A Double Payload Complex between Hypericin and All-Trans Retinoic Acid in the β-Lactoglobulin Protein

Combined therapies are usually used to treat acne vulgaris since this approach can tackle various foci simultaneously. Using a combination of spectroscopic, computational, and microbiological techniques and methods, herein we report on the use of β-lactoglobulin as a double payload carrier of hypericin (an antimicrobial photodynamic agent) and all-trans retinoic acid (an anti-inflammatory drug) for S. aureus in vitro photodynamic inactivation. The addition of all-trans retinoic acid to hypericin-β-lactoglobulin complex renders a photochemically safe vehicle due to the photophysical quenching of hypericin, which recovers its photodynamic activity when in contact with bacteria. The ability of hypericin to photoinactivate S. aureus was not affected by retinoic acid. β-Lactoglobulin is a novel biocompatible and photochemically safe nanovehicle with strong potential for the treatment of acne.

Photosensitive EGFR-Targeted Nanocarriers for Combined Photodynamic and Local Chemotherapy

The major limitation of any cancer therapy lies in the difficulty of precisely controlling the localization of the drug in the tumor cells. To improve this drawback, our study explores the use of actively-targeted chemo-photo-nanocarriers that recognize and bind to epidermal growth factor receptor-overexpressing cells and promote the local on-demand release of the chemotherapeutic agent doxorubicin triggered by light. Our results show that the attachment of high concentrations of doxorubicin to cetuximab-IRDye700DX-mesoporous silica nanoparticles yields efficient and selective photokilling of EGFR-expressing cells mainly through singlet oxygen-induced release of the doxorubicin from the nanocarrier and without any dark toxicity. Therefore, this novel triply functionalized nanosystem is an effective and safe nanodevice for light-triggered on-demand doxorubicin release.

Tetramethylbenzidine: An Acoustogenic Photoacoustic Probe for Reactive Oxygen Species Detection

Photoacoustic imaging is attracting a great deal of interest owing to its distinct advantages over other imaging techniques such as fluorescence or magnetic resonance image. The availability of photoacoustic probes for reactive oxygen and nitrogen species (ROS/RNS) could shed light on a plethora of biological processes mediated by these key intermediates. Tetramethylbenzidine (TMB) is a non-toxic and non-mutagenic colorless dye that develops a distinctive blue color upon oxidation. In this work, we have investigated the potential of TMB as an acoustogenic photoacoustic probe for ROS/RNS. Our results indicate that TMB reacts with hypochlorite, hydrogen peroxide, singlet oxygen, and nitrogen dioxide to produce the blue oxidation product, while ROS, such as the superoxide radical anion, sodium peroxide, hydroxyl radical, or peroxynitrite, yield a colorless oxidation product. TMB does not penetrate the Escherichia coli cytoplasm but is capable of detecting singlet oxygen generated in its outer membrane.

c(RGDfK)- and ZnTriMPyP-Bound Polymeric Nanocarriers for Tumor-Targeted Photodynamic Therapy

Active targeting strategies are currently being extensively investigated in order to enhance the selectivity of photodynamic therapy. The aim of the present research was to evaluate whether the external decoration of nanopolymeric carriers with targeting peptides could add more value to a photosensitizer formulation and increase antitumor therapeutic efficacy and selectivity. To this end, we assessed PLGA-PLA-PEG nanoparticles (NPs) covalently attached to a hydrophilic photosensitizer 5-[4-azidophenyl]-10,15,20-tri-(N-methyl-4-pyridinium)porphyrinato zinc (II) trichloride (ZnTriMPyP) and also to c(RGDfK) peptides, in order to target α_v β₃ integrin-expressing cells. In vitro phototoxicity investigations showed that the ZnTriMPyP-PLGA-PLA-PEG-c(RGDfK) nanosystem is effective at submicromolar concentrations, is devoid of dark toxicity, successfully targets α_v β₃ integrin-expressing cells and is 10-fold more potent than related nanosystems where the PS is occluded instead of covalently bound.

