New sesquiterpenoids from the edible mushroom Pleurotus cystidiosus and their inhibitory activity against α-glucosidase and PTP1B

Terpenoids as potential phytoconstituent in the treatment of diabetes: From preclinical to clinical advancement

BACKGROUND

Diabetes mellitus, a hyperglycemic condition associated with multitudinous organ dysfunction, is a hallmark of the metabolic disorder. This life-threatening condition affects millions of individuals globally, harming them financially, physically and psychologically in the course of therapy.

PURPOSES

The course therapy for illnesses has undergone ground-breaking transformations due to recent technical advances and insights. Alternatively, the administration of hyperglycemia-reducing agents results in several complications, including severe cardiovascular disease, kidney failure, hepatic problems, and several dermatological conditions. Consideration of alternate diabetic therapy having minimal side effects or no adverse reactions has been driven by such problems.

STUDY DESIGN

An extensive literature study was conducted in authoritative scientific databases such as PubMed, Scopus, and Web of Science to identify the studies elucidating the bioactivities of terpenoids in diabetic conditions.

METHODS

Keywords including 'terpenoids', 'monoterpenes', 'diterpenes', 'sesquiterpenes', 'diabetes', 'diabetes mellitus', 'clinical trials', 'preclinical studies', and 'increased blood glucose' were used to identify the relevant research articles. The exclusion criteria, such as English language, duplication, open access, abstract only, and studies not involving preclinical and clinical research, were set. Based on these criteria, 937 relevant articles were selected for further evaluation.

RESULTS

Triterpenes can serve as therapeutic agents for diabetic retinopathy, peripheral neuropathy, and kidney dysfunction by inhibiting several pathways linked to hyperglycemia and its complications. Therefore, it is essential to draw special attention to these compounds' therapeutic effectiveness and provide scientific professionals with novel data.

CONCLUSION

This study addressed recent progress in research focussing on mechanisms of terpenoid, its by-products, physiological actions, and therapeutic applications, particularly in diabetic and associated disorders.

Biocatalyst collection and heterologous expression of sesquiterpene synthases from basidiomycetous fungi: Discovery of a novel sesquiterpene hydrocarbon

Basidiomycetes produce a wide variety of sesquiterpenoids, which attract significant interest in pharmaceutical and industrial applications. Structural diversification of sesquiterpenoids is performed by sesquiterpene synthases (STSs), which produce a wide array of backbone structures; therefore, functional characterization and increased biocatalyst collection of STSs are important for expanding scientific knowledge and meeting the needs of advanced biotechnology. Gene identification and functional annotation of STSs from the basidiomycetous fungi Agaricus bisporus, Auriscalpium vulgare, Lepista nuda, Pleurotus ostreatus and Trametes versicolor were conducted. Through these investigations, the catalytic functions of 30 STSs were revealed using recombinant enzymes heterologously expressed in Saccharomyces cerevisiae. Furthermore, the unique function of an STS from P. ostreatus, PoSTS-06, was revealed to be the production of a novel sesquiterpene hydrocarbon that we named pleostene. The absolute structure of pleostene was determined by NMR spectroscopy and X-ray crystallography using the crystalline sponge method.

Alliacane-Type Secondary Metabolites from Submerged Cultures of the Basidiomycete Clitocybe nebularis

Seven sesquiterpenoids, named nebucanes A-G (1-7), featuring a rare alliacane scaffold with unprecedented furan or pyrrole functions, were isolated from the fermentation broth of Clitocybe nebularis. Their structures were established on the basis of 1D/2D NMR spectroscopic analyses, HR-(+)-ESIMS spectra, and comparison of measured and calculated CD spectra for determination of the absolute configuration. Assessing the biological activities, nebucane D (4) exhibited antifungal effects against Rhodotorula glutinis, while nebucane G (7) displayed significant cytotoxicity against MCF-7 and A431 cell lines.

Sesquiterpenoids Specially Produced by Fungi: Structures, Biological Activities, Chemical and Biosynthesis (2015-2020)

Fungi are widely distributed in the terrestrial environment, freshwater, and marine habitat. Only approximately 100,000 of these have been classified although there are about 5.1 million characteristic fungi all over the world. These eukaryotic microbes produce specialized metabolites and participate in a variety of ecological functions, such as quorum detection, chemical defense, allelopathy, and maintenance of symbiosis. Fungi therefore remain an important resource for the screening and discovery of biologically active natural products. Sesquiterpenoids are arguably the richest natural products from plants and micro-organisms. The rearrangement of the 15 high-ductility carbons gave rise to a large number of different skeletons. At the same time, abundant structural variations lead to a diversification of biological activity. This review examines the isolation, structural determination, bioactivities, and synthesis of sesquiterpenoids that were specially produced by fungi over the past five years (2015-2020).

