Abstract
Antimicrobial activity is one of the well-known biological characteristics of catechins, the main extract of green tea leaves. It is thought that catechins intercalate into the bacterial cell membrane and damage the lipid bilayer. However, the association between catechins and lipopolysaccharides, which consist of an O side chain, core oligosaccharide, and lipid A, has not been previously investigated. In this study, we evaluated the catechin sensitivity of Salmonella enterica mutants that lack the O side chain and have core oligosaccharides of different lengths. These rough mutants were more sensitive to catechins than a bacterial strain with intact lipopolysaccharide. We conclude that the O side chain and core oligosaccharide play an important role in protecting Gram-negative bacteria against the antimicrobial activity of catechins.
Highlights
The health benefits of tea have been known for a long time
Ikigai et al proposes that the differences in susceptibility are due to differences in the bacterial cell surface; i.e., the outer membrane of Gram-negative bacteria constitutes a tight barrier to catechins [3]
While Vibrio species possess an outer membrane with lipopolysaccharide (LPS), the LPS structure is slightly different from that in Enterobacteriaceae [9,10,11,12,13]. These results suggest that the presence or absence of an outer membrane is not the only factor that may affect susceptibility to catechins; the cell surface structures of Gram-negative bacteria should be considered
Summary
The health benefits of tea have been known for a long time. Over the last quarter-century, several molecules in green tea extract with biological activity have been identified. While Vibrio species possess an outer membrane with lipopolysaccharide (LPS), the LPS structure is slightly different from that in Enterobacteriaceae [9,10,11,12,13] These results suggest that the presence or absence of an outer membrane is not the only factor that may affect susceptibility to catechins; the cell surface structures of Gram-negative bacteria should be considered. We investigated the relationship between catechin susceptibility and LPS structure using mutant strains of Salmonella enterica that lack O antigen and have core oligosaccharides of different lengths [14,15] These rough mutant strains had increased susceptibility to catechins, indicating that the O antigen and core oligosaccharide provided some protection against the antimicrobial activity of catechins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