A porphycene-gentamicin conjugate for enhanced photodynamic inactivation of bacteria

A novel photoantimicrobial agent, namely 2-aminothiazolo[4,5-c]-2,7,12,17-tetrakis(methoxyethyl)porphycene (ATAZTMPo-gentamicin) conjugate, has been prepared by a click reaction between the red-light absorbing 9-isothiocyanate-2,7,12,17-tetrakis(methoxyethyl)porphycene (9-ITMPo) and the antibiotic gentamicin. The conjugate exhibits submicromolar activity in vitro against both Gram-positive and Gram-negative bacteria (Staphylococcus aureus and Escherichia coli, respectively) upon exposure to red light and is devoid of any cytotoxicity in the dark. The conjugate outperforms the two components delivered separately, which may be used to enhance the therapeutic index of gentamicin, broaden the spectrum of pathogens against which it is effective and reduce its side effects. Additionally, we report a novel straightforward synthesis of 2,7,12,17-tetrakis(methoxyethyl) porphycene (TMPo) that decreases the number of steps from nine to six.

Fluorine-substituted tetracationic ABAB-phthalocyanines for efficient photodynamic inactivation of Gram-positive and Gram-negative bacteria

Herein, we report the synthesis and characterization of new amphiphilic phthalocyanines (Pcs), the study of their singlet oxygen generation capabilities, and biological assays to determine their potential as photosensitizers for photodynamic inactivation of bacteria. In particular, Pcs with an ABAB geometry (where A and B refer to differently substituted isoindole constituents) have been synthesized. These molecules are endowed with bulky bis(trifluoromethylphenyl) groups in two facing isoindoles, which hinder aggregation and favour singlet oxygen generation, and pyridinium or alkylammonium moieties in the other two isoindoles. In particular, two water-soluble Pc derivatives (PS-1 and PS-2) have proved to be efficient in the photoinactivation of S. aureus and E. coli, selected as models of Gram-positive and Gram-negative bacteria.

Importance of Tetrahydroiso -acids to the Microbiological Stability of Beer

While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and anaerobic Gram-negative bacteria. Beer also contains bitter hop compounds, which are toxic to Gram-positive and Gram-negative bacteria, and contribute to preventing the spoilage of this beverage. In the boiling process, the hop -acids (humulones) are isomerized into iso -acids. These products are responsible for the bitter taste of beer, but they also play an essential role in enhancing foam stability. Antibacterial activity of iso -acids and their hydrogenated derivates (rhoiso -acids and tetrahydroiso -acids) in MRS broth and beer have been evaluated against different LAB (Lactobacillus and Pediococcus) for the determination of their beer-stabilizing capabilities. Besides this, we have determined the minimum inhibitory concentration and the bacteriostatic effect of each compound against Pediococcus. We found that tetrahydroiso-acids (added directly to beer during production processes) are the compounds that present the greatest antibacterial activity against the main agents implicated in beer spoilage.

A combination of photodynamic therapy and antimicrobial compounds to treat skin and mucosal infections: a systematic review

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) is a growing approach to treat skin and mucosal infections. Despite its effectiveness, investigators have explored whether aPDT can be further combined with antibiotics and antifungal drugs.

OBJECTIVE

To systematically assess the in vivo studies on the effectiveness of combinations of aPTD plus antimicrobials in the treatment of cutaneous and mucosal infections.

MATERIALS AND METHODS

Searches were performed in four databases (PubMed, EMBASE, Cochrane library databases, ClinicaTrials.gov) until July 2018. The pooled information was evaluated according to the PRISMA guidelines.

RESULTS

11 full-text articles were finally evaluated and included. The best aPDT combinations involved 5-aminolevulinic acid or phenothiazinium dye-based aPDT. In general, the combination shows benefits such as reducing treatment times, lowering drug dosages, decreasing drug toxicity, improving patient compliance and diminishing the risk of developing resistance. The mechanism of action may be that first aPDT damages the microbial cell wall or membrane, which allows better penetration of the antimicrobial drug.

LIMITATIONS

The number of studies was low, the protocols used were heterogeneous, and there was a lack of clinical trials.

CONCLUSIONS

The additive or synergistic effect of aPDT combined with antimicrobials could be promising to manage skin and mucosal infections, helping to overcome the microbial drug resistance.

