Identification of Inhibitory Effect on Streptococcus mutans by Oleanolic Acid

Lee

et al. 2015

PLoS ONE

Self Cite

This study investigated the antimicrobial action of oleanolic acid against Listeria monocytogenes, Enterococcus faecium, and Enterococcus faecalis. To determine the cytotoxicity of oleanolic acid, HEp-2 cells were incubated with oleanolic acid at 37oC. MICs (minimal inhibition concentrations) for L. monocytogenes, E. faecium, and E. faecalis were determined using two-fold microdilutions of oleanolic acid, and bacterial cell viability was then assessed by exposing the bacteria to oleanolic acid at 2 × MIC. To investigate the mode of antimicrobial action of oleanolic acid, we measured leakage of compounds absorbing at 280 nm, along with propidium iodide uptake. Scanning electron microscope (SEM) images were also analysed. The viability of HEp-2 cells decreased (P < 0.05) at oleanolic acid concentrations greater than 128 μg mL-1. The MICs were 16-32 μg mL-1 for L. monocytogenes and 32-64 μg mL-1 for E. faecium and E. faecalis, and bacterial cell viability decreased (P < 0.05) about 3-4 log CFU mL-1 after exposure to 2 × MIC of oleanolic acid. Leakage of 280 nm absorbing materials and propidium iodide uptake was higher in oleanolic acid –treated cells than in the control. The cell membrane was damaged in oleanolic acid-treated cells, but the control group had intact cell membrane in SEM images. The results indicate that oleanolic acid can kill L. monocytogenes, E. faecium, and E. faecalis by destroying the bacterial cell membrane.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antimicrobial Action of Oleanolic Acid on Listeria monocytogenes, Enterococcus faecium, and Enterococcus faecalis

Lee

et al. 2015

PLoS ONE

Self Cite

“…Currently, there are negative perceptions regarding synthetic additives, and natural materials are attractive as alternative antimicrobial agents because of their limited effects on the environment and their low toxicity to human cells( Kaya et al , 2008 ). Various lifeforms, including microorganisms, plants, and animals, have been investigated to identify novel antimicrobial agents that possess these favored characteristics ( Guliani et al , 2007 ; Yoon and Choi, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Evaluation on Antimicrobial Activity of Psoraleae semen Extract Controlling the Growth of Gram-Positive Bacteria

Korean Journal for Food Science of Animal Resources

Lee

et al. 2017

Self Cite

This study investigated bacterial growth-inhibitory effect of 69 therapeutic herbal plants extracts on 9 bacterial strains using a disc diffusion assay. Especially, the antimicrobial activity of Psoraleae semen, which showed different activity on pathogenic Gram-positive and Gram-negative bacteria, was evaluated by MIC (minimal inhibition concentration) and biofilm formation assay. The effect of Psoraleae semen extract on bacterial cell membranes was examined by measurement of protein leakage (optical density at 280 nm) and scanning electron microscope (SEM). No clear zone was formed on discs containing Gram-negative bacteria, but Gram-positive bacteria exhibited clear zones. The MICs of Psoraleae semen extract were 8 μg/mL for Streptococcus mutans, and 16 μg/mL for Enterococci and Staphylococcus aureus. In addition, biofilm formation was inhibited at concentration 8-16 μg/mL. Protein leakage values and SEM images revealed that cell membranes of Gram-positive bacteria were impaired following exposure to the extract. Further, the extract inhibited the growth of Listeria monocytogenes in sausages. These results indicate that Psoraleae semen extract could be utilized as a natural antimicrobial agent against Gram-positive bacteria.

Inhibitory effect ofn-hexane extract from Korean red ginseng marc againstStreptococcus mutanscausing dental caries

2021

JABC

In this study, to investigate the anticariogenic effect of red ginseng, the antibacterial effect, cell adherence and biofilm formation inhibitory effect of n-hexane extract of red ginseng marc (HERGM) against Streptococcus mutans, the causative bacteria of caries, were measured. The growth of S. mutans was inhibited in proportion to the concentration of HERGM, and was hardly observed at a concentration above 125 μg/mL (MIC =125 μg/mL). It was found that HERGM acts on the cell membrane and the nucleic acid component of the cell was leaked. In addition, HERGM inhibited the adherence and biofilm formation of S. mutans by more than 90% at a concentration of 125 μg/mL. GTase activity was completely inhibited at a concentration of 50 μg/mL of HERGM. In conclusion, it was found that HERGM commonly inhibited the growth and biofilm formation of S. mutans.Keywords Biofilm formation inhibition · Growth inhibition · n-hexane extract of red ginseng marc · Streptococcus mutans 서 론