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PubMed2006

Effects of weak acids, UV and proton motive force inhibitors on pyrazinamide activity against Mycobacterium tuberculosis in vitro.

BACKGROUND: Pyrazinamide is a paradoxical frontline tuberculosis drug characterized by high sterilizing in vivo activity but poor in vitro activity. Pyrazinamide is thought to act by the entrapment of pyrazinoic acid in the bacterial cell, leading to acidification and membrane damage. Consequently, the effects of weak acids and molecules affecting membranes added to pyrazinamide were studied. OBJECTIVES: To examine the effects of weak acids, UV, oxidative stress and additional energy inhibitors on pyrazinamide activity in vitro against Mycobacterium tuberculosis as well as the effect of pyrazinamide on Escherichia coli ampicillin persisters. METHODS: Drug exposure experiments followed by cfu counts were performed to determine the effects of the above various factors on pyrazinamide activity in vitro against M. tuberculosis. RESULTS: Some weak acids such as benzoic acid, sorbic acid and propyl hydroxybenzoic acid could enhance the activity of pyrazinamide in vitro against old tubercle bacilli but not young bacilli whereas other weak acids such as salicylic acid and lactic acid did not appear to enhance pyrazinamide activity. While energy inhibitors carbonylcyanide m-chlorophenylhydrazone and dinitrophenol enhanced pyrazinamide activity for old tubercle bacilli but not young bacilli, valinomycin and KCN increased pyrazinamide activity for both young and old bacilli. Oxidative stresses due to H2O2 and menadione did not have a significant effect on pyrazinamide activity. UV, which presumably damages the membrane, enhanced the activity of pyrazinamide. Pyrazinamide, which otherwise has no activity against actively growing E. coli bacteria, could kill non-growing starved E. coli and also ampicillin-tolerant persisters. CONCLUSIONS: Some weak acids, UV and various energy inhibitors were found to enhance the activity of pyrazinamide in vitro against M. tuberculosis. Pyrazinamide shows preferential activity against both M. tuberculosis and E. coli persisters over the growing forms.

Ampicillin↗
PubMed1987

Hypersensitivity reactions to food additives.

Only seldom have food additives been shown to cause true allergic (immunological) reactions. Adverse effects due to various pharmacological or other mechanisms are much more common. The individual tolerance may be decreased for one reason or another, and may fluctuate from time to time. Many patients suffering from food additive reactions have atopic constitutions and such clinical symptoms as flexural dermatitis, rhinitis and asthma. The most important skin symptoms caused by food additives are urticaria, angioneurotic edema, and contact urticaria. Azo dyes, benzoic acid and several other common food additives may aggravate or, more rarely, even cause urticaria. Spices are one of the most common causes of immunological contact urticaria. Non-immunological contact urticaria is produced by numerous spices, benzoic acid, sorbic acid, cinnamic acid, and many essential oils. Asthma and rhinitis are the main hypersensitivity symptoms in the respiratory tract, and azo dyes, benzoic acid, and sulfitic food additives are the most common causative agents. Systemic and respiratory reactions to food colorants and benzoates have been claimed to occur more frequently in acetylsalicylic acid- (ASA-)sensitive patients than in non-reactors. Hypersensitivity reactions in organs other than the skin and respiratory tract are rare or poorly documented. Psychological factors play an essential role in both food and food additive reactions.

Dermatitis↗
PubMed1999

Combinations of intervention treatments resulting in 5-log10-unit reductions in numbers of Escherichia coli O157:H7 and Salmonella typhimurium DT104 organisms in apple cider.

