Antibacterial and Antidiarrheal Activities of the Combined Extracts of <i>Houttuynia cordata</i> Thunb. and <i>Portulaca oleracea</i> L. Against Enterotoxigenic <i>Escherichia coli</i>

Background/Purpose: As traditional Chinese medicinal herbs are known for their heat-clearing and detoxifying properties, Houttuynia cordata Thunb. and Portulaca oleracea L. are considered safer alternatives to antibiotics. As a compound preparation, they have better efficacy than a single medicine and have multi-target antibacterial activity. However, there is still a gap in the research on the antibacterial and antidiarrheal mechanism of the combination of Houttuynia cordata Thunb. and Portulaca oleracea L. against enterotoxigenic Escherichia coli, thus we studied the antimicrobial and antidiarrheal activities of the combination of ethanol extract and essential oil from Houttuynia cordata Thunb. (HEE and HEO) and ethanol extract from Portulaca oleracea L. (PEE) against enterotoxigenic Escherichia coli. Materials and methods: The combination (CB-HHP) of HEE, HEO, and PEE was detected, and the anti- E. coli activity was determined to study its antibacterial mechanism, and an anti-diarrhea experiment was carried out in mice. Results: The results showed that the combination (CB-HHP) of HEE, HEO, and PEE had a synergistic effect on Escherichia coli, and affected the integrity of the cell membrane by increasing the permeability of cell wall and cell membrane. In vitro, CB-HHP treatment significantly inhibited the formation of E. coli bacterial biofilm. In vivo, gavaging with CB-HHP could significantly relieve the weight loss and diarrhea rate and protect the duodenal villi of mice infected by E. coli, as well as increasing the concentration of immunoglobulin (Ig) G, IgM, and IgA in serum. Conclusion: The CB-HHP demonstrated remarkable antibacterial activity, antidiarrheal activity, and intestinal protective function, with the potential to be used as plant-derived food additives.