Pyrrole alkaloids and ergosterols from Grifola frondosa exert anti-α-glucosidase and anti-proliferative activities

Unveiling the full spectrum of maitake mushrooms: A comprehensive review of their medicinal, therapeutic, nutraceutical, and cosmetic potential

This literature review provides an up-to-date exploration of the multifaceted attributes of maitake mushrooms (Grifola frondosa), elucidating their bioactive phytochemicals and diverse health advantages, including their substantial role in supporting human health and potential incorporation into the medicinal industry. Carbohydrates and protein are the major constituents contributing to the dry weight of G. frondosa, taking up around 70-80 % and 13-21 %, respectively, with emerging research linking these constituents to various health benefits. By synthesising current research findings, this review emphasises the substantial role of maitake mushrooms in supporting human health and underscores their potential incorporation into the medicinal industry. To further advance our understanding, future research should delve into the mechanisms underlying their health-promoting effects, with a focus on conducting quantitative studies to elucidate physiological pathways and potential drug interactions. Additionally, exploring their integration into functional foods or nutraceuticals through quantitative assessments of bioavailability and efficacy will be crucial for maximising their therapeutic benefits. This review aims to provide comprehensive insights, catalysing further research and innovation in utilising maitake mushrooms for improved well-being and industry advancement.

α-glucosidase and α-amylase inhibitory activity of flavonols from Stenochlaena palustris (Burm.f.) Bedd

Stenochlaena palustris (Burm.f.) Bedd., a fern species native to India, Southeast Asia, Polynesia, and Australia, has a long history of medical including as a diabetic therapy. This study aimed to isolate bioactive compounds from S. palustris ethyl acetate extract and assess their in vitro and in silico inhibitory activities against α-glucosidase and α-amylase. The successful separation of five flavonols, namely stenopalustroside A (1), tiliroside (2), kaempferol (3), quercetin (4), and rutin (5), was achieved through phytochemical analysis. The compounds exhibited a range of inhibitory activities against α-glucosidase and α-amylase, with IC50 values ranging from 40 to 250 µg/mL. Notably, the biological activities of compound 1 have been reported for the first time. Compound 4 was the most effective inhibitor of both enzymes among the isolated compounds. Studies performed in silico reveal that the interactions between amino acids in compounds 4 and 5 are remarkably comparable to those observed in the positive control. These compounds share this commonality, and as a result, they both have the potential to be active agents.

Pyrrole: A Decisive Scaffold for the Development of Therapeutic Agents and Structure-Activity Relationship

An overview of pyrroles as distinct scaffolds with therapeutic potential and the significance of pyrrole derivatives for drug development are provided in this article. It lists instances of naturally occurring pyrrole-containing compounds and describes the sources of pyrroles in nature, including plants and microbes. It also explains the many conventional and modern synthetic methods used to produce pyrroles. The key topics are the biological characteristics, pharmacological behavior, and functional alterations displayed by pyrrole derivatives. It also details how pyrroles are used to treat infectious diseases. It describes infectious disorders resistant to standard treatments and discusses the function of compounds containing pyrroles in combating infectious diseases. Furthermore, the review covers the uses of pyrrole derivatives in treating non-infectious diseases and resistance mechanisms in non-infectious illnesses like cancer, diabetes, and Alzheimer's and Parkinson's diseases. The important discoveries and probable avenues for pyrrole research are finally summarized, along with their significance for medicinal chemists and drug development. A reference from the last two decades is included in this review.

Anti-α-glucosidase, Anti-proliferative and Anti-enterovirus 71 Activity of Secondary Metabolites Identified from Grifola Frondosa

Grifola frondosa, an edible and medicinal resource, is widely used as functional foods worldwide. To explore bioactive compounds against α-glucosidase, human tumor cells and enterovirus 71 (EV71), eight compounds were isolated from G. frondosa by chromatographic column. Among the isolated compounds, heptadecanoic acid, uridine and adenosine exhibited potent inhibition activity against α-glucosidase, ergosterols and ergosterol-5,8-peroxide showed anti-proliferative activity on tumor cells, while ergosterol and methyl linoleate displayed inhibition against the replication of EV71. Also, to our knowledge, this is the first study to report that fatty acids isolated from G. frondosa show potent inhibition against α-glucosidase and EV71. Further molecular docking results revealed that the active compounds in G. frondosa form hydrogen bonding, hydrophobic interactive and π-stacking with the active sites on the surface of α-glucosidase, CASP3 and VP1 proteins, thus promoting the active compounds to combine with the target protein to form a stable complex, thus playing an antagonistic role. Our results could provide a new active compound and mode of action for G. frondosa to treat diabetes, cancer and EV71-infected patients.