Triphenylphosphonium cation: A valuable functional group for antimicrobial photodynamic therapy

Light-mediated killing of pathogens by cationic photosensitisers is a promising antimicrobial approach that avoids the development of resistance inherent to the use of antimicrobials. In this study, we demonstrate that modification of different photosensitisers with the triphenylphosphonium cation yields derivatives with excellent photoantimicrobial activity against Gram-positive bacteria (ie, Staphylococcus aureus and Enterococcus faecalis). Thus, the triphenylphosphonium functional group should be considered for the development of photoantimicrobials for the selective killing of Gram-positive bacteria in the presence of Gram-negative species.

Correction: Cationic phthalocyanine dendrimers as potential antimicrobial photosensitisers

Correction for 'Cationic phthalocyanine dendrimers as potential antimicrobial photosensitisers' by Rubén Ruiz-González et al., Org. Biomol. Chem., 2017, 15, 9008-9017.

On the mechanism of Candida tropicalis biofilm reduction by the combined action of naturally-occurring anthraquinones and blue light

The photoprocesses involved in the photo-induced Candida tropicalis biofilm reduction by two natural anthraquinones (AQs), rubiadin (1) and rubiadin-1-methyl ether (2), were examined. Production of singlet oxygen (¹O₂) and of superoxide radical anion (O₂^•−) was studied. Although it was not possible to detect the triplet state absorption of any AQs in biofilms, observation of ¹O₂ phosphorescence incubated with deuterated Phosphate Buffer Solution, indicated that this species is actually formed in biofilms. 2 was accumulated in the biofilm to a greater extent than 1 and produced measurable amounts of O₂^•− after 3h incubation in biofilms. The effect of reactive oxygen species scavengers on the photo-induced biofilm reduction showed that Tiron (a specific O₂^•− scavenger) is most effective than sodium azide (a specific ¹O₂ quencher). This suggests that O₂^•− formed by electron transfer quenching of the AQs excited states, is the main photosensitizing mechanism involved in the photo-induced antibiofilm activity, whereas ¹O₂ participation seems of lesser importance.

Tuning the local solvent composition at a drug carrier surface: the effect of dimethyl sulfoxide/water mixture on the photofunctional properties of hypericin-β-lactoglobulin complexes

Aggregation is a major problem for the anti-microbial photodynamic applications of hydrophobic photosensitizers since it strongly reduces the amount of singlet oxygen generated in aqueous solutions. Binding of hypericin (Hyp) to the milk whey protein β-lactoglobulin (βLG), occurring at the two hydrophobic cavities located at the interface of the protein homodimer, can be exploited to confer water-solubility and biocompatibility to the photosensitizer. The introduction of a small amount of the organic cosolvent dimethyl sulfoxide (DMSO) leads to a remarkable improvement of the photophysical properties of the complex Hyp-βLG by increasing its fluorescence emission and singlet oxygen photosensitization quantum yields. Surprisingly, the ability of the complex to photo-inactivate bacteria of the strain Staphylococcus aureus is strongly reduced in the presence of DMSO, despite the higher yield of photosensitization. The reasons for this apparently contradictory behavior are investigated, providing new insights into the use of carrier systems for hydrophobic photosensitizers.

Cationic phthalocyanine dendrimers as potential antimicrobial photosensitisers

Synthesis, photophysical properties and photoantimicrobial efficiency of cationic Zn(ii) and Ru(ii) dendrimeric phthalocyanines.

Morphology effects on singlet oxygen production and bacterial photoinactivation efficiency by different silica-protoporphyrin IX nanocomposites

Different silica-protoporphyrin IX (PpIX) nanocomposites have been synthesized to evaluate the dependence of singlet oxygen production and bacterial inactivation efficiency on the morphology of the nanomaterials.

Zinc-Substituted Myoglobin Is a Naturally Occurring Photo-antimicrobial Agent with Potential Applications in Food Decontamination

Zinc-substituted myoglobin (ZnMb) is a naturally occurring photosensitizer that generates singlet oxygen with a high quantum yield. Using a combination of photophysical and fluorescence imaging techniques, we demonstrate the interaction of ZnMb with Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. An efficient antibacterial action against S. aureus was observed, with a reduction up to 99.9999% in the number of colony-forming units, whereas no sizable effect was detected against E. coli. Because ZnMb is known to form during the maturation of additive-free not-cooked cured ham, the use of this protein as a built-in photodynamic agent may constitute a viable method for the decontamination of these food products from Gram-positive bacteria.

