Pleurotus eryngii (King Oyster Mushroom): A Comprehensive Reference
1. Identity and Taxonomy
Scientific Name and Classification
Pleurotus eryngii (DC.:Fr.) Quél. is a basidiomycete fungus belonging to the family Pleurotaceae. It is also known by a variety of common names, including king trumpet mushroom, French horn mushroom, eryngi, king oyster mushroom, king brown mushroom, boletus of the steppes, trumpet royale, and ali'i oyster, and it is an Old World species of fungus.
Botanical and Ecological Character
The species name is derived from the fact that it grows in association with the roots of Eryngium campestre or other Eryngium plants (English names: 'sea holly' or 'eryngo'). Unlike other species of Pleurotus, which are primarily wood-decay fungi, the P. eryngii complex are also weak parasites on the roots of herbaceous plants in the carrot family, although they may also be cultured on organic wastes. Pleurotus eryngii is described as a "complex species" due to the significant variations in the morphology, isozymes, and genetic characteristics between specimens, which are derived from geographical and ecological differences in their environment.
Varieties
P. eryngii is a species complex and a number of varieties have been described, with differing plant associates in the carrot family. Recognized varieties include:
- Pleurotus eryngii var. eryngii (DC.) Quél 1872 — associated with Eryngium spp.
- Pleurotus eryngii var. ferulae (Lanzi) Sacc. 1887 — associated with Ferula communis
- Pleurotus eryngii var. tingitanus Lewinsohn 2002 — associated with Ferula tingitana; and Pleurotus eryngii var. elaeoselini Venturella, Zervakis & La Rocca 2000 — associated with Elaeoselinum asclepium
- Pleurotus eryngii var. thapsiae Venturella, Zervakis & Saitta 2002 — associated with Thapsia garganica
Morphology and Natural Source
These edible mushrooms originate from the Mediterranean and are easily cultivated in many parts of Europe for edible purposes. P. eryngii is cultivated widely, and its production has been increasing in Asia, including Japan. P. eryngii is considered to be a health food because it is low in fat and calories but rich in amino acids, vitamins, and dietary fiber.
Common Forms and Preparations
The consumption of these fungi has rapidly increased in recent decades, not only thanks to their nutritional properties and pleasant flavor, but also for their bioactive and medicinal properties. In commerce and research, P. eryngii is available and studied in multiple forms, including: dried and powdered fruiting body preparations; hot-water or hydroalcoholic extracts; polysaccharide fractions isolated from fruiting bodies or mycelium; lyophilized (freeze-dried) powder; UV-irradiated preparations for enhanced vitamin D2; and encapsulated nutraceutical formats. Encapsulation techniques allow whole cells, nutrients, or bioactive molecules to be enclosed within protective matrices, shielding bioactive compounds from adverse environmental conditions and enhancing their stability and bioavailability.
2. Traditional and Historical Use
Pleurotus eryngii (DC. ex Fr.) Quél. has been collected from the wild, cultivated and used in traditional medicines to treat various disorders and diseases since antiquity. In traditional Chinese medicine, the powdered fruiting bodies of Pleurotus eryngii were used for immunostimulation, skin-care, wound-healing, cancer and lumbago treatment.
P. eryngii has been used for centuries in Korea as both a food and a traditional medicine. It contains little fat and digestible carbohydrates, but has higher protein content than most vegetables, and has been reported to have anti-microbial, anti-oxidant, and anti-atherosclerotic properties.
Since ancient time, mushrooms generally played a diverse role in human history for mycolatry, mycophagy and as medicine in folklore and religion. It has been suggested that several human diseases can be treated with extracts from edible mushrooms, as these extracts have biological effects including anticancer, antidiabetic, antiviral, antioxidant, hepatoprotective, immune-potentiating, and hypo-cholesterolemic influences, and many Asian and western countries consider mushrooms as panacea for a large number of diseases and utilize them for consumption as a gourmet food for taste as well as flavor.
Since ancient times, edible fungus has been regarded as a necessary food in many countries due to its unique flavor and delicious taste. Edible fungus is listed in the top ten functional foods in the world for its balanced nutrition, high protein, low fat, and rich dietary fiber, and it can supply the nutrients needed by the body.
