Soybean glycinin improves HDL-C and suppresses the effects of rosuvastatin on hypercholesterolemic rats

Background: This study was an investigation of the effects of ingesting a daily dose of isolated glycinin soy protein (11S globulin), in association with rosuvastatin, on the control of hypercholesterolemia in experimental animals.Methods: Male Wistar rats were kept in individual cages under appropriate controlled conditions of temperature, light and humidity. The animals were divided into five groups (n = 9): 1) standard (STD): fed on casein as protein source; 2) hypercholesterolemic (HC): STD plus 1% cholesterol and 0.5% cholic acid; 3) HC+11S: hypercholesterolemic + glycinin (300 mg/kg/day); 4) HC+ROS: hypercholesterolemic + rosuvastatin (10 mg/kg/day); 5) HC+11S+ROS: HC diet, the 11S protein and the drug in the doses given in (3) and (4). The protein and the drug were administered by gavage for 28 days. The results indicated that the addition of 1% cholesterol and 0.5% cholic acid induced hypercholesterolemia in the animals without interfering with their weight gain.Results: A single daily dose of glycinin contributed an additional 2.8% of dietary protein intake and demonstrated its functional role, particularly in raising HDL-C, decreasing triglycerides in the liver and improving the atherogenic index in animals exposed to a hypercholesterolemic diet.Conclusion: Most of the beneficial effects of the isolated treatments disappeared when the drug (rosuvastatin) and the protein (glycinin) were taken simultaneously. The association was shown not to interact additively, as noted in the plasma levels of total cholesterol and non-HDL cholesterol, and in the significant increase of cholesterol in the liver. Studies are in progress to identify the effects of peptides derived from the 11S globulin and their role in cholesterol metabolism.

beta-Conglycinin (7S) and glycinin (11S) exert a hypocholesterolemic effect comparable to that of fenofibrate in rats fed a high-cholesterol diet

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of pH and temperature on the immunogenicity of glycinin (Glycine max L)

Sensitive immunologic techniques for the detection of alterations that occur in protein antigens were used to evaluate the immunogenicity of soybean glycinin after isolation, heat denaturation and pH alteration. The objective was to determine the effect of these agents on the immunogenic ability of this protein fraction. Immunologic assays performed on heat-denatured glycinin up to 80 degrees C in the presence of antinative glycinin serum demonstrated that glycinin retains its immunogenic properties. Above 90 degrees C this biological property begins to disappear, with protein insolubilization and epitope modification due to the conformational changes imposed by temperature. A reduction in immunogenicity also occurred when glycinin was taken to pH 2.0 (below its pi) and pH 11.00 (above its pi) and exposed to high temperatures in the presence of native antiglycinin serum. From these data one can conclude that, at extreme pH values, intramolecular reactions may occur which, in combination with the structural disorganization caused by high temperatures, may contribute to the reduction of immunogenicity.

Soybean glycinin (11S) increases HDL-cholesterol in hypercholesterolemic rats

Purpose: The purpose of this paper is to determine the effects of isolated soy glycinin (11S) on lipid metabolism in animals subjected to a hypercholesterolemic diet. Design/methodology/approach: Male Wistar rats were kept in individual cages under appropriate conditions. The animals were divided into three groups (n=9): normal diet (STD) given a diet containing casein as protein source, recommended in AIN-93M; hypercholesterolemic (HC) fed a normal diet with 1 per cent cholesterol and 0.5 per cent cholic acid; and hypercholesterolemic+glycinin (HC+11S), fed a hypercholesterolemic diet, plus 11S soy protein (300 mg/kg/day), dissolved in saline and administered by gavage. After 28 days, the animals were sacrificed and blood and liver removed for biochemical analysis of total cholesterol (TC), HDL-cholesterol (HDL-C) and triglycerides (TG) in the plasma, hepatic TC and TG. Findings: A single daily dose of glycinin given to the hypercholesterolemic group demonstrated its functional role, particularly in raising HDL-C and reducing triglycerides in the liver. Originality/value: This study demonstrates the action of the 11S globulin in soybean as a serum lipid lowering agent, in addition to its nutritional properties, especially in raising the HDL-C. © Emerald Group Publishing Limited.

