酵母源金属硫蛋白体外抗氧化能力测定

Determination of in vitro antioxidant capacity of metallothionein from yeast

目的测定酵母源金属硫蛋白(metallothionein,MT)-1、MT-2体外抗氧化能力。方法以动物源金属硫蛋白(Zn-MT)为对照,测定酵母源MT对1,1-二苯基-2-苦苯肼自由基(DPPH)、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基(ABTS^+·)、羟基自由基(OH·)、超氧阴离子自由基(·O_2^-)的清除能力、总还原能力及抑制脂质体过氧化能力大小。结果 3种MT均对自由基有良好的清除能力,在20~100μg/ml范围内,酵母源MT-1、MT-2及Zn-MT随质量浓度的增加,对4种自由基的清除能力均不断增强,且增加趋势几乎一致;3种MT随质量浓度增加,对自由基清除能力的增率趋于平缓。3种MT对ABTS^+·、OH·、·O_2^-的清除能力差异有统计学意义(P<0.01),清除能力大小为Zn-MT>MT-1>MT-2;对DPPH自由基清除能力大小为Zn-MT>MT-1>MT-2,MT-2与Zn-MT及MT-1之间差异有统计学意义(P<0.01)。3种MT总还原能力随质量浓度的增加均不断增强,其中酵母源MT-1与酵母源MT-2及Zn-MT之间的IC_(50)值差异有统计学意义(P<0.01),总还原能力大小为Zn-MT>MT-1>MT-2。3种MT均可有效抑制脂质体过氧化的产生,并随质量浓度的增加对脂质体过氧化的抑制率平缓上升,除酵母源MT-1外,在60~100μg/ml浓度范围内,MT对脂质体过氧化抑制能力的增率小于20~60μg/ml范围,且Zn-MT抑制脂质过氧化的效果优于酵母源MT,其IC_(50)大小为Zn-MT>MT-1>MT-2,其中酵母源MT-1与酵母源MT-2及Zn-MT之间差异有统计学意义(P<0.01)。结论两种酵母源MT对体外自由基均有良好的清除效果及抑制脂质体过氧化的效果,显示出良好的体外抗氧化特性,且其体外抗氧化能力酵母源MT-1>MT-2。

Objective To determine the in vitro antioxidant capacity of metallothionein（MT）-1 and MT-2 from yeast.Methods The abilities of MT from yeast in clearance of free radicals including 1, 1-diphenyl-2-phenylphenyl free radical（DPPH）, 2, 2＇-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid）diammonium salt（ABTS~＋·）, hydroxyl radical（OH·）and superoxide anion radical（·O_2^-）, as well as total reduction capacity and inhibition of liposome peroxidation, were determined using the Zn-MT for animal origin as control. Results All the three MTs showed good ability in clearance of free radicals. The abilities of MT-1, MT-2 and Zn-MT at concentrations of 20 ~ 100 μg/ml increased with the increasing concentration, and the increasing trend was almost in agreement. However, the increased rates of clearance abilities of the three kinds of MTs showed stable tendencies with the increasing concentration. The abilities of MTs in clearance of ABTS~＋·, OH· and ·O_2^-showed significant difference（P 0. 01）. In the turn of clearance abilities to the three free radicals, the MTs were Zn-MT, MT-1 and MT-2. However, in the turn of clearance ability to DPPH, the MTs were Zn-MT,MT-1 and MT-2, while the clearance ability of MT-2 showed significant difference with those of Zn-MT and MT-1（P 0. 01）. The total reduction ability of MTs increased with the increasing mass concentration, while the IC_（50） values of MT-1showed significant difference with those of MT-2 and Zn-MT（P 0. 01）. In the turn of total reduction capacity, the MTs were Zn-MT, MT-1 and MT-2. All the three kinds of MTs effectively inhibited the production of lipid peroxidation, of which the inhibitory rate increased steadily with the increasing concentration. However, the increasing rates of inhibition abilities of Zn-MT and MT-2 at concentrations of 60 ~ 100 μg/ml were lower than those at 20 ~ 60 μg/ml. The inhibitory effect of Zn-MT was superior to that of MTs from yeast. In the turn of IC_（50）, the MTs were Zn-MT, MT-1 and MT-2, while the IC_（50） of MT-1 showed significant difference with those of MT-2 and Zn-MT（P 0. 01）. Conclusion Both the MTs from yeast showed abilities in clearance of free radicals in vitro and inhibition of liposome peroxidation, indicating good antioxidant properties in vitro. However, the antioxidant ability in vitro of MT-1 was higher than that of MT-2.