3. Key Constituents and Active Compounds
Overview of Chemical Composition
Pleurotus eryngii is a nutritionally rich and pharmacologically potent edible fungus, containing high-quality proteins, vitamins, minerals, and diverse bioactive compounds such as polysaccharides, phenolics, terpenoids, and lovastatin-like molecules. Pleurotus species are rich in proteins (approximately 20–30% dry weight), essential amino acids, dietary fiber (approximately 10–25%), vitamins (B-complex, D2), and minerals, while remaining low in fat and calories.
Polysaccharides and β-Glucans
Among the most important compounds found in P. eryngii, there are certainly polysaccharides, especially α- and β-glucans, but also heteroglycans, peptidoglycans, and polysaccharide-protein complexes. Although commonly described as (1→3)-β-glucans with varying degree of (1→6)-branching, the fungal β-glucans constitute a diverse polysaccharide class. The linear (1→6)-β-glucan, branched (1→3)-β-glucan, 3-O-methylated heterogalactan, and heteropolysaccharides have been extracted and purified from P. eryngii fruiting bodies.
Although composition is rich in several compounds that have positive biological effects (dietary fiber, phenolic compounds, bioactive peptides, and triterpenes), β-glucans have been the main target of discussion regarding health-promoting effects. Apart from polyphenols, other important functional components isolated from edible mushrooms include β-glucans, which have demonstrated hypocholesterolemic, antidiabetic, and anticarcinogenic properties, as well as positive effects on the immune system.
Phenolic Compounds
From the analysis of the phenolic profile it has emerged that ferulic acid, gallic acid, epicatechingallate (ECG) and epigallocatechin gallate (EGCG) are the most present compounds, and the presence of gallic acid and EGCG confirms the remarkable antioxidant properties of all P. eryngii isolates studied. Research has concluded that P. eryngii had the highest contents of phenolic compounds among seven Pleurotus species. Among phenolic compounds, ferulic acid was dominant in both analyzed Pleurotus species.
Terpenoids and Sterols
The chemical structure composition of mycochemicals from P. eryngii includes a diterpenoid named eryngiolide A and triterpenoids, i.e., bisabolane-type sesquiterpenes and sterols based on the cyclopentane perhydrophenanthrene ring system such as ergosterol and ergosterol-type derivatives, and ergostane-type sterols as strophasterols E and F, as well as pentacyclic triterpenoids.
Ergothioneine and Lovastatin
These fungi produce varied bioactive compounds, including β-glucans, polysaccharides, phenolics, flavonoids, ergothioneine, and lovastatin, which are related with antioxidant, antimicrobial, anti-inflammatory, antidiabetic, immunomodulatory, and anticancer activities. The presence of lovastatin, a member of the statins family that lowers TC and LDL levels and reduces the risk of coronary heart disease, and the antioxidants ergothioneine and selenium have been detected in relatively high amounts in P. eryngii.
Other Secondary Metabolites
Chemical analyses of P. eryngii extracts have revealed a diverse range of secondary metabolites belonging to different classes, including flavonoids, organic acids, amino acids, carbohydrates, vitamins, nucleic acids, fatty acids, and triterpenoids. HPLC analysis of P. eryngii polysaccharides revealed that glucose (75.23%), galactose (4.96%), glucuronic acid (1.38%), ribose (0.94%), rhamnose (2.35%), and mannose (3.87%) are the main monosaccharide components.
4. Established Mechanisms of Action
Immunomodulation via β-Glucan Receptors
Polysaccharides of P. eryngii are mainly responsible for immunomodulatory effects by binding to specific membrane receptors, stimulating specific inflammatory responses. β-glucan isolated from P. eryngii increased cellular levels of TNF-α, IL-1β, and IL-6, and real-time PCR array revealed that the expression levels of NF-κB and Toll-like receptor signaling genes in cells were upregulated; moreover, the expression of the β-glucan receptor dectin-2 was significantly upregulated, reflecting immune activation through the dectin-2-Syk-(CARD9/Bcl-10/MALT1) pathway.
Antioxidant Mechanisms
The antioxidant activity of polysaccharides is of particular interest as numerous studies have highlighted their ability to reduce oxidative stress induced by an excessive production of reactive oxygen species (ROS); through this property, polysaccharides could mitigate the toxicity associated with ROS overexpression and provide a potential therapeutic approach in the prevention of various diseases.