The U.S. Food and Drug Administration (FDA) recently mandated a warning statement on packaged fruit juices not treated to reduce target pathogen populations by 5 log10 units. This study describes combinations of intervention treatments that reduced concentrations of mixtures of Escherichia coli O157:H7 (strains ATCC 43895, C7927, and USDA-FSIS-380-94) or Salmonella typhimurium DT104 (DT104b, U302, and DT104) by 5 log10 units in apple cider with a pH of 3.3, 3.7, and 4.1. Treatments used were short-term storage at 4, 25, or 35 degrees C and/or freeze-thawing (48 h at -20 degrees C; 4 h at 4 degrees C) of cider with or without added organic acids (0.1% lactic acid, sorbic acid [SA], or propionic acid). Treatments more severe than those for S. typhimurium DT104 were always required to destroy E. coli O157:H7. In pH 3.3 apple cider, a 5-log10-unit reduction in E. coli O157:H7 cell numbers was achieved by freeze-thawing or 6-h 35 degrees C treatments. In pH 3.7 cider the 5-log10-unit reduction followed freeze-thawing combined with either 6 h at 4 degrees C, 2 h at 25 degrees C, or 1 h at 35 degrees C or 6 h at 35 degrees C alone. A 5-log10-unit reduction occurred in pH 4.1 cider after the following treatments: 6 h at 35 degrees C plus freeze-thawing, SA plus 12 h at 25 degrees C plus freeze-thawing, SA plus 6 h at 35 degrees C, and SA plus 4 h at 35 degrees C plus freeze-thawing. Yeast and mold counts did not increase significantly (P < 0.05) during the 6-h storage at 35 degrees C. Cider with no added organic acids treated with either 6 h at 35 degrees C, freeze-thawing or their combination was always preferred by consumers over pasteurized cider (P < 0.05). The simple, inexpensive intervention treatments described in the present work could produce safe apple cider without pasteurization and would not require the FDA-mandated warning statement.

Acids↗
PubMed1982

Drug-nitrite interactions in human saliva: effects of food constituents on carcinogenic N-nitrosamine formation.

A simple and rapid high-pressure liquid chromatographic assay for monitoring N-nitrosodimethylamine (NDMA) in human saliva was developed. The method was used to study in vitro the effects of common food constituents on NDMA formation in saliva from the interaction of salivary nitrite with aminopyrine and oxytetracycline. Natural phenolic compounds, caffeic acid, and tannic acid, and synthetic additives, erythorbic acid, sorbic acid, propyl gallate, and butylated hydroxytoluene--all inhibited NDMA formation (20-80%). With ascorbic acid, up to 90% inhibition of NDMA synthesis in saliva was observed. In contrast, chlorogenic acid (a phenolic component of coffee) acted as a catalyst (up to 48% increase) of the nitrosamine formation under identical experimental conditions.

Adult↗
PubMed2004

Antimicrobial edible films and coatings.

Increasing consumer demand for microbiologically safer foods, greater convenience, smaller packages, and longer product shelf life is forcing the industry to develop new food-processing, cooking, handling, and packaging strategies. Nonfluid ready-to-eat foods are frequently exposed to postprocess surface contamination, leading to a reduction in shelf life. The food industry has at its disposal a wide range of nonedible polypropylene- and polyethylene-based packaging materials and various biodegradable protein- and polysaccharide-based edible films that can potentially serve as packaging materials. Research on the use of edible films as packaging materials continues because of the potential for these films to enhance food quality, food safety, and product shelf life. Besides acting as a barrier against mass diffusion (moisture, gases, and volatiles), edible films can serve as carriers for a wide range of food additives, including flavoring agents, antioxidants, vitamins, and colorants. When antimicrobial agents such as benzoic acid, sorbic acid, propionic acid, lactic acid, nisin, and lysozyme have been incorporated into edible films, such films retarded surface growth of bacteria, yeasts, and molds on a wide range of products, including meats and cheeses. Various antimicrobial edible films have been developed to minimize growth of spoilage and pathogenic microorganisms, including Listeria monocytogenes, which may contaminate the surface of cooked ready-to-eat foods after processing. Here, we review the various types of protein-based (wheat gluten, collagen, corn zein, soy, casein, and whey protein), polysaccharide-based (cellulose, chitosan, alginate, starch, pectin, and dextrin), and lipid-based (waxes, acylglycerols, and fatty acids) edible films and a wide range of antimicrobial agents that have been or could potentially be incorporated into such films during manufacture to enhance the safety and shelf life of ready-to-eat foods.

Anti-Bacterial Agents↗
PubMed2001

[Effects of chemical agents on the prevention of fungal contamination during household wheat storage in Cixian county].

