Abstract
Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria. monocytogenes and Bacillus cereus are pathogenic bacteria that should not be detected in cosmetics and foodstuffs. Therefore, we first investigated the antimicrobial activities of extracts of Scutellariae Radix(SR), Coptidis Rhizoma (CR) and salicylic acid(SA) in these pathogenic microorganisms. Although SA has been known to exhibit anti-inflammation and antimicrobial activity against pathogenic microorganisms, a high concentration of SA may cause serious side effects such as skin redness, skin burning, peeling or tissue damage. Hence, we focused on diminishing side effects followed by treatment of a high concentration of SA and investigated whether the combinations of SA with various concentrations(25-400 mg/mL), SR and CR with a concentration(100 mg/mL) which did not show antimicrobial activity against E. coli and P. aeruginosa exhibited meaningful antimicrobial effect against both strains. In our results, the combinations of SA with the lowest concentration(25 mg/mL), SR(100 mg/mL) and CR(100 mg/mL) exhibited significant antimicrobial activity against E.coli in comparison to SA alone(25 mg/mL) showing no antimicrobial activity. Moreover, the combinations of SA (100 mg/mL), SR and CR showed seven times higher antimicrobial activity against E. coli than SA alone(100 mg/mL) and exhibited a significant antimicrobial activity in comparison to ampicilin (p<0.05). The combinations of SA(100 mg/mL), SR and CR showed two times higher antimicrobial activity against P. aeruginosa than SA alone. Therefore, these results indicated that the combinations of SR, CR and SA with low concentration expressed the synergistic antimicrobial effect against E. coli and P. aeruginosa and showed great potential as an antimicrobial agent.