A new chlorobenzoate derivative from the red alga Solieria sp

A new chlorobenzoate derivative, solieriate (1), together with six known compounds (2-7), were isolated from the red alga Solieria sp. The structures of 1-7 were determined by comprehensive spectroscopic methods and X-ray diffraction analysis. Compound 1 is the first example of halogenated derivative isolated from this genus. In addition, 1 exhibited moderate antibacterial activity on A. baumannii with MIC value of 64 μg/ml.

N,N-Dimethyl-anthranilic Acid from Calvatia nipponica Mushroom Fruiting Bodies Induces Apoptotic Effects on MDA-MB-231 Human Breast Cancer Cells

Breast cancer ranks among the most prevalent malignancies affecting women worldwide, and apoptosis-targeting drugs are attractive candidates for the treatment of cancer. In the current study, we investigated the in vitro cytotoxicity of the mushroom Calvatia nipponica in human breast cancer cells (MDA-MB-231), identified potential antitumor compounds through bioactivity-guided isolation, and elucidated the antitumor, pro-apoptotic molecular mechanisms of the identified bioactive compounds. C. nipponica is edible when young, and it has been used as a food source as well as a traditional medicine in wound dressings. However, only a limited number of studies have reported its chemical composition and biological activities. In the screening test, the methanol extract of C. nipponica fruiting bodies exhibited cytotoxicity against MDA-MB-231 cells. Bioactivity-guided fractionation of the methanol (MeOH) extract and chemical investigation of the active fractions resulted in the isolation of fourteen compounds (1-14), including six alkaloids (1-3, 5, 7, and 8), two phenolic compounds (4 and 6), one fatty acid (9), and five steroids (10-14). The structures of the isolated compounds were determined using NMR spectroscopic methods, liquid chromatography-mass spectrometry, and comparison of data with previously reported values. The isolated compounds (1-14) were tested for cytotoxicity against MDA-MB-231 cells, where compound 1, i.e., N,N-dimethyl-anthranilic acid, exhibited the most significant cytotoxicity against MDA-MB-231 cells, with an IC₅₀ value of 90.28 ± 4.23 μM and apoptotic cell death of 56.01% ± 2.64% at 100 μM. Treatment with compound 1 resulted in an upregulation of protein levels, including cleaved caspase-8, cleaved poly (ADP-ribose) polymerase, Bcl-2-associated X protein (Bax), cleaved caspase-3, cleaved caspase-9, Bad, and Cytochrome c, but decreased the levels of B-cell lymphoma 2 (Bcl-2). Overall, these results indicate that N,N-dimethyl-anthranilic acid (1) may have anti-breast cancer activity and is probably involved in the induction of apoptosis mediated by extrinsic and intrinsic signaling pathways.

Three new lanostane triterpenoids and two new amides from Alternaria sp. with NLRP3 inflammasome inhibitory activity

Three new lanostane triterpenoids (1-3) along with two new amides fatty compounds (4-5) were isolated from the ethyl acetate extract of a culture of the endophytic fungus Alternaria sp. gx-2. Their structures were identified by 1D and 2D NMR spectral data and HRESIMS. Compounds 1-12 were evaluated for their anti-inflammatory and tyrosinase inhibition activities. The isolated compounds did not show inhibitory activities at a concentration of 100 μM against tyrosinase, while under the concentration of 10 μM, the release of lactate dehydrogenase (LDH) inhibition rate of compound 1 was 54.45%, indicating that compound 1 had moderate anti-inflammatory activity on the activation of NLRP3 inflammasome.