OBJECTIVE: To evaluate the effectiveness of several commercial chemical agents (DMF, AP and Chumeijing) on the prevention of fungal contamination in household storage of wheat in Cixian county. METHODS: The antifungal agents tested include dimethyl fumarate, DMF, aluminium phosphide, AP and Chumeijing (a Chinese product comprised of propionic acid, formic acid, sorbic acid and fumaric acid). The chemicals were applied in the wheat containers in the rural households. The fungal contamination and the inhibitory effects on fungal growth in wheat were measured by fungal isolation, culture, identification and count. RESULTS: The fungal contamination in the household wheat before using fungicides were quite common, with an overall contamination rate of 67.5% to 100%. The application of the three chemical fungicides effectively reduced fungal contamination in household stored wheat, and the effective rate for DMF, AP, AMF + AP and Chumeijing was 91.2%, 85.2%, 100% and 100% respectively, while the rate of fungi growth inhibition was (61.9 +/- 21.6)%, (64.0 +/- 21.6)%, (72.5 +/- 18.0)% and (63.1 +/- 24.3)% respectively. CONCLUSION: DMF, AP and Chumeijing are all effective in the prevention of fungal contamination for household stored wheat in Cixian county. AP is not recommended owing to its higher toxicity, compared with the other chemicals tested.

Acids, Acyclic↗
PubMedDate not supplied

Analysis of glycolysis metabolites by capillary zone electrophoresis with indirect UV detection.

The glycolysis metabolites glucose 6-phosphate (G6-P), fructose 6-phosphate (F6-P), fructose 1,6-bisphosphate (F1,6-BP), fructose 2,6-bisphosphate (F2,6-BP), glyceraldehyde phosphate (GAP), dihydroxyacetone phosphate (DHAP), phosphoenolpyruvate (PEP), pyruvate, and lactate were analyzed by capillary zone electrophoresis (CZE) with indirect UV detection. The chromophores phthalic acid, sorbic acid, and 4-hydroxybenzoic acid were studied as background electrolytes. Both detection sensitivity and resolution were found to depend on the pH and the concentration of the carrier electrolyte. Optimum separation and detection of the phosphate compounds were accomplished upon reversal of electroendosmotic flow (EOF) with OFM Anion-BT (Waters Corp., Milford, MA) at a concentration of 4-6 mM 4-hydroxybenzoic acid, pH 11.6-12.0, with the detection wave-length set at 280 nm. The highly alkaline pH allowed the successful separation of the isomers F6-P and G6-P, as well as F1,6-BP and F2,6-BP, respectively. The effect of sample ionic strength on the detection limits of G6-P, F6-P, F1,6-BP, and F2,6-BP was also investigated: These limits ranged from 1 to 3 microM in both low- and high-ionic-strength samples. However, high Mg2+ concentrations in the sample led to a progressive loss of resolution between F1,6-BP and F2,6-BP, unless the inlet reservoir was replenished with fresh electrolyte after every injection. Linearity of detection was observed over one to two orders of magnitude.

Dihydroxyacetone Phosphate↗
PubMed1977

[Food additives and their possible genetic toxicity; microbiological determination].

In the present work we intend to find an accurat methodology to establish in an easy way the mutagenic potential of drugs employed as food additives. For that purpose we first selected a microbiological system for performing this assay. The method assayed consisted of investigating the effect exerted on genetic recombination by the following chemical agents: Chloroacetic Acid, Iodoacetic Acid, Sorbic Acid, Potassium Metabisulfite, Sodium Nitrite, Auramine and Erythrossine. The activity of these agents was detected though their effect on the transformation of an auxotrophic strain of Bacillus subtilis. Comparative assays of reversion of characters have been made with strains of Salmonella typimurium already used by other authors. These assays have also been repeated with several auxotrophic strains of Bacillus subtilis and different genetic characters have been studied. Most results suggest that changes in the recombination process should have occured at different levels according with the drugs assayed. On the other hand, the results of reversion have not been significant enough. We think that more accuracy is afforded by both the recombination and the reversion assay developed to other for this kind of detection.

