Yerba mate (Ilex paraguariensis) is rich in several bioactive compounds that can act as free radical scavengers. Since oxidative DNA damage is involved in various pathological states such as cancer, ...the aim of this study was to evaluate the antioxidant activity of mate tea as well as the ability to influence DNA repair in male Swiss mice. Forty animals were randomly assigned to four groups. The animals received three different doses of mate tea aqueous extract, 0.5, 1.0 or 2.0 g/kg, for 60 days. After intervention, the liver, kidney and bladder cells were isolated and the DNA damage induced by H2O2 was investigated by the comet assay. The DNA repair process was also investigated for its potential to protect the cells from damage by the same methodology. The data presented here show that mate tea is not genotoxic in liver, kidney and bladder cells. The regular ingestion of mate tea increased the resistance of DNA to H2O2-induced DNA strand breaks and improved the DNA repair after H2O2 challenge in liver cells, irrespective of the dose ingested. These results suggest that mate tea could protect against DNA damage and enhance the DNA repair activity. Protection may be afforded by the antioxidant activity of the mate tea's bioactive compounds.
•Ginkgo biloba extract improves short-term memory in a discriminative avoidance task.•Ginkgo biloba has protective and restorative properties in the prefrontal cortex.•The decrease of ...oxidative-stress-related cell death might be related to memory and neuronal survival.
This study assessed the effects of chronic treatment with a standardized extract of Ginkgo biloba L. (EGb) on short-term and long-term memory as well as on anxiety-like and locomotor activity using the plus-maze discriminative avoidance task (PM-DAT). Additionally, we evaluated the antioxidant and neuroprotective effects of EGb on the prefrontal cortex (PFC) and dorsal hippocampus (DH) of middle-aged rats using the comet assay. Twelve-month-old male Wistar rats were administered vehicle or EGb (0.5mgkg−1 or 1.0gkg−1) for 30days. Behavioural data showed that EGb treatment improved short-term memory. Neither an anti-anxiety effect nor a change in locomotor activity was observed. Twenty-four hours after the behavioural tests, the rats were decapitated, and the PFC and DH were quickly dissected out and prepared for the comet assay. The levels of DNA damage in the PFC were significantly lower in rats that were treated with 1.0gkg−1 EGb. Both doses of EGb decreased H2O2-induced DNA breakage in cortical cells, whereas the levels of DNA damage in the EGb-treated animals were significantly lower than those in the control animals. No significant differences in the level of DNA damage in hippocampal cells were observed among the experimental groups. EGb treatment was not able to reduce H2O2-induced DNA damage in hippocampal cells. Altogether, our data provide the first demonstration that chronic EGb treatment improved the short-term memory of middle-aged rats, an effect that could be associated with a reduction in free radical production in the PFC. These data suggest that EGb treatment might increase the survival of cortical neurons and corroborate and extend the view that EGb has protective and therapeutic properties.
An increasing number of evidences suggest the involvement of the eukaryotic elongation factor 1A, a core component of the protein synthesis machinery, at the onset of cell transformation. In fact, ...eEF1A is shown to be up-regulated in cell death; moreover, it seems to be involved in the regulation of ubiquitin-mediated protein degradation. In addition, eEF1A undergoes several post-translational modifications, mainly phosphorylation and methylation, that generally influence the activity of the protein. This article summarizes the present knowledges on the several extra-translational roles of eEF1A also in order to understand as the protein synthesis regulatory mechanisms could offer tools for cancer intervention.
Leaves of
Ilex paraguariensis
are used to prepare a tea known as maté which is a common beverage in several South American countries. The ethanol extract was fractionated to identify the compounds ...responsible for the anti-adipogenic activity in 3T3-L1 cells. Extracts of both fresh and dried maté leaves were subjected to column chromatography using molecular permeation to obtain the saponin (20 % yields) and the polyphenol extracts (40 % yields) from the fresh and dried leaves. The phenolic content was determined using high-performance liquid chromatography analysis and the Folin-Ciocalteau method. Also, maté extracts (50 μg/ml to 1,000 μg/ml) did not display citotoxicity using MTT. The polyphenol extract from the dried leaves was the most effective (50 μg/ml) in the inhibition of triglyceride accumulation in 3T3-L1 adipocytes, and rutin (100 μg/ml) likely accounted for a large portion of this activity. Additionally, maté extracts had a modulatory effect on the expression of genes related to the adipogenesis as PPARγ2, leptin, TNF-α and C/EBPα.