Anti-inflammatory Pathways
In vitro studies have demonstrated that the antiallergic activity of P. eryngii is caused by the downregulation of allergy-related signaling proteins by inhibition of the nuclear factor of activated T cells, nuclear factor-κB (NF-κB), and high-affinity immunoglobulin E receptor (FcεRI) mediated signaling in antigen-stimulated mast cells. A study found that ergothioneine from Pleurotus mushrooms lowered protein expression of TLR4, MyD88, and NF-κB p65.
Antitumor and Apoptotic Pathways
High molecular mass polysaccharide fractions from P. eryngii exhibited stronger growth inhibition against human hepatoblastoma HepG-2 cells, with flow cytometric analysis showing a stimulatory effect on apoptosis of HepG-2 cells, inducing cell-cycle arrest at the S-phase and intracellular ROS production, suggesting that polysaccharides are important nutritional ingredients responsible for the anticancer health benefits of P. eryngii.
Hypolipidemic Mechanisms
Polysaccharides from P. eryngii can inhibit the weight of obese mice and regulate the levels of hypolipidemic metabolites such as triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and free fatty acids (FFA), though research on the associated functional mechanisms is not yet fully elucidated. Polysaccharides purified from P. eryngii inhibit lipid accumulation in foam cells.
5. Scientific Evidence by Area of Use
5.1 Immune Modulation and Antitumor Activity
In vitro and animal evidence: One water-soluble polysaccharide (PEPw), with an average molecular weight of 2.5×104 Da, was isolated from the fruiting bodies of Pleurotus eryngii and evaluated for antitumor and immunomodulatory activity. Animal experiment results showed that PEPw significantly increased relative thymus and spleen indices, promoted spleen lymphocyte proliferation induced by ConA or LPS, elevated the activities of NK cells and CTL in spleen, and increased the serum concentration of TNF-α and IL-2 in Renca tumor-bearing mice; as a result, tumor growth was significantly inhibited by PEPw treatment at the doses of 50, 100, and 200 mg/kg in a dose-dependent manner.
One study concluded that Pleurotus eryngii fruiting bodies powder has a potential application as a natural antitumor agent with immunomodulatory activity, proposedly by targeting the lysosomes of cancerous cells and stimulating macrophage-mediated immune responses.
A β-1,6-glucan fraction (APEP-A-b) at doses of 100 or 200 mg/kg·d significantly increased proliferation of splenocytes stimulated with LPS or ConA, consistent with previous reports that suggest the commonality of P. eryngii polysaccharides in modulating immunity; in previous studies, the dose range from 50 to 800 mg/kg·d of P. eryngii polysaccharides was employed for stimulation of the immune system in mice.
Evidence strength: The immunomodulatory and antitumor evidence base for P. eryngii remains predominantly in vitro (cell culture) and in vivo (rodent) in nature. Recent studies have revealed the crucial role of several edible mushrooms and fungal compounds, mainly polysaccharides, in human health and disease, and the investigation of the immunomodulating effects of mushroom polysaccharides, especially β-glucans, and the link between their anticancer and immunomodulatory properties with their possible prebiotic activity on gut micro-organisms has been the subject of intense research over the last decade. No controlled human clinical trials specifically evaluating the antitumor or immunostimulant activity of P. eryngii as a single agent have been identified; evidence at the human level is therefore absent or very preliminary.
5.2 Metabolic Health: Glucose Regulation and Anti-Obesity
Clinical (human) evidence: A randomized controlled trial (RCT) examined the effects of a Pleurotus eryngii mushroom snack on metabolically unhealthy patients; after harvest, mushrooms were baked and subjected to UV-B irradiation to enhance vitamin D2 content; the trial was conducted for three months with two arms; both groups received conventional nutritional counseling for metabolic disorders, while the intervention group also had to consume the snack daily.
One hundred patients consented and were randomized; compared to the control group, snack consumption regulated glucose levels and reduced body weight, fat, waist and hip circumferences; 25(OH)D2 increased significantly in the intervention group; the levels of LDL and SGOT were lower only in the intervention group; levels of IL-6 and ox-LDL decreased in the mushroom group, while overall physical health increased; these findings suggest potential antidiabetic, antiobesity, anti-inflammatory and antioxidant health benefits of the snack to metabolically unhealthy individuals.
