New benzoate derivatives and hirsutane type sesquiterpenoids with antimicrobial activity and cytotoxicity from the solid-state fermented rice by the medicinal mushroom Stereum hirsutum

Stereuins A-F: Isopentenyl benzene congeners with antibacterial and neurotrophic activities from Stereum hirsutum HFG27

Cultivation and extraction of the fungus Stereum hirsutum (Willd.) Pers. yielded 12 isopentenyl benzene derivatives, including six previously undescribed derivatives, named stereuins A-F. Their structures were established based on NMR and mass spectroscopy analyses, supplemented by comparison with previously reported data. Stereuins A-C are unique benzoate derivatives containing fatty acid subunits. Stereuins D and E feature a valylene group and a 6/6/6 ring system. In vitro, stereuin A significantly promoted neurite outgrowth. Several compounds exhibited antibacterial activity against Staphylococcus aureus. Stereuin F has an IC50 value of 5.2 μg/mL against S. aureus, comparable to the positive control, penicillin G sodium (1.4 μg/mL).

Bioactive Peptides and Other Immunomodulators of Mushroom Origin

For centuries, humans have used mushrooms as both food and pro-health supplements. Mushrooms, especially those related to the functions of the human immune system, are rich in dietary fiber, minerals, essential amino acids, and various bioactive compounds and have significant health-promoting properties. Immunoregulatory compounds in mushrooms include lectins, terpenes, terpenoids, polysaccharides, and fungal immunomodulatory proteins (FIPs). The distribution of these compounds varies from one species of mushroom to another, and their immunomodulatory activities depend on the core structures and chemical modifications in the composition of the fractions. In this review, we describe active compounds from medical mushrooms. We summarize potential mechanisms for their in vitro and in vivo activities and detail approaches used in developing and applying bioactive compounds from mushrooms. Finally, we discuss applications of fungal peptides and highlight areas that require improvement before the widespread use of those compounds as therapeutic agents and explore the status of clinical studies on the immunomodulatory activities of mushrooms and their products, as well as the prospect of clinical application of AMPs as 'drug-like' compounds with great potential for treatment of non-healing chronic wounds and multiresistant infections.

Mining Xanthine Oxidase Inhibitors from an Edible Seaweed Pterocladiella capillacea by Using In Vitro Bioassays, Affinity Ultrafiltration LC-MS/MS, Metabolomics Tools, and In Silico Prediction

The prevalence of gout and the adverse effects of current synthetic anti-gout drugs call for new natural and effective xanthine oxidase (XOD) inhibitors to target this disease. Based on our previous finding that an edible seaweed Pterocladiella capillacea extract inhibits XOD, XOD-inhibitory and anti-inflammatory activities were used to evaluate the anti-gout potential of different P. capillacea extract fractions. Through affinity ultrafiltration coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS), feature-based molecular networking (FBMN), and database mining of multiple natural products, the extract's bioactive components were traced and annotated. Through molecular docking and ADMET analysis, the possibility and drug-likeness of the annotated XOD inhibitors were predicted. The results showed that fractions F4, F6, F4-2, and F4-3 exhibited strong XOD inhibition activity, among which F4-3 reached an inhibition ratio of 77.96% ± 4.91% to XOD at a concentration of 0.14 mg/mL. In addition, the P. capillacea extract and fractions also displayed anti-inflammatory activity. Affinity ultrafiltration LC-MS/MS analysis and molecular networking showed that out of the 20 annotated compounds, 8 compounds have been previously directly or indirectly reported from seaweeds, and 4 compounds have been reported to exhibit anti-gout activity. Molecular docking and ADMET showed that six seaweed-derived compounds can dock with the XOD activity pocket and follow the Lipinski drug-like rule. These results support the value of further investigating P. capillacea as part of the development of anti-gout drugs or related functional foods.

Three new tyrosol derivatives from Huangjing wine

Phytochemical investigation on the concentrate of Huangjing wine, resulted in the isolation of three new tyrosol derivatives 4'''-hydroxyphenethyl 2-(R)-hydroxy-3-phenylpropionate (1), 4'''-hydroxyphenethyl(4'-hydroxy-3'-methoxyphenyl)propionate (2) and 4''-hydroxyphenethyl ethyl succinate (3), together with 5 known compounds, ferulic acid (4), L-phenyllactic acid (5), hydroxytyrosol (6), dihydroferulic acid (7), cyclo(L-Pro-D-Tyr) (8). Their structures were elucidated using spectroscopic analysis and by comparison with the literature data. All compounds displayed antioxidant effect in the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical. Among them, the new compound 2 exhibited obvious antioxidant effect, and new compounds 1 and 3 exhibited medium antioxidant effect.

