An exopolysaccharide from Leuconostoc mesenteroides showing interesting bioactivities versus foodborne microbial targets.

An exopolysaccharide (EPS_B3) produced by a Leuconostoc mesenteroides strain isolated from a semi-hard Italian cheese was chemically and biologically characterized. HPLC-SEC, NMR, FT-IR and monosaccharide composition experiments were performed. Antimicrobial, antibiofilm, bifidogenic, antioxidant, and DNA-protective activity of EPS_B3 were also studied. Results revealed that EPS_B3 was a mixture of two high-molecular-weight dextran with low branching degree. Moreover, EPS_B3 displayed significant antibacterial activity against eight foodborne pathogens and inhibited biofilm formation by Listeria monocytogenes. EPS_B3 also evidenced bifidogenic activity, stimulating the growth of three probiotic bifidobacteria, and improving the tolerance of Bifidobacterium animalis subsp. lactis to oxygen stress. It also protected plasmid DNA from hydrogen peroxide damage. Only limited antioxidant capacity was observed. In conclusion, data suggest that EPS_B3 might be exploited in the context of functional foods especially for its marked antimicrobial activity as well as for the ability to improve the viability of bifidobacteria in probiotic foods. However, further studies should be carried out to assess the ability of EPS_B3 to reach intact the target site (i.e., gastrointestinal tract) to consider the possibility of use it as a new functional ingredient in foods.

Abatement of the ecotoxicological risk of landfill leachate by heterogeneous Fenton-like oxidation.

Landfill leachates are highly contaminated liquid waste, and their treatment and detoxification are a challenging task. The current system of ecotoxicological risk assessment is complex and time-consuming. It is of fundamental importance to develop simpler and faster tools for the evaluation of the treated liquid waste and for an easier preliminary screening of the most active catalytic formulation/reaction conditions of the Fenton-like process. Here, several analytical techniques have been used for the assessment of the reduction of toxicity of the landfill leachate after Fenton process over copper-zirconia catalyst (ZrCu). Ultraviolet-visible (UV-vis) spectroscopy and absorbable organic halogens (AOX) analysis have been coupled to achieve further insight into the degradation of contaminants. In addition, for the first time, the qualitative abatement of organic compounds is monitored through proton nuclear magnetic resonance (1H NMR) analysis, providing a new method for evaluating the effectiveness of the treatment. Spectroscopic techniques reveal that the Fenton process induces a significant abatement of the aromatic and halogen compounds (51%) in the landfill leachate with a reduction of the toxicity that has been confirmed by ecotoxicological test with algae. These results validate the investigated tool for a simple rapid preliminary evaluation of the detoxification efficacy.

Imprinting Pentaphyrin on Conductive Electropolymerized Dipyrromethane Films: A New Strategy towards the Synthesis of Photokilling Materials.

We report herein the synthesis and photoinduced bactericidal activity of two new polymeric materials, obtained by imprinting the photosensitizer 20-(4-carboxyphenyl)-2,13-dimethyl-3,12-diethyl-[22]pentaphyrin (PCox, 1) into suitable electropolymerized dipyrromethane films. 5-Phenyl-dipyrromethane (5-ph-DP) and 5-(4-pyridyl)dipyrromethane (5-py-DP) have been selected as the monomers for the synthesis of the materials in order to assess the correlation between the substituent in C5 and the capability in Pcox uptake. Both films have been tested in their photokilling ability toward Staphylococcus aureus by using a multi-LED blue lamp at a fluence rate of 40 W/m2 . Poly-5-py-DP/PCox, with a PCox load of 10-8  mol/cm2 , achieved a 4-log reduction in microbial viability after 60 min of irradiation. The polymeric films proved to be stable over time and under oxidation conditions; in addition, no loss of photosensitizer was observed during the experiments, thus demonstrating that the bactericidal action was effectively brought by the ROS generated by PCox immobilized in the material. After use, the films were recharged with PCox, with almost complete recovery of their photodynamic efficiency.

CNN pincer ruthenium complexes for efficient transfer hydrogenation of biomass-derived carbonyl compounds.