We identified eukaryotic translation elongation factor 1A (eEF1A) Raf-mediated phosphorylation sites and defined their role in the regulation of eEF1A half-life and of apoptosis of human cancer ...cells. Mass spectrometry identified in vitro S21 and T88 as phosphorylation sites mediated by B-Raf but not C-Raf on eEF1A1 whereas S21 was phosphorylated on eEF1A2 by both B- and C-Raf. Interestingly, S21 belongs to the first eEF1A GTP/GDP-binding consensus sequence. Phosphorylation of S21 was strongly enhanced when both eEF1A isoforms were preincubated prior the assay with C-Raf, suggesting that the eEF1A isoforms can heterodimerize thus increasing the accessibility of S21 to the phosphate. Overexpression of eEF1A1 in COS 7 cells confirmed the phosphorylation of T88 also in vivo. Compared with wt, in COS 7 cells overexpressed phosphodeficient (A) and phospho-mimicking (D) mutants of eEF1A1 (S21A/D and T88A/D) and of eEF1A2 (S21A/D), resulted less stable and more rapidly proteasome degraded. Transfection of S21 A/D eEF1A mutants in H1355 cells increased apoptosis in comparison with the wt isoforms. It indicates that the blockage of S21 interferes with or even supports C-Raf induced apoptosis rather than cell survival. Raf-mediated regulation of this site could be a crucial mechanism involved in the functional switching of eEF1A between its role in protein biosynthesis and its participation in other cellular processes.
Interferon alpha (IFNalpha) induces both apoptosis and a counteracting epidermal growth factor Erk-dependent survival response in cancer cells. In this report, IFNalpha increased eukaryotic ...elongation factor 1A (eEF-1A) protein expression by inhibition of eEF-1A degradation via a proteasome-dependent pathway. The reduction of the expression level of eEF-1A by RNA interference enhanced the apoptosis induced by IFNalpha on the same cells. Moreover, IFNalpha induced the phosphorylation of both serine and threonine in eEF-1A. These effects were paralleled by an increased co-immunoprecipitation and colocalization of eEF-1A with C-Raf. The suppression of C-Raf kinase activity with the inhibitor BAY 43-9006 completely antagonized the increase of both eEF-1A phosphorylation and expression and of C-Raf/eEF-1A colocalization induced by IFNalpha and enhanced apoptosis and eEF-1A ubiquitination. Cell transfection with the mutated K48R ubiquitin increased EF-1A expression and desensitized tumor cells to the modulating effects of IFNalpha. The dynamic simulation of 3Dstructure of eEF-1A identified putative serine and threonine phosphorylation sites. In conclusion, the interaction between eEF-1A and C-Raf increases eEF-1A stability and induces a survival activity.
The aim of the present study was to evaluate the effects of yerba maté extract upon markers of insulin resistance and inflammatory markers in mice with high fat diet-induced obesity. The mice were ...introduced to either standard or high fat diets. After 12 weeks on a high fat diet, mice were randomly assigned to one of the two treatment conditions, water or yerba maté extract at 1.0gkg−1. After treatment, glucose blood level and hepatic and soleus muscle insulin response were evaluated. Serum levels of TNF-α and IL-6 were evaluated by ELISA, liver tissue was examined to determine the mRNA levels of TNF-α, IL-6 and iNOS, and the nuclear translocation of NF-κB was determined by an electrophoretic mobility shift assay. Our data show improvements in both the basal glucose blood levels and in the response to insulin administration in the treated animals. The molecular analysis of insulin signalling revealed a restoration of hepatic and muscle insulin substrate receptor (IRS)-1 and AKT phosphorylation. Our data show that the high fat diet caused an up-regulation of the TNF-α, IL-6, and iNOS genes. Although after intervention with yerba maté extract the expression levels of those genes returned to baseline through the NF-κB pathway, these results could also be secondary to the weight loss observed. In conclusion, our results indicate that yerba maté has a potential anti-inflammatory effect. Additionally, these data demonstrate that yerba maté inhibits hepatic and muscle TNF-α and restores hepatic insulin signalling in mice with high fat diet-induced obesity.