A Comparative Study on Two Cationic Porphycenes: Photophysical and Antimicrobial Photoinactivation Evaluation

Over the last decades, the number of pathogenic multi-resistant microorganisms has grown dramatically, which has stimulated the search for novel strategies to combat antimicrobial resistance. Antimicrobial photodynamic therapy (aPDT) is one of the promising alternatives to conventional treatments based on antibiotics. Here, we present a comparative study of two aryl tricationic porphycenes where photoinactivation efficiency against model pathogenic microorganisms is correlated to the photophysical behavior of the porphycene derivatives. Moreover, the extent of photosensitizer cell binding to bacteria has been assessed by flow cytometry in experiments with, or without, removing the unbound porphycene from the incubation medium. Results show that the peripheral substituent change do not significantly affect the overall behavior for both tricationic compounds neither in terms of photokilling efficiency, nor in terms of binding.

Simultaneous monitoring of Staphylococcus aureus growth in a multi-parametric microfluidic platform using microscopy and impedance spectroscopy

We describe the design, construction, and characterization of a scalable microfluidic platform that allows continuous monitoring of biofilm proliferation under shear stress conditions. Compared to other previous end-point assay studies, our platform offers the advantages of integration into multiple environments allowing simultaneous optical microscopy and impedance spectroscopy measurements. In this work we report a multi-parametric sensor that can monitor the growth and activity of a biofilm. This was possible by combining two interdigitated microelectrodes (IDuEs), and punctual electrodes to measure dissolved oxygen, K+, Na+ and pH. The IDuE has been optimized to permit sensitive and reliable impedance monitoring of Staphylococcus aureus V329 growth with two- and four-electrode measurements. We distinguished structural and morphological changes on intact cellular specimens using four-electrode data modeling. We also detected antibiotic mediated effects using impedance. Results were confirmed by scanning electrode microscopy and fluorescence microscopy after live/dead cell staining. The bacitracin mediated effects detected with impedance prove that the approach described can be used for guiding the development of novel anti-biofilm agents to better address bacterial infection.

Synthesis, spectroscopic, and photophysical characterization and photosensitizing activity toward prokaryotic and eukaryotic cells of porphyrin-magainin and -buforin conjugates

Cationic antimicrobial peptides (CAMPs) and photodynamic therapy (PDT) are attractive tools to combat infectious diseases and to stem further development of antibiotic resistance. In an attempt to increase the efficiency of bacteria inactivation, we conjugated a PDT photosensitizer, cationic or neutral porphyrin, to a CAMP, buforin or magainin. The neutral and hydrophobic porphyrin, which is not photoactive per se against Gram-negative bacteria, efficiently photoinactivated Escherichia coli after conjugation to either buforin or magainin. Conjugation to magainin resulted in the considerable strengthening of the cationic and hydrophilic porphyrin's interaction with the bacterial cells, as shown by the higher bacteria photoinactivation activity retained after washing the bacterial suspension. The porphyrin-peptide conjugates also exhibited strong interaction capability as well as photoactivity toward eukaryotic cells, namely, human fibroblasts. These findings suggest that these CAMPs have the potential to carry drugs and other types of cargo inside mammalian cells similar to cell-penetrating peptides.

Singlet oxygen generation by the genetically encoded tag miniSOG

The genetically encodable fluorescent tag miniSOG is expected to revolutionize correlative light- and electron microscopy due to its ability to produce singlet oxygen upon light irradiation. The quantum yield of this process was reported as ΦΔ = 0.47 ± 0.05, as derived from miniSOG's ability to photooxidize the fluorescent probe anthracene dipropionic acid (ADPA). In this report, a significantly smaller value of ΦΔ = 0.03 ± 0.01 is obtained by two methods: direct measurement of its phosphorescence at 1275 nm and chemical trapping using uric acid as an alternative probe. We present insight into the photochemistry of miniSOG and ascertain the reasons for the discrepancy in ΦΔ values. We find that miniSOG oxidizes ADPA by both singlet oxygen-dependent and -independent processes. We also find that cumulative irradiation of miniSOG increases its ΦΔ value ~10-fold due to a photoinduced transformation of the protein. This may be the reason why miniSOG outperforms other fluorescent proteins reported to date as singlet oxygen generators.