Animals↗
PubMed2000

Lack of specificity of trans,trans-muconic acid as a benzene biomarker after ingestion of sorbic acid-preserved foods.

The benzene metabolite, trans,trans-muconic acid (MA), has been shown to be a sensitive and specific biomarker for ambient benzene exposure levels as low as approximately 0.5 ppm. However, at lower exposure levels, the use of MA as a benzene biomarker is complicated by the fact that it is also a metabolite of the food preservative, sorbic acid. To better assess the extent of this interference, MA was measured in sequential spot urine samples over a 2-day study period from eight volunteers (four adults and two parent-children pairs) who consumed two sorbic acid-preserved foods. Large increases in MA concentration were seen after ingestion of both foods. Individual peaks ranged as high as 1673.7 ng/ml (705.3 ng/mg creatinine) in adults and 1752.1 ng/mg creatinine (1221.3 ng/ml) in children. Ratios of peak to baseline values varied from 2.5 to 60. The average peak in the seven subjects who showed an increase in MA after ingestion of the first sorbic acid-containing food was 531.1 ng/ml (693.2 ng/mg creatinine). The average in the seven participants who ingested the second food was 1102.1 ng/ml (795.3 ng/mg creatinine). Twenty-four-hour personal air benzene levels were all low (< or = 5.6 ppb). Substantial variation in MA results were seen in some males related to creatinine adjustment. These data indicate that sorbic acid-preserved foods have the potential to cause substantial interference with MA as a biomarker for both occupational and environmental benzene exposure in populations, such as in the United States, where consumption of preserved foods is common. Development of methods to minimize and/or assess sorbic acid interference will improve MA specificity in such populations.

Adult↗
PubMed1986

Sorbic acid-induced erythema and edema.

Sorbic acid concentrations as low as 0.1% produced transient erythema with edema and flare after open or closed application to human skin. Multiple areas of the body were tested. Reactions were most intense on the face but also could be produced on the back, forearm, and deltoid areas. Sorbic acid-induced erythema, edema, and flare were not associated with mast cell degranulation. Pretreatment of skin with topical steroids to induce vasoconstriction resulted in a diminished response to sorbic acid. Aspirin blocked the erythematous component, suggesting that prostaglandins are important mediators. Systemic steroids, antihistamines, and hydroxyzine failed to influence sorbic acid-induced erythema and edema. The anti-inflammatory effect of topical steroids was not affected by sorbic acid-induced erythema.

Administration, Topical↗
PubMed2004

Improvement in the disintegration of shellac-coated soft gelatin capsules in simulated intestinal fluid.

Shellac is a natural enteric polymer, which results in good gastric resistance; however, it often dissolves too slowly in intestinal fluids. The objective of this study was to improve the disintegration of shellac-coated soft gelatin capsules in simulated intestinal fluids (phosphate buffer pH 6.8) through the addition of pore-formers, such as organic acids and hydrophilic polymers, while retaining gastric resistance. The mechanical properties (% elongation at rupture, puncture strength at break and modulus at puncture), media uptake and weight loss of shellac films were determined upon exposure in 0.1 N HCl and/or phosphate buffer pH 6.8. Organic acids (e.g., sorbic acid) acted as plasticizers, they reduced the glass transition temperature of ethanol-cast shellac films. The addition of additives effectively decreased the disintegration times in phosphate buffer pH 6.8, while the behavior in 0.1 N HCl remained unchanged. In addition, the hardness and disintegration of shellac-coated soft gelatin capsules were monitored through the whole disintegration experiments. The best disintegration was achieved with sorbic acid as pore-former. Sorbic acid remained in the shellac coating at low pH, but leached in pH 6.8 buffer, thus resulting in good gastric resistance and rapid disintegration in simulated intestinal fluids. The disintegration time of ethanolic shellac-coated soft gelatin capsules decreased with increasing amount of pore-former. The slow disintegration of aqueous shellac-coated soft gelatin capsules could be also improved by the addition of hydrophilic polymers, such as hydroxypropyl methylcellulose (HPMC). However, higher HPMC concentrations were required when compared to sorbic acid.

Capsules↗
PubMed1981

[Agents for the aerosol disinfection of the air in meat freezers].