The ligand HCNNOMe (6-(4-methoxyphenyl)-2-aminomethylpyridine) is easily prepared from the commercially available 6-(4-methoxyphenyl)pyridine-2-carbaldehyde by the reaction of hydroxylamine and hydrogenation (H2, 1 atm) with Pd/C. The pincer complexes cis-[RuCl(CNNOMe)(PPh3)2] (1) and [RuCl(CNNOMe)(PP)] (PP = dppb, 2; and dppf, 3) are synthesized from [RuCl2(PPh3)3], HCNNOMe and PP (for 2 and 3) in 2-propanol with NEt3 at reflux and are isolated in 85-93% yield. Carbonylation of 1 (CO, 1 atm) gives [RuCl(CNNOMe)(CO)(PPh3)] (4) (79% yield) which cleanly reacts with Na[BArf4] and PCy3, affording the cationic trans-[Ru(CNNOMe)(CO)(PCy3)(PPh3)][BArf4] (5) (92% yield). These robust pincer complexes display remarkably high catalytic activity in the transfer hydrogenation (TH) of lignocellulosic biomass carbonyl compounds, using 2-propanol at reflux in a basic medium (NaOiPr or K2CO3). Thus, furfural, 5-(hydroxymethyl)furfural and Cyrene are reduced to the corresponding alcohols with 2 and 3, at S/C in the range of 10 000-100 000, within minutes or hours (TOF up to 1 500 000 h-1). The monocarbonyl complex 5 was found to be extremely active in the TH of cinnamaldehyde, vanillin derivatives and ethyl levulinate at S/C in the range of 10 000-50 000. Vanillyl alcohol is also obtained by the TH of vanillin with 5 (S/C = 500) in 2-propanol in the presence of K2CO3.

Preparation of monocarbonyl ruthenium complexes bearing bidentate nitrogen and phosphine ligands and their catalytic activity in carbonyl compound reduction.

Monocarbonyl complexes [RuCl2(CO)(PR3)(NN)] (R = Cy, NN = en 1, ampy 2; R = iPr; NN = en 3) have been prepared in a one pot reaction from [RuCl2(CO)(dmf)(PPh3)2], PR3 and the NN ligand in CH2Cl2. Treatment of [Ru(OAc)2(CO)(PPh3)2] with NN ligands in methanol gives the cationic derivatives [Ru(OAc)(CO)(PPh3)(NN)]OAc (NN = en 4, ampy 5) in which one acetate acts as a bidentate ligand, whereas the other is not coordinated. Diphosphine complexes [RuCl2(CO)(PP)(PPh3)] (PP = dppb 6, dppf 7, (R)-BINAP 8, (R,Sp)-Josiphos 9 and (R,R)-Skewphos 10) have been obtained starting from [RuCl2(CO)(dmf)(PPh3)2] and the PP ligand in CHCl3 or toluene at reflux. The reaction of [Ru(OAc)2(CO)(PPh3)2] with PP in CH2Cl2 or toluene affords the fluxional acetate derivatives [Ru(OAc)2(CO)(PP)] (PP = dppb 11, dppf 12, (R)-BINAP 13, and (R,R)-Skewphos 14). The cationic diphosphine complexes [RuCl(CO)(PP)(en)]Cl (PP = dppb 15, dppf 16) are prepared from [RuCl2(CO)(dmf)(PPh3)2], PP and en in CH2Cl2 or, alternatively, from [RuCl2(CO)2]n or the 6, 7 derivatives. Similarly, [Ru(OAc)(CO)(PP)(NN)]OAc (PP = dppb, NN = en 17, ampy 18; PP = dppf, NN = en 19, ampy 20) are isolated starting from [Ru(OAc)2(CO)(PPh3)2], PP and NN ligands or from 11, 12. The derivatives [Ru(OAc)2(CO)(PP)] show a fluxional behavior in solution as the result of the flexible coordination of acetate ligands. These complexes are found to be active in the transfer hydrogenation and hydrogenation of ketones and aldehydes, including furfural derivatives, at an S/C up to 10 000 and a TOF up to 18 000 h-1.

Synthesis and biological evaluation of new pentaphyrin macrocycles for photodynamic therapy.

This paper describes the synthesis and in-depth characterization of two new porphyrogenic macrocycles 1 and 2, and provides an evaluation of these molecules as photosensitizer agents. By tuning the reaction conditions and starting from readily available 1,9-diformyl-5-phenyldipyrromethane (4) and tripyrrane dicarboxylic acid (3), both the nonaromatic isopentaphyrin 1, composed of a 24 pi-electron macrocycle, and the aromatic pentaphyrin 2, composed of a 22 pi-electron macrocycle, were obtained in good yield and purity. Confocal laser microscopy and cytofluorimetry studies showed that the newly synthesized pentaphyrins penetrate the cell membranes and localize mainly in the cytoplasm. In the absence of light, 1 and 2 exhibit a nonsignificant cytotoxic effect at concentrations up to 3 mug/mL. In contrast, the synthesized pentaphyrins, when delivered to cells at 1.5 or 3 microg/mL and irradiated with white light (8 mW/cm(2)), promoted a strong and dose-dependent phototoxic effect in four different cell lines. FACS and caspase-3/7 activation assays demonstrated that the pentaphyrins cause cell death by apoptosis.

