Inhibition of alpha-amylase by “insulin plant” (Myrcia sphaerocarpa DC) extracts: an alternative for the treatment of diabetes mellitus.

Diabetes mellitus is an important medical-economical-social problem requiring up search for less costly alternatives for treatment, such as use of medicinal plants. Of the species cited in ethnobotanical studies, the "insulin plant" (Myrcia sphaerocarpa DC) appears among those used by diabetics. The objective of this work was to evaluate the inhibitory activity of alpha-amylase by aqueous extracts of "insulin plant", prepared by different methods at a proportion of 1:200 (w:v), for information about the alleged hypoglycemic effect. For this, five samples of commercially teas "insulin plant" were obtained; aqueous extracts were prepared; and thereafter, they were tested for inhibition of alpha-amylase, before and after exposure to simulated gastric fluid. Results demonstrated before exposure to gastric fluid, a significant inhibition of enzyme activity (greater than 50%) in the samples A and C, using the decoction and sample E in all methods of extraction. Comparing methods of extraction, the decoction was more effective. After exposure to gastric fluid, there was a reduction in the activity of enzyme inhibition, suggesting negative influence of low pH on the properties of the inhibitor. These results do not elucidate the mechanism of the hypoglycemic action reported in folk medicine and literature, but indicate a promising path.

Syzygium sp (Myrtaceae) Extracts: Inhibition of Alpha Amylase.

Aims: The aims of this study were: a) prepare crude extracts of commercial teas Syzygium sp by different methods (maceration, decoction and infusion) in different proportions (1:20, 1:50 and 1:100) and b) submit them the inhibition assays digestive enzyme alpha-amylase before and after exposure to a simulated gastric fluid. Place and Duration of Study: Laboratório de Bioquímica, Instituto de Ciências Biológicas e Naturais, Universidade Federal do Triângulo Mineiro, Brazil, between August 2012 and July 2013. Methodology: Five samples of Syzygium sp teas were purchased commercially from pharmacies, drugstores and health food stores. Results: In the first step - inhibition of enzymatic extracts of the teas without simulated gastric fluid - the results showed significant inhibition of alpha-amylase (mean 92.84%, CV = 3.86%). However, when these extracts were placed in contact with the simulated gastric fluid was observed decreased inhibition of alpha – amylase, suggesting a possible reduction of hypoglycemic potential of these teas under physiological conditions. Conclusion: Aqueous extract Syzygium sp have high percentages of inhibition of the enzyme amylase, suggesting a potential hypoglycemic effect. Additional studies aiming at elucidating the chemical compounds present in the extracts of Syzygium sp using chromatographic techniques will be performed.

Application of Comet assay to assess the effects of white bean meal on DNA of human lymphocytes

This study was conducted to evaluate the potential induction of genotoxic effects of white bean flour using the Comet assay. The test was conducted with human lymphocytes present in whole blood immediately after collection, by incubation with white bean flour in three concentrations (3.92, 9.52 and 18.18 mg/mL) at 37 ºC for 4 h followed by preparation of slides. Samples were considered positive (above 20% damage) when the damage observed to cellular DNA was higher than the negative control. No genotoxic potential was found at the doses tested. However, it would be premature to suggest absence of risk to human health of DNA damage since the exposure of cells to the extract was restricted to four hours rather than a whole cell cycle. Additionally, further information on toxicology should be obtained in future studies.

Este estudo foi realizado para avaliar o potencial de indução de efeitos genotóxicos da farinha de feijão branco utilizando o teste do Cometa. O ensaio foi realizado com linfócitos humanos presentes no sangue imediatamente após a coleta, por incubação com farinha de feijão branco em três concentrações (3,92, 9,52 e 18,18 mg/mL) a 37 ºC por 4 h, seguida de preparação das lâminas. As amostras foram consideradas positivas (acima de 20% de dano), quando os danos observados no DNA celular foram maiores do que o controle negativo. Verificou-se que as doses testadas não mostraram potencial genotóxico. No entanto, seria prematuro fazer recomendações sobre o padrão de riscos para a saúde humana resultantes de danos ao DNA já que exposição das células ao extrato foi restrito ao período de quatro horas e não durante um ciclo celular completo. Além disso, outras informações sobre a toxicologia devem ser obtidas no futuro.