Structure elucidation of linear triquinane sesquiterpenoids, hirsutuminoids A-Q, from the fungus Stereum hirsutum and their activities

Eighteen linear triquinane sesquiterpenoids (LTSs), including seventeen previously undescribed ones (hirsutuminoids A-Q), were isolated from the fermentation of the fungus Stereum hirsutum (Willd.) Pers. The structures and absolute configurations of the isolates were characterized by extensive spectroscopic analysis (1D, 2D NMR, and HRMS data), together with comparing the experimental and calculated data of both electronic circular dichroism and NMR data, as well as X-ray crystallography. Based on the literature survey and efforts on constructing the absolute configurations of these LTSs in this study, one empirical rule about the orientations of substitutions at C-2/C-3/C-7/C-9 was summarized. Anti-inflammatory and cytotoxic bioassays showed that only hirsutuminoid B inhibited the nitric oxide (NO) production in RAW 264.7 macrophages with an IC₅₀ value, 18.9 μM.

Fungal Mushrooms: A Natural Compound With Therapeutic Applications

Fungi are extremely diverse in terms of morphology, ecology, metabolism, and phylogeny. Approximately, 130 medicinal activities like antitumor, immunomodulation, antioxidant, radical scavenging, cardioprotective and antiviral actions are assumed to be produced by the various varieties of medicinal mushrooms. The polysaccharides, present in mushrooms like β-glucans, micronutrients, antioxidants like glycoproteins, triterpenoids, flavonoids, and ergosterols can help establish natural resistance against infections and toxins.. Clinical trials have been performed on mushrooms like Agaricus blazei Murrill Kyowa for their anticancer effect, A. blazei Murrill for its antihypertensive and cardioprotective effects, and some other mushrooms had also been evaluated for their neurological effects. The human evaluation dose studies had been also performed and the toxicity dose was evaluated from the literature for number of mushrooms. All the mushrooms were found to be safe at a dose of 2000 mg/kg but some with mild side effects. The safety and therapeutic effectiveness of the fungal mushrooms had shifted the interest of biotechnologists toward fungal nanobiotechnology as the drug delivery system due to the vast advantages of nanotechnology systems. In complement to the vital nutritional significance of medicinal mushrooms, numerous species have been identified as sources of bioactive chemicals. Moreover, there are unanswered queries regarding its safety, efficacy, critical issues that affect the future mushroom medicine development, that could jeopardize its usage in the twenty-first century.

Progress in biological activities and biosynthesis of edible fungi terpenoids

The edible fungi have both edible and medicinal functions, in which terpenoids are one of the most important active ingredients. Terpenoids possess a wide range of biological activities and show great potential in the pharmaceutical and healthcare industries. In this review, the diverse biological activities of edible fungi terpenoids were summarized with emphasis on the mechanism of anti-cancer and anti-inflammation. Subsequently, this review focuses on advances in knowledge and understanding of the biosynthesis of terpenoids in edible fungi, especially in the generation of sesquiterpenes, diterpenes, and triterpenes. This paper is aim to provide an overview of biological functions and biosynthesis developed for utilizing the terpenoids in edible fungi.

Sterehirsutynes A - C: three new acetylenic aromatic metabolites from Stereum hirsutum

Three new acetylenic aromatic compounds, sterehirsutynes A-C (1-3), along with three known congeners, frustulosinol (4), vibrayne (5), and sterehirsutinol (6), were isolated from the culture broth of Stereum hirsutum. Their structures were determined by detailed analyses of NMR and high-resolution mass. Chiral column analysis showed that compounds 2 and 3 were racemic mixtures. These new compounds were evaluated for porcine pancreatic lipase (PPL) inhibitory activities, and compounds 1 and (±) 3 showed moderate inhibitory activity against PPL, with IC₅₀ values of 23.2 ± 1.04 and 21.8 ± 2.15 μM, respectively.

Fungal Depsides-Naturally Inspiring Molecules: Biosynthesis, Structural Characterization, and Biological Activities

Fungi represent a huge reservoir of structurally diverse bio-metabolites. Although there has been a marked increase in the number of isolated fungal metabolites over the past years, many hidden metabolites still need to be discovered. Depsides are a group of polyketides consisting of two or more ester-linked hydroxybenzoic acid moieties. They possess valuable bioactive properties, such as anticancer, antidiabetic, antibacterial, antiviral, anti-inflammatory, antifungal, antifouling, and antioxidant qualities, as well as various human enzyme-inhibitory activities. This review provides an overview of the reported data on fungal depsides, including their sources, biosynthesis, physical and spectral data, and bioactivities in the period from 1975 to 2020. Overall, 110 metabolites and more than 122 references are confirmed. This is the first review of these multi-faceted metabolites from fungi.

