The antimicrobial effects and metabolomic footprinting of carboxyl-capped bismuth nanoparticles against Helicobacter pylori.

Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 µg/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by (1)H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 µg/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity.

The preventive oral supplementation of a selenium nanoparticle-enriched probiotic increases the immune response and lifespan of 4T1 breast cancer bearing mice.

The immunomodulatory effects of lactic acid bacteria have been demonstrated previously. In this study, a Lactobacillus plantarum strain was selected and enriched with selenium nanoparticles for use as a new immunomodulating agent in a breast cancer murine model. 30 female inbred BALB/c mice were equally divided into a test group and a control group. For 2 weeks prior to tumor induction, each mouse received a daily oral administration of 2.5×108 CFU/ml of L. plantarum enriched with selenium nanoparticles (SeNPs), and then 1×106 4T1 cells were injected subcutaneously. After tumor induction, daily SeNP administration was repeated for 3 cycles of 7 days on/3 days off. Immunological parameters such as levels of cytokines, NK cell activity, tumor growth, and mouse survival were evaluated. The production of the pro-inflammatory cytokines IFN-γ, TNF-α, and IL-2 in spleen cell cultures was increased in test mice administered SeNP-enriched L. plantarum. The test mice also showed significant increases in NK cell activity. The tumor volumes of treated mice were decreased and their survival rate notably increased when compared to mice that received L. plantarum alone or control mice. Administration of SeNP-enriched L. plantarum can induce an efficient immune response through the elevation of the pro-inflammatory cytokines IFN-γ, TNF-α and IL-2 levels and increased NK cell activity. Therefore, this treatment may result in better cancer prognosis.

Biosynthesis of bismuth nanoparticles using Serratia marcescens isolated from the Caspian Sea and their characterisation.

Today, synthesis of nanoparticles (NPs) using micro-organisms has been receiving increasing attention. In this investigation, a bismuth-reducing bacterium was isolated from the Caspian Sea in Northern Iran and was used for intracellular biosynthesis of elemental bismuth NPs. This isolate was identified as non-pigmented Serratia marcescens using conventional identification assays and the 16s rDNA fragment amplification method and used to prepare bismuth NPs. The biogenic bismuth NPs were released by liquid nitrogen and highly purified using an n-octanol water two-phase extraction system. Different characterisations of the purified NPs such as particle shapes, size and purity were carried out with different instruments. The energy-dispersive X-ray and X-ray diffraction (XRD) patterns demonstrated that the purified NPs consisted of only bismuth and are amorphous. In addition, the transmission electron micrograph showed that the small NPs formed larger aggregated NPs around <150 nm. Although the chemical syntheses of elemental bismuth NPs have been reported in the literature, the biological synthesis of elemental bismuth NPs has not been published yet. This is the first report to demonstrate a biological method for synthesising bismuth NPs and their purification with a simple solvent partitioning method.

Isolation of a new quinic acid derivative and its antibacterial modulating activity.

BACKGROUND AND THE PURPOSE OF THE STUDY: The species Hymenocrater calycinus, belongs to the plant family Lamiaceae and grows wildly in the north-east of Iran. Previously, the antimicrobial activity of the plant extracts was reported. In the present study, the bioactivity-guided fractionation of the methanol extract of H. calycinus and the combination effects of the isolated compound with cell wall active agents against S. aureus and E. coli was investigated. METHODS: Column and thin layer chromatographic methods were used for isolation and purification and spectroscopic data (MS, (1)H- and (13)C-NMR, HMQC, HMBC and (1)H-(1)H COSY) were employed for identification of the compound isolated from the extract. A disk diffusion method was used to determine the antibacterial activity of the isolated compound against S. aureus and E. coli in comparison with 7 different antibiotics. RESULTS: The isolated compound 1 was identified as 3-(3, 4- dihydroxyphenyl) lactic acid 2-O-quinic acid. Compound 1 (500 µg/disc) enhanced antibacterial effect of ampicillin, ciprofloxacin, vancomycin and cefepime against S. aureus and activated the effects of ampicillin and vancomycin against E. coli. CONCLUSION: Results showed that the compound 1 was not active against both tested strains at any concentration below 1 mg/disk, and as a result the enhancing effect of the compound could be due its association with antibiotics.

1-methyl malate from Berberis integerrima fruits enhances the antibacterial activity of ampicillin against Staphylococcus aureus.

The enhancement of the antibacterial activity of ampicillin by different extracts of Berberis integerrima fruits was evaluated against Staphylococcus aureus. Disk diffusion and agar dilution methods were used to determine the antibacterial activity of ampicillin in the absence and presence of different plant extracts or various fractions eluted by column chromatography. A clinical isolate of S. aureus was used as a test strain. The active component of B. integerrima fruits involved in the enhancement of ampicillin activity was purified and identified as 1-methyl malate using different spectroscopic methods. Both the ethanol extract of B. integerrima fruits and 1-methyl malate enhanced the antibacterial activity of ampicillin. The total extract as well as 1-methyl malate increased the antibacterial activity of ampicillin against the test strain. The potency of ampicillin against the test strain was increased 64-fold when tested with a sub-toxic concentration of total extract of B. integerrima fruits. Also, 1-methyl malate increased the bactericidal activity of ampicillin. In the presence of 2 mg/mL of 1-methyl malate the MIC of ampicillin for S. aureus decreased from 128 to 1 microg/mL (128-fold).