Studies were carried out on the use of aerosol disinfection with lactic acid and sorbic acid at rates of 15, 30, and 50 mg per 1 m3 air in chambers for the conservation of meat and meat products at temperatures within the range of 0 to 2 degrees C. Moulds of the Penicillium genus and psychrophile organisms (Pseudomonas, Alkaligenes, and Flavobacter) were used as test microbial species. It was found that the disinfection effect of lactic acid used in the form of aerosol was the same as that of sorbic acid when psychorophiles served as test bacteria, and was essentially better in the disinfection of the air in refrigerators and the surface of meat when Penicillium moulds were used. In concentrations of up to 50 mg/m3 both lactic acid and sorbic acid had no adverse effect on the organoleptic indices of meat during refrigerator storage.

Aerosols↗
PubMed2001

Acid tolerance of Escherichia coli O157:H7 and its survival in apple juice.

Outbreaks of diarrhoea and haemolytic uraemic syndrome have been associated with the consumption of apple cider and apple juice. The organism implicated in these outbreaks has been Escherichia coli O157:H7, indicating the resistance of the serotype to acidic pH. On comparing the growth of this serotype with a control strain of E. coli, it was found that strain O157:H7 grew well in trypticase soy broth at pH levels ranging from 2.0 to 9.0, while control strains failed to grow at pH levels below 4.0 and above 9.0. The growth of both strains were inhibited by adding 0.05% of either benzoic acid or sorbic acid. Similarly, O157:H7 grew well in both natural (unpasteurized) as well as in pasteurized apple juice and the growth was inhibited by adding 0.1% of either benzoic acid or sorbic acid. Control strains of E. coli failed to grow in either types of apple juice. The possible sources of contamination of natural apple juice with O157:H7 serotype are discussed.

Acids↗
PubMed2001

Estimation of preservative concentrations in foods and their daily intake based on official inspection results in Japan in fiscal year 1998.

The mean concentration and daily intake of five preservatives were estimated based on the results of an analysis of 89,927 samples of food obtained in official inspections by Japanese local governments in fiscal year 1998. The mean concentration of benzoic acid was 9.5% of the allowable limit, and those of dehydroacetic acid, p-hydroxybenzoic acid, propionic acid, and sorbic acid were 1.5%, 5.7%, 1.7%, and 23.9%, respectively. Daily intake levels of these preservatives per person estimated from the concentration and daily consumption of foods were 6.23 mg, 0.0303 mg, 1.02 mg, 8.10 mg, and 25.0 mg, respectively, and assuming a body weight of 50 kg, the amounts of benzoic acid, p-hydroxybenzoic acid, and sorbic acid consumed were 2.5%, 0.2%, and 2.0% of their acceptable daily intakes, respectively. These values were similar to those obtained based on the results of the official inspections in fiscal years 1994 and 1996.

Benzoic Acid↗
PubMed1990

Immediate contact reactions to chemicals in the fragrance mix and a study of the quenching action of eugenol.

In this study, the nature of non-immune immediate contact reactions (NIICR) produced by cinnamic aldehyde, benzoic acid and sorbic acid were investigated, with particular interest in the 'quenching' ability of eugenol. Three groups of human subjects were studied, and the guinea-pig ear was also used as a model of NIICR. Cinnamic aldehyde, benzoic acid and sorbic acid were all able to produce NIICR in the majority of subjects studied. There was a strong correlation between the susceptibility of each subject to each urticant, but no correlation between the susceptibility to NIICR and age, atopic status or tanning ability. Eugenol caused a reduction in NIICR induced by all three urticants. This 'quenching' effect was apparent even when the eugenol was applied up to 60 min prior to application of cinnamic aldehyde, and its effect was not eliminated by washing. In the guinea-pig-ear model, ear thickening was induced by all three urticants, and this response was inhibited by eugenol.

Acrolein↗
PubMed1996

Investigation of a pulsed-laser thermo-optical absorbance detector for the determination of food preservatives separated by capillary electrophoresis.

