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

Experimental Models in Unraveling the Biological Mechanisms of Mushroom-Derived Bioactives against Aging- and Lifestyle-Related Diseases: A Review

Mushrooms have garnered considerable interest among researchers due to their immense nutritional and therapeutic properties. The presence of biologically active primary and secondary metabolites, which includes several micronutrients, including vitamins, essential minerals, and other dietary fibers, makes them an excellent functional food. Moreover, the dietary inclusion of mushrooms has been reported to reduce the incidence of aging- and lifestyle-related diseases, such as cancer, obesity, and stroke, as well as to provide overall health benefits by promoting immunomodulation, antioxidant activity, and enhancement of gut microbial flora. The multifunctional activities of several mushroom extracts have been evaluated by both in vitro and in vivo studies using cell lines along with invertebrate and vertebrate model systems to address human diseases and disorders at functional and molecular levels. Although each model has its own strengths as well as lacunas, various studies have generated a plethora of data regarding the regulating players that are modulated in order to provide various protective activities; hence, this review intends to compile and provide an overview of the plausible mechanism of action of mushroom-derived bioactives, which will be helpful in future medicinal explorations.

Isolation and target identification of antihepatoma polyprenylphenols from the edible mushroom Suillus granulatus

Eight polyprenylphenol derivatives were isolated from the wild edible mushroom Suillus granulatus, including seven novel compounds, named suillin F-L (2-8), and one previously identified compound (1). The structures of the new compounds were elucidated using HR-ESI-MS and 1D and 2D NMR data. The absolute configuration of compound 8 was assigned based on the comparison of the experimental and calculated ECD data. All isolated compounds were evaluated for their cytotoxicity against HepG2 cancer cell lines. Compounds 1 and 3-6 demonstrated significant antitumor activity compared to the positive control (cisplatin), with IC50 values ranging from 8.19 to 13.97 μM. Furthermore, DARTS assay and LC-MS/MS analysis were used to identify HSP90AA1 as the direct target of compound 5, and the interaction between compound 5 and HSP90AA1 was verified by molecular docking.

Biological Activities of Secondary Metabolites from the Edible-Medicinal Macrofungi

Macrofungi are well-known as edible-medicinal mushrooms, which belong mostly to Basidiomycota, with a few from Ascomycota. In recent years, macrofungi have been recognized as a rich resource of structurally unique secondary metabolites, demonstrating a wide range of bioactivities, including anti-tumor, antioxidant, anti-inflammatory, antimicrobial, antimalarial, neuro-protective, hypoglycemic, and hypolipidemic activities. This review highlights over 270 natural products produced by 17 families of macrofungi covering 2017 to 2023, including their structures, bioactivities, and related molecular mechanisms.

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.

Research Progress of α-Glucosidase Inhibitors Produced by Microorganisms and Their Applications

Based on the easy cultivation of microorganisms and their short cycle time, research on α-glucosidase inhibitors (α-GIs) of microbial origin is receiving extensive attention. Raw materials used in food production, such as cereals, dairy products, fruits, and vegetables, contain various bioactive components, like flavonoids, polyphenols, and alkaloids. Fermentation with specific bacterial strains enhances the nutritional value of these raw materials and enables the creation of hypoglycemic products rich in diverse active ingredients. Additionally, conventional food processing often results in significant byproduct generation, causing resource wastage and environmental issues. However, using bacterial strains to ferment these byproducts into α-GIs presents an innovative solution. This review describes the microbial-derived α-GIs that have been identified. Moreover, the production of α-GIs using industrial food raw materials and processing byproducts as a medium in fermentation is summarized. It is worth analyzing the selection of strains and raw materials, the separation and identification of key compounds, and fermentation broth research methods. Notably, the innovative ideas in this field are described as well. This review will provide theoretical guidance for the development of microbial-derived hypoglycemic foods.

Anti-α-glucosidase and anti-oxidative isoflavonoids from the immature fruits of Maclura tricuspidata

The composition of a plant, together with its efficacy, vary depending on its maturity and plant parts. In this study, the chemical constituents of immature fruits of Maclura tricuspidata (Moraceae) were investigated together with their anti-diabetic and antioxidant effects. A total of 34 compounds were isolated from the immature fruits of M. tricuspidata using various chromatographic methods. Structure elucidation using extensive spectroscopic analysis led to the characterization of isolated compounds as isoflavonoids with prenyl substituents. Among them, macluraisoflavones A-O were first isolated from nature. The anti-diabetic and antioxidant activity of the isolated compounds were also suggested by α-glucosidase inhibitory activity and DPPH radical scavenging activity, respectively. In particular, macluraisoflavone I, an isoflavonoid with 2,2-dimethylpyran and 2-hydroperoxy-3-methylbut-3-enyl moieties, showed potent α-glucosidase inhibitory activity and DPPH radical scavenging activity. Further molecular docking analysis suggested hydrogen bond and alkyl interactions between α-glucosidase and macluraisoflavone I. Therefore, the immature fruits of M. tricuspidata can be used as an important natural product with antioxidant and anti-diabetic properties.

