Resumen Recientes investigaciones demuestran la importancia de los extractos de origen vegetal como potentes antioxidantes, debido a la presencia de componentes químicamente activos, como los polifenoles, antocianinas, flavonoides, entre otros. Esta sinergia de los componentes se convierte en una posible alternativa frente al uso de antioxidantes de origen sintético. En este trabajo la cáscara de la frutaSyzygium cuminifue utilizada para determinar la actividad antioxidante frente al oxígeno singulete. El extracto mostró cantidades apreciables de grupos fenólicos (alrededor de 8,55 AGE mg/g peso fruta). La caracterización por HPLC-DAD muestra por lo menos 3 antocianinas de mayor abundancia relativa (la malvidina 3,5-diglucósido, la delfinidina 3,5-diglucósido y la petunidina 3,5-diglucósido). El porcentaje de desactivación del oxígeno singulete fue determinado a diferentes concentraciones del extracto etanólico, encontrándose un valor del 60% a una concentración 0.39 mg/mL.

Abstract Recent research has shown the importance of plant extracts as powerful antioxidants owing to the presence of chemically active components such as polyphenols, anthocyanins, flavonoids, among others. This synergy of the components becomes a possible alternative to the use of antioxidants of synthetic origin. In this study,Syzygium cuminifruit peel was used to determine the antioxidant activity against singlet oxygen. The extract showed appreciable amounts of phenolic groups (about 8.55 AGE mg/g fruit weight). HPLC-DAD characterization showed at least 3 anthocyanins of higher relative abundance (malvidin 3,5-diglucoside, delphinidin 3,5-diglucoside and petunidin 3,5-diglucoside). The percentage of quenching of singlet oxygen was determined at different concentrations of the ethanolic extract, finding a value of 60% at a concentration of 0.39 mg/mL.

En este trabajo sintetizamos metalocarboxifenilporfirinas (TcPP-M, M= Cu y Zn) y la carboxifenilporfirina libre de metal (TcPPH) y determinamos su eficiencia en la fotooxidación de antraceno bajo luz visible a través de la generación de oxígeno singulete (¹O2). La presencia de ¹O2 fue evidenciada por Resonancia Paramagnética Electrónica (RPE), el cual el oxígeno singulete reacciona con la 2,2,6,6-tetrametil-4-piperidona-N (TEMP) para producir el radical 2,2,6,6-tetrametil-4-piperidona-N-oxil (TEMPO). Los resultados catalíticos indican que la incorporación del metal en el anillo de la porfirina afecta su eficiencia sobre la oxidación del antraceno. La TcPPH mostró la eficiencia fotónica más alta en la conversión de antraceno (31 %) en comparación con la TcPPZn (13 %) y TcPPCu (9 %). Estos resultados pueden ser relacionados a la distorsión de la planaridad del anillo de porfirina. Finalmente se detectó la formación de antraquinona y oxoantrona como productos de oxidación in la reacción del antraceno con ¹O2.

In this work, metallocarboxyphenylporphyrins (TcPP-M, M= Cu y Zn) and metal-free carboxyphenylporphyrin (TcPPH) have been synthesized and their efficiency in the photooxidation of anthracene under visible light (λ> 500 nm) through generation of oxygen singlet (¹O2) has been evaluated. ¹O2 was detected by Electron Paramagnetic Resonance (EPR), where it reacts with 2,2,6,6-tetramethyl-4-piperidone-N (TEMP) to produce 2,2,6,6-tetramethyl-4-piperidone-N-oxyl radical (TEMPO). The catalytic results indicated that the incorporation of the metal in the porphyrin ring strongly affects their efficiency on the anthracene oxidation. The TcPPH showed a higher photonic efficiency (31%) in the anthracene conversion than TcPPZn (13%) and TcPPCu (9%). This result may be related to the disruption of the planarity of the porphyrin ring. Finally, the formation of anthraquinone and oxanthrone was detected as the oxidation products in the anthracene reaction with ¹O2.

El rendimiento cuántico de producción de radical hidroxilo (ΦOH) fue medido desde la fotólisis del peróxido de hidrógeno (H2O2) catalizada por la tetracarboxifenilporfirina de hierro (III) (TCPPFe) bajo luz ultravioleta. ΦOH fue determinado por medidas de fluorescencia del producto de reacción entre el radical hidroxilo (HO•) y el tereftalato disódico. La TCPPFe presenta un ΦOH=0,13, mientras que la reacción estándar de la fotólisis del H2O2, no catalizada, tiene un ΦOH=0,11. La reacción no tiene lugar en ausencia de luz, pero en presencia de luz visible, H2O2 y TcPPFe generan HO•.