Two new alkaloids from the endophytic fungus Schizophyllum sp. HM230 isolated from Vincetoxicum mongolicum Maxim

Endophytic fungi is an important source for the discovery of bioactive natural compounds. A chemical investigation of the ethyl acetate extract of the endophytic fungus Schizophyllum sp. HM230 derived from stems of the herb Vincetoxicum mongolicum Maxim led to isolation of five alkaloids, including two new compounds, schizophyllins M (1) and N (2), along with three known ones (3-5). The planar structures of two new compounds were elucidated by extensive spectroscopic methods including MS, 1D and 2D NMR. Their absolute configurations were determined by Mosher's method and comparison of the ECD data. All the isolates were evaluated for their cytotoxicity and antioxidant activities. Compounds 1-4 showed middle cytotoxicity against MCF-7 cells with IC50 values range of 68.1 ∼ 87.32 μM. Compounds 1-5 displayed obvious antioxidant activity with the IC50 values range of 0.86 ∼ 5.78 mg/mL.

Metabolites extracted from microorganisms as potential inhibitors of glycosidases (α-glucosidase and α-amylase): A review

α-Glucosidase and α-amylase are the two main glycosidases that participate in the metabolism of carbohydrates. Inhibitors of these two enzymes are considered an important medical treatment for carbohydrate uptake disorders, such as diabetes and obesity. Microbes are an important source of constituents that have the potential to inhibit glycosidases and can be used as sources of new drugs and dietary supplements. For example, the α-glucosidase inhibitor acarbose, isolated from Actinoplanes sp., has played an important role in adequately controlling type 2 diabetes, but this class of marketed drugs has many drawbacks, such as poor compliance with treatment and expense. This demonstrates the need for new microorganism-derived resources, as well as novel classes of drugs with better compliance, socioeconomic benefits, and safety. This review introduces the literature on microbial sources of α-glucosidase and α-amylase inhibitors, with a focus on endophytes and marine microorganisms, over the most recent 5 years. This paper also reviews the application of glycosidase inhibitors as drugs and dietary supplements. These studies will contribute to the future development of new microorganism-derived glycosidase inhibitors.

Grifolamine A, a novel bis-γ-butyrolactone from Grifola frondosa exerted inhibitory effect on α-glucosidase and their binding interaction: Affinity and molecular dynamics simulation

A novel bis-γ-butyrolactone grifolamine A (1), the first γ-butyrolactone dimer from nature, together with three known γ-butyrolactones (2-4), was isolated from the byproduct from Grifola frondosa polysaccharides preparation process. The structure and stereochemistry of grifolamine A (1) were elucidated by extensive spectroscopic analysis combined with quantum chemical calculation. The biosynthetic origin of compound 1, as well as 2-4 was proposed. Grifolamine A (1) showed an intense inhibition against α-glucosidase in vitro. The underlying inhibitory mechanism was revealed by surface plasmon resonance (SPR), molecular docking, molecular dynamics (MD) simulation and binding free energy calculation. SPR revealed that grifolamine A exhibited a strong affinity to α-glucosidase with an equilibrium dissociation constant (K_D) value of 1.178 × 10^-4 M. Molecular docking manifested that grifolamine A sat at the active pocket of α-glucosidase by van der Waals force, alkyl interaction and carbon hydrogen bonds, and consequently changed the micro-environmental structure of α-glucosidase. MD simulation revealed that grifolamine A had high binding affinity to α-glucosidase with average free energy of -25.2 ± 3.2 kcal/mol. Free energy decomposition indicated amino acid residues including PHE298, PHE308, PHE309, PHE155 and ARG310 at the binding pocket played a strongly positive effect on the interaction between grifolamine A and α-glucosidase. Our findings provide valuable information for the design and development of novel α-glucosidase inhibitors based on γ-butyrolactone skeleton.

