木贼醇提物不同萃取部位总酚酸、黄酮含量测定及抗氧化活性研究

目的:对木贼的乙醇提取物不同萃取部位进行总酚酸、黄酮含量测定及抗氧化活性比较,以探知木贼抗氧化活性物质基础。方法:木贼经70%乙醇超声提取浓缩后,采用有机溶剂萃取法依次得到石油醚、乙酸乙酯、正丁醇、水相4个部位萃取物;利用紫外-分光光度法比较各萃取部位总黄酮、酚酸含量差异;以抗坏血酸为阳性对照,比较不同萃取部位还原能力、羟自由基(·OH)、1,1-二苯基-2-三硝基苯肼(DPPH·)、2,2'-联氮-双(3-乙基苯并噻唑-6-磺酸)二铵盐(ABTS+·)清除率的差异,评价各部位抗氧化能力强弱。结果:木贼各萃取物总黄酮含量在5.70~61.55 mg/g 范围内,总酚酸含量在4.07~19.10 mg/g 范围内,乙酸乙酯萃取物总黄酮与酚酸含量明显高于其他萃取物,其还原能力、羟自由基、DPPH·、ABTS+·清除率也明显高于正丁醇、石油醚和水相萃取物,乙酸乙酯萃取物对羟自由基、ABTS+·、DPPH·清除能力IC₅₀值分别为:(0.321±0.0026)、(0.213±0.0010)和(0.169±0.0014) mg/mL。结论:经各相溶剂萃取后木贼有效成分得到初步分离,乙酸乙酯相萃取部位总黄酮和酚酸相对含量及抗氧化活性明显强于总提物和其他萃取部位,且其抗氧化能力呈量效关系。实验发现木贼中黄酮和酚酸类成分与其抗氧化能力密切相关。

Determination of total phenolic acids,flavonoids of different solvent extracts from Equisetum hiemale L. and the antioxidant activity effects

Objective:To measure antioxidant activity components in Equisetum hiemale L. by determining the total phenolic acid and flavonoids of different solvent extracts,then comparing the antioxidant activity effects. Methods:70% ethanol ultrasonic extracts from Equisetum hiemale L. were partitioned by petroleum ether,ethyl acetate,n-butanol and water to obtain four extracts respectively. Then UV-spectrophotometry was applied to compare the contents of total flavonoids and phenolic acids. In contrast to Vit. C,differences of the reduction ability and the removing ratio to hydroxyl radical,DPPH·,ABTS+· were found to evaluate the antioxidant activities.Results:There were remarkable differences in both chemical components and antioxidants among the extracts. The total flavonoids contents of different extracts of Equisetum hiemale L. were 5.70~61.55 mg/g,and the total phenolic acid contents 4.07~19.10 mg/g. It indicated that ethyl acetate extracts had the highest contents of total flavonoids and phenolic acids,and the strongest antioxidant activities among all the extracts. The values of IC₅₀ based on hydroxyl radical,ABTS+· and DPPH· were(0.321±0.0026),(0.213±0.0010) mg/mL,and(0.169±0.0014) mg/mL respectively. Conclusion:After the solvent extraction from each phase,the effective components of Equisetum hiemale L. were separated preliminarily. The relative contents of total flavonoids and phenolic acids and their antioxidant activities in the ethyl acetate extract phase were significantly higher than other extraction fractions. And its antioxidant capacity was dose-effect relationship. The experiment showed that the flavonoids and phenolic acids were closely related to their antioxidant capacity.