Neuroprotective Effects of Guarana (Paullinia cupana Mart.) against Vincristine in Vitro Exposure.

BACKGROUND: Vincristine (VCR) is not a specific chemotherapeutic drug, responsible for cause several side effects. In this sense, many natural products have been studied to reduce this problem. Objetives: To examine the guarana neuroprotective effect in mice brain and cerebellum cells against vincristine (VCR) exposition. DESIGN: An in vitro study was performed using mice brain and cerebellum mice in monolayer culture. First, cells were exposed to VCR (0.009 µM for 24 hours and 0.0007 µM for 72 hours) to measure the cytotoxicity effect. Also, the cellular effect of hydroalcoholic extract of guarana (10; 30; 100 and 300 µg/mL) was evaluated in the same cells in 24 and 72 hours. After that, cells were exposed to VCR and guarana extract to evaluate the neuroprotective effect of guarana. MEASUREMENTS: Cell viability was analyzed by MTT, Free dsDNA and LHD Assays. Moreover, metabolism oxidative profile was evaluated by reactive oxygen species (ROS), lipoperoxidation (LPO) and catalase (CAT) levels through DCFH-DA, TBARS and Catalase Activity Assays, respectively. RESULTS: Our findings revealed that VCR caused neuronal cytotoxicity by reducing cell viability and increasing ROS and LPO levels. On the other hand, guarana did not cause cell damage in none of tested concentrations. In addition, guarana exhibited a notable protective effect on brain and cerebellum cells exposed to VCR by increasing cell viability, stimulating CAT activity, reducing levels of ROS and LPO. CONCLUSIONS: In this sense, guaraná is a remarkable antioxidant fruit that could be a target in new therapies development to reduce VCR neurotoxicity. .

Induction of cytotoxicity, oxidative stress and genotoxicity by root filling pastes used in primary teeth.

AIM: To evaluate the cytotoxicity, oxidative stress and genotoxicity in vitro of four iodoform pastes and three calcium hydroxide pastes. METHODOLOGY: Peripheral blood mononuclear cells (PBMCs) and pure calf thymus DNA (dsDNA) were exposed to extracts of the pastes. Cytotoxicity was assessed with the MTT assay. Generation of reactive oxygen species (ROS) was evaluated using a DCFH-DA assay, and lipid peroxidation was evaluated using a TBARS assay. Genotoxicity was evaluated using the alkaline comet assay and Genomodifier capacity assay (GEMO). All tests were performed after 24 h and 72 h of cell exposure, except GEMO. After performing the Kolmogorov-Smirnov test, data were analysed by Kruskal-Wallis and Dunn's post-tests, and anova with Dunnett's post-test, with a significance level established at P < 0.05. RESULTS: The MTT assay revealed that chlorhexidine, Maxitrol and neomycin sulphate + bacitracin pastes decreased cell viability after 24 h (P < 0.05). No group was associated with a significant decreased cell viability or lipid peroxidation after 72 h. Calcium hydroxide pastes increased the cell viability levels at both experimental times (P < 0.05). Lipid peroxidation was observed with the exposure of cells to calcium hydroxide pastes after 24 h (P < 0.05). Exposure to chlorhexidine, Guedes-Pinto and calcium hydroxide pastes resulted in a significant increase in ROS after 24 h (P < 0.05), whereas iodoform pastes and Calen thickened with zinc oxide significantly increased the ROS after 72 h (P < 0.05). The comet assay revealed that exposure of the PBMCs to iodoform pastes did not damage DNA at either period of time (P > 0.05). However, chlorhexidine paste caused DNA damage in dsDNA (P < 0.05). Calcium hydroxide pastes caused DNA damage in both tests (P < 0.05). CONCLUSION: The pastes varied in their ability to induce cytotoxicity, genotoxicity and oxidative stress. In general, Guedes-Pinto, Maxitrol and neomycin sulphate + bacitracin pastes exhibited better biocompatibility in vitro.

Toxicity of irrigating solutions and pharmacological associations used in pulpectomy of primary teeth.

AIM: To evaluate the in vitro toxicity of irrigating solutions and pharmacological associations used in the pulpectomy of primary teeth. METHODOLOGY: The cell viability (MTT), lipid peroxidation (TBARS), alkaline comet assay and GEMO tests were performed to evaluate the cytotoxicity and genotoxicity of solutions: sodium hypochlorite (1% and 2.5%), 2% chlorhexidine, 6% citric acid and 17% EDTA, which were tested, individually and in association, exposing human peripheral blood mononuclear cells (MTT, TBARS and alkaline comet assay), at 24 and 72 h, and dsDNA (GEMO). After performing the Kolmogorov-Smirnov test, data were analysed by anova followed by Dunnett's post hoc test, and Kruskal-Wallis followed by Dunn post hoc test. A significance level was established at P < 0.05. RESULTS: All irrigating solutions and pharmacological associations reduced cell viability at 24 h (P < 0.05). These reductions were maintained after 72 h, except for EDTA and associations of sodium hypochlorite (1% and 2.5%) with EDTA and of chlorhexidine with EDTA. Lipid peroxidation at 24 h was caused by EDTA and by 2.5% sodium hypochlorite with EDTA; it was also caused at 72 h by sodium hypochlorite (1% and 2.5%) and the three associations with citric acid (P < 0.05). All groups caused DNA damage when assessed by the alkaline comet assay, at 24 h and 72 h (P < 0.05). In the GEMO assay, all groups caused dsDNA damage (P < 0.05), except for chlorhexidine with EDTA. CONCLUSION: All groups showed some level of toxicity. Amongst the main solutions, chlorhexidine presented less cytotoxic potential. EDTA was the least cytotoxic of the auxiliary irrigant solutions, and the association of these two solutions showed the lowest toxicity potential amongst all groups.