Anti-diabetic potential of Masclura tricuspidata leaves: Prenylated isoflavonoids with α-glucosidase inhibitory and anti-glycation activity

Investigation of chemical constituents of Masclura tricuspidata leaves resulted in the isolation of 47 isoflavonoids possessing prenyl groups with different numbers and structures. Among them, sixteen compounds named cudracusisoflavones A-P (1-16) were first isolated from nature. The isoflavonoids isolated from M. tricuspidata leaves showed anti-diabetic effects as measured by inhibition on α-glucosidase activity and advanced glycation end-products (AGEs) formations. Especially, cudracusisoflavone L (12), a new compound, together with gancaonin M (27), erysenegalensein E (41) and millewanin G (44) showed strong α-glucosidase inhibition with IC₅₀ values <10.0 μM. In addition, cudracusisoflavones A (1), D (4), M (13) and N (14), together with known prenylated isoflavonoids efficiently inhibited methylglyoxal (MGO)- or glyoxal (GO)-induced AGE formations. Structure activity relationship together with molecular docking analysis suggested the importance of hydroxy group and linear type of prenyl moiety for α-glucosidase inhibition. Conclusively, diverse prenylated isoflavonoids in M. tricuspidata leaves might ameliorate glycotoxicity-induced metabolic diseases.

Novel hypoglycemic compounds from wild mushroom Paxillus involutus

Wild mushrooms are an important source of secondary metabolites possessing a broad range of biological activities. In this study, eight new compounds, named furanopaxin A-F (1-6), deoxybisinvolutone (7), and coumarinvol (8) along with two known compounds were isolated from fruiting bodies of the wild mushroom Paxillus involutus (Batsch) Fr. Their structures were established based on HR-ESI-MS and 1D and 2D NMR spectroscopic data. The results of hypoglycemic assays indicated that compounds 5-8 possessed significant α-glucosidase inhibitory activities, with IC₅₀ values ranging from 14.65 ± 1.68 to 47.55 ± 1.47 μM, and each compound could enhance glucose consumption in insulin-resistance HepG2 cells. Further analysis by molecular docking implied that compounds 5-8 could interact with the amino acid residues of α-glucosidase, supporting the hypoglycemic activity of the compounds.

Isolation of potential α-glucosidase inhibitor from Inonotus obliquus by combining ultrafiltration-liquid chromatography and consecutive high-speed countercurrent chromatography

Inonotus obliquus is a rare medicinal fungus that contains several potential therapeutic ingredients. In this study, the α-glucosidase inhibitory activity of I. obliquus was examined, and a potential α-glucosidase inhibitor, (E)-4-(3,4-dihydroxyphenyl)but-3-en-2-one, was isolated from the I. obliquus extract through ultrafiltration-liquid chromatography (UF-LC). Consecutive high-speed countercurrent chromatography (HSCCC) was used for separation to obtain large quantities of the target compound. The universal quasi-chemical functional group activity coefficient (UNIFAC) model was utilized to prepare a two-phase solvent system, n-hexane/ethyl acetate/ethanol/water (4 : 4.5 : 3.5 : 5, v/v/v/v), wherein the proportions of n-hexane/ethyl acetate/ethanol/water in the stationary and mobile phases were 19.8 : 19.7 : 7.9 : 2.2 (v/v/v/v) and 1 : 16.4 : 57.5 : 136.6 (v/v/v/v), respectively. A flow rate of 2.5 mL min^-1 and a column speed of 860 rpm were maintained. Consequently, 10.3 mg of the target compound (95.9% purity) was obtained from 900 mg (6 × 150 mg) of the I. obliquus extract. The use of the UNIFAC model, in combination with consecutive HSCCC separations, allows the purification of large quantities of samples over a short time. Furthermore, the volume of the organic solvent required is reduced. Thus, UF-LC is an effective technique for screening potential α-glucosidase inhibitors isolated from I. obliquus. This can ultimately aid in the discovery of bioactive compounds for the prevention and treatment of diabetes.