To the best of the investigators' knowledge, this study is the first to demonstrate that P. eryngii mushrooms regulate inflammation and oxidative stress in humans. However, a key caveat is that the snack was UV-irradiated for additional vitamin D2, making it difficult to attribute outcomes solely to P. eryngii constituents per se.
Animal evidence: Through experiments, it was found that oral administration of Pleurotus eryngii polysaccharide (PEP) could inhibit the weight gain of mice and cause a decrease in plasma insulin levels, serum glycerol lipids, cholesterol, low-density lipoproteins, and the level of fasting blood glucose in mice, thereby controlling the lipid level of mice and playing a role in preventing the occurrence of cardiovascular and cerebrovascular diseases.
Evidence strength: There is a single published RCT at the human level, with promising findings for metabolic parameters. The confounding presence of vitamin D2 supplementation in the intervention product limits attribution of effects specifically to P. eryngii bioactives. While there is a variety of literature on the cardioprotective activities of P. eryngii extracts in vitro, as well as in animal studies, no human clinical trials exclusively addressing cardiovascular parameters had been identified as of 2022. Animal and in vitro evidence in this domain is substantial but human data remain limited to one RCT with methodological caveats.
5.3 Lipid-Lowering and Cardiovascular Effects
Animal evidence: The feeding of 5% powder of the fruiting bodies of Pleurotus eryngii to hypercholesterolemic rats reduced their plasma total cholesterol, triglyceride, low-density lipoprotein, total lipid, phospholipids, and LDL/HDL ratio by 24.05%, 46.33%, 62.50%, 24.63%, 19.22%, and 57.14%, respectively, and the mushroom also significantly reduced body weight in hypercholesterolemic rats.
Experiments demonstrated that both acidic and alkaline extracts of mycelial polysaccharides from the mycelium of Pleurotus eryngii significantly increased HDL-C levels and lowered serum levels of LDL-C, VLDL-C, TC, and TG, thereby alleviating dyslipidemia.
Evidence strength: Hypolipidemic effects have been demonstrated consistently in animal models; direct human clinical evidence is absent. The detection of lovastatin-like molecules in P. eryngii provides a plausible mechanistic hypothesis, but the quantities present in food or typical supplement preparations relative to pharmaceutical-grade lovastatin have not been established in controlled human pharmacokinetic studies.
5.4 Anti-inflammatory and Antiallergic Activity
In vivo (animal) evidence: Intranasal instillation of LPS induced marked lung inflammation in mice, and mice administered heat-treated P. eryngii (0.3–1 g/kg, orally) 1 h before LPS challenge showed decreased pulmonary inflammation and ameliorated histopathological damage; these results suggest that heat-treated P. eryngii has anti-inflammatory effects against acute lung injury, and that P. eryngii could be a beneficial food for the prevention of acute lung injury induced by bacterial infection.
In a mouse model of atopic dermatitis, continuous treatment with P. eryngii extracts (PEE) inhibited the development of AD-like skin lesions; PEE suppressed dermatitis severity, serum level of IgE and thymus and activation-regulated chemokine (TARC), and mRNA expression of TNF-α, INF-γ, IL-4, IL-5, and IL-13; PEE also reduced thickness of the dermis and dermal infiltration of inflammatory cells and mast cells; these results indicate that PEE inhibits allergic contact dermatitis through the modulation of Th1 and Th2 responses.
Evidence strength: All anti-inflammatory evidence is from in vitro or animal models. Whether P. eryngii has clinical effectiveness in inflammatory or allergic conditions remains to be determined.
5.5 Antioxidant Activity
Evidence: P. eryngii exhibits a variety of pharmacological activities and important nutritional value, and has gained a great deal of research attention in recent years due to its antioxidant, immunoregulatory, antihyperlipidemic, and other activities. Polysaccharides derived from Pleurotus eryngii possess various bioactive properties, including antioxidant, antidiabetic, anti-inflammatory, and immunomodulatory effects. The antioxidant properties have been primarily established in vitro through DPPH scavenging assays and ex vivo enzymatic assays. The RCT by Kleftaki et al. (2022) found reduced ox-LDL in the mushroom group, providing the sole human-level signal for antioxidant bioactivity.
