Changes Of Content And Antioxidant Activity Of Flavonoids In Hawthorn Leaves At Different Growth Stage

There are plenty of flavonoids, which are widely used in traditional medicine inCrataegus pinnatifida Bge.. Especilly, the hawthorn leaves are rich in flavonoids andhave the very high exploitation value. In this paper,‘Dajinxing’,‘Dahong’,‘Changkou’,‘Dawang’ and wild hawthorn leaves were used as the test materials andcollected once a month from mid-April to mid-October in2011. The samples werestudied on the changes of contents of phenolics and flavonoids, and the activity of therelated enzymes at defferent growth stage; The changes of antioxidant activitiy offlavonoids, which were extracted from the samples, was determined in terms ofscavenging activity of superoxide free radicals, hydroxyl free radicals and DPPH freeradicals, reducing capacity and metal chelating activity. And the optimal process ofthe extraction of flavonoids in hawthorn leaves was studied by using surfactant andethanol as solvent. The result showed that:1. The changes of flavonoids contents of four cultivars and wild hawthorn leaveshad two peaks at defferent growth stage.The first peak was in mid-June, the secondpeak appeared in mid-August or mid-September, and the second peak of theflavonoids contents was slightly higher than the first. Cultivars was higher than wildhawthorn,’Dajinxing’s leaves was higher than other’s.the contents of phenolics aresimilar with flavonoids. The correlation analysis indicated that PAL activities werepositively related to the changes of flavonoids contents, PPO and POD activities werenot.2. Flavonoids which were extracted from hawthorn leaves during their growthwere strong in terms of scavenging activity of superoxide free radicals, hydroxyl freeradicals and DPPH free radicals, reducing capacity and metal chelating activity.Abilities of scavenging free radicals are stronger than Vcs’ and BHT’s. Reductiveabilities were weaker than Vcs’ and BHT’s. Abilities of chelating metal ion werestronger than BHT’s, and weaker than Vcs’. The antioxidant activities of flavonoidsof cultivars were stronger than wild hawthorn, and ‘Dajinxing’s antioxidant activitywere better. 3.‘Dajinxing’s leaves could be the better raw materials.For the purpose ofgetting a lot of flavonoids, the best picking time is in June or August; For the purposeof using both leaves and fruits, the optimum harvesting time should be in October4. This method can increase the extraction rate by using Tween80and ethanol assolvent. And the optimum extracting condition of extracting flavonoids fromhawthorn leaves was showed as follows, mass fraction of Tween80solution2%andvolume fraction of ethanol solution80%; temperature of extraction80℃; time ofextraction4h; the solid-liquid ratio1:25(g:mL).