Mini-review on edible mushrooms as source of dietary fiber: Preparation and health benefits

Agaricus brasiliensis (sun mushroom) affects the expression of genes related to cholesterol homeostasis

PURPOSE

The sun mushroom (Agaricus brasiliensis) is considered a major source of bioactive compounds with potential health benefits. Mushrooms typically act as lipid-lowering agents; however, little is known about the mechanisms of action of A. brasiliensis in biological systems. This study aimed to determine the underlying mechanism involved in the cholesterol-lowering effect of A. brasiliensis through the assessment of fecal and serum lipid profiles in addition to gene expression analysis of specific transcription factors, enzymes, and transporters involved in cholesterol homeostasis.

METHODS

Twenty-four albino Fischer rats approximately 90 days old, with an average weight of 205 g, were divided into four groups of 6 each and fed a standard AIN-93 M diet (C), hypercholesterolemic diet (H), hypercholesterolemic diet +1 % A. brasiliensis (HAb), or hypercholesterolemic diet +0.008 % simvastatin (HS) for 6 weeks. Simvastatin was used as a positive control, as it is a typical drug prescribed for lipid disorders. Subsequently, blood, liver, and feces samples were collected for lipid profile and quantitative real-time polymerase chain reaction gene expression analyses.

RESULTS

Diet supplementation with A. brasiliensis significantly improved serum lipid profiles, comparable to the effect observed for simvastatin. In addition, A. brasiliensis dietary supplementation markedly promoted fecal cholesterol excretion. Increased expression of 7α-hydroxylase (CYP7A1), ATP-binding cassette subfamily G-transporters (ABCG5/G8), and low-density lipoprotein receptor (LDLR) was observed following A. brasiliensis administration.

CONCLUSIONS

Our results suggest that consumption of A. brasiliensis improves the serum lipid profile in hypercholesterolemic rats by modulating the expression of key genes involved in hepatic cholesterol metabolism.

Proteomics of edible mushrooms: A mini-review

Mushrooms are considered an important food for their traditionally famous nutritional and medicinal values, although much information about their potential at the molecular level is unfortunately unknown. Edible mushrooms include fungi that are either collected wild or cultivated. Many important species are difficult to cultivate but attempts have been made with varying degrees of success, with the results showing unsatisfactory economical cultivation methods. Recently, proteomic analysis has been developed as a powerful tool to study the protein content of fungi, particularly basidiomycetes. This mini-review article highlights the contribution of proteomics platforms to the study of edible mushrooms, focusing on the molecular mechanisms involved in developmental stages. This includes extracellular and cytoplasmic effector proteins that have potential or are involved in the synthesis of anticancer, antidiabetic, antioxidant, and antibiotic, in blood pressure control, in the supply of vitamins and minerals, and in other responses to environmental changes. The contribution of different proteomics techniques including classical and more advanced techniques is also highlighted.

Heavy metals determination in edible wild mushrooms growing in former mining area - Slovakia: Health risk assessment

The aim of the paper is to assess a contamination level of forest substrates and aboveground parts of edible wild mushroom (M. procera (Scop.) Singer, B. recitulatus Schaeff., C. cibarius Fr., S. grevillei (Klotzsch) Singer, A. campestris L., R. xerampelina (Schaeff.) Fr., L. salmonicolor R. Heim & Leclair, C. gibba (Pers. Ex Fr.) Kumm., X. chrysenteron (Bull.) Quél., M. oreades (Bolton) Fr.; n = 70) by heavy metals (Cd, Cu, Pb and Zn). The studied location was a broader surroundigs of the historical mining and metal processing area of Banská Bystrica. The collected mushroom samples and underlying substrate samples were analysed using Flame Atomic Absorption Spectrofotometry and Flame Absorption Spectrophotometry with graphite furnace. Bioaccumulation factors (BAF) for individual species and their anatomical parts were calculated from the results obtained. In order to assess a health risk resulting from regular consumption of the mushrooms, provisional tolerable weekly intake (PTWI) was calculated from the results of the monitored heavy metal concentration. Limit values for the studied contaminants (Cd: 0.49 mg.kg-1 and Pb: 1.75 mg.kg-1 for an individual with an average weight of 70 kg) are defined by FAO and WHO. Our results indicate that S. grevillei has a high bioaccumulation ability of Cd. It was confirmed by bioaccumulation factors (BAFH = 3.47 and BAFRFB = 2.30). The PTWICd value was exceeded by 4.11 times. A similar situation occurred in the case of Pb where the highest bioaccumulation factor (BAFH = 0.24 and BAFRFB = 0.19) was also recorded in the samples of S. grevillei and the PTWIPb value was exceeded by 1.35 times. In general, it can be stated that a consumption of edible wild mushrooms represent a relatively small risk of negative impact on the health of consumers.

