José A. S. Cavaleiro

Antimicrobial Photodynamic Therapy: Study of Bacterial Recovery Viability and Potential Development of Resistance after Treatment

Antimicrobial photodynamic therapy (aPDT) has emerged in the clinical field as a potential alternative to antibiotics to treat microbial infections. No cases of microbial viability recovery or any resistance mechanisms against it are yet known. 5,10,15-tris(1-Methylpyridinium-4-yl)-20-(pentafluorophenyl)-porphyrin triiodide (Tri-Py+-Me-PF) was used as photosensitizer. Vibrio fischeri and recombinant Escherichia coli were the studied bacteria. To determine the bacterial recovery after treatment, Tri-Py+-Me-PF (5.0 μM) was added to bacterial suspensions and the samples were irradiated with white light (40 W m−2) for 270 minutes. Then, the samples were protected from light, aliquots collected at different intervals and the bioluminescence measured. To assess the development of resistance after treatment, bacterial suspensions were exposed to white light (25 minutes), in presence of 5.0 μM of Tri-Py+-Me-PF (99.99% of inactivation) and plated. After the first irradiation period, surviving colonies were collected from the plate and resuspended in PBS. Then, an identical protocol was used and repeated ten times for each bacterium. The results suggest that aPDT using Tri-Py+-Me-PF represents a promising approach to efficiently destroy bacteria since after a single treatment these microorganisms do not recover their viability and after ten generations of partially photosensitized cells neither of the bacteria develop resistance to the photodynamic process.

Keggin-type polyoxotungstates as catalysts in the oxidation of cyclohexane by dilute aqueous hydrogen peroxide

Abstract Oxidation of cyclohexane by hydrogen peroxide in the presence of catalytic amounts of the Keggin-type heteropolytungstates [PW 11 O 39 ] 7− and [PW 11 M(L)O 39 ] (7− m )− , M m + =first row transition metal cation, L=H 2 O or CH 3 CN, was found to produce cyclohexanol, cyclohexanone and, in certain cases, cyclohexyl hydroperoxide. The presence of the latter was demonstrated by negative chemical ionization GC-MS. The reactions were carried out in acetonitrile, using tetra n -butylammonium salts of the catalysts and aqueous 30% hydrogen peroxide as oxidant. The polyanions [PW 11 O 39 ] 7− and [PW 11 Fe(H 2 O)O 39 ] 4− showed higher catalytic activity and different selectivity for the oxidation of cyclohexane than did the corresponding Cu-, Co-, Mn- and Ni-substituted complexes.

Phthalocyanine Blends Improve Bulk Heterojunction Solar Cells

A core phthalocyanine platform allows engineering of the solubility properties the band gap, shifting the maximum absorption toward the red. A simple method for increasing the efficiency of heterojunction solar cells uses a self-organized blend of phthalocyanine chromophores fabricated by solution processing.

Chromones and flavanones from artemisia campestris subsp. maritima

Abstract From the acetone extract of Artemisia campestris subsp. maritima six flavanones, two chromones and the coumarin scopoletin were isolated. 5-Hydroxy-7-methoxychromone and 5,7-dimethoxychromone are new compounds, while the flavanone eriodictyol-7,3′-dimethyl ether is reported for the first time in this species. The structures were elucidated by 1D and 2D NMR techniques. The unequivocal assignments of carbon resonances, mainly made by using 1D selective INEPT and 2D HETCOR experiments, allowed us to correct some 1H and 13C resonances of the isolated flavanones and also to differentiate between the flavanone isomers sakuranetin⧹isosakuranetin and eriodictyol-7,3′-dimethyl ether⧹eriodictyol-7,4′-dimethyl ether.

Oxidation of alkylaromatics with hydrogen peroxide catalysed by manganese(III) porphyrins in the presence of ammonium acetate

The oxidation of toluene (1), ethylbenzene (2) and cumene (3) with hydrogen peroxide, in the presence of several manganese(III) porphyrins with electron-withdrawing substituents, was studied using ammonium acetate as a co-catalyst. All products were characterised and their formation was justified by studying the oxidation of primary precursors, under the same conditions. The formation of the nitrate compounds was shown to be dependent on the presence of ammonium acetate. The oxidation of cumene and ethylbenzene afford products resulting from dehydrogenation reactions.

Functional cationic nanomagnet-porphyrin hybrids for the photoinactivation of microorganisms.

Cationic nanomagnet-porphyrin hybrids were synthesized and their photodynamic therapy capabilities were investigated against the Gram (-) Escherichia coli bacteria, the Gram (+) Enterococcus faecalis bacteria and T4-like phage. The synthesis, structural characterization, photophysical properties, and antimicrobial activity of these new materials are discussed. The results show that these new multicharged nanomagnet-porphyrin hybrids are very stable in water and highly effective in the photoinactivation of bacteria and phages. Their remarkable antimicrobial activity, associated with their easy recovery, just by applying a magnetic field, makes these materials novel photosensitizers for water or wastewater disinfection.

Lipophilic Extractives of the Inner and Outer Barks of Eucalyptus globulus

Summary The chemical compositions of the dichloromethane extracts of inner and outer barks of E. globulus were studied by gas chromatography-mass spectrometry. The two fractions show very different chemical compositions: triterpenic acids, such as betulinic, ursolic and oleanolic acids, were the major components of the outer bark extract, whereas β-sitosterol and β-amirin along with palmitic, linoleic and oleic acids predominate in the inner bark extract. Several α-and β-hydroxy fatty acids, recently reported for the first time as E. globulus wood components, were also identified in the outer and inner barks. In the outer bark extract, minor amounts of ferulic acid esters, also previously reported to occur in E. globulus wood were identified. In general, the inner bark lipophilic extractives resemble more closely that of E. globulus wood.

Porphyrin derivatives as photosensitizers for the inactivation of Bacillus cereus endospores.

Aims:  In this study, we propose (i) to study the photodynamic inactivation (PDI) efficiency of neutral and cationic porphyrin derivatives, (ii) to characterize the kinetics of the inactivation process using Bacillus cereus as a model endospore‐producing bacterium and (iii) to conclude on the applicability of porphyrin derivatives in the inactivation of bacterial endospores.

Assignments of the paramagnetically shifted heme methyl nuclear magnetic resonance peaks of cyanometmyoglobin by selective deuteration

Abstract Three of the four paramagnetically shifted heme methyl nuclear magnetic resonance peaks of cyanometmyoglobin could be assigned by comparing the proton nuclear magnetic resonance spectra of myoglobins reconstituted from selectively deuterated hemes. These spectra indicate that the fourth methyl nuclear magnetic resonance peak has to be looked for outside the region −9 to −43 parts per million.

Porphyrins in 1,3-dipolar cycloaddition reactions with sugar nitrones. Synthesis of glycoconjugated isoxazolidine-fused chlorins and bacteriochlorins

Glycoconjugated isoxazolidine-fused chlorins and bacteriochlorins were prepared in moderate to good yields by 1,3-dipolar cycloaddition reactions of meso-tetrakis(pentafluorophenyl)porphyrin with glycosyl nitrones.