Synthesis, characterization, and photoinduced antibacterial activity of porphyrin-type photosensitizers conjugated to the antimicrobial peptide apidaecin 1b

Antimicrobial photodynamic therapy (aPDT) is an emerging treatment for bacterial infections that is becoming increasingly more attractive because of its effectiveness against multi-antibiotic-resistant strains and unlikelihood of inducing bacterial resistance. Among the strategies to enhance the efficacy of PDT against Gram-negative bacteria, the binding to a cationic antimicrobial peptide offers the attractive prospect for improving both the water solubilty and the localization of the photoactive drug in bacteria. In this work we have compared a number of free and apidaecin-conjugated photosensitizers (PSs) differing in structure and charge. Our results indicate that the conjugation of per se ineffective highly hydrophobic PSs to a cationic peptide produces a photosensitizing agent effective against Gram-negative bacteria. Apidaecin cannot improve the phototoxic activity of cationic PSs, which mainly depends on a very high yield of singlet oxygen production in the surroundings of the bacterial outer membrane. Apidaecin-PS conjugates appear most promising for treatment protocols requiring repeated washing after sensitizer delivery.

A genetically-encoded photosensitiser demonstrates killing of bacteria by purely endogenous singlet oxygen

TagRFP, a fluorescent protein capable of photosensitizing the production of singlet oxygen, was expressed in E. coli. Subsequent exposure to green light induced bacterial cell death in a light-dose dependent manner. It is demonstrated for the first time that intracellular singlet oxygen is sufficient to kill bacteria.

On the mechanism of Candida spp. photoinactivation by hypericin

The photoprocesses involved in hypericin photoinactivation of three different Candida species (C. albicans, C. parapsilosis and C. krusei) have been examined. Production of singlet oxygen from the triplet state and of superoxide from both the triplet state and the semiquinone radical anion are demonstrated. Hydrogen peroxide is formed downstream of these early events. The outcome of the photodynamic treatments is dictated by the intracellular distribution of hypericin, which is different in the three species and affects the ability of hypericin to produce the different reactive oxygen species and trigger cell-death pathways. The results are in line with the previously-observed different susceptibilities of the three Candida species to hypericin photodynamic treatments.

In vitro fungicidal photodynamic effect of hypericin on Candida species

Hypericin is a natural photosensitizer considered for the new generation of photodynamic therapy (PDT) drugs. The aim of this study was to evaluate the in vitro fungicidal effect of hypericin PDT on various Candida spp., assessing its photocytotoxicity to keratinocytes (HaCaT) and dermal fibroblasts (hNDF) to determine possible side effects. A 3 log fungicidal effect was observed at 0.5 McFarland for two Candida albicans strains, Candida parapsilosis and Candida krusei with hypericin concentrations of 0.625, 1.25, 2.5 and 40 μm, respectively, at a fluence of 18 J cm(-2) (LED lamp emitting at 602 ± 10 nm). To obtain a 6 log reduction, significantly higher hypericin concentrations and light doses were needed (C. albicans 5 μM, C. parapsilosis 320 μM and C. krusei 320 μM; light dose 37 J cm(-2)). Keratinocytes and fibroblasts can be preserved by keeping the hypericin concentration below 1 μm and the light dose below 37 J cm(-2). C. albicans appears to be suitable for treatment with hypericin PDT without significant damage to cutaneous cells.

Photodynamic inactivation of Acinetobacter baumannii using phenothiazinium dyes: in vitro and in vivo studies

BACKGROUND AND OBJECTIVE

Phenothiazinium dyes have been reported to be effective photosensitizers inactivating a wide range of microorganisms in vitro after illumination with red light. However, their application in vivo has not extensively been explored. This study evaluates the bactericidal activity of phenothiazinium dyes against multidrug-resistant Acinetobacter baumannii both in vitro and in vivo.

STUDY DESIGN/MATERIALS AND METHODS

We report the investigation of toluidine blue O, methylene blue, 1,9-dimethylmethylene blue, and new methylene blue for photodynamic inactivation of multidrug-resistant A. baumannii in vitro. The most effective dye was selected to carry out in vivo studies using third-degree mouse burns infected with a bioluminescent A. baumannii strain, upon irradiation with a 652 nm noncoherent light source. The mice were imaged daily for 2 weeks to observe differences in the bioluminescence-time curve between the photodynamic therapy (PDT)-treated mice in comparison with untreated burns.

