Antibacterial action of 2-bromo-2-nitropropane-1,3-diol (bronopol)

Abstract

Patterns of growth inhibition of Escherichia coli in the presence of 2-bromo-2-nitropropane-1,3-diol (bronopol) indicate a period of biocide-induced bacteriostasis followed by growth at an inhibited rate. The length of the bacteriostatic period, but not the subsequent growth inhibition, was reduced by the addition of excess cysteine. Patterns of growth inhibition were unaffected by catalase or superoxide dismutase. The bactericidal concentrations (100 to 500 ,ug/ml) were considerably in excess of the MIC (13 ,ug/ml) and generally produced first-order reductions in viability. Bactericidal activity was considerably reduced by anoxic conditions and by the presence of catalase or superoxide dismutase. Results indicate that there are two distinct reactions between bronopol and thiols. Under aerobic conditions, bronopol catalytically oxidizes thiolcontaining materials such as cysteine, with atmospheric oxygen as the final oxidant. By-products of this reaction are active oxygen species such as superoxide and peroxide, which are directly responsible for the bactericidal activity of the compound and for the reduced growth rate after the bacteriostatic period. The latter effect probably results from the oxidation of intracellular thiols such as glutathione and cysteine. Catalytic oxidation of thiols in the presence of excess thiol leads to the creation of an anoxic state. Under these conditions, the slower reaction with thiols, which consumes bronopol, predominates. Consumption of bronopol by its reaction with thiols, without the involvement of oxygen, leads to the eventual removal of bronopol from treated suspensions and the resumption of growth.2-Bromo-2-nitropropane-1,3-diol (bronopol) has a broad spectrum of antibacterial activity (12) and is widely used, at concentrations of up to 0.1% (wt/vol), as a preservative for pharmaceutical and cosmetic products (4, 15). Previous studies of the mechanism of action of bronopol all conclude that the antibacterial activity of bronopol relates to its interaction with essential thiols within the cell (3,16,18). Such interaction is thought to lead to the oxidation of thiols through a radical anion intermediate (11). Unlike other thiol-interactive antimicrobial agents, bronopol possesses significant bactericidal activity that cannot be explained solely in terms of thiol oxidation. This paper examines the hypothesis that separate actions are responsible for the growth inhibitory and bactericidal activities of the compound. MATERIALS AND METHODSOrganisms, chemicals, and culture maintenance. Escherichia coli ATCC 8739 was used throughout the study. Cultures were maintained on nutrient agar (Oxoid CM 3) slopes at room temperature in the dark after incubation at 35°C. 2-Bromo-2-nitropropane-1,3-diol (bronopol) was obtained from the Boots Chemical Co., Nottingham, England. Catalase, superoxide dismutase, cytochrome c, cysteine, cystine, cysteine hydrochloride, and cystine dimethyl ester were obtained from the Sigma Chemical Co., St. Louis, Mo. All other reagents were of the purest avail...

Characterization of Corrosive Bacterial Consortia Isolated from Water in a Cooling Tower

“…The antibacterial mechanism of bronopol has been attributed to its interaction with essential thiols within the cell [32,33]. Shepherd et al [36] have also reported that bronopol catalyses the oxidation of thiol groups to disulfides with the consumption of oxygen. Such catalytic reaction also results in the generation of free radicals which subsequently inhibits the growth of the bacteria.…”

“…Nitrite, a specific metabolic inhibitor of corrosive bacteria, especially sulphate reducing bacteria [32,33], is also relatively nontoxic and inexpensive and has been successfully used to inhibit corrosive bacteria [34]. 2-Bromo-2-nitropropane-1,3-diol (bronopol) has a broad spectrum of antibacterial activity and is widely used as a preservative in pharmaceutical and cosmetic products and many industrial environments such as paper mills, oil exploration, and production facilities, as well as a disinfectant in cooling water [35,36]. The present investigation describes 16S rRNA gene sequencing and the identification of bacterial communities (at the species level) present in water from a cooling tower.…”

Repellent Activity of Essential Oils from Cananga odorata Lamk. and Cymbopogon nardus L. on Corn Starch-Based Thixogel

“…These preservatives are widely used in cosmetic preparations due to their neutral, non-irritating, non-toxic and safe to use. [24][25][26] The organoleptic study showed that there were no change in the shape, odor, and color of all formulations during storage at room temperature for 56 days. These result suggest that the essential oils were stable on corn starch-based thixogel, probably due to steady emulsion system in the corn starch-based thixogel.…”

Efficacy of Colloidal Silver-Hydrogen Peroxide and 2-Bromo-2-nitroporopane-1,3-diol Compounds Against Different Serogroups of Legionella pneumophila Strains

“…On the other hand, BNPD has a broad spectrum of antibacterial activity which is a non-oxidizing compound, stable under varying conditions of temperature, relative humidity and exposure to natural light, slightly toxic to avian species, freshwater fish and invertebrates [10]. The antibacterial activity of BNPD relates to its interaction with essential thiols within the cell for the growth inhibition and generation of free radicals causing cell death [11][12][13].…”