Effects of Psidium guajava leaf extract on secretion systems of gram‐negative enteropathogenic bacteria |
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| Authors: | Noboru Nakasone Yasunori Ogura Naomi Higa Claudia Toma Yukiko Koizumi Giichi Takaesu Toshihiko Suzuki Tetsu Yamashiro |
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| Affiliation: | 1. Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Japan;2. Department of Food Science and Nutrition, Nara Women's University, Japan;3. Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, USA;4. Tropical Biosphere Research Center University of the Ryukyus, Nishihara, Japan;5. Department of Bacterial Pathogenesis, Infection and Host Response Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan |
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| Abstract: | In this study, 672 plant‐tissue extracts were screened for phytochemicals that inhibit the function of the type III secretion system (T3SS) of enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC). Among candidates examined, an extract from the leaves of Psidium guajava (guava) was found to inhibit secretion of EPEC‐secreted protein B (EspB) from EPEC and EHEC without affecting bacterial growth. Guava extract (GE) also inhibited EPEC and EHEC from adhering to, and injecting EspB into, HEp‐2 cells. GE seemed to block translocation of EspB from the bacterial cells to the culture medium. In addition, GE also inhibited the T3SS of Yersinia pseudotuberculosis and Salmonella enterica serovar Typhimurium. After exposure to GE, Y. pseudotuberculosis stopped secreting Yersinia outer proteins and was unable to induce apoptosis of mouse bone marrow‐derived macrophages. S. typhimurium exposed to GE stopped secreting Sip proteins and was unable to invade HEp‐2 cells. GE inhibited secretion of EspC, the type V secretion protein of EPEC, but not secretion of Shiga toxin 2 from EHEC. Thus, our results suggest that guava leaves contain a novel type of antimicrobial compound that could be used to treat and prevent gram‐negative enteropathogenic bacterial infections. |
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| Keywords: | leaf extract Psidium guajava type III secretion system |
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