Iron sequestration is not the main mechanism in the inhibition of Staphylococcus aureus growth by cranberry phytochemicals

Abstract

Some edible berries such as cranberry have been shown to process antimicrobial activity. One of the antimicrobial actions is hypothesized to be sequestration of iron required for bacterial growth as berry phytochemicals contain strong iron binding groups. Cranberry phytochemicals obtained by solid phase extracts (SPE) from a commercial cranberry juice were studied for their inhibition of Staphylococcus aureus. At 100 µg gallic acid equivalents/mL of phenolic materials, cranberry SPE inhibited bacteria growth by about 0.82-1.1 log units based on the number of colony forming units/mL. However, supplementation of growth media containing cranberry phytochemicals with added iron at levels high enough to overcome media iron deficiency failed to restore bacteria growth. These would indicate that sequestration of iron is not a major antimicrobial mechanism ofcranberry phytochemicals.

Genistein improves inflammatory response and colonic function through NF-κB signal in DSS-induced colonic injury

“…Intestinal dysfunction with increased permeability and downregulated tight junctions plays an important role in the pathogenesis of IBD and other inflammatory diseases [ 19 , 20 ]. In this study, we found that DSS increased permeability (serum LPS) and downregulated tight junctions expression, while genistein markedly alleviated DSS-induced colonic dysfunction in mice.…”

Tetrasodium EDTA for the prevention of urinary catheter infections and blockages

“…11,28 While the mechanism of action of EDTA against Gram-positive bacteria remains poorly understood, studies suggest the target site for EDTA activity may be intracellular or EDTA potentially chelates ions required for biological processes essential for bacterial growth and survival. 12,13,21,29…”

“…11,28 While the mechanism of action of EDTA against Gram-positive bacteria remains poorly understood, studies suggest the target site for EDTA activity may be intracellular or EDTA potentially chelates ions required for biological processes essential for bacterial growth and survival. 12,13,21,29 The lack of bactericidal activity observed with 7.63 mM tEDTA was due to the absence of sufficient free tEDTA molecules to interact with the bacteria and exert an antimicrobial effect. While the higher concentration of 28 mM tEDTA provided excess molecules for bacterial interaction, this was not sufficient for bactericidal activity against the challenge uropathogens, as dened by a $3 log 10 reduction in bacterial density aer 24 h exposure to tEDTA relative to the starting inoculum.…”

Transcriptional profiling of Salmonella enterica serovar Enteritidis exposed to ethanolic extract of organic cranberry pomace

“…Quercetin and myricetin, the two most abundant components in our flavonoid fraction, are well known for their bivalent metal cations chelation. Due to the presence of ortho dihydroxyl phenolic and hydroxyketo groups, these flavonols can chelate “free” copper and iron ions from the environment, which could be the reason for the increased growth inhibition by CRFp85 [34].…”