Yerba maté (Ilex paraguariensis) is rich in polyphenols, especially chlorogenic acids. Evidence suggests that dietary polyphenols could play a role in glucose absorption and metabolism. The aim of ...this study was to evaluate the antidiabetic properties of yerba maté extract in alloxan-induced diabetic Wistar rats. Animals (n = 41) were divided in four groups: nondiabetic control (NDC, n = 10), nondiabetic yerba maté (NDY, n = 10), diabetic control (DC, n = 11), and diabetic yerba maté (DY, n = 10). The intervention consisted in the administration of yerba maté extract in a 1 g extract/kg body weight dose for 28 days; controls received saline solution only. There were no significant differences in serum glucose, insulin, and hepatic glucose-6-phosphatase activity between the groups that ingested yerba maté extract (NDY and DY) and the controls (NDC and DC). However, the intestinal SGLT1 gene expression was significantly lower in animals that received yerba maté both in upper (p = 0.007) and middle (p < 0.001) small intestine. These results indicate that bioactive compounds present in yerba maté might be capable of interfering in glucose absorption, by decreasing SGLT1 expression.
Abstract Background To understand the molecular changes underlying Helicobacter pylori -related gastric diseases is mandatory to prevent gastric cancer. Proteomic technology is providing a rapid ...expansion of the basic knowledge, particularly in the discovery of new biomarkers involved in the tumourigenesis. Aim To characterise changes in protein expression level of the gastric mucosa in H. pylori -infected patients. Methods The population enrolled comprised 41 dyspeptic patients. Proteins extracted from gastric mucosal specimens were analysed by 2-dimensional electrophoresis, sequenced by MALDI-TOF and identified by Edman's degradation. Results Twenty-one out of 41 patients had H. pylori infection of whom 17 had anti-CagA IgG antibodies. Several proteins were identified, of which Rho guanosine diphosphatase dissociation inhibitor α and heat shock protein 27 increased and glutathione transferase and antrum mucosa protein-18 decreased in H. pylori- positive in respect to H. pylori- negative patients. Interestingly, antrum mucosa protein-18, currently referred as gastrokine-1, showed two isoforms differing in the first N-terminal amino acid residue. Both gastrokine-1 isoforms were observed in the H. pylori -negative group whereas a lower expression or even absence of the gastrokine-1 basic isoform was found in a subgroup (7/21) of H. pylori -positive patients with moderate–severe gastritis. Conclusion Our study demonstrated the presence of gastrokine-1 isoforms of which the basic isoform was reduced in a subset of patients with H. pylori infection.
A thioredoxin reductase (TrxR) has been identified in the hyperthermophilic archaeon
Sulfolobus solfataricus (
Ss). This enzyme is a homodimeric flavoprotein that was previously identified as NADH ...oxidase in the same micro-organism (‘Biotechnol. Appl. Biochem. 23 (1996) 47’). The primary structure of
SsTrxR is made of 323 amino acid residues and contains two putative βαβ regions for the binding of FAD, and a NADP(H) binding consensus sequence in the proximity of a CXXC motif. These findings indicate that
SsTrxR is structurally related to the class II of the pyridine nucleotide-disulphide oxidoreductases family. Moreover, the enzyme exhibits a NADP(H) dependent thioredoxin reductase activity requiring the presence of FAD. Surprisingly, the reductase activity of
SsTrxR is reduced in the presence of a specific inhibitor of mammalian TrxR. This finding demonstrates that the archaeal enzyme, although structurally related to eubacterial TrxR, is functionally closer to eukaryal enzymes. Experimental evidences indicate that a disulphide bridge is required for the reductase but also for the NADH oxidase activity of the enzyme. These results are further supported by the significantly reduced activities exerted by the C147A mutant. The integrity of the CXXC motif is also involved in the stability of the enzyme.
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