ABSTRACT
The antibacterial activity and mechanism of the antimicrobial peptide mutant Cbf-14-2 against NDM-1 carrying recombinant bacteria (E.coli BL21 (DE3)-NDM-1) was investigated in this study.The minimum inhibitory concentration (MIC),minimum bactericidal concentration (MBC) and killing curves (KCs) in vitro were determined by the broth microdilution method.Mice septicemia model was established by interaperitotoneal injection of E.coli BL21 (DE3)-NDM-1 to evaluate the antibacterial activity of this peptide in vivo.Results showed that Cbf-14-2 exhibited a potent antibacterial activity with MIC of 16 μg/mL and killed almost all recombinant bacteria within 120 min.Meanwhile,it significantly improved the survival rate of infected mice up to 70％ with the decreasing of bacterial load in mice lung,liver,spleen and kidney.This powerful clearance ability of Cbf-14-2 against bacteria mainly related to its enhanced membrane penetration ability through neutralizing the negative charges and disrupting the integrity of the bacterial cell membrane.Therefore,Cbf-14-2 is expected to be a potential antimicrobial agent for the treatment of infection induced by multi-drug resistant bacteria,especially for the NDM-1carrying bacteria.
ABSTRACT
Objective:To determine the content of cyclohexane, ethyl acetate, methanol, methylene chloride and trichloromethane in rupatadine fumarate by headspace gaschromatography. Methods:A DB-WAXETRR capillary column(30 m × 0. 32 mm,0. 25 μm)was used and the carrier gas was nitrogen. The detector was an FID and the inlet temperature was 200℃ . The column temperature program was with the initial temperature of 35℃,maintained 10 min,and then risen to 220℃ with the rate of 20℃·min -1 ,and maintained 5 min. Results:Cyclohexane,ethyl acetate,methanol,methylene chloride and trichloromethane showed a good linear relationship within the range of 77. 590 1- 698. 310 9 μg·ml -1(r = 0. 999 7),102. 166 6- 919. 499 4 μg· ml -1(r = 0. 999 8),62. 744 7- 564. 703 2μg·ml -1(r = 0. 999 9),12. 011 2- 108. 101 1 μg·ml-1(r = 0. 999 6)and 1. 262 8-11. 365 6 μg·ml -1(r = 0. 999 6). The average recovery was 103. 9% ,103. 5% ,104. 9% ,107. 1% and 103. 4% and RSD was 2. 3% ,2. 6% ,3. 1% ,2. 8% and 4. 5%(n = 9),respectively. The five residual solvents were not detected out in rupatadine fumarate. Conclusion:The method is stable,simple,sensitive and accurate,and can be used for the determination of residual solvents in rupatadine fumarate.