Adaptabilidad de granos de híbridos de maíz super dulce sh2 al procesamiento industrial. II Enlatado / Super sweet corn hybrid sh2 adaptability for industrial canning process

The super sweet corns Krispy king, Victor and 324 (sh2 hybrids) were evaluated to determine their adaptabilities to the industrial canning process as whole kernels. All these hybrids and Bonanza (control) were sown in San Joaquín (Carabobo, Venezuela), harvested and canned. After 110 days storage at room temperature they were analyzed to be compared physically, chemically and sensorially with Bonanza hybrid. Results did not show significant differences among most of the physical characteristics, except for percentage of broken kernels which was higher in 324 hybrid. Chemical parameters showed significant differences (P < 0.05) comparing each super sweet hybrid with Bonanza. The super sweet hybrids presented a higher sugar content and soluble solid of the brine than Bonanza, also a lower pH. The super sweet whole kernel presented a lower soluble solids content than Bonanza but they were not significant (Krispy king and 324). Appearance, odor and overall quality were the same for super sweet hybrids and Bonanza (su). Color, flavor and sweetness were better for 324 than all the other hybrids. Super sweet hybrids presented a very good adaptation to the canning process, having as an advantage that doesn't require sugar addition in the brine and a very good texture (firm and crispy).

[Suitability study for super sweet corn on the ears hybrids under refrigerated conditions evaluating chemicals microbiological and sensorial characteristics]. / Estudio de la estabilidad de las características químicas, microbiológicas y sensoriales de mazorcas refrigeradas de híbridos de maíz super dulce.

Krispy King, Víctor and 324, super sweet hybrids (sh2) were cultivated in San Joaquín, estado Carabobo, Venezuela. The scheme was stablished to produce refrigerated fresh ears to be commercialized. The chemistry, microbiology and sensorial characteristics were evaluated at 0; 7; 14; 21 and 28 days of storage. One hundred ears of each hybrid were picked at the ripe fresh stage and packed in polystyrene trays covered with polyethylene. The storage temperature was 4 degrees C +/- 1 degree C. The scheme used was well adapted, allowing a good stability of the ears until 28 days of storing. The plastic cover avoid the lost of humidity. The soluble solids, total sugars and pH went down during the storage. The acidity and the microorganisms increased as expected. The sensorial variables kept the same for Krispy king and Víctor, while the hybrid 324 shown the lowest humidity content, the highest count of microorganisms and the poorest sensorial quality.

[Characteristics of Canavalia proteins]. / Estudio de algunas características de las proteínas de Canavalia.

The purpose of this work was the isolation and characterization of grain protein from five Venezuelan Genotypes (U-02, Yaracuy, Valle De La Pascua, Originally Tovar) of Jack Bean (Canavalia ensiformis). The average protein content from these genotypes was 31.37%, it ranged between 28.44% and 33.05%. The protein isolation was performed by solubility extraction procedures, showed: 84.57% of albumins, globulins and non proteic nitrogen and 15.43% of alcohol insoluble reduced glutelin (AIG). The content of anti-nutritional factors (canavanine and hemagglutination title) found in protein fractions were respectively: Albumins 1.96%, +4; globulins 0.17%, +5 and AIG 0.22%, +1. It was observed that protein fractions of genotype Tovar had the lowest canavanine values (0.79%, 0.02% and 0.00% respectively). The globulins gave the highest in vitro protein digestibility (65.20%) followed by Albumins (58.90%) and AIG (37.28%).

[Electrophoretic study of albumins and globulins of 4 genotypes of Canavalia ensiformis]. / Estudio electroforético de las albúminas y globulinas de cuatro genotipos de Canavalia ensiformis.