"Clicking" Porphyrins to Magnetic Nanoparticles for Photodynamic Therapy.

A method for the preparation of superparamagnetic iron oxide nanoparticle-porphyrin (SPION-TPP) conjugates through click chemistry, which can be used as novel theranostic nanoagents for photodynamic therapy is developed. The synthesis, characterisation, and evaluation of the photocytotoxicity profiles of the nanoconjugates prepared is reported. Upon light irradiation, SPION-TPP nanoconstructs promote a photodynamic effect in vitro in murine amelanotic melanoma B78-H1 cells, with IC50 values in the region of 800 nM, similarly to unbound TPP, whereas they remain non-cytotoxic in the dark. However, these nanoconstructs show poor cellular uptake, which influences a linear dose-response effect. Therefore, the improvement of delivery to cells has also been studied by conjugating a well-known cell-penetrating peptide (TAT peptide) to the SPION-TPP nanoparticles. The new nanoconstructs show lower IC50 values (in the region of 500 nM) and a clear dose-response effect. Our results suggest that TAT-conjugated SPION-TPP nanoparticles are efficient nanodevices both for tracking drugs by means of magnetic resonance imaging (MRI)-based techniques and for treating cancer cells through photodynamic therapy, thus functioning as promising theranostic nanoagents.

Metallation of pentaphyrin with Lu(III) dramatically increases reactive-oxygen species production and cell phototoxicity.

Photodynamic therapy (PDT) is an emerging cancer treatment modality based on the excitation of a nontoxic photosensitizer with harmless visible light to produce reactive-oxygen species (ROS) that induce apoptosis and/or necrosis in cancer cells. As the efficacy of this therapy strongly depends of the nature of the photosensitizer, there is a great interest to develop new photoactive molecules. Here we report for the first time the synthesis, characterization and bioactivity of metal complexes between the non-aromatic expanded porphyrin, namely 20-[[4'-(Trimethylsilyl)ethoxycarbonyl]phenyl-2,13-dimethyl-3,12-diethyl-[24] iso-pentaphyrin (PCRed) and Zn(II) [Zn(II)-PCRed] or Lu(III) [Lu(III)-PCRed]. The complexation of these two diamagnetic heavy metal ions to PCRed improved the properties of the free photosensitizer as a PDT drug. We discovered that the 1:1 complex between PCRed and Lu(III) significantly increases the cellular uptake, ROS production and antiproliferative capacity in four cancer cell lines. Our study shows that metal complexation is a useful strategy to potentiate iso-pentaphyrin as a PDT drug.

Salt-assisted thermal desorption of mercury from contaminated dredging sludge.

In this study, we tested a new procedure for the decontamination of mercury-polluted dredging sludge (Marano-Grado Lagoon, northeastern Italy) based on cationic exchange associated with thermal desorption at a low temperature. Four mercury-polluted sludge slurries were treated using thermal desorption at 393 K for 2h. Three different salts, NaCl (sodium chloride), (CH(3))(4)NCl (tetramethylammonium chloride) and (C(4)H(9))(4)NCl (tetrabutylammonium chloride) were used as exchangers. The selected salts have a monovalent cationic part that progressively increases in molecular weight. The results show that the association of cationic exchange with thermal treatment leads to a significant improvement in the removal of mercury from the contaminated material at a low temperature compared to samples that were not treated with salt. The highest levels of decontamination were attained were obtained when the slurries, which had mercury pollution ranging from 20 to 200 ppm, were treated with a 15% solution of (C(4)H(9))(4)NCl. The efficiency of the removal at 393 K (from 24% up to 60%) depended on the nature of the sample. When the samples were treated at a similar temperature without the salt, no remediation of mercury was detected. Our results show that the thermal decontamination temperature can be significantly lowered by this remediation approach, which is the first example based on cationic exchange of the pollutant with an appropriate salt.

Bench-scale tests on ultrasound-assisted acid washing and thermal desorption of mercury from dredging sludge and other solid matrices.