Trans-cinnamaldehyde from Cinnamomum zeylanicum bark essential oil reduces the clindamycin resistance of Clostridium difficile in vitro.

Therapy with antimicrobial drugs, such as clindamycin, that perturb the intestinal flora but fail to inhibit growth of other microorganisms can permit the proliferation of Clostridium difficile and the elaboration of exotoxin. Therefore, there has been increasing interest in the use of inhibitors of antibiotic resistance for use in combination therapy. The essential oil of Cinnamomum zeylanicum bark enhanced the bactericidal activity of clindamycin and decreased the minimum inhibitory concentration of clindamycin required for a toxicogenic strain of C. difficile. Thin-layer chromatography (TLC) analysis of the essential oil separated a fraction (R(f) = 0.54) that was the most effective at enhancing the clindamycin antimicrobial activity. Using gas liquid chromatography and known standards, the active fraction was identified as trans-cinnamaldehyde (3-phenyl-2-Propenal). Combinations of clindamycin and trans-cinnamaldehyde were tested to determine the fractional inhibitory concentration (FIC) index by conventional checkerboard titration. The FIC index for C. difficile was found to be 0.312, which confirmed the synergistic actions of clindamycin and trans-cinnamaldehyde. The presence of 20 microg/mL of trans-cinnamaldehyde decreased the MIC of clindamycin for C. difficile 16-fold, from 4.0 to 0.25 microg/mL. These results signify that low concentrations of trans-cinnamaldehyde elevate the antimicrobial action of clindamycin, suggesting a possible clinical benefit for utilizing these natural products for combination therapy against C. difficile.

Two matrix metalloproteinases inhibitors from Ferula persica var. persica.

Matrix metalloproteinases (MMPs) play a role in several physiologic and pathologic events. There is some evidence indicating the involvement of MMPs in tumor invasion and inflammatory diseases. Here we studied the chloroform extract of Ferula persica var. persica. The influence of these extracts vs. a reference drug, diclofenac sodium, on MMP production by the fibrosarcoma cell line was investigated using an in vitro cytotoxicity assay, sodium dodecyl sulfate-polyacrylamide, and gelatin zymography. The total extract of the roots was found to exhibit a selective inhibitory effect on tumor cell invasion. The bioactivity-guided fractionation of this extract led to the isolation of two compounds. These compounds showed highest MMP inhibitory effect at minimal toxic dose levels. Using conventional spectroscopy methods, the active fractions were identified as t-butyl 3-[(1-methylthiopropyl)dithio]-2-propenyl malonate (persicasulphide B) and umbelliprenin, previously isolated from F. persica var. latisecta. Since inhibition of MMP activity has been employed in modality therapy in diseases such as cancer, this compound might be promising in the preparation of anti-MMP therapeutic derivatives.

A cylinder-plate method for microbiological assay of clavulanic acid.

Clavulanic acid is a natural occurring beta-lactam product of Streptomyces clavuligerus and is a potent inhibitor of bacterial beta-lactamases. The present work reports a microbiological assay based on the cylinder-plate method for determination of clavulanic acid. The assay is based on the inhibitory effect of clavulanic acid in combination with penicillin G upon Escherichia coli ATCC 35218, which is used as the test organism. The correlation between clavulanic acid concentration and the inhibitory effect on E. coli was linear (r > 0.99) and in the range of 8-20 microg/ml. These results indicate that the proposed method is appropriate for the determination of clavulanic acid in commercial samples and can be used in routine quality control.

Piperitone from Mentha longifolia var. chorodictya Rech F. reduces the nitrofurantoin resistance of strains of enterobacteriaceae.

The diluted essential oil of Mentha longifolia (L.) var. chlorodictya Rech F. foliage enhanced the bactericidal activity of nitrofurantoin decreasing the minimum inhibitory concentration (MIC) of nitrofurantoin for nitrofurantoin-resistant strains of Enterobacteriaceae. Thin-layer chromatography (TLC) analysis of the essential oil detected a fraction (R(f) = 0.35, UV lambda(max) of 232.5), which was the most effective in enhancement of nitrofurantoin activity. Using gas liquid chromatography and known standards, the active fraction was identified as piperitone. 1 microl of the piperitone fraction decreased the MIC of nitrofurantoin 3-20 fold for the different strains of Enterobacteriaceae tested.

Inhibition of nitrofurantoin reduction by menthol leads to enhanced antimicrobial activity.

Nitrofurantoin is a nitroaromatic compound used for the treatment of urinary tract infections. Nitrofurantoin activity is regulated by a nitroreduction process. It is first reduced by bacterial nitroreductases to active short-life intermediates, which are further converted to non-toxic molecules, which negatively affect its antibacterial activity. In this study we have shown that resistant strains of Klebsiella sp. inactivate the bactericidal activity of nitrofurantoin. Also we demonstrated a synergistic effect between menthol and nitrofurantoin bactericidal activities against nitrofurantoin susceptible Enterobacteriaceae.