Polyacrylamide gel electrophoresis (PAGE) and PAGE-SDS were used to study seed albumins and globulins of Canavalia ensiformis. In PAGE the concentration of acrylamide used in the upper gel was 4.0% with a pH of 6.7 and in the lower gel 7.5% and 10% of acrylamide were used with a pH of 8.9. In PAGE-SDS the concentration of acrylamide was 4.4% with a pH of 6.8 in the upper gel and 7.5% and 12.6% with a pH of 8.8 in the lower gel. The material used were the Venezuelan genotypes Tovar, Yaracuy, Original and U-02. The albumins and globulins were extracted with a 0.5 M NaCl solution and then separated by dialysis against water and lyophilized. These protein fractions represented 84.85% of the total amount of protein in seeds. The albumins were separated in PAGE with 7.5% acrylamide into five fractions and globulins into six, with similar electrophoretic patterns between genotypes. In a similar manner, the patterns obtained in PAGE with 10% acrylamide were the same for all genotypes, showing five bands for albumins and three bands for globulins. With PAGE-SDS containing 7.5% of acrylamide, albumins were separated into as many as eight components, and globulins into as many as seven bands with mobilities between 0.2981 and 0.9932, with different patterns for each genotype. Also the patterns PAGE-SDS at 12.6% of acrylamide were different for the genotypes, separating proteins into a greater number of bands. The albumins showed as many as twenty-one bands with mobilities between 0.2603 and 0.7398, and globulins as many as sixteen bands with mobilities between 0.2454 and 0.7390. The PAGE patterns of the genotypes analyzed did not show differences between them. However, with PAGE-SDS different electrophoretic patterns were obtained which varied in the number and intensity of the bands, making it possible to distinguish the genotypes studied. The molecular weight of the albumins varied between 76,000 and 12,000 daltons and of the globulins between 80,000 and 12,000 daltons.

In vitro antioxidant properties of amifostine (WR-2721, Ethyol).

PURPOSE: Amifostine (WR-2721), a phosphorylated aminothiol pro-drug which is an analogue of cysteamine, is a selective cytoprotective agent for normal tissues from the toxicities associated with chemotherapy and irradiation. Despite a growing number of reports strongly supporting amifostine's clinical efficacy, few authors have focused on the biochemical basis of amifostine's antioxidant activity. METHODS: We report on amifostine's free-radical scavenging activity against superoxide (O(2;(-))), hydroxyl (OH(-)) and lipoperoxyl radicals in an in vitro model, using pure chemical systems. Amifostine was dephosphorylated to its active metabolite, WR-1065, by adding 10% non-heat-inactivated serum; different amifostine concentrations (1, 10, 50, 100 microM and 200 microM) and pH conditions (pH 5, 7.4 and 9) were tested. RESULTS: Independent of the concentration, amifostine exhibited no major activity against O(2;(-)) ions, neither did any pH variations in the experimental model provide any scavenger effects of the drug against O(2;(-)) radicals. On the other hand, the protective effect of amifostine against OH(-) radicals was confirmed, yielding an EC(50) of 255 microM at pH 7.4 and 230 microM at pH 5. Finally, amifostine exhibited scavenging activity against spontaneous lipoperoxidation, but no apparent antioxidant effect on iron ascorbate-induced lipoperoxidation. CONCLUSIONS: With this in vitro study, we are able to confirm the scavenging activity of the chemo- and radioprotector amifostine, whose activity seems to be particularly important from a biological point of view, since it is exerted mainly against highly reactive OH(-).

Age-dependent changes of antioxidant activities and markers of free radical damage in human skeletal muscle.

This study was conducted in order to provide evidence for the role of reactive oxygen species (ROS) in human skeletal muscle aging. We used human muscle samples obtained from hospitalized patients in an open study with matched pairs of individuals of different ages. The subjects, ranging in age from 17 to 91 years, were grouped as follows: 17-25-, 26-35-, 36-45-, 46-55-, 56-65-, 66-75-, 76-85-, and 86-91-year-old groups. To investigate the relationship between muscle aging and oxidative damage we measured total and Mn-dependent superoxide dismutase (total SOD, MnSOD), glutathione peroxidase (GSHPx), and catalase (CAT) activities; total reduced and oxidized glutathione (GSHtot, GSH, and GSSG) levels; lipid peroxidation (LPO), and protein carbonyl content (PrC). Total SOD activity decreases significantly with age in the 66-75-year-old group, although MnSOD activity increases significantly in the 76-85-year-old group. The activity of the two H2O2 detoxifying enzymes (GSHPx and CAT) did not change with age, as do GSHtot and GSH levels. GSSG levels increased significantly (76-85- and 86-91-year-old groups) with age. We observed a significant increase in LPO levels (66-75- and 76-85-year-old groups), although the PrC content shows a trend of increase without gaining the statistical significance. These results support the idea that ROS play an important role in the human muscle aging process.

