Medicinal plant extracts protect epithelial cells from infection and DNA damage caused by colibactin-producingEscherichia coli, and inhibit the growth of bacteria

Aims To investigate the biological activity of Thai medicinal plant extracts and their active substances on the inhibition of growth and the transcription of colibactin genes of colibactin-producingEscherichia coli, and effect on the pathogenesis from colibactin toxin including transient infections and colibactin-induced DNA damage. Methods and Results Among 16 medicinal plants examined, aqueous extracts ofTerminalia catappa,Psidium guajavaandSandoricum koetjapedemonstrated the growth inhibition againstE. coliATCC 25922, which is known to produce colibactin toxin. These plant extracts contain the active phytochemical compounds, tannin and quercetin, which are able to inhibit the growth ofE. coliATCC 25922. Interestingly, the extracts ofT. catappa,P. guajavaandS. koetjape, and their compounds tannin and quercetin, protected the eukaryotic epithelial cells of Vero cells and Caco-2 cells from infection and DNA damage byE. coliATCC 25922. Moreover, these plant extracts and compounds exhibited efficacy to downregulate the expression of five genes (clbA,clbB,clbM,clbN andclbP) that are required for colibactin biosynthesis. Conclusions The extracts ofT. catappa,P. guajavaandS. koetjape, and their compounds of tannin and quercetin had ability to inhibit the growth and transcription of colibactin genes of colibactin-producingEscherichia coli. Hence, these plant extracts and compounds could protect the transient infection and DNA damage of the eukaryotic epithelial cells. Significance and Impact of the Study This study is the first of its kind to report on the enhancement of the biological properties ofT. catappa,P. guajavaandS. koetjape, and to support the exogenous compound usage of tannin and quercetin, which may be able to protect against the transient infection and DNA damage of eukaryotic cells fromE. colicarrying colibactin toxin.

Automated summary

The study found that extracts from Terminalia catappa, Psidium guajava, and Sandoricum koetjape can inhibit the growth and gene transcription of colibactin-producing Escherichia coli, as well as protect eukaryotic epithelial cells from infection and DNA damage. These plant extracts and compounds have the potential to protect against transient infections and DNA damage caused by E. coli carrying colibactin toxin.