The quantum yield to production of hydroxyl radical (ΦOH) was measured from the photolysis of hydrogen peroxide (H2O2) catalyzed by tetra-carboxy-phenyl-porphyrin Fe (III) (TCPPFe) under UV irradiation. ΦOH was determined by fluorescence measurements by the reaction product between hydroxyl radical (HO•) and the disodium terephthalate. The TCPPFepresented a ΦOH = 0.13 while the standard uncatalyzed photolysis reaction of H2O2 presented a ΦOH=O.11. Under light irradiation on H2O2 and TcPPFe, the radical HO• was generated and, the reaction did not occur in the absence of light.

La sensibilización del dióxido de titanio con porfirinas es esencial para la generación de especies reactivas del oxígeno inducida con luz visible. Sin embargo, estos sensibilizadores tienden a lixiviarse en el medio de reacción. La distribución del tamaño de partícula es una propiedad fundamental para caracterizar sistemas de partículas en suspensión. En este trabajo se estudió la distribución del tamaño de partícula de la tetracarboxifenilporfirina de cobre (II) anclada sobre dióxido de titanio por la técnica de dispersión dinámica de luz. Los resultados indican que la técnica de dispersión dinámica de luz es adecuada para determinar la estabilidad de estos sistemas, mostrando un solo tipo de partícula para el sistema TCPPCu/TiO2 con diámetro promedio de 211,1 nm.

The sensitization of titanium dioxide with porphyrins is essential to the generation of reactive oxygen species under irradiation with visible light. However, these sensitizers tend to leach into the reaction medium. The particle size distribution is a critical property for characterizing particles in suspension systems. In this work we determinated the particle size distribution of copper (II) tetracarboxyphenylporphyrin anchored on titanium dioxide by the technique of dynamic light scattering (DLS). The results showed only one type of particle to the system TCPPCu/TiO2 with average diameter of 211.1 nm and that DLS is suitable for determining the stability of these systems.

In this work we studied the influence of incorporation of copper into TiO2 thin films on structural, optical and surface properties of TiO2 thin films. The as-grown TiO2 was synthesized by sol gel method using titanium isopropoxide, and the TiO2 thin films were deposited by spin coating method. TiO2 copper-doped (Cu:TiO2) was synthesized by impregnation method using Cu(NO3).H2O as source of Cu(II), the Cu:TiO2 thin films were deposited by spin coating method. The properties of the compounds obtained were evaluated by measurements of X-ray diffraction (XRD) and diffuse reflectance. The XRD results showed that Cu doping change the crystalline phase radio of the films, XRD pattern of TiO2 indicated that films grow with anatase structute, while Cu:TiO2 thin films presented a polycrystalline mixture of anatase/rutile. Reflectance analysis indicated that TiO2 presents an energy band gap of 3.25 eV and the Cu:TiO2 presents a shift-red of the band gap to 2,9 eV. The results suggest that doping with copper improved the harvesting of the TiO2 to visible radiation.

A redução da excitabilidade do córtex motor primário (M1) dominante melhora o desempenho manual ipsilateral: a inibição do M1 não-dominante poderia, analogamente, aprimorar a função manual direita. Para investigar esta hipótese, utilizou-se a estimulação magnética transcraniana repetitiva (EMTr) de baixa frequência e o teste Purdue Pegboard. Submetemos 28 voluntários a 10 minutos de EMTr sobre o M1 direito (0,5 Hz) ou a EMTr placebo (bobina perpendicular ao escalpo). O teste foi executado antes, imediatamente após e 20 minutos após a EMTr. Nos dois grupos, o desempenho manual mostrou significativa melhora entre as sessões. A inibição do M1 não-dominante não influenciou significativamente a destreza motora ipsi ou contralateral, apesar da conclusão limitada pelo desempenho discrepante dos grupos na primeira sessão. Este resultado contrasta com a melhora da função manual esquerda descrita após a EMTr sobre o M1 esquerdo e sugere uma inibição transcalosa fisiológica menos intensa do M1 direito para o esquerdo.

Reduction of excitability of the dominant primary motor cortex (M1) improves ipsilateral hand function in healthy subjects. In analogy, inhibition of non-dominant M1 should also improve ipsilateral performance. In order to investigate this hypothesis, we have used slow repetitive transcranial magnetic stimulation (rTMS) and the Purdue Pegboard test. Twenty-eight volunteers underwent 10 minutes of either 0.5Hz rTMS over right M1 or sham rTMS (coil perpendicular to scalp). The motor task was performed before, immediately after, and 20 minutes after rTMS. In both groups, motor performance improved significantly throughout the sessions. rTMS inhibition of the non-dominant M1 had no significant influence over ipsilateral or contralateral manual dexterity, even though the results were limited by unequal performance between groups at baseline. This is in contrast to an improvement in left hand function previously described following slow rTMS over left M1, and suggests a less prominent physiological transcallosal inhibition from right to left M1.