Antioxidant status and alpha1-antiproteinase activity in subarachnoid hemorrhage patients.

The antiproteasic activity of alpha1-antitrypsin (alpha1-AT) is reduced in cases of subarachnoid hemorrhage from ruptured intracranial aneurysm and particularly in patients currently smoking; alpha1-AT is very sensitive to oxidant agents. About 50% of physiological anti-oxidant systemic capacity is represented by Vitamin A, E and C. Plasmatic amounts of alpha1-AT, alpha1-AT Collagenase Inhibitory Capacity (CIC) and levels of vitamin A, vitamin E and vitamin C were analyzed in 39 patients, 26 women and 13 men, operated for intracranial aneurysm; 11 patients with unruptured intracranial aneurysm were considered as controls while 28 patients were included within 12 hours from subarachnoid hemorrhage (SAH). Plasmatic levels of vitamin A and vitamin E were significantly lower (p=0.038 and p=0.0158) in patients suffering SAH than in controls, while no statistically significant differences were found in mean plasmatic vitamin C levels. Level of alpha1-AT was not statistically different in controls and in patients with SAH; however, the activity of alpha1-AT, evaluated as CIC, is significantly reduced in patients with SAH (p=0.019). We have observed that systemic plasmatic levels of vitamins did not significantly differ in relation to smoking habit. Vitamin A and E represent an important defensive system against free radicals reactions. Particularly, vitamin E acts as an antioxidant by scavenging free-radicals. A reduced anti-oxidant status might be related to the higher sensibility of alpha1-AT to oxidative reactions and the activity of alpha1-AT is dependent on the antioxidant capacity of liposoluble vitamins. We can speculate that an acute systemic oxidative stress condition might influence the rupture of intracranial aneurysms.

Amifostine (WR-2721, Ethyol(TM)) can protect human endothelial but not tumor cells from cisplatin-induced cytotoxicity.

Amifostine (WR-2721, Ethyol(TM)) is a chemo-and radioprotective agent which is increasingly used in clinical practice to minimize antitumor therapy-induced toxicities. The key of this property of amifostine is certainly its selective action in terms of differential protection of normal tissue and not of tumor cells. Using HUVEC cells and three different cancer cell lines (A549 non-small cell lung cancer, DND-1A melanoma and HeLa cervical carcinoma) we provide evidence that amifostine could protect normal, and not cancer cells, from cisplatin (CDDP)-induced cytotoxicity in vitro. Furthermore, low doses of amifostine, easily attainable in vivo, can protect 50% of normal cells in vitro from CDDP-induced cytotoxicity.

[Chemical and nutritional characteristics from grains of five genotypes of Canavalia ensiformis]. / Características químicas y nutricionales del grano de cinco (5) genotipos de Canavalia ensiformis.

This study evaluated the raw meals from grains of five genotypes of Canavalia ensiformis, by means of the chemical composition, the presence of antinutritional factors (Canavanine and hemaglutination activity) and in vitro protein digestibility. The genotypes studied were: Original, Yaracuy, Tovar, Valle de la Pascua and U-02. The results of chemical composition, showed significance difference between them, except moisture content, found the following average values: Protein 31.37%, fiber: 8.10%, ash: 2.93% and moisture: 11.68%. The canavanine content of the genotypes was variable oscillating between 2.02 and 4.86%, the genotype U-02 presented the higher value, respect to the hemaglutination title changed between: +2 and +5. The in vitro protein digestibility of the raw meals showed significance differences between the genotype, it changed between 47.51% and 51.84%, these values were lower than the casein (97.3%).

Blood free radical antioxidant enzymes and lipid peroxides following long-distance and lactacidemic performances in highly trained aerobic and sprint athletes.

