黄芪多糖对黄嘌呤氧化酶活性的抑制作用

Inhibitory Effects of Astragalus Polysaccharideon Activity of Xanthine Oxidase

摘要:

黄嘌呤氧化酶是尿酸生成的关键酶，通过抑制黄嘌呤氧化酶的活性可以有效降低机体内尿酸的含量。为探究黄芪多糖对黄嘌呤氧化酶的抑制作用，采用紫外分光光度法测定单位时间内酶促反应体系中酶活力的变化，计算不同质量浓度的黄芪多糖对黄嘌呤氧化酶的抑制率，得到半抑制浓度IC₅₀。双倒数作图法判断黄芪多糖对黄嘌呤氧化酶的抑制类型，并计算抑制常数K_i值，等毒法评价黄芪多糖与别嘌呤醇的联合作用效果。黄芪多糖能够抑制黄嘌呤氧化酶的活性，其IC₅₀为1.37 mg/mL。动力学分析表明，黄芪多糖对黄嘌呤氧化酶为竞争性可逆抑制作用，抑制常数K_i为0.59 mg/mL。黄芪多糖与别嘌呤醇的联合作用表现为拮抗作用，黄芪多糖对黄嘌呤氧化酶的活性有抑制作用。

Abstract:

Xanthine oxidase is a key enzyme in uric acid formation, which can effectively reduce the content of uric acid in vivo by inhibiting the activity of xanthine oxidase. To explore the inhibitory effects of Astragalus polysaccharide on xanthine oxidase, the variation of uric acid content of reaction system per unit time was determined by UV-Spectrophotometry, and the inhibition ratio of Astragalus polysaccharide to xanthine oxidase was calculated. The semi-inhibitory concentration IC₅₀ was also obtained. The inhibition type of Astragalus polysaccharide on xanthine oxidase was determined by the Lineweaver-Burk plot, and a Dixon plot was used to obtain the inhibition kinetic parameter(K_i). The inhibitory effects of Astragalus polysaccharide combining allopurinol were explored by the toxicological studies. Astragalus polysaccharide could inhibit the activity of xanthine oxidase, and the IC₅₀ was 1.37 mg/mL. The kinetic analysis showed that Astragalus polysaccharide had competitive and reversible inhibitory effect on xanthine oxidase, with an inhibition constant (K_i ) of 0.59 mg/mL. There was antagonism effect when Astragalus polysaccharide was combined with allopurinol. Astragalus polysaccharide could inhibit the activity of xanthine oxidase.