基于Ce(IV)分光光度法的天然产物抗氧化活性的评价

基于在H2SO4,Na2SO4介质中稳定存在的Ce(IV)的还原,在320 nm时,采用紫外可见分光光度计测定Ce(IV)吸光度,建立还原率与样品浓度的剂量关系,以线性关系的斜率为主要评价指标,评价样品的抗氧化活性。结果表明:针对5种结构相近的黄酮化合物,抗氧化活性顺序为:槲皮素>山奈酚>木犀草素>芹菜素>黄芩素;针对中药植物湖北旋覆花,抱石莲和吉祥草的提取物,正丁醇、乙酸乙酯部位是抗氧化活性成分的主体部位,但在旋覆花和抱石莲中,正丁醇部位抗氧化活性更强,而在吉祥草中,乙酸乙酯部位明显强于正丁醇部位;此外,不同提取方法得到的提取物抗氧化活性不同,低温回流和超声提取均可提高效率,但超声提取的时间应该控制在30 min以内。本评价方法操作简单,结果稳定可靠,检测限低,适合于天然产物抗氧化活性植物及活性部位的快速筛选。

Determination of antioxidant activity of natural products based on the spectroscopic absorbance of Ce(IV)

The relationship between reductivity of Ce(IV)in the medium of H2SO4+Na2SO4,which was measured by spectrophotometric absorbance in a wavelength at 320 nm,and the anti-oxidation activity of natural sample was established.It was found that the trends of antioxidant activity was auercetin>luteolin>kaempferol>apigenin>baicalein for 5 flavonoids with similar structures which was consistent with relative reports.For the plant extracts of inula hupehensis,lepidogrammitis drymoglossoide and reineckea carnea,n-butanol and ethyl acetate parts contained the main antioxidant components.In inula hupehensis and lepidogrammitis drymoglossoide,antioxidant activity of n-butanol extract was stronger than ethyl acetate extract;but for reineckea carnea,antioxidant activity of ethyl acetate extract was stronger.Warm reflux and ultrasonic method could improve the extraction efficiency for antioxidation components,but the time of ultrasonic extraction should be controlled within 30 min.The build measurement was simple for operation,as well as stable and reliable,and low detection limit.It was suitable for the determination of low concentration flavonoid compounds,and rapid screening of antioxidant activity of natural products.