Nutritional composition and nutraceutical properties of the Pleurotus fruiting bodies: Potential use as food ingredient

Edible mushrooms as a novel protein source for functional foods

Fast demographic growth has led to increasing interest in low-cost alternative protein sources to meet population needs.

Assessment of speciation and in vitro bioaccessibility of selenium in Se-enriched Pleurotus ostreatus and potential health risks

Due to the two-dimensional effect of selenium (Se) to health, which form of Se is most effective for increasing the bioaccessible Se content in P. ostreatus and whether these products have potential health risks are worth considering. Three Se supplements were applied at different application rates into substrates for cultivating P. ostreatus. The total content and speciation of Se in P. ostreatus fruit bodies were analyzed, and the bioaccessibility of Se was determined via an in vitro physiologically based extraction test (PBET). Results showed that P. ostreatus had the highest utilization efficiency with selenite, followed by Se yeast and selenate. Organic Se (46%-90%) was the major Se speciation in P. ostreatus regardless applied Se species. Although the Se bioaccessibility of the gastrointestinal digestion of P. ostreatus was high (70%-92%), the estimated daily intake and target hazard quotient values are all within the safe ranges. Se-enriched P. ostreatus can be safely used as a dietary source of Se for increasing Se intake.

Polysaccharides of mushroom Pleurotus spp.: New extraction techniques, biological activities and development of new technologies

The biodiversity of mushrooms Pleurotus spp. is impressive due to its complexity and diversity related to the composition of chemical structures such as polysaccharides, glycoproteins and secondary metabolites such as alkaloids, flavonoids and betalains. Recent studies of polysaccharides and their structural elucidation have helped to direct research and development of technologies related to pharmacological action, production of bioactive foods and application of new, more sophisticated extraction tools. The diversity of bioactivities related to these biopolymers, their mechanisms and routes of action are constant focus of researches. The elucidation of bioactivities has helped to formulate new vaccines and targeted drugs. In this context, in terms of polysaccharides and the diversity of mushrooms Pleurotus spp., this review seeks to revisit the genus, making an updated approach on the recent discoveries of polysaccharides, new extraction techniques and bioactivities, emphasising on their mechanisms and routes in order to update the reader on the recent technologies related to these polymers.

Effect of pre-treatment conditions on the antiatherogenic potential of freeze-dried oyster mushrooms

Oyster mushroom (Pleurotus ostreatus L.) is a valuable food product. It possesses an antiatherogenic potential, which has to be preserved during processing. The paper features the production of oyster mushroom sublimates. It focuses on such pre-treatment conditions as grinding, disinfection, and cryostabilisation, and their effect on the antiatherogenic potential of oyster mushrooms. A set of in vitro experiments was performed to measure the levels of lovastatin and antioxidant, catalase, anti-inflammatory, and thrombolytic properties. Various pre-treatment conditions proved to produce different effects on the biological activity of the freeze-dried oyster mushroom product. The best results were obtained after the mushrooms were reduced to pieces of 0.5 cm, underwent UV disinfection, blanched, treated with hot air, and cryostabilised with a 1.5% apple pectin solution. The best conditions for the antioxidant properties included ozonation, UV disinfection, and cryoprotection with pectin. The critical conditions for the antioxidant properties included homogenisation, blanching, and cryostabilisation with 10% solutions of sucrose and lactose. The catalase properties did not depend on the degree of grinding and were most pronounced after ozonation. The optimal conditions for the anti-inflammatory properties included UV disinfection and cryostabilisation with lactose. Ozonation proved to be critical for anti-inflammatory properties. The optimal conditions for thrombolytic properties included ozonation and cryoprotection with a 5% sorbitol solution, while hot air disinfection proved critical. Therefore, the research provided an experimental substantiation for individual pre-treatment conditions or their combinations that turn sublimated oyster mushrooms into a valuable functional product with antiatherogenic properties.

Unusual and Highly Bioactive Sesterterpenes Synthesized by Pleurotus ostreatus during Coculture with Trametes robiniophila Murr

