甜叶菊废渣提取物的主要成分分析及其抗氧化作用

Main Components of Stevia Residue Extract and Their Antioxidant Activities

研究甜叶菊废渣提取物的主要成分及其抗氧化活性,并阐明其对甜叶菊废渣提取物总抗氧化能力的贡献情况。通过高效液相色谱-串联质谱法和高效液相色谱法对甜叶菊废渣提取物的主要成分进行定性和定量分析,采用1,1-二苯基-2-三硝基苯肼法、2,2’-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐法、铁离子还原法3种体外抗氧化方法分别对甜叶菊废渣提取物中主要成分的抗氧化活性进行测定,并采用抗氧化活性综合(antioxidant potency composite,APC)指数法进行比较分析。甜叶菊废渣提取物含有8种主要成分分别为绿原酸、隐绿原酸、咖啡酸、异绿原酸A、异绿原酸B、异绿原酸C、槲皮苷和槲皮素,其中异绿原酸C最高((126.7±1.27)mg/g),其次为咖啡酸((97.2±0.36)mg/g)和绿原酸((46.5±0.29)mg/g)。APC指数显示8种主要成分抗氧化活性由强到弱依次为:咖啡酸(92.56%)>槲皮素(78.31%)>异绿原酸B(62.09%)>绿原酸(58.92%)>异绿原酸A(48.15%)>异绿原酸C(36.55%)>隐绿原酸(35.5%)>槲皮苷(34.24%)。通过对模拟提取物和甜叶菊废渣提取物的抗氧化性进行比较发现,在质量浓度为50~400μg/mL时,甜叶菊废渣提取物的抗氧化能力均强于模拟提取物。结果表明,甜叶菊废渣提取物富含绿原酸类和黄酮类化合物,具有较强的抗氧化能力,其中咖啡酸对甜叶菊废渣提取物抗氧化活性贡献最大。除8种主要成分外,甜叶菊废渣提取物中还存在其他抗氧化活性物质。

The objectives of this study were(1) to analyze the main components of stevia residue extract and their antioxidant activities and(2) to elucidate their contributions to the total antioxidant capacity of stevia residue extract. Methods: The main components of stevia residue extract were qualitatively and quantitatively analyzed by high performance liquid chromatographytandem mass spectrometry(HPLC-MS/MS) and HPLC. The antioxidant activities were determined by 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2’-azino-bis(3-ethylbenzthiozoline-6)-sulphonic acid(ABTS) and ferric reducing/antioxidant power(FRAP) methods, and comparatively evaluated using antioxidant potency composite(APC) index. The eight main components of stevia residue extract were 5-CQA, 4-CQA, caffeic acid, 3,4-diCQA, 3,5-diCQA, 4,5-diCQA, quercetin-3-rhamnoside and quercetin, among which, 4,5-diCQA was the most abundant, whose content was(126.7 ± 1.27) mg/g,followed by caffeic acid((97.2 ± 0.36) mg/g) and 5-CQA((46.5 ± 0.29) mg/g). The results of APC indexes showed that the antioxidant activities of the main components declined in the following order: caffeic acid(92.56%) > quercetin(78.31%) > 3,4-diCQA(62.09%) > 5-CQA(58.92%) > 3,5-diCQA(48.15%) > 4,5-diCQA(36.55%) > 4-CQA(35.5%) > quercetin-3-rhamnoside(34.24%). At concentrations of 50–400 μg/mL, the antioxidant activity of stevia residue extract was stronger than that of its simulant. Stevia residue extract contained high contents of chlorogenic acids and flavonoids and exhibited strong antioxidant activity, and caffeic acid contributed the most to its antioxidant. In addition to the eight main components, other components with antioxidant activities may also exist in stevia residue extract.