均有较强的抑菌效果,对上述各种菌的最低抑菌浓度(minimal inhibitory concentration,MIC)值分别为2.50、1.25、1.25、0.62、0.16 mg/mL;壳寡糖的抗氧化能力整体上随着数均分子质量的增加而减弱,COS50清除DPPH自由基的能力最强,清除自由基一半所需浓度(IC 50)为0.90 mg/mL,COS70 s的总还原力最强(每克相当于9.87 mg抗坏血酸的还原力),COS50次之。综合考虑抗菌抗氧化活性,COS50(数均分子质量为2362 Da)为具备抗菌抗氧化性能的最优壳寡糖。该研究为虾源壳寡糖的开发应用提供理论参考。

To clarify the correlation between the antibacterial and antioxidant activities of shrimp-derived chitosan oligosaccharide and their average molecular weight,this study used ethanol fractional precipitation method to separate shrimp-derived chitosan hydrolysate,and obtained four chitosan oligosaccharide(COS50,COS60,COS70,COS70 s)with the average molecular weight of 2365,2807,3105,1390 Da,respectively.The antibacterial and antioxidant activities of the four chitosan oligosaccharides were compared.It was found that COS50(the average molecular weight of 2362 Da)had strong antibacterial effects on Escherichia coli,Bacillus subtilis,Staphylococcus aureus,Pseudomonas,and Shewanella,and the minimum inhibitory concentration(MIC)for the above-mentioned bacteria were 2.50,1.25,1.25,0.62,0.16 mg/mL,respectively.Overall,the antioxidant activity of chitosan oligosaccharides decreased with the increase of molecular weight.COS50 had the strongest ability to scavenge DPPH radicals with IC 50 of 0.90 mg/mL.COS70s had the strongest total reducing power(equivalent to 9.87 milligram ascorbic acid per g),followed by COS50.Therefore,considering the antibacterial and antioxidant activities,COS50(average molecular weight of 2362 Da)was the optimal chitosan oligosaccharide.This study provides a theoretical reference for the development and application of shrimp-derived chitosan oligosaccharide.