Antioxidant Abilities On Different Parts Of Forsythia Suspensa And Forsythia Suspense Leaves During Different Growth Periods

Objective:The antioxidant abilities of Forsythia suspensa flower, leaves (from March to October), fruit methanol extracts were compared, and the antioxidant component in Forsythia suspensa flower, leaves, fruit was analyzed, and its contribution to antioxidant activities of each crube extract sample of Forsythia suspensa was evaluated.Methods: Forsythia suspensa flower, leaves were collected during March 2008 to October 2008, and were dried, ground, sieved. The sample powder was defatted and extracted with 60% methanol by ultrasound-assisted method. The antioxidant abilities were estimated by DPPH radical scavenging activity and ABTS redical scavenging activity, respectively. The total flavonoid content in each extract was investigated by the AlCl3 coloring method, the total phenolic content was investigated by the Folin-ciocalteu method. The chlorogenic acid, forsythiaside and rutin in each Forsythia suspensa extract were qualitatived and quantified by High Performance Liquid Chromatography (HPLC). Statistical comparisons and the correlation between antioxidant component and antioxidant activities were made with the version 13.0 of SPSS Soft ware.Results:1 The DPPH radical scavenging activity and ABTS radical scavenging activity of Forsythia suspensa flower, leaves (from March to October), fruit methanol extract were significantly different. The leaves picked in March had the highest DPPH and ABTS radical scavenging activities.2 The total flavonoid content and total phenolic content of Forsythia suspensa flower, leaves (from March to October), fruit methanol extract were significantly different (P < 0.05). The leaf sample harvested at March exhibited the highest total flavonoid content of 15.95 g rutin/100 g and the high total phenolic content of 5.13 g gallic acid/100 g.3 There is a significant positive relationship between total flavonoid content, total phenolic content and DPPH radical scavenging activity, and their correlation coefficients are 0.892 and 0.841, respectively. Also there is a significant positive relationship between total flavonoid content, total phenolic content and ABTS radical scavenging activity, and their correlation coefficients are 0.952 and 0.870, respectively.4 The antioxidant component- chlorogenic acid, forsythiaside and rutin content in Forsythia suspensa flower, leaves (from March to October), fruit methanol extract were significantly different (P < 0.05). The leaf sample harvested at March had the highest chlorogenic acid content. The highest forsythiaside content arised in leaf sample of June. The content of rutin in Forsythia sunspensa flower was significantly higher than other samples (P < 0.05).5 The DPPH and ABTS radical scavenging activity of chlorogenic acid, forsythiaside, rutin were significantly different (P < 0.05). The order of DPPH radical scavenging activity was chlorogenic acid > rutin > forsythiaside; the order of the ABTS radical scavenging activity was chlorogenic acid > forsythiaside > rutin.6 According to the content of chlorogenic acid, forsythiaside, rutin in Forsythia suspensa flower, leaves (from March to October), fruit methanol extract and its DPPH radical scavenging activity, ABTS redical scavenging activity, its contribution to antioxidant activities of each crube extract sample of Forsythia suspensa was evaluated. Chlorogenic acid was the main antioxidant compound in the leaf sample harvested at March due to its higher contribution to DPPH and ABTS radical scavenging activities.Conclusion:1 The Forsythia suspensa leaf on March had the highest DPPH redical scavenging activity, ABTS redical scavenging activity, the total flavonoid content, the total phenolic content, and chlorogenic acid content, this suggest that Forsythia suspensa leaves, especially fresh young leaf can be considered as a valuable sourse of antioxidant products.2 The Forsythia suspensa leaf harvested at March exhibited the highest chlorogenic acid content, and it suggest that Forsythia suspensa young leaf can be used as a better source of chlorogenic acid.