RESULTS

All the dyes were effective in vitro against A. baumannii after 30 J/cm(2) irradiation of 635 or 652 nm red light had been delivered, with more effective killing when the dye remained in solution. New methylene blue was the most effective of the four dyes, achieving a 3.2-log reduction of the bacterial luminescence during PDT in vivo after 360 J/cm(2) and an 800 microM dye dose. Moreover, a statistically significant reduction of the area under the bioluminescence-time curve of PDT-treated mice was observed showing that the infection did not recur after PDT.

CONCLUSIONS

Phenothiazinium dyes, and especially new methylene blue, are potential photosensitizers for PDT to treat burns infected with multidrug-resistant A. baumannii in vivo.

Cationic porphycenes as potential photosensitizers for antimicrobial photodynamic therapy

Structures of typical photosensitizers used in antimicrobial photodynamic therapy are based on porphyrins, phthalocyanines, and phenothiazinium salts, with cationic charges at physiological pH values. However, derivatives of the porphycene macrocycle (a structural isomer of porphyrin) have barely been investigated as antimicrobial agents. Therefore, we report the synthesis of the first tricationic water-soluble porphycene and its basic photochemical properties. We successfully tested it for in vitro photoinactivation of different Gram-positive and Gram-negative bacteria, as well as a fungal species (Candida) in a drug-dose and light-dose dependent manner. We also used the cationic porphycene in vivo to treat an infection model comprising mouse third degree burns infected with a bioluminescent methicillin-resistant Staphylococcus aureus strain. There was a 2.6-log(10) reduction (p < 0.001) of the bacterial bioluminescence for the PDT-treated group after irradiation with 180 J·cm(-2) of red light.

Singlet oxygen in Escherichia coli: New insights for antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy is an emerging treatment for bacterial infections that is becoming increasingly more attractive because of its effectiveness and unlikelihood of inducing bacterial resistance. However, there is limited knowledge about the localization of the photoactive drug in the bacteria and about the details of production of the main cytotoxic species, singlet oxygen. This article describes a combination of spectroscopic and time-resolved photophysical techniques that provide such information for a cationic porphyrin photosensitizer in gram-negative Escherichia coli bacteria. Our results reveal a double localization of the photosensitizer, inside (bound to the nucleic acids) and outside (bound to the cell wall) of the E. coli cells. Singlet oxygen is produced at both sites and is able to cross the cell wall.

Importance of tetrahydroiso alpha-acids to the microbiological stability of beer

While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and anaerobic Gram-negative bacteria. Beer also contains bitter hop compounds, which are toxic to Gram-positive and Gram-negative bacteria, and contribute to preventing the spoilage of this beverage. In the boiling process, the hop alpha-acids (humulones) are isomerized into iso alpha-acids. These products are responsible for the bitter taste of beer, but they also play an essential role in enhancing foam stability. Antibacterial activity of iso alpha-acids and their hydrogenated derivates (rhoiso alpha-acids and tetrahydroiso alpha-acids) in MRS broth and beer have been evaluated against different LAB (Lactobacillus and Pediococcus) for the determination of their beer-stabilizing capabilities. Besides this, we have determined the minimum inhibitory concentration and the bacteriostatic effect of each compound against Pediococcus. We found that tetrahydroiso alpha-acids (added directly to beer during production processes) are the compounds that present the greatest antibacterial activity against the main agents implicated in beer spoilage.

Survivability of Salmonella cells in popcorn after microwave oven and conventional cooking

The survivability of Salmonella cells in popcorn preparation was determined for two distinct cooking methods. The first method used a standard microwave oven. The second method used conventional cooking in a pan. Prior to thermal processing in independent experiments, 12 suspensions in a range between 1x10(3) and 8x10(6) colony-forming units (CFU) per gram of Salmonella cells were inoculated in both raw microwave popcorn and conventional corn kernels. The influence of the initial concentration of Salmonella cells in the raw products and the lethal effects on Salmonella by thermal treatments for cooking were studied. Survival of Salmonella cells was determined in the thermally processed material by pre-enrichment and enrichment in selective medium, in accordance with the legislation for expanded cereals and cereals in flakes. Viable experimental contaminants were recovered from the conventionally cooked popcorn with initial inoculation concentrations of 9x10(4)cells/g or greater. Salmonella cell viability was significantly reduced after microwave oven treatment, with recoveries only from initial concentrations of 2x10(6)cells/g or superior.

