OBJECTIVE:To study the antioxidant activity in vitro of neutral polysaccharides and its graded component from 3samples of white ginseng and red ginseng. METHODS:The decoction method was used to extract the crude polysaccharides fromwhite ginseng,100 ℃ and 120 ℃ processed red ginseng;the crude polysaccharides were further separated through ion exchangecolumn to extract neutral polysaccharides;Sephadex G-75 gels filter column was used to grade the neutral polysaccharides accordingto the molecular weight,antioxidant activity in vitro of 9 samples in 3 neutral polysaccharides and were detected by DPPH andOH free radical scavenging test and reduction capacity test(FRAP value),and vitamin C was used as positive control. RESULTS:The 3 neutral polysaccharides all obtained component Ⅰ and component Ⅱ after grading. Neutral polysaccharides and its gradedcomponent showed certain antioxidant activity in vitro in a certain concentration range,and increased by concentration increasing.The activity of neutral polysaccharides and component Ⅱ from 120 ℃ processed red ginseng was the strongest,of which 50% inhibitoryconcentration(IC50)on DPPH free radical was 0.258 g/L and 0.253 g/L,on OH free radical was 7.157 g/L and 6.845g/L,FRAP values were 2.8 and 3.0 mmol/L(when concentration was 1.2 g/L),respectively. CONCLUSIONS:The antioxidant activityin vitro from 120 ℃ processed red ginseng is higher than that of 100 ℃ processed red ginseng and white ginseng,in whichcomponent Ⅱ makes important contribution to the antioxidant activity.

Objective To construct a hexon-chimeric human adenovirus type 3 ( HAd3 ) vector expressing two neutralizing epitopes of hepatitis B surface antigen preS 1 (HBsAg-preS1) and to analyze the antigenicity of the chimeric epitopes .Methods Two neutralizing epitopes of HBsAg-preS1 including KR359 and KR127 were inserted into hypervariable region 1 ( HVR1) and hypervariable region 2 ( HVR2) of HAd3 hexon .Chimeric hexon gene encoding the two epitopes was amplified by overlap PCR and then subcloned in -to shuttle plasmid pBR322-L/R containing the homologous recombination regions .The digested shuttle plas-mid containing chimeric hexon gene was co-transfected into Escherichia coli BJ5183 cells together with back-bone plasmid pBRAdΔE3GFP to construct pBRAdΔE3GFP-preS1 vector.Then pBRAdΔE3GFP-preS1 vector was digested with AsiSⅠand transfected into AD293 cells to construct recombinant virus (rAD3E-preS1). CsCl gradient centrifugation was used for purification .Glutathione S-transferase ( GST ) fusion protein KR359KR127 ( GST-KR359KR127 ) was expressed in Escherichia coli BL21 by using expression vector pGEX-4T3.Female BALB/c mice at age 6-8 weeks were intraperitoneally injected with 1010 virus particles or 80 μg GST fusion protein .Serum samples were collected to analyze the antigenicity of two epitopes by ELISA and Western blot .Results ELISA showed that KR 359 and KR127 were successfully exposed on viral sur-faces by using hexon-chimeric HAd3 vector .The induced polyclonal antibodies in serum samples could rec-ognize GST fusion protein and native HBsAg from patients infected with hepatitis B virus .Conclusion The antigen capsid-incorporation strategy could be used to display epitopes on viral surface .Enhanced antigen-specific responses could be achieved through inserting multiple foreign epitopes into hexon HVRs .This study provided evidence for further application of hexon -chimeric human adenovirus type 3 vector in the developmentof vaccine, especially for the development of multivalent hepatitis B vaccine .