Candida albicans and Cryptococcus neoformans, human-pathogenic fungi found worldwide, are receiving increasing attention due to high morbidity and mortality in immunocompromised patients. In the present work, 110 fungus pairs were constructed by coculturing 16 wood-decaying basidiomycetes, among which coculture of Trametes robiniophila Murr and Pleurotus ostreatus was found to strongly inhibit pathogenic fungi through bioactivity-guided assays. A combination of metabolomics and molecular network analysis revealed that 44 features were either newly synthesized or produced at high levels in this coculture system and that 6 of the features that belonged to a family of novel and unusual linear sesterterpenes contributed to high activity with MICs of 1 to 32 μg/ml against pathogenic fungi. Furthermore, dynamic ¹³C-labeling analysis revealed an association between induced features and the corresponding fungi. Unusual sesterterpenes were ¹³C labeled only in P. ostreatus in a time course after stimulation by the coculture, suggesting that these sesterterpenes were synthesized by P. ostreatus instead of T. robiniophila Murr. Sesterterpene compounds 1 to 3 were renamed postrediene A to C. Real-time reverse transcription-quantitative PCR (RT-qPCR) analysis revealed that transcriptional levels of three genes encoding terpene synthase, farnesyl-diphosphate farnesyltransferase, and oxidase were found to be 8.2-fold, 88.7-fold, and 21.6-fold higher, respectively, in the coculture than in the monoculture, indicating that biosynthetic gene cluster 10 was most likely responsible for the synthesis of these sesterterpenes. A putative biosynthetic pathway of postrediene A to postrediene C was then proposed based on structures of sesterterpenes and molecular network analysis.IMPORTANCE A number of gene clusters involved in biosynthesis of secondary metabolites are presumably silent or expressed at low levels under conditions of standard laboratory cultivation, resulting in a large gap between the pool of discovered metabolites and genome capability. This work mimicked naturally occurring competition by construction of an artificial coculture of basidiomycete fungi for the identification of secondary metabolites with novel scaffolds and excellent bioactivity. Unusual linear sesterterpenes of postrediene A to C synthesized by P. ostreatus not only were promising lead drugs against human-pathogenic fungi but also highlighted a distinct pathway for sesterterpene biosynthesis in basidiomycetes. The current work provides an important basis for uncovering novel gene functions involved in sesterterpene synthesis and for gaining insights into the mechanism of silent gene activation in fungal defense.

Aromatic ginger (Kaempferia galanga L.) extracts with ameliorative and protective potential as a functional food, beyond its flavor and nutritional benefits

Aromatic ginger (Kaempferia galanga L) is native to India and believed to be originated in Burma. Despite substantial uses in a pickle and south-east Asian cuisines, aromatic ginger is chemically less studied than white and red ginger. Multi-directional investigations have been performed to evaluate chemical composition, nutritional values, ameliorative and protective potential of aromatic ginger (Kaempferia galanga) rhizome (KGR). Macro and micro components analysis confirmed that KGR contains protein, fiber, and high amount of essential minerals (potassium, phosphorous, and magnesium) along with appreciable amounts of iron, manganese, zinc, cobalt, and nickel. The anti-proliferative potential of KGR evaluated nine human cell lines. We have evaluated the anti-proliferative potential of hydrodistillate, extract, and key compound isolated from KGR on nine human cancer cell line and also reporting the safety to normal peritoneal macrophage cells. The current study demonstrates the anticancer potential of the KGR on MDA-MB-231 and WRL-68 cells. Very likely, results can be extrapolated to an animal or human system. Ethyl p-methoxy cinnamate (EPMC) was responsible for inhibiting the proliferation action which varied in a tested cell by intracellular reactive oxygen species (ROS) production. The present study demonstrates KGR as safe and high energy value medicinal spices with chemo-preventive action, without toxic phytochemicals, and tolerable other anti-nutritional factors.

The hepatoprotective effect of polysaccharides from Pleurotus ostreatus on carbon tetrachloride-induced acute liver injury rats

This study was conducted to evaluate the hepatoprotective effect of polysaccharides from Pleurotus ostreatus (POP) on carbon tetrachloride-induced acute liver injury (ALI) in rats. The hepatoprotective effect of POP against ALI was reflected by the decreased alanine transaminase and aspartate transaminase levels in blood, increased superoxide dismutase, catalase, and glutathione peroxidase levels, and decreased malondialdehyde levels in blood and liver. TUNEL and immunohistochemistry analyses showed that TUNEL apoptosis cell rate and Bax, cytochrome C, caspase-3, caspase-9, and apoptosis-inducing factor expression levels were obviously decreased, whereas Bcl-2 expression levels obviously increased after POP treatment. A total of 11 metabolites belonging to energy, amino acid, fatty acid, and gut bacteria metabolism were identified as biomarkers by using metabolite analysis of liver homogenate based on ultra-performance liquid chromatography-tandem mass spectrometry. POP exhibited hepatoprotective effects on CCl₄-induced ALI, and the underlying mechanism is correlated with antioxidants that regulate metabolic pathway disorders and alleviate liver mitochondria apoptosis.

