Sterols, aromatic compounds, and cerebrosides from the Hericium erinaceus fruiting body

The ethnopharmacology, phytochemistry and pharmacology of the genus Hericium

ETHNOPHARMACOLOGICAL RELEVANCE

Mushrooms in the genus Hericium are used as functional food and traditional medicines for a long history in East Asian countries such as China, India, Japan, and Korea. Some species of Hericium are called as monkey head mushroom (Houtougu) in China and Yamabushitake in Japan, which are traditionally considered as rare and precious health promoting food and medicinal materials for the treatment of dyspepsia, insomnia, chronic gastritis, and digestive tract tumors.

THE AIM OF THE REVIEW

This review aims to summarize the ethnopharmacology and structural diversity of secondary metabolites from Hericium species, as well as the pharmacological activities of the crude extracts and pure compounds from Hericium species in recent years.

MATERIALS AND METHODS

All the information was gathered by searching Scifinder, PubMed, Web of Science, ScienceDirect, Springer, Wiley, ACS, CNKI, Baidu Scholar, Google Scholar databases and other published materials (books and Ph.D. and M. Sc. Dissertations) using the keywords "Hericium", "Traditional uses", "Chemical composition", "Quality control" and "Pharmacological activity" (1971-May 2023). The species name was checked with https://www.mycobank.org/.

RESULTS

The traditional uses of Hericium species were summarized, and 230 secondary metabolites from Hericium species were summarized and classified into six classes, mainly focusing on their chemical diversity, biosynthesis, biological activities. The modern pharmacological experiments in vivo or in vitro on their crude and fractionated extracts showed that the chemical components from Hericium species have a broad range of bioactivities, including neuroprotective, antimicrobial, anticancer, α-glucosidase inhibitory, antioxidant, and anti-inflammatory activities.

CONCLUSIONS

The secondary metabolites discovered from Hericium species are highly structurally diverse, and they have the potential to be rich resources of bioactive fungal natural products. Moreover, the unveiled bioactivities of their crude extracts and pure compounds are closely related to critical human health concerns, and in-depth studies on the potential lead compounds, mechanism of pharmacological effects and pharmaceutical properties are clearly warranted.

Structure and Biological Activity of Ergostane-Type Steroids from Fungi

Mushrooms are known not only for their taste but also for beneficial effects on health attributed to plethora of constituents. All mushrooms belong to the kingdom of fungi, which also includes yeasts and molds. Each year, hundreds of new metabolites of the main fungal sterol, ergosterol, are isolated from fungal sources. As a rule, further testing is carried out for their biological effects, and many of the isolated compounds exhibit one or another activity. This study aims to review recent literature (mainly over the past 10 years, selected older works are discussed for consistency purposes) on the structures and bioactivities of fungal metabolites of ergosterol. The review is not exhaustive in its coverage of structures found in fungi. Rather, it focuses solely on discussing compounds that have shown some biological activity with potential pharmacological utility.

Total Synthesis, Structure Revision, and Neuroprotective Effect of Hericenones C-H and Their Derivatives

The first total syntheses of hericenones C-H and "putative 3-hydroxyhericenone F" were achieved. Highlights of the synthesis include the straightforward construction of the resorcinol core and geranyl side chain, assembly of the natural product skeleton by sequential O-geranylation and a clay/zeolite-mediated O → C rearrangement reaction, and a biomimetic cyclization to form a variety of bicyclic natural hericenones and their congeners. The structure of the "putative 3-hydroxyhericenone F" was revised as the 5-exo cyclization product (named: hericenone Z) of epoxyhericenone C through in-depth analyses of the cyclization modes in addition to NMR spectroscopic studies. To gain insights into the biological functions of geranyl-resorcinols in Hericium erinaceus, potential neuroprotective effects against endoplasmic reticulum (ER) stress-dependent cell death were evaluated systematically to clarify a fundamental structure-activity relationship. Among the compounds assayed, the linoleate-containing hericenone analogue, i.e., the regioisomer of hericene D, was found to possess the most potent neuroprotective effect against tunicamycin and thapsigargin-induced ER stress-dependent cell death.

