不同生长期蓝莓叶多酚物质含量及抗氧化活性研究

Study on phenolic contents and antioxidant activity in blueberry leaves during different growth periods

为了探明不同生长期蓝莓叶酚类物质变化情况及抗氧化活性,从而为蓝莓叶的适时采摘及加工利用提供参考依据,分别采集5、6和8、9月此4个生长时期的蓝莓叶,经不同方法干燥粉粹后制备蓝莓叶醇提物,测定并比较分析了不同生长时期蓝莓叶醇提物中的总酚与总黄酮含量、铁离子还原力、对DPPH自由基的清除率及总抗氧化能力(FRAP值)。结果表明:微波干燥处理的蓝莓叶醇提物其总酚、总黄酮含量均高于常规热风干燥处理的,而自然干燥处理的效果较差;微波干燥处理的蓝莓叶在其4个生长期中总酚含量的变化不大,其总黄酮含量在8、9月迅速升高,显著高于5、6月的总黄酮含量,9月的总黄酮含量最高,为(96.76±2.50)mg·g-1,显著大于8月的总黄酮含量,8月其含量为(75.52±2.09)mg·g-1,P <0.05;5月采摘的叶片其铁还原能力最强,其次是9月,最差的是6月;9月蓝莓叶醇提物对DPPH自由基的清除率最高,其半数清除浓度最小,EC50值为(61.59±1.31)μg·mL-1,5、8和9月其EC50值的差异均不显著,但此3个生长期与6月的EC50值的差异显著(P <0.05);4个生长时期其叶片醇提物的FRAP值的大小顺序为9月> 5月> 8月> 6月,但4个时期其醇提物的FRAP值均远低于对照维生素C。总体上,9月蓝莓叶的抗氧化能力(除铁还原力外)均高于其他3个生长时期的,即9月较适宜于蓝莓叶的大量采摘及开发利用。

In order to explore phenolic substances changes and antioxidant activity in blueberry leaves during differentgrowth periods,and to provide some bases for timely picking,processing and utilization of blueberry leaves,blueberryleaves at four growth periods(May,June,August and September)were collected,and were dried and ground withdifferent methods,and then ethanol extraction was prepared.Several indicators in ethanol extraction were determined andcompared,including total phenols content,total flavonoid content,Ferric ion reduction,scavenging rate to DPPH radical,and total antioxidant activity(FRAP value).The results showed that the contents of total phenol and total flavonoidsin ethanol extraction dried by microwave were higher than those by hot air and natural drying.Under microwavedrying conditions,the total phenol content at four growth periods had no significant changes,total flavonoids contentswere increased rapidly in August(75.52±2.09mg·g-1,P<0.05)and September(96.76±2.50mg·g-1),which weresignificantly higher than those in May and June,and the content was the highest in September.The leaves of Ferriciron reducing ability was the strongest in May,followed by the leaves in September,and the worst was that in June.The ethanol extraction in September had the highest DPPH radical scavenging rate and the lowest half scavengingconcentration,EC50value was(61.59±1.31)μg·mL-1,but the EC50values was no significantly differences from thosein May and August,and the EC50values at three periods were significantly different from that in June(P<0.05).theorder of the four periods based on FRAP values of ethanol extractions was September>May>August>June,butall of the FRAP values were much lower than the control(vitamin C).In general,the antioxidant capacity of blueberryleaves in September was higher than those of the other three growth periods,so Septermber was fit for massive picking,development,and utilization of blueberry leaves.