Toward an Increased Functionality in Oyster ( Pleurotus) Mushrooms Produced on Grape Marc or Olive Mill Wastes Serving as Sources of Bioactive Compounds

Pleurotus ostreatus, P. eryngii, and P. nebrodensis were cultivated on nonconventional substrates containing grape marc (GMC) or olive mill byproducts (OMB); wheat straw (WHS) served as control. GMC-based media demonstrated equal/better mushroom productivity than WHS for P. eryngii and P. nebrodensis, while the cultivation performance of P. eryngii was improved in OMB-based media. Both GMC and OMB substrates led to large increase of fruit-bodies content in phenolic acids, resveratrol, triterpenic compounds, and ergosterol; in particular, P. eryngii mushrooms presented significantly more total phenolics and exhibited much higher antioxidant activity (2- to 8-fold increase). Furthermore, substrates containing GMC or OMB presented up to 27% increase in mushroom β-glucans. Overall, Pleurotus species responded in a different and mostly substrate-specific manner by selectively absorbing organic compounds. Phenolics and squalene content of substrates correlated very well with mushrooms antioxidant activity and ergosterol, respectively; the same was observed for triterpenics' content of substrates and mushrooms.

Yield, Nutritional Content, and Antioxidant Activity of Pleurotus ostreatus on Corncobs Supplemented with Herb Residues

Improper disposal of herb residues in China has caused severe problems to the surrounding environment and human safety. Three herb residues, i.e., compound Kushen injection residues (CKI) and part one and part two of Qizhitongluo Capsule residues (QC1 and QC2, respectively), were used for the cultivation of Pleurotus ostreatus. The effect of the supplementation of corncobs (CC) with different herb residues on yield, nutritional composition, and antioxidant activity of P. ostreatus was investigated. Compared to the control, the higher mycelial growth rate was observed on substrates CC +30% CKI and CC +30% QC1, while the higher yield was obtained from substrates CC +30% QC2 and CC +30% CKI. Moreover, chemical analysis of fruit bodies revealed that the addition of herb residues to CC significantly increased proteins, amino acids, ashes, minerals (Na and Ca), and total phenolic contents but significantly reduced carbohydrates and IC50 values of DPPH radicals. In addition, no heavy metals (Pb, Cd, and As) were detected in the fruiting bodies harvested from different substrate combinations. These results demonstrated that mixtures of CC with herb residues might be utilized as a novel, practical, and easily available substrate for the cultivation of P. ostreatus, which is beneficial for the effective management of herb residues.

Circular reuse of bio-resources: the role of Pleurotus spp. in the development of functional foods

The basidiomycetes fungi belonging to the genus Pleurotus could make an important contribution to sustainable functional food design because they possess an elevated protein content with a valuable essential amino acid scoring pattern, a unique dietary fibre profile, mainly comprised of branched β-glucan, high levels of some vitamins of the B group, vitamin D, Fe, Zn, Cu, Se and some bioactive mycochemicals, while the Na and fat contents are low. Moreover, Pleurotus spp. can grow efficiently on various clean by-products of food processing, such as wheat straw, wheat stalk and spent beer grain, thus representing a sustainable food source. This review illustrates the compositional variability of Pleurotus spp. grown on various by-products, in order to clarify its potential ability to address the needs of populations with endemic nutritional deficiencies as well as those populations at risk or affected by some chronic diseases. The perspectives for Pleurotus applications in functional foods decisively depend on consumers' acceptability. Hence, the sensory properties of Pleurotus spp. are also clarified herein. Lastly, the three main strategies of functional food development using Pleurotus spp. are summarized, namely its use as a fortifying agent, high-cost protein replacer and prebiotic ingredient.

Mycochemical Changes Induced by Selenium Enrichment in P. ostreatus Fruiting Bodies

The effects of selenium enrichment on the biological efficiency, phenolic compounds, amino acid profile, antioxidant capacity, and cellular antioxidant activity (CAA) were evaluated in Pleurotus ostreatus fruiting bodies (FB) harvested during three sequential flushes. Sodium selenate was used to reach selenium content of 17.5 or 5.8 mg/kg in the sorghum straw substrate. Biological efficiency and total selenium content increased. One of the main differences among treatments was in ergothioneine content, an indicator of oxidative stress that was positively related with valine and isoleucine contents and negatively related to leucine and phenylalanine. Besides ergothioneine, nucleosides derived from adenine and uracyl were the major peaks observed in all treatments, and coumaric and ferulic acids were found in the bound phenolics extract. Selenium enrichment also affected the antioxidant capacity, and particularly the methanolic extract obtained from the second flush of FB cultivated in selenium-enriched substrate (17.5 mg/kg) had the best CAA.