OBJECTIVE:To compare antioxidant activity of different extraction parts from flower buds of Buddlejae flos in vi-tro. METHODS:Ethanol crude extract (ET) was extracted from flower buds of B. flos with 60% ethanol and diffused by water;and petroleum ether,ethyl acetate and n-butanol were used to extract ET to obtain PE,EA,BU and water samples(SH). Using di-butyl hydroxy toluene(BHT)as positive control,the antioxidant capacity of PE,EA,BU and SH were investigated by using 1, 1-diphenyl-2-picrylhydrazyl(DPPH),2,2′-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid)diammonium salt(ABTS)free radi-cal scavenging method and ironion reduction/oxidation resistance ability (FRAP) method. IC50 and antioxdant equivalent TEAC were calculated. RESULTS:Compared with other samples,ET and EA had stronger antioxidant activity,and IC50 of EA scaveng-ing DPPH and ABTS free radical were 13.75,9.78 μg/ml,and those of ET were 14.93,11.41 μg/ml;scavenging ability of EA to DPPH free radical was stronger than that of BHT(IC50 was 18.71 μg/ml). TEAC of EA,ET and BHT were 1 657.67,1 586.25 and 1 581.68μmol/g. CONCLUSIONS:The ethyl acetate extract from flower buds of B. flos has good antioxidant activity.

Objective:In order to develop a safer vaccine strain exploit Salmonella typhimurium vaccine strain .A ΔsipB mutant of Salmonella typhimurium SL 1344 strain was constructed.Methods: Firstly, the recombinant suicide plasmid containing the missing 585 bp sipB ( PREΔsipB ) was built by homologous recombination , and screenned by two-step method.Results: PCR and sequencing results showed that SL 1344ΔsipB was successfully constructed.It was no significant changes compared with SL 1344.But compared with the parent strains SL 1344 , the mutant strain had obvious change in its virulence , oral challenge of bacteria in mice revealed that LD50 of the mutant strain was 1.70 ×108 CFU,the toxicity reduced about 1.4%.The protection rate induced by the sipB mutant was 50%,and the serum antibody peaked 14 d post-immunization.Conclusion:The SL1344ΔsipB mutant was constructed suc-cessfully,and genetic stability ,significantly reduced virulence.The study provides a new approach for further study of the relationship between the gene and pathogenicity of Salmonella typhimurium.It is likely that the ΔsipB mutant could be adapted to develope attenuated Salmonella vaccine.