枇杷花不同花期醇提物抗氧化活性的比较

Antioxidant Activity of Ethanol Extracts of Loquat Flowers at Different Flowering Phases

以不同花期(花蕾期、露白期、初放期、盛开期)枇杷花为对象,研究枇杷花开放过程抗氧化性变化规律。采用70%乙醇二次回流提取以及Folin-Ciocalteu比色法、硝酸铝比色法、Fenton体系法、普鲁士蓝法和ABTS法分析评价枇杷花在不同花期的黄酮、总酚含量和总抗氧化能力。结果表明:枇杷花从花蕾期到盛开期,黄酮和总酚含量、抗氧化性能整体呈先上升后下降的趋势,其中在露白期的黄酮、总酚和Vc含量最高,分别为13.39±0.45mg/g、76.06±1.18 mg/g和(2.73±0.28)10-2mg/g,差异性显著高于其他花期(P<0.05);露白期枇杷花对羟基自由基的清除率、总抗氧化能力、总还原力和DPPH自由基清除率达到最高,分别为49.91±0.34%、61.50±0.21 mmol/g、0.67±0.01、74.28±0.73%。枇杷花具有较好的抗氧化性能,以露白期的抗氧化性最好,枇杷花采摘时期及开发利用时期应以露白期为佳。

The changes of flavonoids and the total phenolics contents and antioxidant activity in four different stages of loquat flowers （the budding, the bud swelling and white petals forming, the petals spreading and the petals opening stages） were studied using twice reflux extraction （70% ethanol as solvent） for extraction of loquat flower. Results showed that antioxidant materials contents and antioxidant activity of the extracts of flower sampled fi＇om the bud stages to the petals opened of loquat flowers exhibited an initial increase and a final decrease. Compared with the samples at other three flowering phases, the flowers samples at the stage of the bud swelling and white petals forming showed the highest flavonoids, the total phenolics and Vc contents, being of 13.39±0.45 mg/g, 76.06±1.18 mg/g and （2.73±0.28）×10-2 mg/g, respectively. In this phase, the flower extracts also showed the highest scavenging ability on.OH flee radical, reducing power, total antioxidant capacity and scavenging ability on DPPH free radical, indicating that loquat flower at the phase of bud swelling can be used for further development.