Ultra-performance liquid chromatography/tandem mass spectrometry for the simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer

The simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer was carried out by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS). Mycotoxins were extracted, purified and concentrated from the beer sample in one step using a solid-phase extraction (SPE) cartridge that contained a polymeric sorbent. Optimization of different parameters, such as type of SPE sorbent, type and amount of wash solvent and pH of the sample, was carried out. The mobile phase consisted of a gradient of methanol + water (0.1% HCOOH) and a reversed-phase C18 column was used for the separation. The mass spectrometer used an electrospray ionization source operated in the positive mode to detect aflatoxins and in the negative mode to detect ochratoxin. UPLC/MS/MS is a rapid and sensitive technique that allows the separation of the five toxins in only 3.2 min. The limit of detection is 1 pg.

Two-dimensional thin-layer chromatographic method for the analysis of ochratoxin A in green coffee

A low-cost thin-layer chromatographic method has been developed for the presumptive measurement of ochratoxin A (OTA) at 5 microg/kg in green coffee beans. The analytical method consisted of extracting OTA by shaking the beans with a mixture of methanol and aqueous sodium bicarbonate solution, which was then purified by liquid-liquid partition into toluene. OTA was separated by normal-phase two-dimensional thin-layer chromatography and detected by visual estimation of fluorescence intensity under a UV lamp at 365 nm. The chromatography solvents were toluene-methanol-formic acid (8:2:0.03) for the first development and petroleum ether-ethyl acetate-formic acid (8:10:1) for the second dimension development. This method was tested with uncontaminated green coffee bean samples spiked with an OTA standard at four different concentrations (5, 10, 20, and 30 microg/kg). The method is rapid, simple, and very easy to implement in coffee-producing countries. It is highly selective and does not involve the use of chlorinated solvents in the sample extraction step. This inexpensive method has been applied to different types of green coffee samples from various countries (Zimbabwe, Brazil, India, Uganda, Colombia, and Indonesia) and different manufacturers, and no OTA below the detection limit of 5 microg/kg was detected in any samples analyzed.

Di-(2-ethylhexyl)phthalate in sewage sludge and post-treated sludge: quantitative determination by HRGC-MS and mass spectral characterization

DEHP was quantified into sewage sludge, thermally dried sludge and compost samples from different areas of Catalonia (North East Spain) using high-resolution gas chromatography (HRGC) coupled to a mass spectrometry (MS). The aim of the work was to determine the evolution of this ubiquitous environmental contaminant along some post-treatment sludge processes, such as composting and thermally drying. DEHP concentration detected in some sludges are above the maximum limit suggested by the EC (100 ppm d.m.) for agricultural use. However, the composting and thermally drying reduce the amount of DEHP in sewage sludge to acceptable level for safe land application. The study was completed with the characterization and long-term observation of DEHP in sewage sludge, composted sludge and thermally dried sludge mixed with two types of soils. In all cases, the percentage of DEHP degraded was higher than 50% after 9 months of incubation.

Determination of aflatoxins B1, G1, B2 and G2 in medicinal herbs by liquid chromatography-tandem mass spectrometry

An easy method for the determination of aflatoxins B1, G1, B2 and G2 in Rhammus purshiana by LC coupled to mass spectrometry has been developed. Aflatoxins were extracted with a mixture of methanol and water and then it was purified by solid-phase clean-up using a polymeric sorbent, not described previously, for the determination of these toxins. The eluted extract was injected into the chromatographic system using a reversed-phase C18 short column with an isocratic mobile phase composed of methanol-water (30:70). A single-quadruple mass spectrometry using an electrospray ionization source operating in the positive ion mode was used to detect aflatoxins due to derivatization presenting several disadvantages. Recoveries of the full analytical procedure were 110% for aflatoxin B1, 89% for aflatoxin B2, 81% for aflatoxin G1 and 77% for aflatoxin G2. Detection limit (S/N = 3) was 10 ng and quantification limit (S/N = 10) was 25 ng, calculated as amount in medicinal herb.

