scholarly journals Lethal Hydroxyl Radical Accumulation by a Lactococcal Bacteriocin, Lacticin Q

2013 ◽  
Vol 57 (8) ◽  
pp. 3897-3902 ◽  
Author(s):  
Mengqi Li ◽  
Fuminori Yoneyama ◽  
Nayu Toshimitsu ◽  
Takeshi Zendo ◽  
Jiro Nakayama ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Pore Formation ◽  
Membrane Lipid ◽  
Gram Positive Bacteria ◽  
Antimicrobial Mechanism ◽  
Toroidal Pore ◽  
Hydroxyl Radical Scavengers ◽  
Selective Antimicrobial Activity

ABSTRACTThe antimicrobial mechanism of a lactococcal bacteriocin, lacticin Q, can be described by the toroidal pore model without any receptor. However, lacticin Q showed different degrees of activity (selective antimicrobial activity) against Gram-positive bacteria even among related species. The ability of lacticin Q to induce pore formation in liposomes composed of lipids from different indicator strains indicated that its selective antimicrobial activity could not be attributed only to membrane lipid composition. We investigated the accumulation of deleterious hydroxyl radicals after exposure to lacticin Q as a contributing factor to cell death in the indicator strains. When lacticin Q of the same concentration as the MIC or minimum bactericidal concentration was added to the indicator cultures, high levels of hydroxyl radical accumulation were detected. Treatment with hydroxyl radical scavengers, thiourea and 2,2′-bipyridyl, decreased the levels of hydroxyl radical accumulation and recovered cell viability. These results suggest that, with or without pore formation, the final antimicrobial mechanism of lacticin Q is the accumulation of hydroxyl radicals, which varies by strain, resulting in the selective antimicrobial activity of lacticin Q.

scholarly journals Ferrous ion-EDTA-stimulated phospholipid peroxidation. A reaction changing from alkoxyl-radical- to hydroxyl-radical-dependent initiation

1984 ◽  
Vol 224 (3) ◽  
pp. 697-701 ◽  
Author(s):  
J M C Gutteridge
Keyword(s):  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Superoxide Radicals ◽  
Ferrous Ion ◽  
Radical Scavengers ◽  
Alkoxyl Radical ◽  
Phospholipid Peroxidation ◽  
Hydroxyl Radical Scavengers

The stimulatory effect of ferrous salts on the peroxidation of phospholipids can be enhanced by EDTA when the concentration of Fe2+ in the reaction is greater than that of EDTA. Hydroxyl-radical scavengers do not inhibit peroxidation until the concentrations of Fe2+ and EDTA in the reaction are equal. Lipid peroxidation is then substantially initiated by hydroxyl radicals derived from a Fenton-type reaction requiring hydrogen peroxide. Superoxide radicals appear to play some role in the formation of initiating species.

scholarly journals Inhibition of microsomal oxidation of alcohols and of hydroxyl-radical-scavenging agents by the iron-chelating agent desferrioxamine

1983 ◽  
Vol 210 (1) ◽  
pp. 107-113 ◽  
Author(s):  
A I Cederbaum ◽  
E Dicker
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Radical Scavenging ◽  
Chelating Agent ◽  
Dimethyl Sulphoxide ◽  
The Other ◽  
Radical Scavengers ◽  
Primary Alcohols ◽  
Hydroxyl Radical Scavengers ◽  
Oxidation Of Ethanol

Rat liver microsomes (microsomal fractions) catalyse the oxidation of straight-chain aliphatic alcohols and of hydroxyl-radical-scavenging agents during NADPH-dependent electron transfer. The iron-chelating agent desferrioxamine, which blocks the generation of hydroxyl radicals in other systems, was found to inhibit the following microsomal reactions: production of formaldehyde from either dimethyl sulphoxide or 2-methylpropan-2-ol (t-butylalcohol); generation of ethylene from 4-oxothiomethylbutyric acid; release of 14CO2 from [I-14C]benzoate; production of acetaldehyde from ethanol or butanal (butyraldehyde) from butan-1-ol. Desferrioxamine also blocked the increase in the oxidation of all these substrates produced by the addition of iron-EDTA to the microsomes. Desferrioxamine had no effect on a typical mixed-function-oxidase activity, the N-demethylation of aminopyrine, nor on the peroxidatic activity of catalase/H2O2 with ethanol. H2O2 appears to be the precursor of the oxidizing radical responsible for the oxidation of the alcohols and the other hydroxyl-radical scavengers. Chelation of microsomal iron by desferrioxamine most likely decreases the generation of hydroxyl radicals, which results in an inhibition of the oxidation of the alcohols and the hydroxyl-radical scavengers. Whereas desferrioxamine inhibited the oxidation of 2-methylpropan-2-ol, dimethyl sulphoxide, 4-oxothiomethylbutyrate and benzoate by more than 90%, the oxidation of ethanol and butanol could not be decreased by more than 45-60%. Higher concentrations of desferrioxamine were required to block the metabolism of the primary alcohols than to inhibit the metabolism of the other substrates. The desferrioxamine-insensitive rate of oxidation of ethanol was not inhibited by competitive hydroxyl-radical scavengers. These results suggest that primary alcohols may be oxidized by two pathways in microsomes, one dependent on the interaction of the alcohols with hydroxyl radicals (desferrioxamine-sensitive), the other which appears to be independent of these radicals (desferrioxamine-insensitive).

