Bactericidal activities of health-promoting, food-derived powders against the foodborne pathogens Escherichia coli, Listeria monocytogenes, Salmonella enterica, and Staphylococcus aureus.

Unlabelled: We evaluated the relative bactericidal activities (BA(50) ) of 10 presumed health-promoting food-based powders (nutraceuticals) and, for comparison, selected known components against the following foodborne pathogens: Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The relative activities were evaluated using quantitative bactericidal activity [(BA(50) value, defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in colony forming units]. The BA(50) values were determined by fitting the data to a sigmoidal curve by regression analysis using concentration-antimicrobial response data.

The olive compound 4-hydroxytyrosol inactivates Staphylococcus aureus bacteria and Staphylococcal Enterotoxin A (SEA).

The foodborne pathogen Staphylococcus aureus produces the virulent staphylococcal enterotoxin A (SEA), a single chain protein which consists of 233 amino acid residues with a molecular weight of 27078 Da. SEA is a superantigen that is reported to contribute to animal (mastitis) and human (emesis, diarrhea, atopic dermatitis, arthritis, and toxic shock) syndromes. Changes in the native structural integrity may inactivate the toxin by preventing molecular interaction with cell membrane receptor sites of their host cells.

Recipes for antimicrobial wine marinades against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica.

We have evaluated bactericidal activities against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica of several antimicrobial wine recipes, each consisting of red or white wine extracts of oregano leaves with added garlic juice and oregano oil. Dose-response plots were used to determine the percentage of the recipes that resulted in a 50% decrease in colony-forming units (CFU) at 60 min (BA(50)). Studies designed to optimize antibacterial activities of the recipes demonstrated that several combinations of the naturally occurring plant-derived ingredients rapidly inactivated the above mentioned 4 foodborne pathogens.

Mechanical, barrier, and antimicrobial properties of apple puree edible films containing plant essential oils.

Edible films, as carriers of antimicrobial compounds, constitute an approach for incorporating plant essential oils (EOs) onto fresh-cut fruit surfaces. The effect against Escherichia coli O157:H7 of oregano, cinnamon, and lemongrass oils in apple puree film-forming solution (APFFS) and in an edible film made from the apple puree solution (APEF) was investigated along with the mechanical and physical properties of the films. Bactericidal activities of APFFS, expressed as BA50 values (BA50 values are defined as the percentage of antimicrobial that killed 50% of the bacteria under the test conditions) ranged from 0.

Antimicrobial activities of tea catechins and theaflavins and tea extracts against Bacillus cereus.

We evaluated the antimicrobial activities of seven green tea catechins and four black tea theaflavins, generally referred to as flavonoids, as well as the aqueous extracts (infusions) of 36 commercial black, green, oolong, white, and herbal teas against Bacillus cereus (strain RM3190) incubated at 21 degrees C for 3, 15, 30, and 60 min. The results obtained demonstrate that (i) (-)-gallocatechin-3-gallate, (-)-epigallocatechin-3-gallate, (-)-catechin-3-gallate, (-)-epicatechin-3-gallate, theaflavin-3, 3'-digallate, theaflavin-3'-gallate, and theaflavin-3-gallate showed antimicrobial activities at nanomolar levels; (ii) most compounds were more active than were medicinal antibiotics, such as tetracycline or vancomycin, at comparable concentrations; (iii) the bactericidal activities of the teas could be accounted for by the levels of catechins and theaflavins as determined by high-pressure liquid chromatography; (iv) freshly prepared tea infusions were more active than day-old teas; and (v) tea catechins without gallate side chains, gallic acid and the alkaloids caffeine and theobromine also present in teas, and herbal (chamomile and peppermint) teas that contain no flavonoids are all inactive. These studies extend our knowledge about the antimicrobial effects of food ingredients.

Antibacterial activities of plant essential oils and their components against Escherichia coli O157:H7 and Salmonella enterica in apple juice.

We evaluated 17 plant essential oils and nine oil compounds for antibacterial activity against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica in apple juices in a bactericidal assay in terms of % of the sample that resulted in a 50% decrease in the number of bacteria (BA(50)). The 10 compounds most active against E. coli (60 min BA(50) range in clear juice, 0.

Antibacterial activities of phenolic benzaldehydes and benzoic acids against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica.

We evaluated the bactericidal activities of 35 benzaldehydes, 34 benzoic acids, and 1 benzoic acid methyl ester against Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica when these compounds were substituted on the benzene ring with 0, 1, 2, or 3 hydroxy (OH) and/or methoxy (OCH3) groups in a pH 7.0 buffer. Dose-response plots were used to determine the percentage of the sample that induced a 50% decrease in CFU after 60 min (BA50).

Effect of feeding solanidine, solasodine and tomatidine to non-pregnant and pregnant mice.

The aglycone forms of three steroidal glycoalkaloids-solanidine (derived by hydrolytic removal of the carbohydrate side chain from the potato glycoalkaloids alpha-chaconine and alpha-solanine), solasodine (derived from solasonine in eggplants) and tomatidine (derived from alpha-tomatine in tomatoes)-were evaluated for their effects on liver weight increase (hepatomegaly) in non-pregnant and pregnant mice and on fecundity in pregnant mice fed for 14 days on a diet containing 2.4 mmol/kg of aglycone. In non-pregnant mice, observed ratios of % liver weights to body weights (%LW/BWs) were significantly greater than those of the control values as follows (all values in % vs matched controls+/-S.

Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica.