Estudo experimental do efeito da proteína glicinina da soja (Glycine max L.) no metabolismo do colesterol

Pós-graduação em Alimentos e Nutrição - FCFAR

Metformin and soybean-derived bioactive molecules attenuate the expansion of stem cell-like epithelial subpopulation and confer apoptotic sensitivity in human colon cancer cells

Colorectal cancer (CRC) is a disease whose genesis may include metabolic dysregulation. Cancer stem cells are attractive targets for therapeutic interventions since their aberrant expansion may underlie tumor initiation, progression, and recurrence. To investigate the actions of metabolic regulators on cancer stem cell-like cells (CSC) in CRC, we determined the effects of soybean-derived bioactive molecules and the anti-diabetes drug metformin (MET), alone and together, on the growth, survival, and frequency of CSC in human HCT116 cells. Effects of MET (60 μM) and soybean components genistein (Gen, 2 μM), lunasin (Lun, 2 μM), β-conglycinin (β-con, 3 μM), and glycinin (Gly, 3 μM) on HCT116 cell proliferation, apoptosis, and mRNA/protein expression and on the frequency of the CSC CD133(+)CD44(+) subpopulation by colonosphere assay and fluorescence-activated cell sorting/flow cytometry were evaluated. MET, Gen, and Lun, individually and together, inhibited HCT116 viability and colonosphere formation and, conversely, enhanced HCT116 apoptosis. Reductions in frequency of the CSC CD133(+)CD44(+) subpopulation with MET, Gen, and Lun were found to be associated with increased PTEN and reduced FASN expression. In cells under a hyperinsulinemic state mimicking metabolic dysregulation and without and with added PTEN-specific inhibitor SF1670, colonosphere formation and frequency of the CD133(+)CD44(+) subpopulation were decreased by MET, Lun and Gen, alone and when combined. Moreover, MET + Lun + Gen co-treatment increased the pro-apoptotic and CD133(+)CD44(+)-inhibitory efficacy of 5-fluorouracil under hyperinsulinemic conditions. Results identify molecular networks shared by MET and bioavailable soy food components, which potentially may be harnessed to increase drug efficacy in diabetic and non-diabetic patients with CRC.

Particle formation during soy protein precipitation

The current success of soy foods is driving soy ingredient manufacturers to develop innovative products for food manufacturers. One such innovation is separating the soy proteins glycinin and beta-conglycinin to take advantage of their individual functional and nutritional properties. Precipitation by acidification is a low-cost method for separating these two proteins. Separation is achieved by preferentially precipitating glycinin at pH ~ 6 while beta-conglycinin remains in solution. Understanding the particle formation during protein precipitation is important as it can influence the efficiency of the precipitation process as well as subsequent downstream processes such as the particle-liquid separation step, usually achieved by centrifugation. Most of the previous soy protein precipitation studies are limited to precipitation at pH 4 as this is the pH range most commonly used in the commercial manufacturing of soy protein isolates. To date, there have been no studies on the particle formation during precipitation at pH > 5.Precipitation of soy protein is generally thought to occur by the rapid formation of primary particles in the size range of 0.1 - 0.3 microns followed by aggregation of these particles via collision to aggregates of size about 1 - 50 microns. The formation of the primary particles occurs on a time scale much shorter than that of the overall precipitation process (Nelson and Glatz, 1985). This study shows that precipitation of soy protein is indeed rapid. At high pH levels, binary liquid-liquid separation occurs forming a protein-rich heavy phase. The protein-rich phase appears as droplets which can be coalesced to form a uniform bulk layer under centrifugation forces. Upon lowering the pH level by the addition of acid, further protein is precipitated as amorphous material which binds the droplets together to form aggregates of amorphous precipitates. Liquid-liquid separation has been observed in many protein solutions but this phenomenon has only scarcely been reported in the literature for soy proteins. It presents an exciting opportunity for an innovative product. Features of the liquid-phase protein such as protein yield and purity will be characterized.