大眼金枪鱼头蛋白酶解物1 ku超滤组分的抗氧化活性及其理化性质

研究大眼金枪鱼头蛋白酶解物1 ku超滤组分体外的还原力、自由基清除能力及对衰老小鼠体内抗氧化能力的影响,分析1 ku超滤组分的一般成分、氨基酸组成及分子量分布,为进一步分离纯化金枪鱼头抗氧化肽提供基础。体外结果显示,1 ku超滤组分对羟基自由基、超氧阴离子和DPPH自由基的清除活性随浓度的增加而增强,IC50分别为1.38、0.73与0.93mg/mL,还原力也随浓度的增加而增大,在浓度为12.5 mg/mL时为0.763;体内结果显示,灌胃30 mg/kg的1 ku超滤组分连续42 d,D-半乳糖致衰老小鼠肝组织的超氧化物歧化酶(SOD)活性、肝组织和血清的谷胱甘肽过氧化物酶(GSH-PX)活性显著提高(P<0.05),血清丙二醛(MDA)含量显著降低(P<0.01);理化分析结果显示,1 ku超滤组分(干基计)蛋白质含量为96.40%,脂肪0.11%,灰分4.86%,疏水性氨基酸占氨基酸总量的35.8%,活性组分分子量在1 802~2 519 u和422~922 u。

Antioxidant activity and physicochemical properties of 1 ku fraction by ultrafiltration of bigeye tuna (Thunnus obesus) head protein hydrolysate

To produce bioactive peptides from the by-products of fish processing, bigeye tuna (Thunnus obesus) head was hydrolyzed by alcalase, and the tuna head protein hydrolysate (THPH) was fractionated through ultrafiltration membranes with a range of molecular weight cutoffs (MWCO) of 8, 5, 3 and 1 ku, respectively, to yield the fraction THPH-1 with MW distribution<1 ku. The antioxidant activities of THPH-1were evaluated using reducing power, free radical scavenging and aged model mice induced by D-galactose. The physicochemical properties of THPH-1 were analysed also. THPH-1 showed evident radical scavenging activity in a dose-dependent manner with the IC₅₀ values for hydroxyl radical, superoxide radical and 1,1-diphenyl-2-pycrylhydrazyl (DPPH) radical being 1.38, 0.73 and 0.93 mg/mL respectively. The reducing power of THPH-1 was 0.763 at 12.5 mg /mL. The activities of superoxide dismutase (SOD) of liver and the activities of glutathione peroxidase (GSH-PX) of liver and serum in aged model mice were significantly increased (P<0.05) compared with that of the normal control group mice after 42 days administrated orally at a dose of 30 mg/kg THPH-1, and the content of malondialdehyde (MDA) of serum in aged model mice was significantly decreased (P<0.01).The physicochemical properties showed that THPH-1contained 96.40% of protein(on dry basis), 0.11% of fat and 4.86% of ash. The total hydrophobic amino acids content of THPH-1was 35.8% of the total amino acids content. The molecular weight distribution of the higher activity fractions of THPH-1were located at 1 802-2 519 u and 422-922 u.These results indicate that THPH-1from tuna head hydrolysate would be very fairly helpful in the preparation of antioxidative peptides and a beneficial ingredient for functional food.