Una visión moderna sobre la desactivación de cetonas aromáticas por beta-fenilos

La desactivación por beta fenilos (en inglés, Beta Phenylquenching o BPQ) es una reacción que se produce a partirdel estado triplete de cetonas aromáticas con un grupofenilo en posición beta. Esta revisión presenta las principalescaracterísticas que definen la reacción de BPQ. Sediscute el mecanismo de reacción y los efectos de los sustituyentes,disolventes y la restricción de la rotación de losgrupos fenilo

Octanol-water partition coefficients of highly hydrophobic photodynamic therapy drugs: a computational study

Photodynamic therapy is a novel treatment for solid tumorsbased on the selective induction of cell death by the generation of cytotoxic reactive oxygen species within neoplastic tissues. Oxygen photosensitization is promoted as a consequence of the activation (using light) of a photosensitizer, which must reach the desired tissue by cellular transport. Hydrophobicity (expressed as the logarithm of octanol/water partition coefficient, logP), becomes a key factor in these processes. Unfortunately, there is no computational method to unambiguously predict the logP value for high hydrophobic photosensitizers. In this study, a total of 12 computational methods have been tested for predicting the logP value of tetrapyrrolic derivatives. Furthermore, in the attempt to correlate logP with experimental HPLC measurements (log(k’)), validation of the results leads to the proposal of a sigmoidal regression for the two parameters (log(k’) and logP)

Innovative light sources for phototherapy

AbstractThe use of light for therapeutic purposes dates back to ancient Egypt, where the sun itself was an innovative source, probably used for the first time to heal skin diseases. Since then, technical innovation and advancement in medical sciences have produced newer and more sophisticated solutions for light-emitting sources and their applications in medicine. Starting from a brief historical introduction, the concept of innovation in light sources is discussed and analysed, first from a technical point of view and then in the light of their fitness to improve existing therapeutic protocols or propose new ones. If it is true that a "pure" technical advancement is a good reason for innovation, only a sub-system of those advancements is innovative for phototherapy. To illustrate this concept, the most representative examples of innovative light sources are presented and discussed, both from a technical point of view and from the perspective of their diffusion and applications in the clinical field

photosensitizing proteins for antibacterial photodynamic inactivation

n/

Fast isomerizing methyl iodide azopyridinium salts for molecular switches

The usefulness of azopyridinium methyl iodide salts for designing new promising light-controlled molecular switches is presented. Large absorbance changes have been produced in the samples by irradiation with light at λ ) 355 nm. The thermal recovery of the initial state took place completely within 130-450 ms, which is much faster than that reported previously for other push-pull azobenzene-doped nematic mixtures.Fil: Garcia Amorós, Jaume. Centro de Investigación en Nanociencia y Nanotecnología (CIN2); España. Universidad de Barcelona. Facultad de Química; EspañaFil: Massad, Walter Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universitat Ramon Llull; EspañaFil: Nonell, Santi. Universitat Ramon Llull; EspañaFil: Velasco, Dolores. Centro de Investigación en Nanociencia y Nanotecnología (CIN2); España. Universidad de Barcelona. Facultad de Química; Españ

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 photoinducedantibiofilm activity, whereas 1O2 participation seems of lesser importance.Fil: Marioni, Juliana. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Bresolí Obach, Roger. Universitat Ramon Llull; EspañaFil: Agut, Montserrat. Universitat Ramon Llull; EspañaFil: Comini, Laura Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; ArgentinaFil: Cabrera, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; ArgentinaFil: Paraje, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Nonell, Santi. Universitat Ramon Llull; EspañaFil: Núñez Montoya, Susana Carolina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

Kinetic study of the fast thermal cis-to-trans isomerisation of para-, ortho- and polyhydroxyazobenzenes

The thermal cis-to-trans isomerisation process has been studied for a series of para-, ortho- and polyhydroxy-substituted azobenzenes in different solvents. The kinetics of the thermal back reaction for the p-hydroxy-substituted azobenzenes depend strongly on the nature of the solvent used, with relaxation times ranging from 200-300 milliseconds in ethanol to half an hour in toluene. Otherwise, the process rate is mainly independent of the solvent nature for the ortho substituted analogues. Polyhydroxy-substituted azobenzenes show very much faster kinetics than the para- and ortho- monohydroxyazoderivatives. With relaxation times of 6-12 milliseconds in ethanol, they are optimal molecules for designing fast optical switching devices. All the hydroxyazoderivatives thermally isomerise from the metastable cis form to the thermodynamically stable trans isomer through a rotational mechanism.Fil: Garcia Amorós, Jaume. Universidad de Barcelona; EspañaFil: Sánchez Ferrer, Antoni. Universidad de Barcelona; EspañaFil: Massad, Walter Alfredo. Universitat Ramon Llull; España. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Nonell, Santi. Universitat Ramon Llull; España. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Velasco, Dolores. Universidad de Barcelona; Españ