A series of ultrasonic assisted acid washing and thermal desorption tests were performed on sludge and other solid matrices with the aim to assay these removal technologies and to determine if the application of low frequency ultrasound was effective to enhance mercury removal. Unpolluted dredging sludge, 820 K calcinated dredging sludge, silica and alumina were characterized, polluted with a known concentration of mercury and treated both by acid washing and thermal desorption with and without low frequency ultrasound application. The acid washing was carried out by a 4% HNO(3) acid solution and the thermal desorption was performed in a 370-620K range. X-ray semi-quantitative analysis of dredging sludge before and after acid washing and granulometric curves of the matrices after the ultrasonic treatment were considered in order to evidence chemical or physical changes during these treatments. Total residual mercury measurements were carried out before and after sonication. Results showed not measurable acid washing extraction from polluted dredging sludge, a little (3%) extraction from 820K heat-treated sludge and a significant (10-20%) extraction from alumina and silica within 120 min of treatment. The ultrasound application gave generally poor improvement of the mercury removal. On the contrary thermal desorption of mercury was somewhat effective for alumina, silica and heat-treated dredging sludge samples in which mercury removal was 30-40% at 370 K and 90-99% at 570 K. Likewise ultrasound application did not improve desorption. Instead, the thermal treatment of dredging sludge had a negligible amount of mercury desorption at 370 K but it reached 95% at 570 K. The application of ultrasound improved the thermal extraction of 25% in the 470-520 K range of temperature.

Long-range-distance NMR effects in a protein labeled with a lanthanide-DOTA chelate.

A two-thiol reactive lanthanide-DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) chelate, CLaNP-3 (CLaNP=caged lanthanide NMR probe), was synthesized for the rigid attachment to cysteine groups on a protein surface, and used to obtain long-range-distance information from the {15N,1H} HSQC spectra of the protein-lanthanide complex. The DOTA ring exhibits several isomers that are in exchange; however, single resonances were observed for most amide groups in the protein, allowing determination of a single, apparent magnetic-susceptibility tensor. Pseudocontact shifts caused by Yb-containing CLaNP-3 were observed for atoms at 15-35 A from the metal. By using Gd-containing CLaNP-3, relaxation effects were observed, allowing distances up to 30 A from the paramagnetic center to be determined accurately. Similar results were obtained with a Gd-DTPA (diethylene-triaminepentaacetic acid) chelate, CLaNP-1, bound in the same bidentate manner to the protein. This study demonstrates that bidentate attachment of a paramagnetic probe enables determination of long-range distances.

Cobalt(II) dioxygen carriers based on simple diamino ligands: kinetic and ab initio studies.

The kinetics of the oxygenation reaction of CoL2(2+) complexes (L=ethylenediamine (en), N,N'-dimethylethylenediamnine (dmen)) have been investigated in dimethyl sulfoxide (dmso) at 298 K and in a medium adjusted to 0.1 mol dm(-3) with Et4NClO4 by means of a UV-vis spectrophotometric technique. The reaction mechanisms are consistent with the fast formation of superoxo 1:1 initial CoL2-O2 species (L=en, dmen), whereas the dimeric mu-peroxo (CoL2)2O2 adduct is formed only when L=en, in the rate determining step. The kinetic results are discussed taking into account the effects of ligand/solvent substitution. EPR results give information on the electronic structure and the coordination geometry of the Co(II) complexes and further confirm the stoichiometry of the species formed. Ab initio calculations provide insights on the geometrical parameters of all the complexes investigated and allow us to draw some hypotheses about the influence of H.H nonbonded interactions in the eventual formation of the dimeric mu-peroxo (CoL2)2O2 complexes. Solvational effects are also considered. The formation of the (CoL3)2O2 adduct is also proved when L=en by means of O2 volumetric absorption.

SOLVERSTAT: a new utility for multipurpose analysis. An application to the investigation of dioxygenated Co(II) complex formation in dimethylsulfoxide solution.

A new utility for multipurpose analysis, SOLVERSTAT, taking advantage of the versatility of spreadsheets is here described. By means of this tool advanced statistical tests have introduced in Microsoft Excel Solver thus allowing regression diagnostic and discrimination between different models. The utility is here applied to the determination, by UV-Vis spectroscopy, of the stability constant for the uptake of molecular dioxygen by the 1:2 complex of Co(II) with N,N'-dimethylethylenediamine (dmen) in the aprotic solvent dimethylsulfoxide (dmso) at 298 K and in a medium adjusted to 0.1 mol dm(-3) with Et(4)NClO(4). The reliability of the model and parameters obtained are discussed and the results compared with those obtained by Dynafit, a different software package, and by independent voltammetric measurements. The validity of SOLVERSTAT has been also examined applying it to the discrimination between different models already discussed in the literature.