Thermo-optical absorbance (TOA) detection using a KrF excimer waveguide laser for detection of benzoic acid, dehydroacetic acid and sorbic acid separated by capillary electrophoresis (CE) was studied. Detection limits were, on average, ten times better than those for on-column UV absorbance methods with CE, and two or more times better than those for UV absorbance with HPLC. The influence of increased laser power on TOA detection sensitivity was found to be strong for benzoic and dehydroacetic acids but quite weak for sorbic acid. It was discovered that photoisomerization of sorbic acid (2,4-hexadienoic acid) occurred readily in the detection volume at moderate laser powers (P(ave) = 3 mW) and increased with slow electroosmotic flows (< 6 cm/min). The TOA method described here shows improved detection sensitivity for CE analyses of compounds having only weak absorptivities (< 5% of maximum) at lambda = 248 nm, and thus demonstrates its utility for determination of a variety of analytes in a single separation.

Electrophoresis, Capillary↗
PubMed2001

Parallel and comparative analysis of the proteome and transcriptome of sorbic acid-stressed Saccharomyces cerevisiae.

Exposure of Saccharomyces cerevisiae to 0.9 mM sorbic acid at pH 4.5 resulted in the upregulation of 10 proteins; Hsp42, Atp2, Hsp26, Ssa1 or Ssa2, Ssb1 or Ssb2, Ssc1, Ssa4, Ach1, Zwf1 and Tdh1; and the downregulation of three proteins; Ade16, Adh3 and Eno2. In parallel, of 6144 ORFs, 94 (1.53%) showed greater than a 1.4-fold increase in transcript level after exposure to sorbic acid and five of these were increased greater than two-fold; MFA1, AGA2, HSP26, SIP18 and YDR533C. Similarly, of 6144 ORFs, 72 (1.17%) showed greater than a 1.4-fold decrease in transcript level and only one of these, PCK1, was decreased greater than two-fold Functional categories of genes that were induced by sorbic acid stress included cell stress (particularly oxidative stress), transposon function, mating response and energy generation. We found that proteomic analysis yielded distinct information from transcript analysis. Only the upregulation of Hsp26 was detected by both methods. Subsequently, we demonstrated that a deletion mutant of Hsp26 was sensitive to sorbic acid. Thus, the induction of Hsp26, which occurs during adaptation to sorbic acid, confers resistance to the inhibitory effects of this compound.

DNA, Complementary↗
PubMed1999

The Saccharomyces cerevisiae weak-acid-inducible ABC transporter Pdr12 transports fluorescein and preservative anions from the cytosol by an energy-dependent mechanism.

Growth of Saccharomyces cerevisiae in the presence of the weak-acid preservative sorbic acid results in the induction of the ATP-binding cassette (ABC) transporter Pdr12 in the plasma membrane (P. Piper, Y. Mahe, S. Thompson, R. Pandjaitan, C. Holyoak, R. Egner, M. Muhlbauer, P. Coote, and K. Kuchler, EMBO J. 17:4257-4265, 1998). Pdr12 appears to mediate resistance to water-soluble, monocarboxylic acids with chain lengths of from C(1) to C(7). Exposure to acids with aliphatic chain lengths greater than C(7) resulted in no observable sensitivity of Deltapdr12 mutant cells compared to the parent. Parent and Deltapdr12 mutant cells were grown in the presence of sorbic acid and subsequently loaded with fluorescein. Upon addition of an energy source in the form of glucose, parent cells immediately effluxed fluorescein from the cytosol into the surrounding medium. In contrast, under the same conditions, cells of the Deltapdr12 mutant were unable to efflux any of the dye. When both parent and Deltapdr12 mutant cells were grown without sorbic acid and subsequently loaded with fluorescein, upon the addition of glucose no efflux of fluorescein was detected from either strain. Thus, we have shown that Pdr12 catalyzes the energy-dependent extrusion of fluorescein from the cytosol. Lineweaver-Burk analysis revealed that sorbic and benzoic acids competitively inhibited ATP-dependent fluorescein efflux. Thus, these data provide strong evidence that sorbate and benzoate anions compete with fluorescein for a putative monocarboxylate binding site on the Pdr12 transporter.

ATP-Binding Cassette Transporters↗