| Summary: | 博士 === 國立中興大學 === 微生物暨公共衛生學研究所 === 100 === The prevention and treatment of infections of human wounds is an important issue. The most common bacteria isolated from infected wound include Staphylococcus aureus, Escherichia coli and Pseudomonas aeurginosa. Nevertheless, the emergence of antibiotic resistant bacterial strains is a growing problem and the use of natural medicines has increased gradually. In this investigation five herbal plants (Aloe barbadensis, Mentha piperita, Lithospermi radix, Callicarpa japonica and Forsythia suspensa) were selected, and their antibacterial effects were elucidated. Of these five herbal plants, the two with the strongest antibacterial effects were selected and their morphological changes were examined using a scanning electron microscope (SEM) and the differential expression of bacterial proteins treated with them was determined by two-dimensional gel electrophoresis (2D-GE). Two proteins of weakly expressed spots from the highest matching percentage of 2D-GE were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS). The results indicated that the Lithospermi radix and Aloe barbadensis have the best minimal inhibitory concentration (MIC). The SEM examination reveals different bactericidal morphological changes and colony distributions obtained using Lithospermi radix or Aloe barbadensis. 2D-GE reveals that the matching percentage of Staphylococcus aureus treated with Lithospermi radix or Aloe barbadensis are 90.93% and 82.99%, 79.98 % and 87.3 % with Escherichia coli and 84.65 ％ and 70.77 ％ with Pseudomonas aeurginosa. Then identification of two proteins that are weakly expressed in Staphylococcus aureus treated with Lithospermi radix by MALDI-TOF/MS reveals that they are Holliday junction ATP-dependent DNA helicase RuvB and D-alanine:D-alanine ligase (DDI). RuvB is an ATP-dependent DNA helicase, and play an important role in the homologous recombination. Homologous recombination is the most common type of DNA recombinations. The main function of D-alanine:D-alanine ligase is on the synthesis of cell wall and it is an important target for developing new antibiotics. These results are noteworthy to suggest that Lithospermi radix may be used as an antibacterial medicine to human wound infection.
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