5.6 Gut Microbiota and Prebiotic Activity
Lyophilized Pleurotus eryngii mushrooms, selected due to their strong lactogenic effect and anti-genotoxic, immunomodulatory properties, underwent in vitro static batch fermentation for 24 h by fecal microbiota from eight elderly apparently healthy volunteers (>65 years old); fermentation-induced changes in fecal microbiota communities were examined using Next Generation Sequencing of the hypervariable regions of the 16S rRNA gene. These findings suggest that the prebiotic effects of Pleurotus mushrooms may help improve intestinal dysbiosis and protect against inflammatory bowel disease.
Evidence strength: The prebiotic/gut microbiota research is currently at the in vitro fermentation stage. No controlled clinical trials evaluating specific microbiome changes in human subjects given P. eryngii supplements have been published as of the available literature. The evidence is preliminary.
5.7 Neuroprotective Activity
The neuroprotective effects of mushrooms have been investigated in neurodegenerative diseases, particularly Alzheimer's disease; AD is characterized by atrophy of the cerebral cortex and synaptic degeneration resulting from neuronal death, leading to impairments in motor, psychological, and memory functions. Components of P. eryngii contribute to a broad spectrum of biological effects, including neuroprotective activities. However, neuroprotective evidence for P. eryngii specifically is confined to cell and animal studies; no human clinical data were identified in the available literature.
5.8 Antimicrobial Activity
Both varieties of P. eryngii possess significant antimicrobial properties, which can be attributed to their unique phytochemical profiles rich in bioactive compounds; chemical analyses revealed a diverse range of constituents, including organic acids, fatty acids, amino acid derivatives, known for their health benefits and antimicrobial effects; the extracts exhibited varying degrees of effectiveness against a spectrum of microbial strains. The potential antimicrobial activity of extracts was tested against phytopathogenic bacteria (including Clavibacter michiganensis, Bacillus megaterium, Pseudomonas viridiflava, Xanthomonas campestris, and Escherichia coli) and fungi (Aspergillus fumigatus, Penicillium italicum, among others); both extracts demonstrated antimicrobial activity against the most tested microorganisms.
Evidence strength: Antimicrobial studies are currently limited to in vitro and agricultural applications. Clinical (human) evidence for any antimicrobial indication is absent.
6. Body Systems and Health Areas Associated with Pleurotus eryngii
Based on the peer-reviewed research surveyed, the body systems and health domains associated with P. eryngii research include:
- Immune system: Macrophage activation, NK cell stimulation, lymphocyte proliferation, cytokine modulation (TNF-α, IL-2, IL-6, IL-1β)
- Cardiovascular system: Cholesterol and lipid regulation, antihyperlipidemic effects, inhibition of foam cell lipid accumulation
- Metabolic system: Blood glucose regulation, insulin level modulation, anti-obesity effects, adipose tissue reduction
- Gastrointestinal system: Dietary fiber content, prebiotic fermentation, gut microbiota modulation
- Dermatological / allergic system: Inhibition of IgE-mediated mast cell responses, Th1/Th2 balance modulation in atopic dermatitis models
- Pulmonary system: Anti-inflammatory effects in acute lung injury models
- Neurological system: Preliminary neuroprotective and anti-neuroinflammatory activity in cell and animal models
- Hepatic system: Hepatoprotective effects identified in animal studies
Several medicinal and therapeutic properties have been conferred on the Pleurotus genus, such as regulation of the intestinal flora, antioxidant and anti-inflammatory activities, anticancer, and modulation of immune response. Reviews have summarized that mushrooms of the genus Pleurotus have antihypertensive, antihypercholesterolemic, antiatherogenic, antihyperlipidemic, antioxidant, anti-inflammatory, antihyperglycemic, and antiviral properties.
7. Dosage Forms and Reported Dosages
The dosages below are reported directly from identified research sources and are not recommendations.
Animal Studies
- Antitumor polysaccharide (PEPw): Doses of 50, 100, and 200 mg/kg body weight in tumor-bearing mice, administered in a dose-dependent manner.