In vitro conidial germination in Arthrinium aureum and Arthrinium phaeospermum

This paper describes the microscopic details of conidial germination and the influence of pH, sodium chloride concentration, 3% glucose, 3% saccharose and ultraviolet irradiation on the conidial germination in Arthrinium species. Under laboratory conditions, germination started after an incubation period of 90 minutes in 2% malt extract broth at 25 degrees C. In vitro, the conidia of Arthrinium species have a very low percentage of germination (A. phaeospermum: 7.9%; A. aureum: 15.8%). Conidia of this genus have a characteristic equatorial slit. Conidia may break spontaneously at this slit, releasing their cytoplasmic contents. Arthrinium phaeospermum attains its optimum germination percentage when its conidia are suspended in a sterile saline solution (pH 3.5) in a water bath at 20 degrees C for 15 minutes before being inoculated on 2% malt extract agar. Conidial suspensions of A. aureum may be held in the same conditions, but for 30 minutes.

Observation of Protoplasts from the Conidia of Arthrinium Aureum

Protoplast formation from conidia of Arthrinium aureum was achieved with Lysing Enzyme L-2265 (Sigma Chemical) from Trichoderma harzianum. Scanning electron microscopy of conidia protoplasts showed the acquired spherical shape.

Analysis of ochratoxin a in coffee by solid-phase cleanup and narrow-bore liquid chromatography-fluorescence detector-mass spectrometry

A method for the analysis of ochratoxin A (OTA) in green and roasted coffee has been developed. OTA was extracted from coffee with 1% NaHCO(3), and the extract was filtered and purified by solid-phase cleanup using a polymeric column that exhibits reversed-phase and anion-exchange functionalities. OTA was analyzed on a narrow-bore reversed-phase C(18) HPLC column with acetonitrile/water (0.1% formic acid) (40:60) as mobile phase and quantified with a fluorescence detector. The presence of OTA in coffee was confirmed by single-quadruple mass spectrometry using an electrospray ionization source. The method has been validated, obtaining a recovery of 82.5% and a detection limit of 0.1 ng/g. It has been applied to 20 coffee samples from various countries and different manufacturers with no detection of OTA.

Observation of woronin bodies in Arthrinium aureum by scanning electron microscopy

Woronin bodies are cytoplasmic organelles of filamentous fungi that can be observed on one, or both sides of each septum. The goal of this paper is to illustrate the presence of them in hyphae of Arthrinium aureum by means of scanning electron microscopy and to show that they act as a safety plug to close septa pores in hypha. Results show that Woronin bodies as an immediate response to prevent a cytoplasm loss. Results support hypothesis proposed previously in literature.

Vaginal microbiota in healthy pregnant women and prenatal screening of group B streptococci (GBS)

The microbiota of the lower female genital tract was evaluated from vaginal swabs obtained from 623 healthy pregnant women at gestation periods of 35-40 weeks. Isolated and identified microorganisms were expressed as percentages of total samples. As expected, lactobacilli made up the dominant vaginal microbiota (70%). Enterobacteriaceae, mainly Escherichia coli, Klebsiella spp. and Proteus, were present in 38% of the samples, which might reflect the possible contamination of vaginal tract with rectal microorganisms. Candida albicans was present in 10% of healthy pregnant woman assayed. Streptoccocci (Streptococcus sp. and Enterococcus faecalis with 3% and 4%, respectively) and other gram-positive cocci (Staphylococcus sp., 5%), along with other microorgansisms such as Gardnerella vaginalis (5%) and Pseudomonas aeruginosa (2%) may represent a potential infection risk. Streptococcus agalactiae (group B streptococci beta-hemolytic, GBS) was detected in 7% of the samples. GBS infection is a leading cause of neonatal morbidity and mortality in the developed world. Furthermore, GBS was often co-isolated with C. albicans (54.5%) in the samples. A complete and detailed evaluation of the vaginal biota swab, with particular attention to the presence of potential pathogens such as GBS, is a preventive strategy that can provide useful information to obstetricians and gynecologist in managing the last days of pregnancy and delivery.