Influence of Green Tea Added to Cherry Wine on Phenolic Content, Antioxidant Activity and Alpha-Glucosidase Inhibition during an In Vitro Gastrointestinal Digestion

Cherries are a good source of bioactive compounds, with high antioxidant activity as well as nutritional and therapeutic importance. In this study, cherry wines enriched with green tea infusion (mild and concentrated) were produced, and their biological properties were evaluated. During winemaking, the main vinification parameters (alcohol, reducing sugars, acidity, total polyphenol content) as well biological activity (antioxidant activity, alpha-glucosidase inhibition potential) were determined. An in vitro digestion process was also performed to evaluate the impact of the gastrointestinal environment on the biological stability of the wines, and to analyze the interactions of wine-intestinal microflora. The addition of green tea to the cherry wine significantly increased the total polyphenol content (up to 2.73 g GAE/L) and antioxidant activity (up to 22.07 mM TE/L), compared with the control wine. However, after in vitro digestion, a reduction in total polyphenols (53–64%) and antioxidant activity (38–45%) were noted. Wines fortified with green tea expressed a stronger inhibition effect on intestinal microflora growth, of which E. coli were the most sensitive microorganisms. The tea-derived bioactive compounds significantly increased the potential of alpha-glucosidase inhibition. The proposed wines could be a good alternative type of wine, with an increased polyphenol content and the potential to control the insulin response supporting therapy for diabetes.

Combining NMR and MS to Describe Pyrrole-2-Carbaldehydes in Wheat Bran of Radiation

Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) are indispensable analytical tools to provide chemical fingerprints in metabolomics studies. The present study evaluated radiation breeding wheat lines for chemical changes by non-targeted NMR-based metabolomics analysis of bran extracts. Multivariate analysis following spectral binning suggested pyrrole-2-carbaldehydes as chemical markers of four mutant lines with distinct NMR fingerprints in a δ_H range of 9.28-9.40 ppm. Further NMR and MS data analysis, along with chromatographic fractionation and synthetic preparation, aimed at structure identification of marker metabolites and identified five pyrrole-2-carbaldehydes. Quantum-mechanical driven ¹H iterative full spin analysis (QM-HiFSA) on synthetic pyrrole-2-carbaldehydes provided a precise description of complex peak patterns. Biological evaluation of pyrrole-2-carbaldehydes was performed with nine synthetic products, and six compounds showed hepatoprotective effects via modulation of reactive oxygen species production. Given that three out of five identified in wheat bran of radiation were described for hepatoprotective activity, the value of radiation mutation to greatly enhance pyrrole-2-carbaldehyde production was supported.

New Terpenoids from the Corticioid Fungus Punctularia atropurpurascens and their Antimycobacterial Evaluation

Chemical investigation of Punctularia atropurpurascens strain HM1 (Punctulariaceae), a corticioid isolated from a decorticated piece of Quercus bark collected in Bosque de Tlalpan, Mexico City, led to the isolation of a new drimane, 1-α-hydroxy-isodrimenine (1: ) and a new tetrahydroxy kauranol, 16-hydroxy-phlebia-nor-kauranol (2: ), together with the known N-phenylacetamide (3: ). Structures of all compounds were elucidated by spectroscopic and spectrometric methods, and the absolute configuration of 1: and 2: was confirmed via single-crystal X-ray crystallography. The isolated compounds showed modest antimycobacterial activity.

Structures and Biological Activities of Alkaloids Produced by Mushrooms, a Fungal Subgroup

Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.

Binding Interaction of Betulinic Acid to α-Glucosidase and Its Alleviation on Postprandial Hyperglycemia

Inhibiting the intestinal α-glucosidase can effectively control postprandial hyperglycemia for type 2 diabetes mellitus (T2DM) treatment. In the present study, we reported the binding interaction of betulinic acid (BA), a pentacyclic triterpene widely distributed in nature, on α-glucosidase and its alleviation on postprandial hyperglycemia. BA was verified to exhibit a strong inhibitory effect against α-glucosidase with an IC₅₀ value of 16.83 ± 1.16 μM. More importantly, it showed a synergistically inhibitory effect with acarbose. The underlying inhibitory mechanism was investigated by kinetics analysis, surface plasmon resonance (SPR) detection, molecular docking, molecular dynamics (MD) simulation and binding free energy calculation. BA showed a non-competitive inhibition on α-glucosidase. SPR revealed that it had a strong and fast affinity to α-glucosidase with an equilibrium dissociation constant (K_D) value of 5.529 × 10⁻⁵ M and a slow dissociation. Molecular docking and MD simulation revealed that BA bound to the active site of α-glucosidase mainly due to the van der Waals force and hydrogen bond, and then changed the micro-environment and secondary structure of α-glucosidase. Free energy decomposition indicated amino acid residues such as PHE155, PHE175, HIE277, PHE298, GLU302, TRY311 and ASP347 of α-glucosidase at the binding pocket had strong interactions with BA, while LYS153, ARG210, ARG310, ARG354 and ARG437 showed a negative contribution to binding affinity between BA and α-glucosidase. Significantly, oral administration of BA alleviated the postprandial blood glucose fluctuations in mice. This work may provide new insights into the utilization of BA as a functional food and natural medicine for the control of postprandial hyperglycemia.

