Eliane Fialho

Resveratrol chemosensitizes breast cancer cells to melphalan by cell cycle arrest.

Melphalan (MEL) is a chemotherapeutic agent used in breast cancer therapy; however, MELs side effects limit its clinical applications. In the last 20 years, resveratrol (RSV), a polyphenol found in grape skins, has been proposed to reduce the risk of cancer development. The aim of this study was to investigate whether RSV would be able to enhance the antitumor effects of MEL in MCF‐7 and MDA‐MB‐231 cells. RSV potentiated the cytotoxic effects of MEL in human breast cancer cells. This finding was related to the ability of RSV to sensitize MCF‐7 cells to MEL‐induced apoptosis. The sensitization by RSV involved the enhancement of p53 levels, the decrease of procaspase 8 and the activation of caspases 7 and 9. Another proposed mechanism for the chemosensitization effect of MCF‐7 cells to MEL by RSV was the cell cycle arrest in the S phase. The treatment with RSV or MEL increased the levels of p‐Chk2. The increase became pronounced in the combined treatments of the compounds. The expression of cyclin A was decreased by treatment with RSV and by the combination of RSV with MEL. While the levels of cyclin dependent kinase 2 (CDK2) remained unchanged by treatments, its active form (Thr160‐phosphorylated CDK2) was decreased by treatment with RSV and by the combination of RSV with MEL. The activity of CDK7, kinase that phosphorylates CDK2 at Thr160, was inhibited by RSV and by the combination of RSV with MEL. These results indicate that RSV could be used as an adjuvant agent during breast cancer therapy with MEL. J. Cell. Biochem. 113: 2586–2596, 2012.

Cellular antioxidant activity of feijoada whole meal coupled with an in vitro digestion.

Consumption of plant food rich meals, such as feijoada, a traditional meal in Brazil, is associated with the reduction of chronic disease. The objectives of this study were to determine phytochemical content and antioxidant activity by chemical and cellular antioxidant assays (CAA) of feijoada with or without in vitro digestion. Feijoada showed no difference in phenolics and flavonoids after digestion. Bound and residue contributions to total phenolics were 20.9% and 32.2%, respectively, suggesting that phenolics reach the colon after intake. Flavonoids in residue and bound fractions represented 50% of total flavonoids. Antioxidant activity of feijoada without digestion was higher than that with digestion; however, it showed lower antiproliferative activity and CAA. Feijoada with in vitro digestion also yielded phenolics with higher CAA. Analyses of whole meals should be used to evaluate phytochemicals present in food mixtures consumed, especially with digestion models coupled with CAA resulting in information similar to those in physiological conditions.

Effect of high hydrostatic pressure on phenolic compounds, ascorbic acid and antioxidant activity in cashew apple juice

The cashew apple is native to Brazil, but there is insufficient information regarding the nutritional properties of this fruit. The objective of this study was to evaluate the impact of high pressure processing (HPP) at room temperature (25 °C) on phenolic compound and ascorbic acid contents and antioxidant capacity of cashew apple juice. This study showed that HPP at 250 or 400 MPa for 3, 5 and 7 min did not change pH, acidity, total soluble solids, ascorbic acid or hydrolysable polyphenol contents. However, juice pressurized for 3 and 5 min showed higher soluble polyphenol contents. Antioxidant capacity, measured by the ferric-reducing antioxidant power method, was not altered by HPP, but when treated at 250 MPa for 3 min, it resulted in an increased value when 2,2-diphenyl-1-picrylhydrazyl was used. These data demonstrate that HPP can be used in the food industry for the generation of products with higher nutritional quality.

Oocyte fertilization triggers acid phosphatase activity during Rhodnius prolixus embryogenesis

Acid phosphatase activity, previously identified in Rhodnius prolixus oocytes, was studied during egg development. Fertilized eggs exhibited a five fold increase of total acid phosphatase activity during the first days of development. In contrast non-fertilized oviposited eggs showed no activation of this enzyme. An optimum pH of 4.0 for pNPP hydrolysis in a saturable linear reaction and a strong inhibition by lysosomal acid phosphatase inhibitors such as NaF (10 mM) and Na(+)/K(+) tartrate (0.5 mM) are the major biochemical properties of this enzyme. Fractionation of egg homogenates through gel filtration chromatography revealed a single peak of activity with a molecular mass of 94 kDa. The role of this enzyme in VT dephosphorylation was next evaluated. Western blots probed with anti-phosphoserine polyclonal antibody demonstrated that VT phosphoaminoacid content decreases during egg development. In vivo dephosphorylation during egg development was confirmed by following the removal of (32)P from (32)P-VT in metabolically labeled eggs. Vitellin was the only phosphorylated molecule able to inhibit pNPPase activity of partially purified acid phosphatase. These data indicate that acid phosphatase activation follows oocyte fertilization and this enzyme seems to be involved in VT dephosphorylation.