Lanostane Triterpenoids with PTP1B Inhibitory and Glucose-Uptake Stimulatory Activities from Mushroom Fomitopsis pinicola Collected in North America

A chemical investigation on the fruiting bodies of Fomitopsis pinicola led to the isolation and identification of 28 lanostane triterpenoids including 11 new compounds (1-11) and 17 known analogues (12-28). Their structures were elucidated by extensive one-dimensional NMR, two-dimensional NMR, and MS spectra. All isolates were tested for their anti-inflammatory activity, protein tyrosine phosphatase 1B (PTP1B) inhibitory activity in vitro, and effect on glucose uptake in insulin-resistant HepG2 cells. Compounds 1, 4, 22, 23, and 27 inhibited the nitric oxide released from the LPS-induced RAW 264.7 cell assay with IC₅₀ values in the range of 21.4-27.2 μM. Compounds 18, 22, 23, and 28 showed strong PTP1B inhibitory activity with IC₅₀ values in the range of 20.5-29.9 μM, comparable to that of the positive control of oleanolic acid (15.0 μM). Compounds 18 and 22 were confirmed to be good competitive inhibitors of PTP1B by kinetic analysis. In addition, compounds 18, 22, and 28 were found to stimulate glucose uptake in the insulin-resistant HepG2 cells in the dose from 6.25 to 100 μM. These findings indicated the potential of F. pinicola in the development of functional food or medicine for the prevention and treatment of diabetes.

Amplisins A–E, chromone methide polymers with hypoglycemic activity from a new fungicolous fungus Amplistroma fungicola

Five new non-enzymatic 1,4-Michael addition of chromone methide polymers, (±)-amplisins A–D (1–4) and amplisin E (5), with hypoglycemic and anti-inflammatory activities, were isolated from a new fungicolous fungus Amplistroma fungicola.

Rapid Characterization of Chemical Components in Edible Mushroom Sparassis crispa by UPLC-Orbitrap MS Analysis and Potential Inhibitory Effects on Allergic Rhinitis

Sparassis crispa is a kind of edible fungus widely grows in the north temperate zone, which shows various medicinal properties. Due to the complexity of chemical constitutes of this species, few investigations have acquired a comprehensive configuration for the chemical profile of it. In this study, a strategy based on ultra-high performance liquid chromatography (UPLC) combined with Orbitrap mass spectrometer (MS) was established for rapidly characterizing various chemical components in S. crispa. Through the summarized MS/MS fragmentation patterns of reference compounds and systematic identification strategy, a total of 110 components attributed to six categories were identified for the first time. Moreover, allergic rhinitis (AR) is a worldwide inflammatory disease seriously affecting human health, and the development of drugs to treat AR has been a topic of interest. It has been reported that the extracts of S. crispa showed obvious inhibitory effects on degranulation of mast cell- and allergen-induced IgE and proinflammatory mediators, but the active components and specific mechanism were still not clear. Src family kinases (SFKs) participate in the initial stage of allergy occurrence, which are considered the targets of AR treatment. Herein, on the basis of that self-built chemical database, virtual screening was applied to predict the potential SFKs inhibitors in S. crispa, using known crystal structures of Hck, Lyn, Fyn, and Syk as receptors, followed by the anti-inflammatory activity evaluation for screened hits by intracellular calcium mobilization assay. As results, sparoside A was directly confirmed to have strong anti-inflammatory activity with an IC50 value of 5.06 ± 0.60 μM. This study provides a useful elucidation for the chemical composition of S. crispa, and demonstrated its potential inhibitory effects on AR, which could promote the research and development of effective agents from natural resources.

