Giuseppina Pace Pereira Lima

Exercise and oxidative stress: Potential effects of antioxidant dietary strategies in sports

Free radicals are produced during aerobic cellular metabolism and have key roles as regulatory mediators in signaling processes. Oxidative stress reflects an imbalance between production of reactive oxygen species and an adequate antioxidant defense. This adverse condition may lead to cellular and tissue damage of components, and is involved in different physiopathological states, including aging, exercise, inflammatory, cardiovascular and neurodegenerative diseases, and cancer. In particular, the relationship between exercise and oxidative stress is extremely complex, depending on the mode, intensity, and duration of exercise. Regular moderate training appears beneficial for oxidative stress and health. Conversely, acute exercise leads to increased oxidative stress, although this same stimulus is necessary to allow an up-regulation in endogenous antioxidant defenses (hormesis). Supporting endogenous defenses with additional oral antioxidant supplementation may represent a suitable noninvasive tool for preventing or reducing oxidative stress during training. However, excess of exogenous antioxidants may have detrimental effects on health and performance. Whole foods, rather than capsules, contain antioxidants in natural ratios and proportions, which may act in synergy to optimize the antioxidant effect. Thus, an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain an optimal antioxidant status. Antioxidant supplementation may be warranted in particular conditions, when athletes are exposed to high oxidative stress or fail to meet dietary antioxidant requirements. Aim of this review is to discuss the evidence on the relationship between exercise and oxidative stress, and the potential effects of dietary strategies in athletes. The differences between diet and exogenous supplementation as well as available tools to estimate effectiveness of antioxidant intake are also reported. Finally, we advocate the need to adopt an individualized diet for each athlete performing a specific sport or in a specific period of training, clinically supervised with inclusion of blood analysis and physiological tests, in a comprehensive nutritional assessment.

POLIAMINAS E ATIVIDADE DA PEROXIDASE EM FEIJÃO (Phaseolus vulgaris L.) CULTIVADO SOB ESTRESSE SALINO

Putrescine, spermidine and spermine contents and peroxidase activity (EC 1.11.1.7) were determined in plants of Phaseolus vulgaris L. cv Carioquinha submitted to saline stress (50 and 100 mM NaCl). Changes were observed in polyamine contents, mainly in putrescine. Increase in peroxidase activity also occurred with NaCl concentration, for both concentrations used. The results showed alterations in the polyamines contents and peroxidase activity in plants of Phaseolus vulgaris grown under salinity.

A Magnetically Drivable Nanovehicle for Curcumin with Antioxidant Capacity and MRI Relaxation Properties

Curcumin possesses wide-ranging anti-inflammatory and anti-cancer properties and its biological activity can be linked to its potent antioxidant capacity. Superparamagnetic maghemite (γ-Fe2 O3 ), called surface-active maghemite nanoparticles (SAMNs) were surface-modified with curcumin molecules, due to the presence of under-coordinated Fe(III) atoms on the nanoparticle surface. The so-obtained curcumin-modified SAMNs (SAMN@curcumin) had a mean size of 13±4 nm. SAMN@curcumin was characterized by transmission and scanning electron microscopy, UV/Vis, FTIR, and Mössbauer spectroscopy, X-ray powder diffraction, bulk susceptibility (SQUID), and relaxometry measurements (MRI imaging). The high negative contrast proclivity of SAMN@curcumin to act as potential contrast agent in MRI screenings was also tested. Moreover, the redox properties of bound curcumin were probed by electrochemistry. SAMN@curcumin was studied in the presence of different electroactive molecules, namely hydroquinone, NADH and ferrocyanide, to assess its redox behavior. Finally, SAMN@curcumin was electrochemically probed in the presence of hydrogen peroxide, demonstrating the stability and reactivity of bound curcumin.