Transformation of COUPY fluorophores into a novel class of visible light-cleavable photolabile protecting groups

Although photolabile protecting groups (PPGs) have found widespread applications in several fields of chemistry, biology and materials science, there is a growing interest in expanding the photochemical toolbox to overcome some of the limitations of classical caging groups. In this work, the synthesis of a new class of visible-light-sensitive PPGs based on low-molecular weight COUPY fluorophores with several attractive properties, including long-wavelength absorption, is reported. Besides being stable to spontaneous hydrolysis in the dark, COUPY-based PPGs can be efficiently photoactivated with yellow (560 nm) and red light (620 nm) under physicological-like conditions, thereby offering the possibility of unmasking functional groups from COUPY photocages under irradiation conditions in which other PPGs remain stable. Additionally, COUPY photocages exhibit excellent cellular uptake and accumulate selectively in mitochondria, opening the door to delivering caged analogues of biologically active compounds into this organell

Mitochondria-Targeted COUPY Photocages: Synthesis and Visible-Light Photoactivation in Living Cells

Releasing bioactive molecules in specific subcellular locations from the corresponding caged precursors offers great potential in photopharmacology, especially when using biologically compatible visible light. By taking advantage of the intrinsic preference of COUPY coumarins for mitochondria and their long wavelength absorption in the visible region, we have synthesized and fully characterized a series of COUPY-caged model compounds to investigate how the structure of the coumarin caging group affects the rate and efficiency of the photolysis process. Uncaging studies using yellow (560 nm) and red light (620 nm) in phosphate-buffered saline medium have demonstrated that the incorporation of a methyl group in a position adjacent to the photocleavable bond is particularly important to fine-tune the photochemical properties of the caging group. Additionally, the use of a COUPY-caged version of the protonophore 2,4-dinitrophenol allowed us to confirm by confocal microscopy that photoactivation can occur within mitochondria of living HeLa cells upon irradiation with low doses of yellow light. The new photolabile protecting groups presented here complement the photochemical toolbox in therapeutic applications since they will facilitate the delivery of photocages of biologically active compounds into mitochondria

Nanostructured AABB Zn (II) phthalocyanines as photodynamic agents for bacterial inactivation

In this work, the ability of amphiphilic Phthalocyanine (Pc) photosensitizers (PS) (Zn(II)Pcs PS1, PS2, and PS3) to assemble into cationic nanoparticles in water and to photo-inactivate bacterial strains is demonstrated. All the synthesized Zn(II)Pcs exhibit an AABB functionalization pattern, having a binaphthyloxy-linked bisisoindole (AA) functionalized at the chiral binaphthol core with branched (PS1) or linear (PS2 and PS3) poly-ammonium chains, and two non-functionalized isoindole rings (BB). The aggregation behavior and the stability of the nanoparticles formed by the three PS in water is studied by UV–vis, fluorescence and circular dichroism (CD) spectroscopies, and their shape and size is determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The PS nanoparticles prove efficient in the photoinactivation of S. aureus and E. coli. Although PS2 and PS3 present better photophysical features in their monomeric form (i.e., improved singlet oxygen quantum yield), PS1 is more effective in killing both types of strains, especially the gram-negative E. coli. This observation may derive from the low stability found for PS1 nanoparticles, which easily disassemble after binding to the bacteria surface, recovering the photophysical properties of the non-aggregated speciesThe authors gratefully acknowledge financial support from the Spanish AEI through grants PID2020-116490GB-I00, PID2020-115801RB-C21, and PID2020- 115801RB-C22. The authors also thank financial support to the Comunidad de Madrid and the Spanish State through the Recovery, Transformation and Resilience Plan [“Materiales Disruptivos Bidimensionales (2D)” (MAD2D-CM) (UAM1)-MRR Materiales Avanzados], and the European Union through the Next Generation EU funds. IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Program for Centers of Excellence in R&D (MINECO, Grant SEV2016-0686). S.N. thanks the Departament de Recerca i Universitats de la Generalitat de Catalunya for the support given to the research group (2021 SGR 01023) and the ICREA-Catalan Institution for Research and Advanced Studies for grant No. Ac223230