RESUMO
Herein, we report the synthesis of novel selenocyanates and assessment of their effect on the oxidative challenge elicited by hydrogen peroxide (H2O2) in cultured mouse neurons. First, α-methylene-ß-hydroxy esters were prepared as precursors of allylic bromides. A reaction involving the generated bromides and sodium selenocyanate was conducted to produce the desired selenocyanates (3a-f). We next prepared cultures of neurons from 7-day-old mice (n = 36). H2O2 (10-5 M) was added into the culture flasks as an oxidative stress inducer, alone or combined with one of each designed compounds. (PhSe)2 was used as a positive control. It was carried out assessment of lipid (thiobarbituric acid reactive species, 4-hydroxy-2'-nonenal, 8-isoprostane), DNA (8-hydroxy-2'-deoxyguanosine), and protein (carbonyl) modification parameters. Finally, catalase and superoxide dismutase activities were also evaluated. Among the compounds, 3b, 3d, and 3f exhibited the most pronounced pattern of antioxidant activity, similar to (PhSe)2. These novel aromatic selenocyanates could be promising to be tried in most sophisticated in vitro studies or even at the preclinical level.
Assuntos
Cianatos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Compostos de Selênio/farmacologia , 8-Hidroxi-2'-Desoxiguanosina/metabolismo , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Catalase/metabolismo , Células Cultivadas , Cianatos/síntese química , Peróxido de Hidrogênio/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Neurônios/citologia , Neurônios/metabolismo , Compostos de Selênio/síntese química , Superóxido Dismutase/metabolismoRESUMO
Cadmium (Cd) toxicity is a concern to the tobacco-smoking sub-population which includes millions of people worldwide. Although this metal may cause severe damage to embryos and the reproductive organs, the precise mechanisms underlying its toxicity remain unclear. In the present study, the Cd effect on ovary δ-aminolevulinate dehydratase (δ-ALA-D) activity was investigated in vitro and ex vivo. We observed that low concentrations of Cd inhibited cow ovary δ-ALA-D activity in vitro and the IC50 value obtained was 19.17 µM. Furthermore, the protective effect of a novel organic selenium compound (seleno-furanoside) in restoring enzyme activity was evaluated. Seleno-furanoside (10, 50, 100, 200, 400 and 1000 µM) did not reverse the Cd toxicity in bovine ovarian tissue in vitro. According to the in vitro reults, acute Cd exposure (2.5 and 5 mg kg(-1)) caused a significant inhibition in ovary δ-ALA-D activity in mice (around 27% and 34%, respectively). Therapy with seleno-furanoside (100 µmol kg(-1)) was able to restore enzyme activity. Thus, we demonstrated for the first time that δ-ALA-D activity from ovary is inhibited by Cd both in vitro and ex vivo. Additionally, seleno-furanoside therapy was effective in restoring ovarian enzyme activity inhibited by Cd exposure in mice, but it did not reverse the in vitro metal effect. This study detected a new toxicity marker of Cd toxicity on ovarian tissue as well as the beneficial effect of a new compound to manage the metal effect after acute exposure.
Assuntos
Antioxidantes/farmacologia , Cloreto de Cádmio/antagonistas & inibidores , Cloreto de Cádmio/toxicidade , Poluentes Ambientais/antagonistas & inibidores , Poluentes Ambientais/toxicidade , Compostos Organosselênicos/farmacologia , Ovário/enzimologia , Pentoses/farmacologia , Sintase do Porfobilinogênio/biossíntese , Animais , Bovinos , Relação Dose-Resposta a Droga , Feminino , Camundongos , Oxirredução , Sintase do Porfobilinogênio/antagonistas & inibidores , Biossíntese de Proteínas/efeitos dos fármacosRESUMO
The synthesis of seleno-galactopyranosides in a short and efficient manner is described, starting from the parent carbohydrate d-galactose. The approach described allows the synthesis of small libraries of compounds with a number of structural variations at the group attached to selenium. Compounds with aryl, propargyl, allyl, acyl, and alkyl substituents are described.
Assuntos
Galactose/química , Compostos Organosselênicos/síntese química , Selênio/química , Configuração de Carboidratos , Sequência de Carboidratos , Compostos Organosselênicos/química , EstereoisomerismoRESUMO
Plants of the genus Polygala have been shown to possess protective effects against neuronal death and cognitive impairments in neurodegenerative disorders related to excitotoxicity. Moreover, previous reports from our group have shown the neuroprotective effects of the plant Polygala paniculata against methylmercury (MeHg)-induced neurotoxicity. In this work, we have examined the potential protective effects of three compounds (7-prenyloxy-6-methoxycoumarin, quercetin, and 1,5-dihidroxi-2,3-dimethoxy xanthone) from Polygala species against MeHg- and mercuric chloride (HgCl2)-induced disruption of mitochondrial function under in vitro conditions using mitochondrial-enriched fractions from mouse brain. MeHg and HgCl2 (10-100 microM) significantly decreased mitochondrial viability; this phenomenon was positively correlated to mercurial-induced glutathione oxidation. Among the isolated compounds, only quercetin (100-300 microM) prevented mercurial-induced disruption of mitochondrial viability. Moreover, quercetin, which did not display any chelating effect on MeHg or HgCl2, prevented mercurial-induced glutathione oxidation. The present results suggest that the protective effects of quercetin against mercurial-induced mitochondrial dysfunction is related to the removal of oxidant species generated in the presence of either MeHg or HgCl2. Reinforcing this hypothesis, MeHg and HgCl2 increased the production of hydrogen peroxide in the brain mitochondria, as well as the levels of malondialdehyde. These oxidative phenomena were prevented by co-incubation with quercetin or catalase. These results are the first to show the involvement of hydrogen peroxide as a crucial molecule related to the toxic effects of both organic and inorganic mercurials in brain mitochondria. In addition, the study is the first to show the protective effect of quercetin against mercurial-induced toxicity, pointing to its capability to counteract mercurial-dependent hydrogen peroxide generation as a potential molecular mechanism of protection. Taken together, these data render quercetin a promising molecule for pharmacological studies with respects to mercurials' poisoning.