scholarly journals Different Inactivation Behaviors of MS-2 Phage and Escherichia coli in TiO2 Photocatalytic Disinfection

2005 ◽  
Vol 71 (1) ◽  
pp. 270-275 ◽  
Author(s):  
Min Cho ◽  
Hyenmi Chung ◽  
Wonyong Choi ◽  
Jeyong Yoon
Keyword(s):  
Escherichia Coli ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Mode Of Action ◽  
Microbial Inactivation ◽  
Chemical Degradation ◽  
Main Role ◽  
Chlorobenzoic Acid ◽  
E Coli ◽  
Hydroxyl Radical Scavengers

ABSTRACT Despite a wealth of experimental evidence concerning the efficacy of the biocidal action associated with the TiO2 photocatalytic reaction, our understanding of the photochemical mechanism of this particular biocidal action remains largely unclear. It is generally accepted that the hydroxyl radical (�OH), which is generated on the surface of UV-illuminated TiO2, plays the main role. However, our understanding of the exact mode of action of the hydroxyl radical in killing microorganisms is far from complete, and some studies report that other reactive oxygen species (ROS) (H2O2 and O2�−, etc.) also play significant roles. In particular, whether hydroxyl radicals remain bound to the surface or diffuse into the solution bulk is under active debate. In order to examine the exact mode of action of ROS in inactivating the microorganism, we tested and compared the levels of photocatalytic inactivation of MS-2 phage and Escherichia coli as representative species of viruses and bacteria, respectively. To compare photocatalytic microbial inactivation with the photocatalytic chemical degradation reaction, para-chlorobenzoic acid, which rapidly reacts with a hydroxyl radical with a diffusion-limited rate, was used as a probe compound. Two different hydroxyl radical scavengers, tert-butanol and methanol, and an activator of the bulk phase hydroxyl radical generation, Fe2+, were used to investigate their effects on the photocatalytic mode of action of the hydroxyl radical in inactivating the microorganism. The results show that the biocidal modes of action of ROS are very different depending on the specific microorganism involved, although the reason for this is not clear. It seems that MS-2 phage is inactivated mainly by the free hydroxyl radical in the solution bulk but that E. coli is inactivated by both the free and the surface-bound hydroxyl radicals. E. coli might also be inactivated by other ROS, such as O2�− and H2O2, according to the present results.

scholarly journals Antimicrobial Activity of Tetrabromobisphenol A (TBBPA) against Staphylococcus aureus Skin Infections

2018 ◽  
Author(s):  
Chang Wang ◽  
Fang Ji ◽  
Fengjie Chen ◽  
Bolei Chen ◽  
Zhen Zhou ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Wound Closure ◽  
Tetrabromobisphenol A ◽  
Gram Positive ◽  
Inflammatory Infiltration ◽  
Gram Positive Bacteria ◽  
Bactericidal Effects ◽  
Selective Antimicrobial Activity

AbstractTetrabromobisphenol A (TBBPA) is a brominated flame retardant with selective antimicrobial activity against Gram-positive bacteria. We show that TBBPA exerts bactericidal effects by damaging the cell wall and membrane of Staphylococcus aureus (SA) without inducing antimicrobial resistance. In vivo skin infection assays indicate that a low dose of TBBPA could contribute to wound closure and attenuate SA infection and inflammatory infiltration. TBBPA has potential for use as an antimicrobial agent against Gram-positive pathogens.

scholarly journals Polycarbonates with Potent and Selective Antimicrobial Activity toward Gram-Positive Bacteria

2016 ◽  
Vol 18 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Alekhya Nimmagadda ◽  
Xuan Liu ◽  
Peng Teng ◽  
Ma Su ◽  
Yaqiong Li ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Selective Antimicrobial Activity