Biological and chemical diversity go hand in hand: Basidiomycota as source of new pharmaceuticals and agrochemicals

The Basidiomycota constitutes the second largest higher taxonomic group of the Fungi after the Ascomycota and comprises over 30.000 species. Mycelial cultures of Basidiomycota have already been studied since the 1950s for production of antibiotics and other beneficial secondary metabolites. Despite the fact that unique and selective compounds like pleuromutilin were obtained early on, it took several decades more until they were subjected to a systematic screening for antimicrobial and anticancer activities. These efforts led to the discovery of the strobilurins and several hundreds of further compounds that mainly constitute terpenoids. In parallel the traditional medicinal mushrooms of Asia were also studied intensively for metabolite production, aimed at finding new therapeutic agents for treatment of various diseases including metabolic disorders and the central nervous system. While the evaluation of this organism group has in general been more tedious as compared to the Ascomycota, the chances to discover new metabolites and to develop them further to candidates for drugs, agrochemicals and other products for the Life Science industry have substantially increased over the past decade. This is owing to the revolutionary developments in -OMICS techniques, bioinformatics, analytical chemistry and biotechnological process technology, which are steadily being developed further. On the other hand, the new developments in polythetic fungal taxonomy now also allow a more concise selection of previously untapped organisms. The current review is dedicated to summarize the state of the art and to give an outlook to further developments.

Protein tyrosine phosphatase 1B inhibitors from natural sources

Since PTP1B enzyme was discovered in 1988, it has captured the research community's attention. This landmark discovery has stimulated numerous research studies on a variety of human diseases, including cancer, inflammation, and diabetes. Tremendous progress has been made in finding PTP1B inhibitors and exploring PTP1B regulatory mechanisms. This review investigates for the natural PTP1B inhibitors, and focuses on the common characteristics of the discovered structures and structure-activity relationships. To facilitate understanding, all the natural compounds are here divided into five different classes (fatty acids, phenolics, terpenoids, steroids, and alkaloids), according to their skeletons. These PTP1B inhibitors of scaffold structures could serve as a theoretical basis for new concept drug discovery and design.

Three new amino acid derivatives from edible mushroom Pleurotus ostreatus

Three new amino acid derivatives, oxalamido-L-phenylalanine methyl ester (1), oxalamido-L-leucine methyl ester (2), and lumichrome hydrolyzate (3), together with nine known compounds (4-12), were isolated from the solid culture of edible mushroom Pleurotus ostreatus. Their structures were elucidated on the basis of extensive spectroscopic analysis. The absolute configurations of 1 and 2 were established by the chiral synthesis and confirmed by circular dichroism (CD) analysis of their total synthesis products and natural isolates. All new compounds were evaluated for their antioxidant effects, antimicrobial activities, and cytotoxic activity. Compounds 1-3 showed weak antifungal activities against Candida albicans with minimum inhibitory concentration (MIC) value of 500 μg/ml.

Bioactive alkaloids from the aerial parts of Houttuynia cordata

ETHNOPHARMACOLOGICAL RELEVANCE

Houttuynia cordata is an important traditional Chinese medicine used in heat-clearing and detoxifying, swelling and discharging pus, promoting diuresis and relieving stranguria which recorded in Pharmacopoeia of the people's Republic of China (2015 Edition). H. cordata has been recorded in the book Bencaogangmu which was written by Shizhen Li for the treatment of pyretic toxicity, carbuncle swelling, haemorrhoids, and rectocele diseases.

AIM OF THE STUDY

Phytochemical investigation of the aerial parts of H. cordata and evaluation of their PTP1B inhibitory activities and hepatoprotective activities.

MATERIALS AND METHODS

The dried aerial parts of H. cordata were fractionated by liquid-liquid extraction to obtain CHCl₃, ethyl acetate, and n-butanolic fractions. The CHCl₃ fraction was confirmed active fraction by the bioactivity-guided investigation, which was isolated and purified by chromatographing over silica gel, Sephadex LH-20, MPLC, and preparative HPLC. The chemical structures of the purified compounds were identified by their spectroscopic data and references.

RESULTS

Eight new compounds (1-8), together with fourteen known compounds (9-22) were isolated from the aerial parts of H. cordata. The known compounds (9-22) were obtained from this plant for the first time. Among them, some compounds exhibited moderate bioactivities.

CONCLUSION

Compounds (1-8) were identified as new alkaloids, and the known alkaloids (9-22) were isolated from this plant for the first time. Compounds 1, 4, 14, and 19 showed significant PTP1B inhibitory activities with IC₅₀ values of 1.254, 2.016, 2.672, and 1.862µm, respectively. Compounds 1, 3, 6, 11, 17, and 20 (10µm) exhibited moderate hepatoprotective activities against D-galactosamine-induced WB-F344 cells damage.