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.

Inhibitory Effects of Nitrogenous Metabolites from a Marine-Derived Streptomyces bacillaris on Isocitrate Lyase of Candida albicans

Two nitrogenous metabolites, bacillimide (1) and bacillapyrrole (2), were isolated from the culture broth of the marine-derived actinomycete Streptomyces bacillaris. Based on the results of combined spectroscopic and chemical analyses, the structure of bacillimide (1) was determined to be a new cyclopenta[c]pyrrole-1,3-dione bearing a methylsulfide group, while the previously reported bacillapyrrole (2) was fully characterized for the first time as a pyrrole-carboxamide bearing an alkyl sulfoxide side chain. Bacillimide (1) and bacillapyrrole (2) exerted moderate (IC50 = 44.24 μM) and weak (IC50 = 190.45 μM) inhibitory effects on Candida albicans isocitrate lyase, respectively. Based on the growth phenotype using icl-deletion mutants and icl expression analyses, we determined that bacillimide (1) inhibits the transcriptional level of icl in C. albicans under C2-carbon-utilizing conditions.

Effects of Alkaloid-Rich Extracts Obtained from Grifola frondosa on Gut Microbiota and Glucose Homeostasis in Rats

Grifola frondosa (GF), also known as maitake (a type of mushroom), has been widely used as a food item and it exhibits various health-beneficial hypoglycemic activities. Rats fed with a...

Grifola frondosa may play an anti-obesity role by affecting intestinal microbiota to increase the production of short-chain fatty acids

BACKGROUND

Grifola frondosa (G. frondosa) is a fungus with good economic exploitation prospects of food and medicine homologation. This study aims to investigate the effects of G. frondosa powder suspension (GFPS) on the intestinal contents microbiota and the indexes related to oxidative stress and energy metabolism in mice, to provide new ideas for developing G. frondosa weight loss products.

METHODS

Twenty Kunming mice were randomly divided into control (CC), low-dose GFPS (CL), medium-dose GFPS (CM), and high-dose GFPS (CH) groups. The mice in CL, CM, and CH groups were intragastrically administered with 1.425 g/(kg·d), 2.85 g/(kg·d), and 5.735 g/(kg·d) GFPS, respectively. The mice in CC group were given the same dose of sterile water. After 8 weeks, liver and muscle related oxidative stress and energy metabolism indicators were detected, and the intestinal content microbiota of the mice was detected by 16S rRNA high-throughput sequencing.

RESULTS

After eight weeks of GFPS intervention, all mice lost weight. Compared with the CC group, lactate dehydrogenase (LDH) and malondialdehyde (MDA) contents in CL, CM, and CH groups were increased, while Succinate dehydrogenase (SDH) and Superoxide Dismutase (SOD) contents in the liver were decreased. The change trends of LDH and SDH in muscle were consistent with those in the liver. Among the above indexes, the change in CH is the most significant. The Chao1, ACE, Shannon, and Simpson index in CL, CM, and CH groups were increased. In the taxonomic composition, after the intervention with GFPS, the short-chain fatty acid (SCFA)-producing bacteria such as unclassified Muribaculaceae, Alloprevotella, and unclassified Lachnospiraceae increased. In linear discriminant analysis effect size (LEfSe) analysis, the characteristic bacteria in CC, CL, CM, and CH groups showed significant differences. In addition, some characteristic bacteria significantly correlated with related energy metabolism indicators.

CONCLUSION

The preventive effect of G. frondosa on obesity is related to changing the structure of intestinal content microbiota and promoting the growth of SCFAs. While excessive intake of G. frondosa may not be conducive to the antioxidant capacity and energy metabolism.

