Effects of Psidium guajava leaf extract on secretion systems of Gram-negative enteropathogenic bacteria

Noboru Nakasone; Yasunori Ogura; Naomi Higa; Claudia Toma; Yukiko Koizumi; Giichi Takaesu; Toshihiko Suzuki; Tetsu Yamashiro

doi:10.1111/1348-0421.12604

Effects of Psidium guajava leaf extract on secretion systems of Gram-negative enteropathogenic bacteria

Microbiol Immunol. 2018 May 23. doi: 10.1111/1348-0421.12604. Online ahead of print.

Authors

Noboru Nakasone¹, Yasunori Ogura², Naomi Higa¹, Claudia Toma¹, Yukiko Koizumi³, Giichi Takaesu⁴, Toshihiko Suzuki⁵, Tetsu Yamashiro¹

Affiliations

¹ Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa 903- 0215, Japan.
² Department of Food Science and Nutrition, Nara Women's University, Nara 630-8506.
³ Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, 3852 E Medical Center Dr, Ann Arbor, MI 48109, USA.
⁴ Tropical Biosphere Research Center University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan.
⁵ Department of Bacterial Pathogenesis, Infection and Host Response Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, bunkyo-ku 1130034, Tokyo, Japan.

PMID: 29790584
DOI: 10.1111/1348-0421.12604

Abstract

We screened a total of 672 plant-tissue extracts to search 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, we found that an extract from the leaves of Psidium guajava (guava) inhibited the secretion of the EspB protein from EPEC and EHEC without affecting bacterial growth. The guava extract (GE) also inhibited EPEC and EHEC from adhering to and injecting EspB protein into HEp-2 cells. GE seemed to block the translocation of EspB from the bacterial cells to the culture medium. In addition to EPEC and EHEC, GE also inhibited the T3SS of Yersinia pseudotuberculosis and Salmonella enterica serovar Typhimurium. After exposure to GE, Y. pseudotuberculosis stopped the secretion of Yop proteins and lost its ability to induce the apoptosis of mouse bone marrow-derived macrophages. S. Typhimurium exposed to GE ceased the secretion of Sip proteins and lost its ability to invade HEp-2 cells. GE inhibited EspC secretion, the type V secretion protein of EPEC, but not Shiga toxin2 from EHEC. Thus, our results suggest that guava leaves contain a novel type of antimicrobial compound that could be used for the therapeutic treatment and prevention of gram-negative enteropathogenic bacterial infections.

Keywords: Psidium guajava; leaf extract; type III secretion system.