Hypercholesterolemia and Ecto-enzymes of Purinergic System: Effects of Paullinia cupana.

Hypercholesterolemia is a metabolic disorder characterized by high levels of low-density lipoprotein and blood cholesterol, causing inflammatory lesion. Purinergic signaling modulates the inflammatory and immune responses through adenine nucleotides and nucleoside. Guaraná has hypocholesterolemic and antiinflammatory properties. Considering that there are few studies demonstrating the effects of guaraná powder on the metabolism of adenine nucleotides, we investigated its effects on the activity of ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) and ecto-adenosine deaminase activity in lymphocytes of rats with diet-induced hypercholesterolemia. The rats were divided into hypercholesterolemic and normal diet groups. Each group was subdivided by treatment: saline, guaraná powder 12.5, 25, or 50 mg/kg/day and caffeine concentration equivalent to highest dose of guaraná, fed orally for 30 days. An increase in adenosine triphosphate hydrolysis was observed in the lymphocytes of rats with hypercholesterolemia and treated with 25 or 50 mg/kg/day when compared with the other groups. The hypercholesterolemic group treated with the highest concentration of guaraná powder showed decreased ecto-adenosine deaminase activity compared with the normal diet groups. Guaraná was able to reduce the total cholesterol and low-density lipoprotein cholesterol to basal levels in hypercholesterolemic rats. High concentrations of guaraná associated with a hypercholesterolemic diet are likely to have contributed to the reduction of the inflammatory process.

Cytoprotective and genoprotective effects of ß-glucans against aflatoxin B1-induced DNA damage in broiler chicken lymphocytes.

The polysaccharide ß-glucan presents beneficial effects on the immune system, although the mechanisms of the immunomodulatory effect remain poorly understood. The potential cytoprotective and genoprotective effects of ß-glucans were evaluated in broiler chicken lymphocytes exposed to increasing concentrations of aflatoxin B1 (AFB1) and/or ß-glucans. AFB1 significantly decreased cell viability at the concentrations of 10 and 20 µg/ml at 72 h of incubation (p<0.01 and p<0.001, respectively). Moreover, the AFB1 concentrations of 1, 10 and 20 µg/ml increased DNA fragmentation levels at 24 h (p<0.001). Conversely, lymphocyte death was prevented by ß-glucans at the concentrations of 1% and 10%, indicating a cytoprotective effect. Reactive oxygen species levels were increased in the cells treated with 20 µg/ml AFB1 at 24 h (p<0.05) and 10% ß-glucans with or without AFB1 at 24, 48 and 72 h of incubation (p<0.001). DNA damage increased by more than 100% in AFB1-treated lymphocytes when compared to control group. ß-glucans at 1% was able to fully revert the AFB1-induced lymphocyte DNA damage, indicating a genoprotective effect and maintaining DNA integrity. In conclusion, ß-glucans showed in vitro dose-dependent cytoprotective and genoprotective effects in broiler chicken lymphocytes exposed to AFB1.

Thioredoxin reductase-dependent inhibition of MCB cell cycle box activity in Saccharomyces cerevisiae.

Mlu1 cell cycle box (MCB) elements are found near the start site of yeast genes expressed at G1/S. Basal promoters dependent on the elements for upstream activating sequence activity are inactive in Deltaswi6 yeast. Yeast were screened for mutations that activated MCB reporter genes in the absence of Swi6. The mutations identified a single complementation group. Functional cloning revealed the mutations were alleles of the TRR1 gene encoding thioredoxin reductase. Although deletion of TRR1 activated MCB reporter genes, high copy expression did not suppress reporter gene activity. The trr1 mutations strongly (20-fold) stimulated MCB- and SCB (Swi4/Swi6 cell cycle box)-containing reporter genes, but also weakly (3-fold) stimulated reporter genes that lacked these elements. The trr1 mutations did not affect the level or periodicity of three endogenous MCB gene mRNAs (TMP1, RNR1, and SWI4). Deletion of thioredoxin genes TRX1 and TRX2 recapitulated the stimulatory effect of trr1 mutations on MCB reporter gene activity. Conditions expected to oxidize thioredoxin (exposure to H2O2) induced MCB gene expression, whereas conditions expected to conserve thioredoxin (exposure to hydroxyurea) inhibited MCB gene expression. The results suggest that thioredoxin oxidation contributes to MCB element activation and suggest a link between thioredoxin-oxidizing processes such as ribonucleotide reduction and cell cycle-specific gene transcription.