Protective role of rutin dietary supplementation mediated by purinergic signaling in spleen of silver catfish Rhamdia quelen exposed to organophosphate pesticide trichlorfon.

Evidence suggests the involvement of purinergic signaling, a mechanism mediated by extracellular nucleotides and nucleosides, with the impairment of immune and inflammatory responses in silver catfish (Rhamdia quelen) exposed to trichlorfon. Plant-derived substances have been considered potent anti-inflammatory agents due to effects on the purinergic system, such as the use of the flavonoid rutin. The aim of this study was to determine whether a diet containing rutin is able to prevent or reduce trichlorfon-induced impairment of immune responses through alteration of the purinergic pathway. Spleen adenosine triphosphate (ATP) levels were significantly higher in silver catfish exposed to 11 mg/L trichlorfon for 48 h compared to the control group, while adenosine (Ado) levels were significantly lower. Spleen ectonucleoside triphosphate diphosphohydrolase (NTPDase) activity was significantly lower in silver catfish exposed to trichlorfon compared to control group, while adenosine deaminase activity was significantly higher. Spleen metabolites of nitric oxide, interleukin-1, and IL-6 were significantly higher in silver catfish exposed to trichlorfon compared to control group. Diet with 3 mg rutin/kg diet was able to prevent all the alterations elicited by trichlorfon, except restoring spleen ATP levels. The purinergic exposure signaling is involved in impairment of immune and inflammatory responses in fish exposed to trichlorfon due to reduction in ATP hydrolyses and by an increase in Ado deamination, leading to release of pro-inflammatory mediators. Use of rutin-added diet exerted an essential role in protecting the silver catfish spleen from trichlorfon-induced impairment on immune and inflammatory responses, preventing all alterations on splenic purinergic signaling.

DNA photocleavage and melanoma cells cytotoxicity induced by a meso-tetra-ruthenated porphyrin under visible light irradiation.

Porphyrins are used as photosensitizing agents in photodynamic therapy (PDT) for several pathologies. Here we demonstrate the DNA photocleavage and cytotoxicity properties of a free-base meso-tetra-ruthenated porphyrin (H2RuTPyP) in purified DNA samples and in a melanoma cell line, respectively. Cytotoxicity of H2RuTPyP was investigated by the tetrazolium dye (MTT) colorimetric assay and its genotoxic potential by direct plasmid DNA photocleavage after incubation with specific DNA repair enzymes. H2RuTPyP porphyrin efficiently induced DNA damage at the lower concentration of 5.0 µM, whereas it induced complete DNA degradation at 15 µM. The addition of different scavengers for reactive oxygen species (ROS) during the visible light exposures did not decrease the DNA damage formation, suggesting a hydrolytic mechanism for the induction of DNA breaks. Also, H2RuTPyP exhibited a much higher cytotoxicity in melanoma cells in comparison to a keratinocyte cell line. The detection of intracellular reactive oxygen species (ROS) produced by H2RuTPyP through the DCF-DA assay also suggests that ROS have a minor role in the induction of cytotoxicity. Therefore, H2RuTPyP seems to be a very effective photosensitizer, representing a promising alternative for the development of new skin cancer treatments using PDT process.