Modulation of Cholesterol-Related Gene Expression by Dietary Fiber Fractions from Edible Mushrooms

Mushrooms are a source of dietary fiber (DF) with a cholesterol-lowering effect. However, their underlying mechanisms are poorly understood. The effect of DF-enriched fractions from three mushrooms species on cholesterol-related expression was studied in vitro. The Pleurotus ostreatus DF fraction (PDF) was used in mice models to assess its potential palliative or preventive effect against hypercholesterolemia. PDF induced a transcriptional response in Caco-2 cells, suggesting a possible cholesterol-lowering effect. In the palliative setting, PDF reduced hepatic triglyceride likely because Dgat1 was downregulated. However, cholesterol-related biochemical data showed no changes and no relation with the observed transcriptional modulation. In the preventive setting, PDF modulated cholesterol-related genes expression in a manner similar to that of simvastatin and ezetimibe in the liver, although no changes in plasma and liver biochemical data were induced. Therefore, PDF may be useful reducing hepatic triglyceride accumulation. Because it induced a molecular response similar to hypocholesterolemic drugs in liver, further dose-dependent studies should be carried out.

Nutritional value and proteases of Lentinus citrinus produced by solid state fermentation of lignocellulosic waste from tropical region

This paper examined the growth and yield performance of Lentinus citrinus on cupuaçu exocarp (Theobroma grandiflorum) mixed with litter (CE + LI) or rice bran (Oryza sativa) (CE + RB) in the ratio of 2:1 (800 g:200 g) to investigate the nutritional composition and proteolytic potential of the fruiting body produced. Significance values of yield were determined on substrate combinations. In CE + LI the biological efficiency of the mushrooms was 93.5% and the content of fat (4.5%), fiber (11.0%), protein (27.0%) and amino acids were higher when compared with CE + RB. Among the amino acids, the amount of glutamic acid, aspartic acid, alanine, arginine and leucine was high. The biological efficiency on CE + RB reduced to 84.2% and based on the nutritional value, carbohydrates (53.59%), energy (324.33 kcal) and minerals such as zinc, iron, copper, potassium and phosphorus were higher in this substrate combination. Protease activity from fruiting body was significant in CE + LI (463.55 U/mL). This protease showed an optimal activity at 50 °C in neutral and alkaline pH with maximum stability at 30 °C at alkaline pH. This is the first report of L. citrinus fruiting body nutritional composition with potential for human food and application in industrial processes.

Mushroom dietary fiber from the fruiting body of Pleurotus tuber-regium: fractionation and structural elucidation of nondigestible cell wall components

The cell wall of mushroom fruiting body is constituted of nondigestible macromolecules that are a rich source of dietary fiber with biological functions that are beneficial to human health. The cell wall components of an edible mushroom fruiting body from Pleurotus tuber-regium (PTR) were fractionated, and their chemical structures were investigated by chemical, physicochemical, and microscopic analyses. The present results suggest that the cell wall of the PTR mushroom fruiting body contains four main fractions: an outer fraction of polysaccharide and protein complex, which can be extracted using boiling water; a cold alkali-soluble fraction of heteropolysaccharides associated with a small amount of proteins; a hot alkali-soluble fraction of hyper-branched glucans; and an alkali-insoluble fraction of glucan-chitin complex with a normalized relative percentage of 3.6:21.9:55.7:18.8. The anomeric linkage of all the glucans was revealed by infrared spectroscopy to be β type. The structure of the major mushroom fruiting body cell wall polysaccharide (the hot alkali-soluble one, FHA-I) was elucidated by the methylation analysis to be composed of →1)-Glcp-(4→ linkages as the backbone with a 52% degree of branching consisting of →1)-Glcp-(6→ linkages in the side chains, whereas some →1)-Glcp-(3→ linkages might exist in the backbone or side chains. Size exclusion chromatography coupled with multiangle laser light scattering analysis revealed that FHA-I had a molecular weight of 4.224 × 10(6) g/mol and a root-mean-square radius of 30.4 nm. Both scanning electron and atomic force microscopy further showed the highly branched microstructure of FHA-I when dispersed in an aqueous sodium dodecyl sulfate solution.