Establishment Of HPLC Fingerprint Of Purple Sweet Potato And Study On The Components Of Antioxidant Activity

In this article, we established the HPLC fingerprint of 38 purple sweet potatoes from Engineering and Technology Research Center for Sweetpotato of Chongqing.We tested antioxidant activity in vitro by methanol extracts of 33 purple sweet potatoes from that center and then screened the ones which have good antioxidant activity in vitro. We also studied the main anthocyanins Contained in Yuzi 263 by extracting,sperating and purifying,and then we tested antioxidant activity in vitro of that parts by purifying. As a result,we found the good antioxidant activity parts.we are still studing the components of that parts.1.We established fingerprintes of purple sweet potatoe by HPLC.We extracted 38 purple sweet potatoes using methanol,and we got total anthocyanins extracts with methods of filtration,AB-8 Macroporous Resin and extraction. We established HPLC fingerprintes of purple sweet potatoe in condiation of methanol-water solvent programming elution,3% formic acid contained in mehthanol.We found all that same main 14 peaks in 38 HPLC fingerprintes of purple sweet potatoes included and those peaks are characteristic peaks of that 38 purple sweet potatoes in common..These 14 peak areas occupy more than 90% of total peak areas, which can be considered as chemical bar codes of purple sweet potatoe.And the main differents among anthocyanins of these 38 purple sweet potatoe are content contrasts of 14 anthocyanins. This indicates that the purple sweet potatoes from Engineering and Technology Research Center for Sweetpotato of Chongqing are not notable in kinds of anthocyanins by crossing over.This result is the same to the point of view that genes which control anthocyanins synthetise are not easy to mutation in purple sweet potatoes.2. We tested antioxidant activities of all 33 purple sweet potatoes in vitro.33 fresh purple sweet potato were washed, crushed and extracted with a 1:20 material-extracts by methanol incoluding 1% acid overnight. We tesed the total antioxidant capacity, clearing the DPPH free radical, anti-lipid peroxidation of linoleic acid system and the hydroxyl radical scavenging capacity of 33 sample with vitamin C as reference substance.Then we tesed contents of all anthocyanins in these 33 sample by method of extinction coefficient and deal with data by correlation analysis and linear regression.The results indicate:The contents of anthocyanins have conspicuous positive correlation with the total antioxidant capacity, the hydroxyl radical scavenging capacity and clearing the DPPH free radical but weak positive correlation with anti-lipid peroxidation of linoleic acid system.The anthocyanins contents in all 33 samples between 0.033-0.126mg/ml have good antioxidant activities especially Yuzi 43,6-24-50, Yuzi 263,8-13-28,6-15-6 and 6-6-16.3. On the basis of antioxidant activities results tested in this experiments,we did futher study on Yuzi 263.We extracted anthocyanins in first Yuzi 263 first and then separated it to different parts in order to testing their antioxidant activities and structures. fresh purple sweet potato Yuzi 263 were washed, crushed and extracted with 95% ethanol incoluding 1% HCl.The extracts were separated by AB-8 Macroporous Resin and eluted by 30% ethano,50% ethano and 100% ethano in proper order.HPLC and absorptivity method determining resulted that most of the anthocyanins are included in 30% ethanol elution part.So we separated 30% ethanol elution part by RP-Silica Gel Column Chromatography and eluted with methanol-water solvent programming elution,1% formic acid contained in mehthanol.As a result,we got 11 elution parts named Fr1-Fr11.We tested antioxidant activities and structures of all these 11 parts.The results indicate:Fr2 and Fr3 are aglycones of anthocyanin; Fr1,Fr4 and Fr5 are monoglycosides of anthocyanin; Fr6 and Fr10 have caffeoylquinic acid in structure; Fr11 have coumaroyl acid in structure; Fr9 are monoglycosides of anthocyanin with caffeoylquinic acid in structure;Fr7 are bioside of anthocyanin and Fr8 are bioside of anthocyanin with caffeoylquinic acid in structure. Fr9,Fr11,Fr10,Fr6 and Fr2 have good antioxidant activities. Among them Fr9 and Fr11 have batter antioxidant activities than vitamin C. Fr2,Fr9,Fr3,Fr4,Fr10 and Fr7 have good ability in hydroxyl radical scavenging capacity.All 11 parts have good ability in anti-lipid peroxidation of linoleic acid system.. Fr9,Fr10,Fr7 and Fr2 have the most antioxidant activities in all 11 parts and the anthocyanins contained in these 11 parts need to study futher more.