One-pot multi-component synthesis of novel chromeno[4,3-b]pyrrol-3-yl derivatives as alpha-glucosidase inhibitors

A green and efficient one-pot multi-component protocol was developed for the synthesis of some novel dihydrochromeno[4,3-b]pyrrol-3-yl derivatives through the reaction of arylglyoxals, malono derivatives, and different 4-amino coumarins in ethanol at reflux condition. In this method, all products were obtained in good to excellent yield. Next, all synthesized derivatives were evaluated for their α-glucosidase inhibitory activity. Most of the compounds displayed potent inhibitory activities with IC₅₀ values in the range of 48.65 ± 0.01–733.83 ± 0.10 μM compared to the standard inhibitor acarbose (IC₅₀ = 750.90 ± 0.14 μM). The kinetic study of compound 5e as the most potent derivative (IC₅₀ = 48.65 ± 0.01 μM) showed a competitive mechanism with a K_i value of 42.6 µM. Moreover, docking studies revealed that dihydrochromeno[4,3-b]pyrrol-3-yl effectively interacted with important residues in the active site of α-glucosidase.

Inhibitory effect of triterpenoids from the mushroom Inonotus obliquus against α-glucosidase and their interaction: Inhibition kinetics and molecular stimulations

Bioassay-guided fractionation led to the isolation of a series of triterpenoids (1-46) including 12 new ones (1-12) from the mushroom Inonotus obliquus. The structures of all the compounds were elucidated by spectroscopic analysis as well as by comparison with literature data. Triterpenoids 1-3, 6, 7, 16, 24, 25, 27, 38, 43, 44 and 46 showed strong α-glucosidase inhibition, with IC₅₀ values from 11.5 to 81.8 μM. Their structure-activity relationships were discussed. Inonotusol F (24) showed the strongest inhibitory activity and it presented noncompetitive inhibition against α-glucosidase. Molecular docking and molecular dynamics stimulation further demonstrated that GLU302 and PHE298 were key amino acids for the inhibition of inonotusol F (24) towards α-glucosidase. This study indicates the vital role of triterpenoids in explaining hypoglycemic effect of Inonotus obliquus and provides important evidence for further development and utilization of this mushroom.

New bioactive α-pyrone from wild mushroom Paxillus involutus

Chemical investigation of Paxillus involutus (Batsch) Fr. led to the isolation of a pair of new enantiomers (E)-5-(4-methoxy-2-oxo-2H-pyran-6-yl)pent-4-en-1-yl 2-hydroxypropanoate (1a/1b) along with 14 known compounds (2-15) for the first time from this mushroom. The structures of new compounds were elucidated based on extensive spectroscopic data analysis of MS, 1D and 2D NMR, and their absolute configurations were confirmed by comparison of the experimental and calculated ECD data. Compounds 1a and 1b exhibited radical scavenging activities with IC₅₀ values ranging from 10.39 ± 2.26 to 20.43 ± 3.74 μg/mL. Compounds 1a and 1b also showed moderate anti-tyrosinase activity with IC₅₀ value of 25.66 ± 2.84 and 26.82 ± 3.19 μg/mL.

Synthesis, in vitro evaluation, and molecular docking studies of novel hydrazineylideneindolinone linked to phenoxymethyl-1,2,3-triazole derivatives as potential α-glucosidase inhibitors

In this work, a novel series of hydrazineylideneindolinone linked to phenoxymethyl-1,2,3-triazole derivatives were designed, synthesized, and evaluated for their anti-α-glucosidase activity due to an urgent need to develop effective anti-diabetic agents. Among tested 15 compounds, 8 derivatives (9a, 9b, 9c, 9d, 9e, 9f, 9h, and 9o) demonstrated superior potency compared to that of positive control, acarbose. Particularly, compound 9d possessed the best anti-α-glucosidase activity with around a 46-fold improvement in the inhibitory activity. Additionally, 9d showed a competitive type of inhibition in the kinetic study and the molecular docking study demonstrated that it well occupied the binding pocket of the catalytic center through desired interactions with residues, correlating to the experimental results.

