Extraction Process Optimizing Of Active Components From Ginkgo Biloba Leaves On The Basis Of Antioxidant Effect And Its Antioxidant Activity Assessment

Anti-aging biology and free radical biology were two hot topics of modern life science in the recent years. Assessment and screening high anti-oxidant activity (AOA) of nature resources is the trend of research for biology, medical science and food science.In this paper, Microwave and ultrasonic assisted extraction (MAE and UAE) method were employed to extract the anti-oxidative active components from Ginkgo biloba leaves, the extraction technology was optimized by IC50 of scavenging DPPH free radical as the activity monitoring parameter. The extractions of Ginkgo biloba leaves with two methods were separated by solvent extraction and macroporous resin and the antioxidant activity of its extractions were assessed by scavenging DPPH free radical, hydroxyl radical and super oxidized anionic radical. Meanwhile, the synergistic antioxidant effect of the separating compounds with TBHQ and Vc were also investigated. The main results were as follows:1. Creatively designed with IC50 of scavenging DPPH free radical as the activity monitoring index, MAE and UAE were employed to extract anti-oxidative active components from Ginkgo biloba leaves. Under the optimum extraction conditions, the IC50 of scavenging DPPH free radical of extractions by these two methods were 1.29μg/mL and 1.04μg/mL respectively. Both extractions showed strong anti-oxidant activity.2. Petroleum Ether(PE), Ethyl acetate and n-butanol were used in solvent extraction to separate the extractions of Ginkgo biloba leaves by MAE and UAE. The scavenging effect on DPPH free radical, hydroxyl radical and super oxidized anionic radical of solvent extracting separation products from two extraction method as follows:Solvent extraction separations of MAE scavenging capacity on DPPH free radical order is the same of UAE. The aqueous phase after Ethyl acetate extraction of UAE scavenging effect on DPPH free radical was preferred among the discussed separations, its IC50 is 1.23μg/mL.Solvent extraction separations of MAE scavenging capacity on hydroxyl radical order is the same of UAE. The aqueous phase after Ethyl acetate extraction of MAE and UAE scavenging effect on hydroxyl radical are the highest antioxidative activity and both of scavenging effect is equivalent, which their IC50 are 5.42μg/mL and 5.47μg/mL respectively.Most of solvent extraction separations of MAE and UAE showed stronger scavenging effect on super oxidized anionic radical. The aqueous phase after PE extraction of MAE exhibited the highest antioxidative activity and its IC50 is 1.08μg/mL.3. In this experiment, AB-8 macroporous adsorption resin was used to separate extractions of Ginkgo biloba leaves and the extractions were eluted with 10%,30%,50%, 80% ethanol. The scavenging effect on DPPH free radical, hydroxyl radical and super oxidized anionic radical of resin separations as follows:The scavenging capacity on DPPH free radical order of resin eluants of MAE is the same of UAE, that is 30% eluant> 50% eluant> 10% eluant> 80% eluant.The scavenging capacity on hydroxyl radical order of resin eluants of MAE is the same of UAE, that is 80% eluant>30% eluant>50% eluant> 10% eluant.The scavenging capacity on super oxidized anionic radical order of resin eluants of MAE is the same of UAE, that is 10% eluant> 50% eluant> 30% eluant> 80% eluant.4. The antioxidant activity of solvent extraction and resin separates of Ginkgo biloba leaves, TBHQ, BHT, VC and VE was comparatively studied.In the solvent extraction separations of Ginkgo biloba leaves extracted by MAE and UAE, the aqueous phase after Ethyl acetate extracted by two methods showed the strongest scavenging capacity on DPPH radical, which IC50 is 1.44μg/mL and 1.23μg/mL respectively.In the resin separations of Ginkgo biloba leaves extracted by MAE and UAE, 30% eluant by UAE showed the strongest scavenging capacity on DPPH radical, its IC50 is 1.47μg/mL, while 30% eluant extracted by MAE scavenging capacity is only lower than TBHQ, its IC50 is 1.65μg/mL.5. In the solvent extraction separations of Ginkgo biloba leaves extracted by MAE and UAE, Ethyl acetate extracts, n-butanol extracts showed synergistic antioxidative activities evidently with TBHQ and VC.In the resin separations of Ginkgo biloba leaves extracted by MAE and UAE, the DPPH scavenging rate of the mixed antioxidants composed of 10% eluant,50% eluant, 80% eluant with TBHQ, Vc is higher than their individual, which showed strong synergistic antioxidative activitiy.