Selective antimicrobial activity of biochanin A

Planta Medica ◽  
2009 ◽  
Vol 75 (09) ◽  
Author(s):  
J Flesar ◽  
O Sklenickova ◽  
E Vlkova ◽  
J Malik ◽  
L Kokoska
Keyword(s):  
Antimicrobial Activity ◽  
Biochanin A ◽  
Selective Antimicrobial Activity

Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation

1998 ◽  
Vol 38 (6) ◽  
pp. 147-154 ◽  
Author(s):  
Hideo Utsumi ◽  
Sang-Kuk Han ◽  
Kazuhiro Ichikawa
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Spin Trapping ◽  
Active Species ◽  
Generation Rate ◽  
Peak Height Ratio ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phenol Derivatives ◽  
Semiquinone Radicals

Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 X 10-6M of DMPO-OH, indicating that 1.4% of •OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance •OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.

Synthesis, SAR, In-Silico appraisal and Anti-Microbial Study of substituted 2-aminobenzothiazoles derivatives

2019 ◽  
Vol 15 ◽  
Author(s):  
Devidas G. Anuse ◽  
Suraj N. Mali ◽  
Bapu R. Thorat ◽  
Ramesh S. Yamgar ◽  
Hemchandra K. Chaudhari
Keyword(s):  
Antimicrobial Activity ◽  
In Silico ◽  
Docking Study ◽  
Moderate Activity ◽  
Molecular Docking Study ◽  
Mass Spectral ◽  
Gram Positive Bacteria ◽  
Ft Ir ◽  
In Silico Molecular Docking

Background: Antimicrobial resistance is major global health problem, which is being rapidly deteriorating the quality of human health. Series of substituted N-(benzo[d]thiazol-2-yl)-2-(4-(6-fluorobenzo[d]isoxazol-3-yl)piperidin-1-yl)acetamide (3a-j) were synthesized from substituted N-(benzo[d]thiazol-2-yl)-2-chloroacetamide/bromopropanamide (2a-j) and 6-fluoro-3-(piperidin-4-yl)benzo[d]isoxazole (2) and further evaluated for their docking properties and antimicrobial activity. Methods: All synthesized compounds were characterized by FT-IR, NMR and Mass spectral analysis. All compounds were allowed to dock against different antimicrobial targets having PDB ID: 1D7U and against common antifungal target having PDB ID: 1EA1. Results: The compounds 3d and 3h were showed good activity against Methicillin-resistant Staphylococcus aureus (MRSA, resistance Gram-positive bacteria). All synthesized compounds showed good to moderate activity against selected bacterial and fungal microbial strains. If we compared the actual in-vitro antimicrobial activity and in-silico molecular docking study, we found that molecules 3i and 3h were more potent than the others. Conclusion: Our current study would definitely pave the new way towards designing and synthesis of more potent 2-aminobenzothiazoles derivatives.

Chemical Composition and in-vitro antimicrobial screening of leaf essential oil of Plectranthus gerardianus Benth., and isolation of the major constituent of oil

2020 ◽  
Vol 10 ◽  
Author(s):  
Navadha Bhatt ◽  
Navabha Joshi ◽  
Kapil Ghai ◽  
Om Prakash
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oil ◽  
Major Constituent ◽  
In Vitro Antimicrobial Activity ◽  
Gram Positive Bacteria ◽  
Medicinal Value ◽  
Leaf Essential Oil ◽  
Plant Families ◽  
Total Oil

Background: The Lamiaceae (Labiatae) is one of the most diverse and widespread plant families’ in terms of ethno medicine and its medicinal value is based on the volatile oils concentration. This family is important for flavour, fragrance and medicinal properties. Manyplants belonging to this family have indigenous value. Method: The essential oil of Plectranthus gerardianusBenth. (Lamiaceae), was analysed by GC and GC-MS analysis, while the major component was isolated and conformed by NMR spectroscopy. Result: The oil was found to be rich in oxygenated monoterpenes, which contribute around 62% of the total oil. The major components identified were fenchone (22.90%) and carvenone oxide (16.75%), besides other mono and sesquiterpenoids. The in-vitro antimicrobial activity of essential oil was tested against three gram negative bacteria viz. Pasteurellamultocida, Escherichia coli, and Salmonella enterica, two gram positive bacteria viz. Staphylococcus aureus and Bacillus subtilis and two fungi viz. Candida albicans and Aspergillusflavus. The antimicrobial activity of the oil was also compared to the antimicrobial activity of leaf essential oil of another Himalayan plant viz. Nepetacoerulescens. Conclusion: The oil showed in-vitro antimicrobial activity against all the microbial strains and can lessen the ever-growing demand of potentially hazardous antibiotics for treatment.

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