In the recent past, it has been demonstrated that both pure
polyphenols have antibacterial effects against Helicobacter pylori
(Díaz-Gomez, Lopez-Solís, Obreque-Slier, & Toledo-Araya, 2013).
However, not much is known about the effect of pure gallic acid and
pure catechin, or about any eventual synergy or interference between
them, on E. coli growth. The aim of this study was to evaluate
the antimicrobial effect of gallic acid and catechin, alone or in
combination, against E. coli cultures. To this end, both qualitative
(agar well-diffusion method) and quantitative (dilution method)
assays were used.