- Immunostimulatory polysaccharides: A dose range from 50 to 800 mg/kg·d of P. eryngii polysaccharides was employed for stimulation of the immune system in mice, with specific evaluations at 100, 200, and 500 mg/kg·d.
- Heat-treated P. eryngii for anti-inflammatory effects: Doses of 0.3–1 g/kg orally in mice, administered 1 h before inflammatory challenge.
- Hypolipidemic effect in rats: 5% powder of the fruiting bodies of P. eryngii incorporated into the diet of hypercholesterolemic rats.
Human Clinical Studies
- Randomized controlled trial in metabolically unhealthy patients: Baked and UV-B irradiated P. eryngii mushroom snack consumed daily for three months; both groups also received conventional nutritional counseling. The specific gram weight of the snack per serving was not extractable from the available search results.
Preparation Notes
A bioactive Pleurotus eryngii aqueous extract powder (SPAE) obtained by spray drying exhibited a more uniform particle size distribution than crude P. eryngii polysaccharide (PEP), with higher antioxidant abilities and superior resistance to digestion in vitro. Notably, none of the clinical studies reviewed in one systematic evaluation utilized the technological development of nutraceuticals using Pleurotus mushrooms, highlighting a critical gap in the development of nutraceutical formulations.
8. Safety Considerations and Known Interactions
General Safety of Commercially Cultivated Pleurotus eryngii
Cultivated Pleurotus spp. have been analyzed for their diverse elemental content, revealing differences in accumulation patterns and no health risks associated with consumption; commercially available Pleurotus mushrooms (including P. eryngii) collected from their producers between 2009 and 2015 do not induce health risks to consumers due to their multi-element content.
A study on P. pulmonarius grown in oil-contaminated soil revealed hydrocarbon levels exceeding the non-cancer daily reference dose, rendering it unsafe for human consumption — a finding that underscores the significance of the substrate on which Pleurotus species are cultivated when assessing safety of the final mushroom product.
Occupational Inhalation Allergy / Hypersensitivity Pneumonitis
Pleurotus eryngii is among the mushrooms associated with hypersensitivity pneumonitis resulting from inhalation of mushroom spores. A potential increased risk has been reported of hypersensitivity pneumonitis in complementary medicine practitioners who handle exotic mushroom varieties; asthma and rhinitis to mushroom spores may occur.
A large number of spores from fruiting bodies can lead to allergic reactions and other problems during the cultivation of edible mushrooms, including Pleurotus eryngii; a cultivar harboring a sporulation-deficient (sporeless) mutation would be useful for preventing these problems.
Occupational Anaphylaxis
Constant exposure of indoor mushroom cultivators to Pleurotus spores increases the risk of respiratory allergy development, and cases of occupational anaphylaxis and work-related asthma have been documented. Although the most documented cases in the published allergy literature involve P. ostreatus spores, P. eryngii is listed among the causal species for hypersensitivity pneumonitis.
Lovastatin-like Compounds: Potential Drug Interaction Consideration
The presence of lovastatin, a member of the statins family that lowers TC and LDL levels and reduces the risk of coronary heart disease, has been detected in relatively high amounts in P. eryngii. The pharmacological significance of the lovastatin-like content in typical food or supplement servings relative to pharmaceutical statin doses has not been established in human studies; however, individuals taking statin medications who consume large quantities of P. eryngii preparations should be aware of this constituent.
Immunomodulatory Considerations
The polysaccharides of P. eryngii are mainly responsible for immunomodulatory effects by binding to specific membrane receptors and stimulating specific inflammatory responses. The immunostimulatory properties of β-glucans theoretically warrant caution in populations receiving immunosuppressive therapy or in autoimmune contexts, though no clinical adverse event data specific to P. eryngii in these populations have been identified in the available literature.
Evidence Gaps
Future research should emphasize clinical validation, molecular mechanism elucidation, and biotechnological enhancement for pharmaceutical and nutraceutical applications. Although the exact protective mechanisms of mushroom polysaccharides against various diseases remain poorly understood, accumulated literature has confirmed that antidiabetes-related activities may involve the antioxidant and pro-oxidant properties of polysaccharides. The overwhelming majority of biological evidence for P. eryngii comes from in vitro and animal studies, and human clinical evidence is currently limited to a single published RCT in the metabolic health domain.
References
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