White Bean Flour (Phaseolus vulgaris): Therapeutic and Toxicological Research in Wistar Rats.

The objective was to evaluate the possible therapeutic and toxic effects resulting from administration of white bean flour (WBF) in Wistar rats for 21 days. The assay was performed to assess the consequences of using WBF crude, at a the concentration corresponding to the recommended daily dose to cause weight loss and hypoglycemic effect, which is 1,000 mg of phaseolamin/day. The administration of WBF at 1 mg/g body weight in Wistar rats with diabetes induced by STZ in a period of 21 days, did not alter physiological parameters (consumption of food and water, urine volume), biochemical markers (total cholesterol, HDL cholesterol and triglycerides), liver enzymes (gamma-GT, AST and ALT), and weight of organs (liver and pancreas) as well as fecal excretion of proteins and lipids. An increased excretion of carbohydrate fecal confirms the results of inhibition of α-amylase. Despite the tendency to decrease blood glucose from 20 days of treatment, there was no significant reduction during the period evaluated in the treated group. It can be concluded that despite the decreasing tendency of hyperglycemia and possibly aid in weight loss by decreasing absorption of carbohydrates in the diet, high doses of WBF may have deleterious effects on the body resulting from chronic use.

Hemaglutinina de folhas de mandioca (Manihot esculenta Crantz): purificação parcial e toxicidade / Hemaglutinin of cassava leaves (Manihot esculenta Crantz): partial purification and toxicity

Um dos componentes da multimistura para suplementação alimentar de populações carentes é a farinha de folhas de mandioca (FFM) que possui elevado conteúdo em proteínas, vitaminas e minerais. Todavia, as folhas de mandioca também apresentam substâncias antinutritivas e/ou tóxicas, como cianeto, polifenóis, nitrato, ácido oxálico, hemaglutinina, saponinas e inibidores de tripsina. Objetivou-se neste trabalho extrair as proteínas da FFM, purificando-as em coluna cromatográfica e determinar sua atividade hemaglutinante e toxicidade. Foram testadas várias estratégias de extração e precipitação das proteínas, sendo que o maior teor protéico e atividade hemaglutinante foi obtido na extração com água destilada na proporção 1:20 (p/v) seguida da precipitação com sulfato de amônio a 80 por cento de saturação. As proteínas precipitadas foram purificadas em coluna Q-Sepharose. Das quatro frações obtidas na purificação (I, II, III e IV), a I e a II apresentaram maiores atividades hemaglutinantes. As mesmas frações foram injetadas via intraperitoneal em camundongos com doses de 2mg (fração I), 3mg (fração II), 54mg (fração III) e 52mg (fração IV) para cada animal com 20g de peso médio, não sendo observadas mortes ou quaisquer efeitos adversos após 120h.

One of the components of the multimixture to the feed supplementation of low-income populations is cassava leaf flour (FFM), with high content of proteins, vitamins and minerals. However, cassava leaves also present substance regarded as antinutritive and/or toxic, such as cyanide, polyphenols, nitrate, oxalic acid, hemagglutinin, saponins and trypsin inhibitors. The aim of this work was to extract proteins from FFM, purifying them in chromatographic column and determine their hemagglutinating activity and toxicity. A number of strategies of extraction and precipitation of proteins were tested; the highest protein content and hemagglutinating activity were obtained in the extraction with distilled water at the 1:20 ratio (p/v) followed by the precipitation with ammonium sulfate at 80 percent of saturation. The precipitated proteins were purified in Q-Sepharose Fast Flow column. Out of the four purification fractions (I, II, III e IV), the I and II activities presented higher specific activity. The same fractions were injected intraperitoneal via in mice of 20g weight with doses of 2mg (fraction I), 3mg (fraction II), 54mg (fraction III) and 52mg (fraction IV). No deaths or any adverse effects was observed after 120h.