OBJECTIVE: We have determined the differences of the influence of prolonged exercise or higher intensity lactacidemic exercise, on plasma lipid peroxidation and on erythrocyte antioxidant enzymatic defence system. EXPERIMENTAL DESIGN: We measured plasma indices of lipid peroxidation, conjugated dienes (CD) and malondialdehyde (MDA) and erythrocyte enzymes superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase (CAT). The biochemical evaluations were performed in six healthy control males (C) and twelve athletes: six marathon runners (MR) and six sprint-trained athletes (STA) at rest and after a half-marathon (MR) and a training session of 6 x 150 m (STA). RESULTS: In resting conditions MDA was higher in STA and MR than in C (p < 0.01), while only the MR showed significantly elevated levels of CD (p < 0.05). In STA the enzymatic scavenging capacity showed a significantly higher SOD (p < 0.01) and GSHPx (p < 0.01), while CAT was lower than in controls (p < 0.05). In MR only SOD (p < 0.01) was significantly higher than in C. It increased significantly immediately after half-marathon, while CAT decreased 24 and 48 hours postexercise respectively. In these athletes the lipoperoxidative indices increased in the early postexercise phase, while at 24 and 48 hrs both CD and MDA levels decreased. In STA enzyme activities were not modified by anaerobic performance while CD showed a peak 6 hrs postexercise and the MDA showed a progressive increase until 48 hrs afterwards. CONCLUSIONS: Both strenuous long duration exercise and exhaustive sprint training overwhelm our capacity to detoxify ROS, producing oxidative stress. Thus an adequate supply of antioxidants could be appropriate.

Oxidative stress after acute and chronic application of beta-amyloid fragment 25-35 in cortical cultures.

The aim of this work was to investigate whether free radical reactions play a role in beta-amyloid neurotoxicity. Rat cortical neurons were exposed acutely (24 h) or chronically (3, 7 days) to beta-amyloid biologically active fragment beta 25-35 (50 microM). In these conditions, where only the longest exposure induced neuronal death, superoxide dismutase activity was increased after acute exposure but no change was detected after chronic treatments, whereas a different pattern was observed for glutathione peroxidase. In the basal condition, there was an eight-fold increase in dichlorofluoroscein, used as peroxide production marker, in neuronal cells after 7 days treatment with beta 25-35. Moreover, the intracellular peroxide production induced by Fe2+/ascorbate stimulation was amplified by beta 25-35, increasingly up to 7 days of exposure, by which time the dichlorofluoroscein-stimulated levels were 33 times higher than in controls. In conclusion, our results show that oxidative stress and free radical production are linked to beta 25-35 exposure and may contribute to neurodegenerative events associated with beta-amyloid deposits in Alzheimer's disease.

Oxidative events in neuronal and glial cell-enriched fractions of rat cerebral cortex.

The aim of this work was to investigate how neurons and glial cells separated from rat brain cortex respond to "in vitro" oxidative stress induced by incubation of the cellular fractions in the presence of prooxidant mixtures; in addition, the endogenous enzymatic antioxidant capacity of the purified fractions was investigated. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex following passages of the tissue through meshes and centrifugations. The following parameters were evaluated: antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), and glucose-6-phosphate dehydrogenase (G6PDH); lipid peroxidation products (TBARS) prior to (basal) and after (iron-stimulated) incubation with a mixture of iron and ascorbic acid; intracellular production of reactive oxygen species (ROS) using a fluorescent probe, dichlorofluorescin-diacetate, in basal, iron-stimulated, and menadione stimulated conditions. SOD and GSHPx activities showed no significant changes between neurons and glia, whereas CAT and G6PDH activities were found to be significantly lower in glia than in neurons. TBARS levels were significantly lower in the glial fraction than in neurons, both in basal and iron-stimulated conditions. ROS production showed no differences between neurons and glia in both basal and menadione-stimulated conditions. Iron-stimulation produced a marked increase in ROS production, limited to the neuronal fraction, with the glial values being similar to the basal ones. Our conclusion is that glia and neurons isolated from rat cerebral cortex show a similar pattern of the most important antioxidant enzymes and of their basal ROS production, whereas glia is more resistant in "oxidative stress" conditions.

[Extraction and characterization of zeins from kernels of 10 maize cultivars]. / Extracción y caracterización de las zeínas del grano de diez cultivares de maíz.

