Effect of starvation and refeeding on biochemical and immunological status of Balb/c mice: an experimental model of malnutrition.

CONTEXT: Although new methods for the induction of malnutrition disorders in laboratory animals have been developed, the bulk of the models described in the literature are essentially based on dietary restriction/starvation principle. In this context, little data are available about the metabolic and the immune system parameters of Balb/c mice under starvation/refeeding. OBJECTIVE: This study examined the effects of starvation and refeeding on the biochemical and immunological status of undernourished Balb/c mice. METHODS: Female Balb/c mice, weighing 20 g, were starved for 3 days and then refed with commercial pelleted diet for 8 days. The variables considered were as follows: body weight; serum protein and amino acid concentrations; liver protein content, and cholinesterase and arginase activities; jejunal protein and DNA contents as well as oligosaccharidase levels; hematological parameters (bone marrow and peripheral blood cellularity); peritoneal macrophage activation; and humoral and cell-mediated immune functions. RESULTS: Profound alterations in both biochemical and immunological conditions appeared after the starvation period. Refeeding resulted in the normalization of serum albumin levels, the intestinal DNA content and the gut-mucosal associated enzymatic activities, the blood lymphocyte counts, and the number of peritoneal macrophages. The markers of liver metabolic function (cholinesterase and arginase activities), and those of bone marrow hemopoiesis and the adaptive immune response (T-dependent antibody titres and delayed-type hypersensitivity response) remained altered after refeeding compared with control mice. CONCLUSION: These findings suggest that fasted mice can be used as an animal model of acute starvation that might prove useful in evaluating the effectiveness of nutritional and immunopharmacological interventions.

Utilisation of Chlorella vulgaris cell biomass for the production of enzymatic protein hydrolysates.

Studies on enzymatic hydrolysis of cell proteins in green microalgae Chlorella vulgaris 87/1 are described. Different proteases can be used for production of hydrolysates from ethanol extracted algae. The influence of reaction parameters on hydrolysis of extracted biomass with pancreatin was considered, and the composition of hydrolysates (Cv-PH) was investigated in relation to the starting materials. Significant changes in the degree of hydrolysis were observed only during the first 2h and it remained constant throughout the process. An enzyme-substrate ratio of 30-45 units/g algae, an algae concentration of 10-15% and pH values of 7.5-8.0 could be recommended. Differences in the chromatographic patterns of Cv-PH and a hot-extract from Chlorella biomass were observed. Adequate amounts of essential amino acids (44.7%) in relation to the reference pattern of FAO for human nutrition were found, except for sulfur amino acids. Cv-PH could be considered as a potential ingredient in the food industry.

Proximal Composition, Nutraceutical Properties, and Acute Toxicity Study of Culinary-Medicinal Oyster Mushroom Powder, Pleurotus ostreatus (Agaricomycetes).

A compositional study was performed on fruiting-body powder of the culinary-medicinal oyster mushroom Pleurotus ostreatus for applications as a nutraceutical/functional food. Carbohydrates (55 g/100 g dry weight [dw]) and proteins (27.45 g/100 g dw, with an in vitro digestibility of 75%) appear to be the major components, but fat content was low (4 g/100 g dw). Pleurotus powder has important micronutrients such as minerals (Fe, Cu, Zn, Mn, Mg, and Co) and ascorbic acid, as well as nonnutrients (i.e., phenolics) with antioxidant potential. A powder-derived aqueous extract had a phenolic compound content of 138 mg/100 g that showed 2,2-diphenyl-1-picrylhydrazyl radical scavenging and inhibition of membrane-lipid peroxidation activities of 58.3% and 61.4%, respectively. The presence of ß-1,3-1,6-D-glucans was also demonstrated (1.54 g/100 g). An acute toxicity test proved that Pleurotus powder was safe after oral administration to both male and female mice at a dose of 2000 mg/kg. The combination of rich nutritional composition, bioactivity, and safety in P. ostreatus fruiting-body powder highlights its potential as a nutraceutical agent promoting health and life quality.

Oral administration of an aqueous extract from the oyster mushroom Pleurotus ostreatus enhances the immunonutritional recovery of malnourished mice.