Natural Alkaloids and Diabetes Mellitus: A Review

BACKGROUND

The use of herbal therapies for treatment and management of diabetes mellitus and complications associated with this chronic condition is increasing. Plants contain a bounty of phytochemicals that have been proven to be protective by reducing the risk of various ailments and diseases, including alkaloids. Moreover, alkaloids are known to be among the oldest natural products used by humans for highlighting drugs that play crucial roles as therapeutic agents. The reason for this expanding interest and uses of alkaloids as a part of plant natural compounds-based treatments is that a significant proportion of diabetic patients do not respond very well to conventional therapeutic medication. Furthermore, other explanations to this fact are the cost of medication, side-effects, accessibility, and availability of health facilities and drugs and the inefficiency of these medicines in certain cases.

OBJECTIVE

In this study we aimed to review the literature on the valuable effects of herbs and plants and their isolated alkaloids compounds as medication for management of diabetes, a prevalent risk factor for several other disorders and illnesses.

METHODS

In the current review, PubMed, ScienceDirect, Springer and google scholar databases were used and the criterion for inclusion was based on the following keywords and phrases: diabetes, hyperglycemia, complications of diabetes, alkaloids, antidiabetic alkaloids, hypoglycemic alkaloids, alkaloids and complications of diabetes mellitus, mechanisms of action and alkaloids.

RESULTS

In the current review, we demonstrate that alkaloids in the form of extracts and isolated molecules obtained from a large variety of species demonstrated their efficiency for improving raises in blood glucose either in animal models via experimental studies or in human subjects via clinical trials. Medicinal species as chillies (Capsicum annuum), turmeric (Curcuma longa), barberry (Berberis vulgaris) and cress (Lepidium sativum) are among the most common and therapeutic plants used for controlling diabetes that were the subject of several experimental and clinical investigations. Whereas, isolated alkaloids such as berberine, capsaicin and trigonelline have received more interest in this field. Interestingly, the therapeutic impact of alkaloids against blood glucose pathogenesis is mediated through a variety of signaling cascades and pathways, via inhibiting or stimulating diversity of systems such as inhibition of α-glucosidase enzyme, blockade of PTP- 1B, deactivation of DPP-IV, increasing insulin sensitivity and modulating the oxidative stress.

CONCLUSION

Based on the findings of the present review, alkaloids could be used as preventive and curative agents in the case of endocrine disorders, particularly diabetes and could play a promoting function for the discovery of new antidiabetic agents.

Bioactive Ingredients and Medicinal Values of Grifola frondosa (Maitake)

Grifola frondosa (G. frondosa), generally known as hen-of-the-woods or maitake in Japanese and hui-shu-hua in Chinese, is an edible mushroom with both nutritional and medicinal properties. This review provides an up-to-date and comprehensive summary of research findings on its bioactive constituents, potential health benefits and major structural characteristics. Since the discovery of the D-fraction more than three decades ago, many other polysaccharides, including β-glucans and heteroglycans, have been extracted from the G. frondosa fruiting body and fungal mycelium, which have shown significant antitumor and immunomodulatory activities. Another class of bioactive macromolecules in G. frondosa is composed of proteins and glycoproteins, which have shown antitumor, immunomodulation, antioxidant and other activities. A number of small organic molecules such as sterols and phenolic compounds have also been isolated from the fungus and have shown various bioactivities. It can be concluded that the G. frondosa mushroom provides a diverse array of bioactive molecules that are potentially valuable for nutraceutical and pharmaceutical applications. More investigation is needed to establish the structure–bioactivity relationship of G. frondosa and to elucidate the mechanisms of action behind its various bioactive and pharmacological effects.

Fruit, vegetables, and mushrooms for the preparation of extracts with α-amylase and α-glucosidase inhibition properties: A review

The inhibition of the α-amylase and α-glucosidase activity facilitates the maintenance of circulating glucose levels by decreasing the rate of blood sugar absorption. Existing enzyme inhibitors such as acarbose, miglitol, and voglibose are used for inhibiting the activity of these enzymes, however, alternative solutions are required to avoid the side-effects of using these drugs. The current study aims to review recent evidence regarding the in vitro α-amylase and α-glucosidase inhibition activities of extracts derived from selected fruit, vegetables, and mushrooms. The mechanisms of action of the extracts involved in the inhibition of both enzymes are also presented and discussed. Compounds including flavonoids, phenolic acids, anthocyanins, saponins, carotenoids, terpenes, sugars, proteins, capsaicinoids, fatty acids, alkaloids have been shown to have α-amylase and α-glucosidase inhibition activities. Harvesting period, maturity stage, sample preparation, extraction technique, and solvent type are parameters that affect the α-amylase and α-glucosidase inhibition activities of the extracts.

