番石榴叶乙酸乙酯萃取物的体外抗氧化活性及化学成分的分离鉴定

Isolation and Identification of Chemical Constituents and In Vitro Antioxidant Activity of Ethyl Acetate Extracts from Psidium guajava Linn Leaves

本文研究了番石榴叶乙酸乙酯萃取物的体外抗氧化活性及活性物质基础。采用95%乙醇溶液浸泡提取、正己烷和乙酸乙酯萃取后得到粗提物,首先分析了乙酸乙酯萃取物的体外抗氧化活性,然后通过硅胶柱色谱、Sephadex LH-20凝胶柱色谱、质谱和核磁共振等技术对乙酸乙酯萃取物的化学成分进行了分离和鉴定。结果表明,乙酸乙酯萃取物对DPPH自由基、超氧阴离子、羟自由基具有较强的体外抗氧化活性,清除能力随着浓度的增大而增强,当浓度为1 mg/m L时,对DPPH自由基、超氧阴离子和羟自由基的清除率分别达94.15%、87.88%和67.3%,清除效果接近或强于同浓度的Vc。通过硅胶柱色普、Sephadex LH-20凝胶柱色谱等技术从番石榴叶乙酸乙酯萃取部位中分离纯化得到5个化合物,通过MS和NMR等波谱数据和结合文献,最终确定了4个化合物,分别为:去甲氧基荚果蕨(1)、胶藤素(2)、槲皮素(3)和异槲皮苷(4),其中化合物2为首次从番石榴属植物中分离得到的二氢黄酮类化合物。

The in vitro antioxidant activity and the material basis for its antioxidant activity of the ethyl acetate extracts from Psidium guajava leaves were investigated in this study. The antioxidant ability of ethyl acetate extracts was first analyzed in vitro after 95% ethanol percolating, n-hexane and ethyl acetate extraction from Psidium guajava leaves, and then the chemical compounds were isolated and identified by combing column chromatography（such as silica gel column chromatography, Sephadex LH-20） and spectrometry（such as mass spectrometry, nuclear magnetic resonance spectroscopy）. The results showed that the ethyl acetate extracts had strong antioxidant activity in vitro to scavenge DPPH radicals, superoxide anion free radicals, and hydroxyl radicals in a dose-dependent manner, and when the concentration was 1 mg/m L, the scavenging abilities for 1,1-diphenyl-2-picrylhydrazyl（DPPH） radicals, superoxide radicals and hydroxyl radical were 94.15%, 87.88%, 67.3%, respectively, which were close to or better than those of Vc. Five compounds were isolated and purified from the ethyl acetate extracts of Psidium guajava leaves by silica gel column chromatography and Sephadex LH-20 column chromatography, four of which were identified as demethoxymatteucinol（1）, cryptostrobin（2）, quercetin（3）, and isoquercitri（4）, respectively, by comparison of their mass spectrometry（MS） and nuclear magnetic resonance（NMR） spectroscopic data with those in literatures. Furthermore, compound 2 was the first flavanone isolated from the genus Psidium Linn.