Ineficiência de acibenzolar-S-methyl na indução de resistência de feijoeiro comum à murcha-de-Curtobacterium

O efeito da inducao de resistencia promovido por acibenzolar-S-methyl foi avaliado em tres cultivares de feijoeiro (Phaseolus vulgaris), com diferentes niveis de resistencia a murcha-de-Curtobacterium, em dois ensaios distintos, sob condicoes de casa de vegetacao. O primeiro ensaio visou avaliar a acao do acibenzolar-S-methyl na inducao de resistencia a murcha-de-Curtobacterium e o segundo, objetivou avaliar a acao deste produto na atividade das enzimas peroxidase e polifenoloxidase e no nivel de proteinas totais soluveis, em amostras de folhas e caule, sem inoculacao do patogeno. Em ambos os ensaios o indutor foi pulverizado na dosagem de 100 µg i.a./ml, cinco dias apos o transplante das plantas para vasos. O acibenzolar-S-methyl foi ineficiente, tanto para controlar a doenca na cultivar suscetivel (IAC Carioca), quanto para incrementar os niveis de resistencia das cultivares resistentes (IAC Carioca Akyta e IAC Carioca Pyata). A peroxidase apresentou maior atividade nas plantas pulverizadas com o indutor, tanto na folha, como no caule. A polifenoloxidase mostrou maior atividade apenas no caule das plantas pulverizadas. O nivel de proteinas totais soluveis foi maior no caule das plantas pulverizadas do que nas nao-pulverizadas, porem nao diferiu na folha. As enzimas e proteinas avaliadas apresentaram maiores niveis na folha do que no caule das plantas de feijoeiro avaliadas.

Analysis of tolerance to copper and zinc in Aechmea blanchetiana grown in vitro

The aim of this study was to evaluate the growth and development of Aechmea blanchetiana Baker L.B. Sm. in vitro on medium with 0.0, 0.145, 1.45 and 14.5 μM Cu and 0.0, 2.75, 27.5 and 275 μM Zn. Significant accumulation of Cu and Zn occurred at 14.5 μM Cu and 27.5 and 275 μM Zn, respectively, and there were no significant changes in contents of the other macro- and micronutrients. Superoxide dismutase (SOD) activity significantly changed in the presence of both metals. Spermine content increased as Zn concentration increased and decreased with increasing concentrations of Cu. There was an accumulation of H2O2 in the leaf tissue of plants grown in 1.45 and 14.5 μM Cu and 27.5 and 275 μM Zn. A. blanchetiana was found tolerant to the Cu and Zn in concentrations used in this study and displays the capacity to accumulate these metals.

Relationship Among Phenolic Contents, Seed Predation, and Physical Seed Traits in Mimosa bimucronata Plants

Phenolic contents were compared between Mimosa bimucronata seeds from infested and non-infested fruits to assess induced defense response. By measuring leg length of the bruchid beetle Acanthoscelides schrankiae, we verified whether phenolic contents affected bruchid body size. In addition, the relationship between physical seed traits and phenolic contents was examined. Results showed that seeds from infested fruits had significantly greater phenolic contents than seeds from non-infested fruits, which suggested induced defense. Body size variation in A. schrankiae was marginally nonsignificant according to phenolic contents among plants (negative trend), indicating that phenols may interfere directly with bruchid performance. Seeds that were more irregularly shaped had significantly greater phenolic contents than those that were more uniform. Therefore, the most perfectly spherical seeds may be more vulnerable to seed predation, and our results suggest that the production of phenolic compounds was increased in infested fruits, which in turn may affect A. schrankiae development.