Mycotoxins from Fusarium proliferatum: new inhibitors of papain-like cysteine proteases

Papain-like cysteine proteases (PLCPs) in plants are essential to prevent phytopathogen invasion. In order to search for cysteine protease inhibitors and to investigate compounds that could be associated to pineapple Fusarium disease, a chemistry investigation was performed on Fusarium proliferatum isolated from Ananas comosus (pineapple) and cultivated in Czapek medium. From F. proliferatum extracts, nine secondary metabolites were isolated and characterized by nuclear magnetic resonance spectroscopy and mass spectrometry experiments: beauvericin (1), fusaric acid (2), N-ethyl-3-phenylacetamide (3), N-acetyltryptamine (4), cyclo(L-Val-L-Pro) cyclodipeptide (5), cyclo(L-Leu-L-Pro) cyclodipeptide (6), cyclo(L-Leu-L-Pro) diketopiperazine (7), 2,4-dihydroxypyrimidine (8), and 1H-indole-3-carbaldehyde (9). Compounds 1, 3, and 6 showed significant inhibition of papain, with IC50 values of 25.3 ± 1.9, 39.4 ± 2.5, and 7.4 ± 0.5 μM, respectively. Compound 1 also showed significant inhibition against human cathepsins V and B with IC50 of 46.0 ± 3.0 and 6.8 ± 0.7 μM, respectively. The inhibition of papain by mycotoxins (fusaric acid and beauvericin) may indicate a mechanism of Fusarium in the roles of infection process.

Optimization of ergosterol extraction from Pleurotus mushrooms using response surface methodology

In this study, heat-assisted extraction (HAE) was used to optimise the extraction of ergosterol from Pleurotus ostreatus (PO) and Pleurotus eryngii (PE) using response surface methodology (RSM).

Hypoglycemic and hypolipidemic activities of Grifola frondosa polysaccharides and their relationships with the modulation of intestinal microflora in diabetic mice induced by high-fat diet and streptozotocin

This study aimed to investigate the hypoglycemic and hypolipidemic activities of polysaccharides from Grifola frondosa (GFP) in diabetic mice induced by high-fat diet (HFD) and streptozotocin (STZ). Results showed that oral administration of GFP markedly reduced the serum levels of fasting blood glucose (FBG), oral glucose tolerance (OGT), cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C), and significantly decreased the hepatic levels of TC, TG and free fatty acids (FFA). Meanwhile, high-dose of GFP supplementation (900 mg/kg day) also showed powerful effects on moderating the composition of intestinal microflora in diabetic mice, especially altering the functionally relevant intestinal microbial phylotypes. Spearman's correlation network analysis revealed that key microbial phylotypes responding to GFP intervention were strongly correlated with the glucose and lipid metabolic disorders associated parameters. Moreover, GFP treatment regulated mRNA expression levels of the genes responsible for hepatic glucose and lipid metabolism. It is noteworthy that GFP treatment markedly increased mRNA expression of cholesterol 7α-hydroxylase (CYP7A1) and bile salt export pump (BSEP), suggesting an enhancement of bile acids (BAs) synthesis and excretion in liver. These findings demonstrated that GFP could prevent hyperglycemia and hyperlipidemia in diabetic mice by altering gut microbiota and regulating hepatic glycolipid metabolism related genes, and therefore could be used as potential functional food ingredients for the prevention or treatment of hyperglycemia and hyperlipidemia.

Grifola frondosapolysaccharides ameliorate lipid metabolic disorders and gut microbiota dysbiosis in high-fat diet fed rats

G. frondosapolysaccharides have the potential to ameliorate lipid metabolic disorders in part through modulating gut microbiota and mRNA expression of genes involved in hepatic lipid and cholesterol metabolism.