Mushroom nutriceutical components have lately attracted interest for developing immunonutritional support. However, there is relatively little information pertaining to the use of mushroom preparations for modulating the metabolic and immunological disorders associated to malnutrition. This study was aimed to evaluate the effects of oral administration of an aqueous extract (CW-P) from Pleurotus ostreatus on the recovery of biochemical and immunological functions of malnourished mice. 8-week old female BALB/c mice were starved for 3days and then refed with commercial diet supplemented with or without CW-P (100mg/kg) for 8days. Regardless of the diet used during refeeding, animal body weights and serum protein concentrations did not differ between groups. Oral treatment with CW-P normalized haemoglobin levels, liver arginase and gut mucosal weight. CW-P increased total liver proteins and also DNA and protein contents in gut mucosa. Pleurotus extract provided benefits in terms of macrophages activation as well as in haemopoiesis, as judged by the recovery of bone marrow cells and leukocyte counts. Moreover, CW-P stimulated humoral immunity (T-dependent and T non-dependent antibodies responses) compared to non-supplemented mice. CW-P extract from the oyster mushroom can be used to develop specific food or nutritional supplement formulations with potential clinical applications in the immunotherapy.

Considerations on endopolygalacturonase activity and determination of comparison ratios with emphasis on the influence of the degree of substrate esterification.

A study on the determination and standardization of endopolygalacturonase (EPG) activity is reported, with emphasis on the influence of the degree of substrate esterification using pure yeast EPG. Differences in the results, depending on how the EPG activity unit was defined, are described and discussed. From a theoretical analysis of the expressions established, a general equation for expressing EPG activity in standard international units was obtained, together with the proportional coefficient for each of the substrates studied. It was observed that for a wide range of enzyme concentrations good linear correlations were obtained. Analysis of the comparison ratio (CR) values calculated revealed that these do not differ significantly, except for low-methoxyl apple pectin, confirming the validity of the general expression obtained for pectins with different degrees of esterification. The anomalous CR value found for low-methoxyl (LM) apple pectin is discussed.

[Treatment of coloured industrial effluents with Pleurotus spp]. / Tratamiento de efluentes industriales coloreados con Pleurotus spp.

The decolouration of fermentation residues (vinasse) and liquid extract of coffee pulp by the mushroom Pleurotus ostreatus was studied in addition to laccase activity. The fungus was inhibited in both residues when they remained undiluted. In submerged cultivation on wastewaters a good production of biomass (14.8 g/l for vinasse and 5.4 g/l for extract of coffee pulp) and also laccase activity (14.1 U/ml for vinasse and 3.0 U/ml for extract of coffee pulp) up to the 10 days of fermentation was observed, being significantly greater in the culture with vinasse. It was shown that treatment with this mushroom reduces both the chemical oxygen demand and the colour, contributing to their biological treatment.

Polygalacturonase and ethanol production in Kluyveromyces marxianus: potential use of polygalacturonase in foodstuffs.

The coproduction of ethanol and polygalacturonase (PG) in a pilot-scale batch fermentor using yeast extract--glucose (YD)--and sugar beet molasses (SBM)-based media was implemented utilizing a new high-PG-producing strain of Kluyveromyces marxianus. A certain growth inhibition was observed in SBM medium, causing ethanol and PG production to be lower. Ethanol productivity and accumulation values of 1.94 g/(L x h) and 40 g/L, respectively, were attained in YD, whereas the best fermentation efficiency (95.1%) was achieved with SBM medium. Maximal PG synthesis occurred at the end of cell growth, with values of 1.08 and 0.46 U/(mg x h) for the YD and SBM media, respectively. When the cultures reached stationary phase, PG production stopped. The highest accumulation level (17 U/mL) occurred in YD medium, in agreement with previous laboratory-scale studies carried out for this strain. The potential applications of the crude enzyme preparations were evaluated with different fruit juices and vegetable slices. The enzyme was able to increase the filtration rate of orange, pear, and apple juices by twofold. Additionally, complete clarification of apple juice was readily accomplished, whereas cucumber, carrot, and banana tissues were macerated to a lesser extent.

Oral administration of an enzymatic protein hydrolysate from the green microalga Chlorella vulgaris enhances the nutritional recovery of malnourished mice.

This study examined the effects of oral administration of an enzymatic protein hydrolysate from green microalga Chlorella vulgaris (Cv-PH) on the nutritional recovery of malnourished Balb/c mice after a 3-day fasting period. Mice were refed with commercial diet supplemented or not supplemented with Cv-PH (500 mg/kg) for 8 days. Regardless of the diet used during refeeding, animal body weights and serum protein concentrations did not differ between groups. Mice given Cv-PH had a significant increase in hemoglobin concentrations. Most serum amino acid levels were similar in the control and Cv-PH animals. Starved mice refed with Cv-PH showed normal liver functions, as judged by liver weight, protein concentration, and the enzymatic activities of cholinesterase and arginase. Cv-PH increased DNA, protein content, and gut-mucosal weight. In addition, brush-border oligosaccharidase activities were also higher in the Cv-PH group. These findings suggest that Chlorella protein hydrolysate can be used to develop specific formulations suitable for pharmacologic nutrition.