Evaluation of alcoholic extract of macroalgae as the efflux pump inhibitors for secondary active drug transporter AcrB from Escherichia coli

• Main Authors: Lai, Margaret, 賴柏穎
• Other Authors: Lin, Hong-Ting
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/fxy262

碩士 === 國立臺灣海洋大學 === 食品科學系 === 106 === Multi-drug resistance (MDR) of Gram-negative bacteria constitutes a major obstacle in the antibacterial fight worldwide. The AcrAB-TolC efflux pump is the most well-studied resistance nodulation division (RND) pump and responsible for most intrinsic drug resistance in Escherichia coli. To combat MDR, several efflux pump inhibitors (EPIs) that act against the AcrAB-TolC efflux pump have already been described. Seaweeds are considered as a source of bioactive compounds as they are able to produce a great variety of secondary metabolites which characterized by a broad spectrum of biological activities. This study aimed to evaluate the potential of macroalgae extracts which inhibit the level of secondary active drug transporter AcrB from Escherichia coli. Four seaweeds were extracted by 95% ethanol and combined with serveral antibiotics against E. coli Kam3 pSYC and pSYC-acrB which determined by antibacterial activity assay, modulation assay, time-kill assay, ethidium bromide (EtBr) accumulation and finally identified four algae extracts by GC-MS. The result of modulation showed that Laminaria japonica, Sargassum horneri and Gracilaria sp. significantly reduced IC50 of E. coli harboring pSYC in erythromycin and clarithromycin by at least 2 to 8-fold. Laminaria japonica, Sargassum horneri, Gracilaria sp. and Porphyra dentata also significantly reduced IC50 of E. coli harboring pSYC-acrB in erythromycin and clarithromycin by at least 2 to 16-fold. Four macroalgae in different concentrations could modulate with clarithromycin to reduce log10 cfu below the initial log10 cfu at 0 h in pSYC-acrB. All seaweed extracts in pSYC-acrB slightly increased the accumulation of EtBr in relation to the EtBr control, in which L. japonica and Gracilaria sp. increased the level of EtBr accumulation higher than S. horneri and P. dentata. Most components in four algae were identified by using GC-MS and they contained the same structure of benzene. In conclusion, four macroalgae potentiated antibiotic activity by inhibiting AcrB efflux pump in E. coli. They could be applied as a potential efflux pump inhibitor to restore antibiotic activity. Keywords : Escherichia coli, AcrB, Efflux pump inhibitor, Algae extracts, Antibacterial activity assay