Reguladores vegetais e atividade de invertases em cana-de-açúcar em meio de safra

The objective of this research was to evaluate the activity of acid and neutral invertases in controling the storage of sucrose in sugarcane variety SP80-3280 due to plant regulators application in the middle of the cropping season in Igaracu do Tiete (SP), Brazil. The experiment was carried out in ratoon cane (crop 2004 and 2005) in a randomized block design with five replications. The treatments consisted of four plant regulators application of the class of growth retainers (Ethephon, Ethyl.trinexapac, Potassium nitrate and Potassium nitrate + Boron) and a control (natural ripening), whose commercial products (c.p.) were Ethrel, Moddus, Krista Kana and Krista Kana Plus, with dosage of 2L c.p. ha-1, 0.8L c.p. ha-1, 3kg c.p. ha-1 and 3c.p. kg ha-1, respectively, without adjuvants application. The growth regulators provide alterations of different and significant intensity in soluble acid invertase and neutral invertase levels enzymes. The agricultural efficiency of maturators was affected significatively by the weather and time of application. The treatments with maturators, were affected most in 2004, when wheater conditions were unfavourable to natural ripening, were favour the ripening sugarcane process implicating in improvement technological quality of stems.

Estudo das poliaminas na morfogênese in vitro de Hemerocallis sp.

In tissue culture, the action of induction of the vegetal development and also oxidative control of cells and tissues are attributed to the polyamines. This study was aimed at verifing the participation of the polyamines spermidine (SPD), spermine (SPM) and putrescine (PUT) in the induction of callus differentiation and in the oxidative control at Hemerocallis sp. cultivated in vitro. Cell mass produced by callus in vitro were cultivated in medium MS, supplemented with SPD, SPM and PUT in different concentrations and combinations, by evaluating endogenous contents of polyamines and soluble proteins, and peroxidase activity (EC 1.11.1.7), number and height of shoots, hyperhydricity and necrosis, and formation of calluses. The results indicate that polyamines participate not only at the morphogenesis induction, but also to the oxidative standards of cells and tissues. At the end of the study PUT, isolated (10µM PUT) or with SPD (10µM 10 SPD + 10µM PUT) or SPM (10µM SPM + 10µM PUT), induced the biggest average related to number and height of differentiated shoots. Already the combination of the three polyamines in the medium (10µM SPD + 10µM SPM + 10µM PUT) induced mayor parts (60%) of micro shoots in the callus. The SPD and SPM combination (10µM SPD + 10µM SPM) induced the biggest quantity of necrosis tissue (65%). It was verified that SPM, applied exogenously in the medium (10 µM SPM) can act as antioxidant in the tissue culture of this species.

Teores de poliaminas em alguns alimentos da dieta básica do povo brasileiro

The level of polyamines changes as well as the daily necessity since they are directly related to the cell growth. In the present work we analyzed the levels of putrescine, spermidine and spermine in several foods from vegetables and eggs. The cooking did not affect the level of polyamines in rice and bean, but in potato there were differences and frying process increased the level of putrescine. Lettuce, orange, banana and tomato presented significant levels of putrescine while onion, garlic, egg, rice and bean presented specially spermidine and spermine. Those results can help for elaboration of dietary guidelines according to the level of polyamines of those foods and their daily necessity.

Antioxidant content in guava (Psidium guajava) and araca ´ (Psidium spp.) germplasm from different Brazilian regions

Guava (Psidium guajava) and araca´ (Psidium spp.) plants are important for the Brazilian economy, as their fruit is both accepted by the consumers, and makes a beneficial contribution to the human diet thanks to their content in vitamin C, carotenoids and phenolic compounds. Here, we report the content in the fruit of free ascorbic acid, lycopene, b-carotene, flavonoids and phenolic compounds, and the total antioxidant activity present in a collection of guava and aracaaccessions curated at the Embrapa Semiarido germplasm bank. Guava fruits with a red-coloured pulp flesh contained a significant amount of carotenoids, especially lycopene, and a high concentration of phenolic compounds. These compounds were largely responsible for the antioxidant activity of the aracaaccessions. Among the guava accessions, phenolic compounds were also responsible for the antioxidant activity. High levels of free ascorbic acid were present in most accessions. In both guava and araca´, there is substantial potential to develop cultivars with a good level of consumer acceptability.