Characterization of α-glucosidase inhibitory constituents of the fruiting body of lion's mane mushroom (Hericium erinaceus)

ETHNOPHARMACOLOGICAL RELEVANCE

Hericium erinaceus, commonly called lion's mane mushroom, is an edible and medicinal mushroom that has been traditionally used for the treatment of metabolic disorders, gastrointestinal diseases and memory impairment. In this study, potential anti-hyperglycemic constituents were identified to support the traditional usage of H. erinaceus.

MATERIALS AND METHODS

The components of H. erinaceus were purified using various column chromatography techniques. The structure of the separated compounds was determined based on spectroscopic data analysis, i.e., 1D and 2D NMR analysis. The anti-hyperglycemic activity of the isolated compounds was evaluated by measuring the inhibitory effects on α-glucosidase activity. Molecular docking analysis was also conducted for elucidation of α-glucosidase inhibitory activity of isolated compounds.

RESULTS

Ten compounds including four new compounds, erinacenols A-D (1-4), were isolated from the fruiting bodies of H. erinaceus. Investigation of the anti-hyperglycemic effect of isolated compounds demonstrated that erinacenol D (4), 4-[3',7'-dimethyl-2',6'-octadienyl]-2-formyl-3-hydroxy-5-methyoxybenzylalcohol (6), hericene A (7), hericene D (8) and hericenone D (9) strongly inhibited α-glucosidase activity with IC₅₀ values of <20 μM. The structure activity relationship suggested the importance of long side chain for α-glucosidase inhibitory activity. Further analysis by molecular docking demonstrated the interaction of α-glucosidase and isolated compounds, which supported the inhibitory activity of α-glucosidase.

CONCLUSION

Our present study demonstrated the beneficial effect of H. erinaceus by characterization of α-glucosidase inhibitory compounds, including four new compounds. This approach can be valuable support for the traditional use of H. erinaceus for the treatment of diabetes and metabolic diseases, which needs to be clarified by further in-vivo study.

Total Synthesis of Isohericenone J via a Stille Coupling Reaction

The first total synthesis of isohericenone J is reported. Key features of this synthetic strategy are a Friedel-Crafts reaction to construct the isobenzofuranone unit and a Pd-catalyzed Stille coupling reaction for the formation of the C5-C1' bond, generating the natural product, as well as one of its isomers, in 6.0% overall yield in eight steps. This strategy provides a foundation for the synthesis of challenging isobenzofuranone and isoindolinone-type derivatives.

Pre-protective effect of polysaccharides purified from Hericium erinaceus against ethanol-induced gastric mucosal injury in rats

The β-glucan H6PC20 (Mw: 2390 kDa) and α-heteropolysaccharide HPB-3 (Mw: 15 kDa) were purified from the fruiting body of Hericium erinaceus according to the previous methods. Their gastroprotective activities and corresponding structure-activity relationship were studied in the ethanol-induced gastric ulcer model of rats. After intragastric administrated with H6PC20 and HPB-3 for 14 days, macroscopic and histological evaluation of gastric mucosa was improved significantly. The defense and repair factors (EGF, bFGF and PGE₂) were increased, meanwhile, the inflammatory cytokines (IL-1β and TNF-α) and MDA were reduced. These results indicated that H6PC20 and HPB-3 presented gastroprotective activities with the mechanism of activating repair and defense system, decreasing the inflammatory response and alleviating the oxidative injury. Furthermore, the structure-activity relationship showed that the macromolecular β-glucan was better for repair and defense system, while the low weight molecular α-heteropolysaccharide focused on the anti-inflammatory effect. The polysaccharides purified from H. erinaceus can be developed as a potential gastroprotective ingredient for applications in pharmaceutical field.