Inhibitory Effects of Tea Leaf and Medicinal Plant Extracts on Enteric Pathogenic Bacteria Growth, Oxidation and Epithelial Cell Adhesion

Background: Diarrhea disease was noted by WHO as the major target for control that the leading cause of diarrhea diseases are enteric pathogenic bacteria. Biological properties of tea leaf and medicinal plant which promoted the alternative way to inhibit enteric pathogenic bacteria. Objectives: To investigate antibacterial activity of tea leaf combined with medicinal plant extracts for inhibition of growth and the adhesion of enteric pathogenic bacteria on epithelial cells. Materials and Methods: Among the Camellia sinensis tea leaves; green, oolong and black tea, and 14 medicinal plants examined, aqueous and ethanolic extracts demonstrated growth inhibition against Escherichia coli, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus and Vibrio cholerae. Antioxidation, phenolics and flavonoids contents were also determined. Tea leaf and medicinal plant extracts were combined for the development of herbal tea that subsequently evaluated the inhibition of bacterial adhesion on epithelial cells. Results: The aqueous and ethanolic extracts of green tea and Garcinia cowa showed effectiveness against all enteric pathogenic bacteria, especially the fraction of ethanolic extracts that revealed the greatest bactericidal activity. Moreover, the ethanolic extract of green tea showed the highest content of phenolics and flavonoids, which also correlated with the antioxidant activity. In addition, the ethanolic extract of G. cowa had the highest flavonoid content. Hence, the combination of green tea with G. cowa extract revealed its effectiveness against enteric pathogenic bacteria and had an inhibitory effect against the adhesion of bacteria on epithelial cells. Conclusion: Herbal tea, the combination of green tea and G. cowa extract exhibited the beneficial antibacterial and antioxidant activities, which could be considered as an alternative treatment for enteric pathogenic bacteria infections and promote health benefits.