| In vitro: |
| Int J Antimicrob Agents. 2018 Jul;52(1):96-99. | | Antioxidant-based synergistic eradication of methicillin-resistant Staphylococcus aureus (MRSA) biofilms with bacitracin.[Pubmed: 29567095] | Biofilms of methicillin-resistant Staphylococcus aureus (MRSA) have serious clinical implications. However, it is difficult to eradicate MRSA biofilms due to the increased tolerance to antimicrobials of biofilms.
METHODS AND RESULTS:
In this study, we investigated the synergistic anti-biofilm effect of the combination of Octyl Gallate (OG), an antioxidant approved by the US Food and Drug Administration (FDA) as a food additive, and bacitracin, an antimicrobial peptide commonly used in topical antimicrobial ointments. The results of biofilm assays showed that OG enabled bacitracin at concentrations as low as 10-3 U/ml to inhibit biofilm formation in MRSA. A confocal microscopic analysis exhibited that the combination of bacitracin and OG suppressed biofilm formation in MRSA highly effectively compared to the single treatment of either bacitracin or OG. The synergistic anti-biofilm activity of bacitracin and OG was also confirmed in MRSA strains from humans, including USA300, which is the predominant clone of community-associated MRSA in the US.
CONCLUSIONS:
To the best of our knowledge, this is the first report about the synergistic anti-biofilm activity of an antimicrobial peptide and an antioxidant against MRSA. | | Food Funct. 2017 Jul 19;8(7):2500-2511. | | Octyl gallate, a food additive with potential beneficial properties to treat Helicobacter pylori infection.[Pubmed: 28640317 ] | Helicobacter pylori infection is marked by intense production of reactive oxygen species (ROS) through the activation of neutrophils that are constantly attracted to the infected gastric mucosa.
METHODS AND RESULTS:
Here, gallic acid and its alkyl esters were evaluated as compounds able to act as antimicrobial agents and inhibitors of ROS released by H. pylori-activated neutrophils simultaneously. We found that the higher hydrophobicity caused by esterification of gallic acid led to a significant increase in its ability as a cytotoxic agent against H. pylori, a scavenger of ROS and an inhibitor of NADPH oxidase in neutrophils. Octyl Gallate, a widely used food additive, showed the highest antimicrobial activity against H. pylori, with a minimum inhibitory concentration (MIC) value of 125 μg mL-1, whereas gallic acid had a MIC value higher than 1000 μg mL-1. The production of superoxide anion radicals was almost 100% abolished by the addition of 10 μM (2.82 μg mL-1) Octyl Gallate, whereas gallic acid inhibited around 20%. A similar tendency was also found when measuring the production of hypochlorous acid. The protective effect of the esters was cytochemically confirmed.
CONCLUSIONS:
In conclusion, this study showed that hydrophobicity is a crucial factor to obtain a significant anti-ROS and anti-H. pylori activity. Finally, it highlights Octyl Gallate, a food additive widely used in the food industry, as a promising molecule in the treatment of H. pylori infection. | | Antiviral Res. 2007 Feb;73(2):85-91. | | Antiviral effect of octyl gallate against DNA and RNA viruses.[Pubmed: 16950523] | The effects of gallic acid (3,4,5-trihydroxybenzoic acid) and its alkyl esters on virus growth and virion infectivity were examined.
METHODS AND RESULTS:
All the compounds tested showed an inhibitory effect on the growth of herpes simplex virus type 1 (HSV-1) in HEp-2 or Vero cells. The antiviral activity of gallic acid alkyl esters was enhanced by increasing the number of carbon in the alkyl moieties of the compounds, reaching maximum at a carbon number of 12 (lauryl gallate), but both cytocidal activity and cytopathic effect of the compounds were also significantly increased simultaneously. Among these compounds, Octyl Gallate showed a marked antiviral effect with a relatively moderate cytotoxity. In addition, Octyl Gallate suppressed the multiplication of RNA viruses, such as vesicular stomatitis virus and poliovirus.
CONCLUSIONS:
Quantitative characterization of the HSV-1 infection in the presence of Octyl Gallate revealed that: (1) this reagent can directly inactivate HSV-1 (virucidal activity), (2) it suppresses both the intracellar multiplication and the release of the virus, (3) it selectively accelerates death of the virus-infected cells and (4) the addition of the reagent even at 6-h post infection completely abolishes the formation of progeny virus in the infected cells. | | Int J Food Microbiol. 2002 Dec 15;79(3):193-201. | | Antifungal activity of octyl gallate.[Pubmed: 12371654] |
Antifungal activities of propyl (C3), octyl (C8) and dodecyl (C12) gallates (3,4,5-trihydroxybenzoate) were tested against Saccharomyces cerevisiae ATCC7754 and Zygosaccharomyces bailii ATCC 60483.
METHODS AND RESULTS:
Octyl Gallate was found to be the only active compound with the minimum fungicidal concentration of 25 microg/ml (89 microM) against S. cerevisiae and of 50 microg/ml (177 microM) against Z. bailii, respectively. The inactivation study showed that Octyl Gallate was fungicidal against both S. cerevisiae and Z. bailii at any stage of growth. These fungicidal activities were not influenced by pH values. Octyl Gallate at 100 microg /ml reduced plasma membrane fluidity to 48% of control. On the other hand, dodecyl gallate at the same concentration reduced it to 76% of control.
Only Octyl Gallate inhibited glucose-induced medium acidification, indicating direct or indirect inhibition of plasma membrane H +-ATPase.
CONCLUSIONS:
The primary fungicidal activity of Octyl Gallate comes from its ability to act as a nonionic surface-active agent (surfactant), though it can not be inferred that membrane damage, such as a decrease in the membrane fluidity, is the only cause of the lethal effect. |
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