Qualidade protéica de linhagens de soja com ausência do Inibidor de Tripsina Kunitz e das isoenzimas Lipoxigenases / Protein quality of soy lines lacking Kunitz's Trypsin Inhibitor and Lipoxygenase isozymes

OBJETIVO: Avaliar a qualidade protéica de farinhas de soja, que diferem entre si com relação à presença de lipoxigenases e/ou Inibidor de Tripsina Kunitz. MÉTODOS: Procedeu-se aos ensaios biológicos com ratos, em que foram avaliados a Razão da Eficiência Protéica, Razão Protéica Líquida, Utilização Protéica Líquida e a digestibilidade. Determinou-se a composição aminoacídica das farinhas e cálculo do Escore Químico Corrigido pela Digestibilidade. RESULTADOS: Os valores de Razão da Eficiência Protéica, Razão Protéica Líquida, Utilização Protéica Líquida para as variedades de soja foram inferiores aos valores obtidos para caseína. Para as farinhas sem Inibidor de Tripsina Kunitz foram obtidos valores de digestibilidade maiores que para as farinhas com Inibidor de Tripsina Kunitz, e esses foram bem próximos aos da caseína. Com relação ao teor aminoacídico, constatou-se que o aminoácido limitante dessa soja é lisina e não metionina, ao contrário do que aponta a literatura. CONCLUSAO: A eliminação genética do Inibidor de Tripsina Kunitz melhora consideravelmente a digestibilidade da proteína de soja. Os resultados do Escore Químico Corrigido pela Digestibilidade não indicaram diferença entre as farinhas sem Inibidor de Tripsina Kunitz das farinhas derivadas de linhagens com Inibidor de Tripsina Kunitz, como foi observado pelos resultados da digestibilidade in vivo.

Soybean trypsin inhibitor confers protection against rotavirus infection in infant mice.

OBJECTIVE: To study the effects of soybean trypsin inhibitor (TI) on glycine uptake, glutathione (GSH) levels and morphological changes of intestine in rotavirus (RV) infected infant mice. METHODS: A total of 144 infant mice (7/8 days old) were divided in 3 groups (i.e. control, RV and RV + inhibitor). Infant mice were orally inoculated with the EB strain of RV and Trypsin protease inhibitor (TI) and 8 animals each were sacrificed on days 0,1,3,5,7 and 10 post infection (p.i). Glycine uptake (in vitro), GSH levels and histological changes were assessed in the jejunum, ileum and colon. RESULTS: Glycine uptake and GSH levels were significantly reduced on days 3 and 5 p.i in jejunum and ileum of RV inoculated animals, compared to the controls. Glycine uptake and GSH levels were maintained as in controls in the RV + TI inoculated animals on days 3 and 5 p.i in jejunum and colon but not in ileum where lesser values were recorded. Histology showed vacuolar degeneration in ileum towards the apical portion whereas normal morphology was observed in jejunum, similar to controls. No histological changes were observed in colon in any of the groups. Electron microscopic study confirmed the viral infection. CONCLUSION: Administration of Trypsin protease inhibitor along with RV reverted the effects of RV infection on amino acid uptake and GSH levels completely in the jejunum and partially in the ileum.

Avaliação biológica de soja com baixas atividades de inibidores de tripsina e ausência do inibidor Kunitz / Biological evaluation of soybean line with low trypsin inhibitor activities

The soybean cultivar BR 36 with conventional levels of trypsin inhibitors activity and the soybean line BRM95-5262, which was genetically selected to contain low activity of trypsin inhibitors were used for biological assays with rats. BR 36 and BRM95-5262 contained 40 and 20, and 30 and 20 of relative residual activity of trypsin inhibitors, respectively. The mean values of PER and NPR showed that treatments with crude soybeans were minor than treatments with soybean thermically processed. However, the treatments of thermically processed soybean did not showed significative differences (p > or = 0.05). When the trypsin inhibitors activity were 8.61 and 8.44 UIT/mg of samples or 20 and 30 of relative residual activity of cultivar BR 36 and line BRM95-5262, respectively, it was observed that mean values of PER and NPR were not significatives. The mean values of CDA and CDV of treatments with crude soybeans were minor than treatment with casein and similar to the treatments with soybean thermically processed. So, it can be concluded that the biological evaluation obtained with soybean protein were dependent of initial trypsin inhibitors activities and of its respective thermical treatment. There was advantage in the use of BRM95-5262 soybean line with low trypsin inhibitors activity.

Sucralfate in the prevention of acute gastric lesions induced by ischemia-reperfusion

En ratas Wistar, se estudió el rol del Sucralfato en la prevención de las lesiones agudas gástricas, en el modelo de la isquemia-reperfusion por oclusión total del tronco celiaco y su comparación con bloqueadores de los radicales libres, como el Alopurinol, el Inhibidor de la Tripsina de Soja y la Superóxido Dismutasa. En ratas controles, el área necrótica macroscópica de la mucosa gástrica fue de un 80%; en cambio, las drogas antioxidantes dieron un área necróticia entre el 7 al 15% y Sucralfato dio escasamente un 4%. Se concluyó que Sucralfato como ciroprotector y antioxidante, al incrementar la barrera defensiva gástrica fue más importante que la agresión secundaria de los radicales libres

Evaluación del valor nutricional de leches de soya preparadas a partir de granos de soya tratados con microondas / Evaluation of the nutritive value of soybean milk prepared with microwave-treated soybeans

Se prepararon extractos acuosos de soya a partir de granos previamente sometidos a microondas, para la inactivación casi completa de la lipoxigenasa. Las leches de soya así obtenidas se evaluaron nutricionalmente. Todas las leches sometidas a estudio presentaron menor contenido de proteína, lípidos, ceniza y sólidos totales, en comparación con el alimento control, preparado a partir de granos no tratados por microondas. La leche obtenida de granos de soya con 8.7% de humedad inicial, irradiados con microondas durante 240 segundos, acusó el mejor puntaje químico de aminoácidos esenciales y la mayor disponibilidad aparente de metionina y PER. La inactivación completa de la actividad inhibidora de la tripsina se obtuvo en la leche preparada a partir de granos de soya con 56.8% de humedad, tratados por microondas durante 180 segundos. Por otro lado, la leche obtenida de granos de soya con 38.8% de humedad, irradiados con microondas durante 180 segundos, resultó ser la de mayor digestibilidad de la proteína in vitro

Secondary structure of soybean trypsin inhibitor (Kunitz): a study by infrared spectroscopy

The infrared spectrum (amide I'region) of Kunitz soybean trypsin inhibitor (SBTI) was obtained in D2O solution and resolved into Gaussian componentes. A prominent broad band centered at 1643 cm -1 is shown on the unresolved spectrum, which is usually assigned to N-deuterated peptide groups in an unordered structure, since SBTI is known to be devoid of alfa-helix by CD and X-ray crystallographic studies. In addition, shoulders are evident at 1632 cm**-1 and 1676 cm**-1, which correspond probably to the v(PI,0) and v(O,pi) components assigned to an antiparallel chain ß-pleated sheet structure. Parameters (maximum absorptivity, wavenumber at the maximum of the band, and half-width at the band at half-height) for the four Gaussian component bands (in which the amide I' band was resolved) are given. A crude estimation of 4% is obtained for antiparallel ß-sheet in SBTI, i.e., this protein would be practically devoid of such a ß-structure. Notwithstanding the fact that this results is apparently in agreement with the far-UV CD spectrum (data reported in the literature), the predominant conformation class found in SBTI has been demonstrated to be approximate ß-sheet structures, with a small amount of regular sheet