Preparation and Antioxidant Activity of Proanthocyanidins Dimers from Acacia mearnsii De Willd
ZHOU Meng;LIU Gongjun;HE Lingxiao;WANG Fei;Jiangsu Co-innovation Center of Efficient Processing and Utilization of Forest Resources,Nanjing Forestry University;College of Chemical Engineering,Nanjing Forestry University;Jiangsu Key Lab.of Biomass-based Green Fuels and Chemicals;
Proanthocyanidins were ultrasonic extraction was adopted to extract proanthocyanidins( PC) from Acacia mearnsii De Willd bark powders. Oligomeric proanthocyanidins( OPC)( ethyl acetate extract) were obtained by solvent extraction. Sephadex LH-20 and fast protein liquid chromatography( FPLC) were applied to the separation and purification of PC dimers. The compound was characterized by HPLC-MS. The results indicated that the yield of PC was about 50. 21%. The extract was separated by Sephadex LH-20 to obtain the sample Ⅰ with the purity of 60% and the yield of about 5%. The sample Ⅰ was further separated by FPLC with water-methanol as mobile phase,and then the dimer were obtained with the purity of 91. 72% and the yield of about 13%. The result of HPLC-MS analysis showed that the relative molecular weight of dimer was 578 and the structure was supposed to be procyandin-( 4,6)-prorobinetinidin. Meanwhile,the results of radical scavenging ability assay indicated that the antioxidant activity of PC dimer was higher than that of catechin and epigallocatechin gallate( EGCG). The scavenging rate of dimer( 60 μmol/L) was ≥80% which is higher than that of EGCG( 68%) and catechin( 50%).