An improved method of sample preparation was used in a microplate assay to evaluate the bactericidal activity levels of 96 essential oils and 23 oil compounds against Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica obtained from food and clinical sources. Bactericidal activity (BA50) was defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in CFU relative to a buffer control. Twenty-seven oils and 12 compounds were active against all four species of bacteria.

Feeding of potato, tomato and eggplant alkaloids affects food consumption and body and liver weights in mice.

Reduced liver weight was used to evaluate the potential toxicity in mice of four naturally occurring steroidal glycoalkaloids: alpha-chaconine and alpha-solanine, alpha-tomatine and solasonine. Increased liver weights was used to evaluate the three corresponding steroidal aglycones: solanidine, tomatidine, and solasodine and the non-alkaloid adrenal steroid dehydroepiandrosterone (DHEA). Adult female Swiss-Webster mice were fed diets containing test compound concentrations of 0 (control), 1.

Incorporation of a micronucleus study into a developmental toxicology and pharmacokinetic study of L-selenomethionine in nonhuman primates.

Concomitant to a developmental toxicology study of selenium in long-tailed macaques (Macaca fascicularis), a transplacental bone marrow micronucleus assay was conducted in the fetuses of treated animals. Selenium was administered as L-selenomethionine by nasogastric intubation at 0, 150 or 300 micrograms/kg-day to pregnant macaques daily throughout organogenesis (gestation days 20-50). Pregnancy was terminated on gestation day 100 +/- 2 and fetuses were obtained by hysterotomy.

Absence of genotoxicity of potato alkaloids alpha-chaconine, alpha-solanine and solanidine in the Ames Salmonella and adult and foetal erythrocyte micronucleus assays.

To assess whether reported toxicities of potato-derived glycoalkaloids could be the result of interactions with cellular DNA, the genotoxic effects of alpha-solanine, alpha-chaconine and solanidine were studied, using the Ames test (Salmonella strains TA98 and TA100), the mouse peripheral blood micronucleus test and the mouse transplacental micronucleus test. The Ames test for mutagenicity with alpha-solanine was weakly positive in TA100 with S-9 activation (29 revertants per millimole per plate). However, pooled data from duplicate tests gave a negative effect.

Hepatic ornithine decarboxylase induction by potato glycoalkaloids in rats.

The induction of hepatic ornithine decarboxylase (ODC) activity in rat livers by the potato glycoalkaloids alpha-solanine, alpha-chaconine, and their aglycone solanidine, has been studied. Ip administration of alpha-solanine at 7.5, 15 and 30 mg/kg body weight produced markedly elevated enzyme activity at 4 hr after treatment, with a linear dose response.

The in vivo erythrocyte micronucleus test: measurement at steady state increases assay efficiency and permits integration with toxicity studies.

The mouse erythrocyte micronucleus assay has been traditionally carried out using one or two exposures to the test agent, followed by sampling at two or three postexposure times to obtain a sample near the time of the transient peak of micronucleated polychromatic erythrocytes (PCEs). We have demonstrated that frequencies of micronucleated RNA-positive (PCEs) and RNA-negative erythrocytes in blood and bone marrow come to steady state during "continuous" exposure via diet or drinking water, or during repeated daily exposures to test agents by ip injection, gavage, or inhalation. Under these exposure conditions, frequencies of micronucleated cells in peripheral blood approached steady state within 2-3 days in RNA-positive erythrocytes and in 5-6 weeks in RNA-negative erythrocytes.

The fetal blood erythrocyte micronucleus assay: classification of RNA-positive erythrocytes into two age populations by RNA aggregation state.

The use of a fluorescent stain containing Hoechst 33258 and pyronin Y in the fetal mouse transplacental micronucleus assay allows classification of erythrocytes into three subpopulations on the basis of RNA staining, and permits micronuclei to be scored in all three subpopulations. The youngest erythrocytes stain uniformly positive for RNA (UEs). In older erythrocytes RNA aggregates to give the cells a stippled appearance (SEs) and ultimately disappears, leaving cells which do not stain positively for RNA.

Mutagenicity of flavones, chromones and acetophenones in Salmonella typhimurium. New structure-activity relationships.

28 flavones and 11 structurally-related flavonoids, chromones, and acetophenones, were tested for mutagenicity in the Salmonella typhimurium his reversion assay. 7 flavones, all of which were hydroxy- or methoxy-substituted at position 8, were moderate to strong mutagens in strain TA100 in the presence of rat liver S9 mix. In each case, the response of strain TA98 was either not significant or was very much weaker than that observed in strain TA100.

Effects of Propionibacterium acnes treatment on the course of Mycobacterium leprae infection in mice.

Studies were carried out to determine the effects of treatment with killed suspensions of Propionibacterium acnes (formerly designated Corynebacterium parvum) on the course of Mycobacterium leprae infection in mice. Systemic (intravenous or intraperitoneal) treatment with P. acnes failed to significantly alter the growth of M.

Effects of treatment with muramyl dipeptide and certain of its analogs on resistance to Listeria monocytogenes in mice.

Studies were carried out to determine whether treatment of mice with the synthetic adjuvant muramyl dipeptide (MDP) afforded any resistance to infection with Listeria monocytogenes. Regardless of the timing, dose, or route of administration, there was no evidence that treatment with either MDP or two of its analogs (des-MDP or MDP-D-D) induced any resistance to listeria infection in BALB/c, CBA/J, or C57BL/6J mice. In contrast, pretreatment with MDP induced marked protection to infection with Streptococcus pneumoniae (type III).