The study consisted in the extraction and characterization of zeins of Venezuelan maizes, according to their solubility and molecular properties. The cultivars analyzed were the hybrids Ceniap PB8, Tocoron 127, Arichuna, Obregón, Ceniap 3, Corocito 101 and the varieties Máquina del Ceniap, Venezuela-1 and Venezuela-1 Opaco-2. Zeins were extracted with 70% ethanol and fractionated by two methods: 95% ethanol and column filtration with Sephadex G-200. The molecular weight was determined by electrophoresis in a discontinuous polyacrilamide gel with sodium dodecyl sulfate (PAGE-SDS). The results demonstrated that zeins account for 36.57% of the total protein present in normal corn grain and 9.38% in Opaque-2 corn. Prolamines presented a soluble fraction in 95% ethanol (alpha zeins) which represented 33,12% of zeins and another insoluble (beta zeins) the 66.88%. In column fractionation, three fractions were obtained, two major A and C and another B in minor quantity, which varied in proportion between cultivars. Zeins which were reduced with 2-mercaptoethanol separated into two subunits with molecular weights of 21,300 and 24,300 daltons, whereas unreduced zeins presented large sized aggregates which remained at the origin and large numbers of bands (nine) whose molecular weights oscillated between 24,300 and 87,000 daltons. The electrophoretic patterns of normal maizes were similar, but differ from the pattern of the Opaque-2. In this maize, zeins reduced presented only the band with molecular weight 24,300 daltons and the unreduced zeins showed those with molecular weights of 87,000; 78,500; 48,500 and 24,300 daltons. Reduced alpha and beta are made up of the same basic components of zeins. Likewise unreduced alpha zeins are made up of the same polypeptides as unreduced zeins. The difference between Opaque-2 zeins and normal ones in that they contain more alpha zeins and less polypeptides of high molecular weight.

[Extraction and characterization of grain prolamins of 6 sorghum Sorghum bicolor L. Moench cultivars]. / Extracción y caracterización de las prolaminas del grano de seis cultivares de sorgo Sorghum bicolor L. Moench.

The purpose of this work was to isolate and characterize prolamines from grains of sorghum, by their solubility and molecular properties. One variety, Zaraza-1 (SV-V51), and five hybrids (Dekalb-55, Dekalb-64, Wac-5005, Pioneer-815B and Savanna-5) were used. The prolamines, called kafirins, were extracted with 70% isopropanol at 60 degrees C, and then fractionated by two methods: 95% ethanol and gel filtration with Sephadex G-200. The molecular weight was determined by electrophoresis in a discontinuous polyacrylamide gel with sodium dodecyl sulfate (PAGE-SDS). The alpha kafirin (soluble fraction in 95% ethanol), and 7.13% of the grain's total protein, and the beta kafirin represents 21.64% of kafirin (the insoluble fraction), represents 78.36% of the kafirin and 25.39% of total protein. Three fractions were obtained from the column fractionation, two important ones (A and C), and one (B) in a lesser amount. The proportion of these fractions varied between cultivars, so that in SV-V51, D-64 and Wac-5005, A is predominant, and in high tannin sorghum, C is the predominant one. Kafirins reduced with 2-mercaptoethanol were separated in four subunits with molecular weights of: 15,000, 21,300, 24,300 and 51,500 daltons. Unreduced kafirin showed a larger number of subunits (six) whose molecular weights were: 15,000, 24,300, 48,500, 69,000, 80,000 and 93,500 daltons. Reduced and kafirin showed the same number of subunits as those of nonfractioned kafirin reduced with 2-mercaptoethanol.

[Characterization of corn proteins of the cultivars Venezuela-1, Arichuna, Obregon and Venezuela-1 Opaque-2]. / Caracterización de las proteínas de los maíces Venezuela-1, Arichuna, Obregón y Venezuela-1 Opaco-2.

A study is presented on the protein composition of the Venezuelan corn cultivars Venezuela-1, Arichuna, Obregón and Venezuela-1 Opaque-2. The proteins were isolated and analyzed for their molecular weight and lysine and tryptophan content. Protein fractionation showed significant differences between normal corn cultivars and Opaque-2. The latter showed a low level of zein and a high content of alcohol-insoluble reduced glutelins (AIG), albumins and globulins in relation to the normal kernel. The relative increase of these protein fractions, rich in lysine and tryptophan, results in a higher concentration of these amino acids in the Opaque kernel, as revealed by the analysis of these compounds carried out in different cultivars. Electrophoretic analysis showed only small differences in the number and intensity of bands from the protein fractions of the maize cultivars under study.