Isolation of a Calcium-binding Phosphoprotein from the Oocytes and Hemolymph of the Blood-sucking Insect Rhodnius prolixus

A novel calcium-binding phosphoprotein was isolated from the oocytes of the blood-sucking bug Rhodnius prolixus. This protein exhibits an apparent molecular mass of 18 kDa on gel filtration, but migrates as an 8-kDa band on N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine/SDS-polyacrylamide gels. It has a high content of serine (24% of the total number of residues), and phosphoserine is the sole amino acid phosphorylated in vivo. A similar protein was partially purified from the hemolymph. It resembles the oocyte form of the protein in its NH2-terminal sequence and its ability to be taken up by growing ovaries. 45Ca binding to the oocyte phosphoprotein was determined after SDS-polyacrylamide gel electrophoresis followed by blotting on nitrocellulose membranes. Titration of Ca2+-binding sites shows a high capacity (≅50 mol/mol of protein), but a low affinity (K0.5 ≅ 10−3 M). Based on these characteristics, we have named this protein Rhodnius calcium-binding phosphoprotein. It resembles phosvitin, a phosphoprotein present in the oocytes of nonmammalian vertebrates.

Transient Transfection of a Wild-Type p53 Gene Triggers Resveratrol-Induced Apoptosis in Cancer Cells

Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells) cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal p53 function.

Sucos de laranja industrializados e preparados sólidos para refrescos: estabilidade química e físico-química

Fresh orange juice is considered to be one of the best sources of vitamin C. Nevertheless, hand squeezed juice is often inconvenient for consumers who seek practical and fast ways to prepare their meals. The objective of this study was to analyze the chemical and physicochemical stability of ready to drink and refreshments prepared from orange juice powder commercially available in the city of Rio de Janeiro. The ascorbic acid (AA) content, total soluble solids (TSS), total tritatable acidity (TAA) and pH were determined. The AA content of ready to drink orange juice ranged from 17.25mg% to 62.40mg (p = 0.05). In two batches the AA content was lower than that established by the Brazilian legislation. The AA content of refreshments prepared from orange juice powder ranged from 0.67mg% to 32.00mg% among samples (p = 0.05). TSS and pH values were stable, while TTA changed during the storage time. Industrialized ready to drink orange juices may be considered a source of vitamin C, whereas most of the cheaper refreshments prepared from powder orange juice are not.

Protein phosphorylation during Rhodnius prolixus embryogenesis: protein kinase casein kinase II activity

Protein kinase casein kinase II (CK II) activity was assayed during Rhodnius prolixus embryogenesis. Vitellin (VT) is the main endogenous substrate during the whole development. It is maximally phosphorylated at the third day of embryogenesis by CK II and then its phosphorylation decreases to a basal level by the time of first instar eclosion. When dephosphorylated casein was used as an exogenous substrate a different profile of enzyme activity was obtained. CK II activity increases on day 1 after fertilization and reaches a plateau on day 7 and its activity remains elevated until eclosion. Extracts obtained from oocytes or from 3-day old eggs were fractionate through gel filtration chromatography. CK II activity was assayed in each fraction and the enzyme obtained from the 3-day old eggs was shown to be three times more active than that obtained from oocytes, although the amount of enzyme present in the fractions was the same. These enriched CK II fractions were assayed against different effectors, such as: cAMP, H-8, H-89, calphostin C, sphingosine, polylysine and heparin. Heparin was the most effective one. When CK II activity was assayed in non-fertilized eggs, no activation of the enzyme was observed when compared to fertilized eggs. These data indicate that CK II is activated in a fertilization dependent process. The decrease in CK II activity against VT coincides with the beginning of VT proteolysis processing suggesting a possible relationship between protein phosphorylation and yolk degradation.

Four Conventional Soybean (Glycine max (L.) Merrill) Seeds Exhibit Different Protein Profiles As Revealed by Proteomic Analysis

Soybeans have several functional properties due to their composition and may exert beneficial health effects that are attributed to proteins and their derivative peptides. The present study aimed to analyze the protein profiles of four new conventional soybean seeds (BRS 257, BRS 258, BRS 267, and Embrapa 48) with the use of proteomic tools. Two-dimensional (2D) and one-dimensional (1D) gel electrophoreses were performed, followed by MALDI-TOF/TOF and ESI-Q-TOF mass spectrometry analyses, respectively. These two different experimental approaches allowed the identification of 117 proteins from 1D gels and 46 differentially expressed protein spots in 2D gels. BRS 267 showed the greatest diversity of identified spots in the 2D gel analyses. In the 1D gels, the major groups were storage (25-40%) and lipid metabolism (11-25%) proteins. The differences in protein composition between cultivars could indicate functional and nutritional differences and could direct the development of new cultivars.

Panorama atual dos programas de pós-graduação em Nutrição no Brasil

The aim of the present study is to describe the current profile of Brazilian graduate study programs in nutrition, based on selected indicators produced by annual reports of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior. Some descriptive data are presented for 11 programs allocated in the Medicine II committee for 2002-2004, referring to the total number of published papers, proportions of papers according to the Qualis system, and average number of international papers per permanent faculty member in nine programs. Six of 11 programs were from the Northeast and Central West regions, 4 from the Southeast, and 1 from the South. The overall evaluation for 2001-2003 showed that 2 programs received grade 5.3 and grade 4, and the other 6 grade 3. Universidade Federal de Pernambuco granted degrees to most Masters students (n= 51), while 5 programs granted degrees to 28 or more students. Only the Universidade Federal de Sao Paulo and Universidade Federal do Rio Grande do Norte Programs averaged more than 1 international paper per permanent faculty member for the period as a whole (2002-2004). In conclusion, there are still few graduate studies programs in the field of nutrition in Brazil, the existing programs are recent, and the trend towards higher standards necessarily involves a substantial increase in academic output. A significant improvement in the evaluation process is antecipated in the near future.