Mushroom Species Stereum hirsutum as Natural Source of Phenolics and Fatty Acids as Antioxidants and Acetylcholinesterase Inhibitors

Many lignicolous mushroom species are used as a food supplement and may represent an alternative treatment of Alzheimer's disease (AD). This study aimed to evaluate acetylcholinesterase inhibition (AChEI) of Stereum hirsutum together with antioxidant activity (AO) and cytotoxic activity against HepG2 cells. Different extracts (water, ethanol, methanol, polysaccharide) were analyzed, with respect to their mineral composition and chemical content. Ethanol extract was the most potent in AChEI (98.44 %) and demonstrated cytotoxic activity (91.96 % at 900.00 μg/mL), while the highest AO was demonstrated for polar extracts (methanol and water) as well. These activities may be attributed to determined phenolics (hydroxybenzoic and quinic acid) and fatty acids (FA), while biflavonoid amentoflavone may be responsible for cytotoxic activity. The most prevalent FA was linoleic (40.00 %) and the domination of unsaturated FA (UFA) (71.91 %) over saturated (26.96 %) was observed. This is the first report of AChEI of S. hirsutum extracts and first detection of amentoflavone. Due to high amount of UFA and well-expressed AChEI, this species can be considered as a potent food supplement in the palliative therapy of AD.

Sesquiterpenoids and their quaternary ammonium hybrids from the mycelium of mushroom Stereum hirsutum by medium optimization

The fungal genus Stereum (Stereaceae) produces a broad variety of specialised metabolites, including a wide range of terpenes. This probably relates to the presence of an extensive biosynthetic machinery for this group of compounds: genomic analysis of Stereum hirsutum has identified 16 terpene synthase gene clusters, 6 polyketide synthase gene clusters, and 1 polyketide synthase non-ribosomal polypeptide heterodimer gene cluster in S. hirsutum FP-91666. In the present study, the One Strain Many Compounds (OSMAC) approach was employed to discover undescribed metabolites from this strain. Fermentation was carried out in five media and the products of the strain cultivated on different media were analyzed by LC-MS. From cultures grow in WGB medium (30.0 g wheat bran, 20.0 g glucose, 1.5 g KH₂PO₄, and 1.5 g MgSO₄), four previously undescribed metabolites, a sesquiterpene sterostrein X and three mixed terpenes (stereumamides I-K) were isolated, together with seven known compounds (drimene-2,11-diol, stereumamide E, stereumamide D, stereumamide B, stereumamide A, stereumamide C, and sterostrein Q). The drimane-type sesquiterpene drimene-2,11-diol was found in S. hirsutum FP-91666 for the first time. All structures were elucidated by spectroscopic data analysis. The absolute configurations of stereumamides I, J and K were assigned by comparing their experimental and calculated electronic circular dichroism (ECD) spectra. An anti-Mycobacterium tuberculosis experiment showed that stereumamides I-K and sterostrein Q had weak antibacterial activity against this pathogen.

Production of minor ginsenosides by combining Stereum hirsutum and cellulase

Minor ginsenosides (MGs) (include ginsenoside F2, Compound K, PPT, etc), which are generally not produced by ginseng plants naturally, are obtained by deglycosylation of major ginsenosides. However, the conventional processes used to produce deglycosylated ginsenosides focus on the use of intestinal microorganisms for transformation. In this study, an edible and medicinal mushroom Stereum hirsutum JE0512 was screened from 161 β-glucosidase-producing soil microorganisms sourced from wild ginseng using the plate coloration method. Furthermore, JE0512 was used for the production of CK from ginseng extracts (GE) in solid-state fermentation (SSF) using 20 g corn bran as substrate, 4 g GE, and 20% inoculation volume, and the results showed that the highest CK content was 29.13 mg/g. After combining S. hirsutum JE0512 with cellulase (Aspergillus niger), the MGs (F2, CK, and PPT) content increased from 1.66 to 130.79 mg/g in the final products. Our results indicate that the Stereum genus has the potential to biotransform GE into CK and the combination of S. hirsutum JE0512 and cellulase could pave the way for the production of MGs from GE.

A Review on Antistaphylococcal Secondary Metabolites from Basidiomycetes

Fungi are a rich source of secondary metabolites with several pharmacological activities such as antifungal, antioxidant, antibacterial and anticancer to name a few. Due to the large number of diverse structured chemical compounds they produce, fungi from the phyla Ascomycota, Basidiomycota and Muccoromycota have been intensively studied for isolation of bioactive compounds. Basidiomycetes-derived secondary metabolites are known as a promising source of antibacterial compounds with activity against Gram-positive bacteria. The continued emergence of antimicrobial resistance (AMR) poses a major challenge to patient health as it leads to higher morbidity and mortality, higher hospital-stay duration and substantial economic burden in global healthcare sector. One of the key culprits for AMR crisis is Staphylococcus aureus causing community-acquired infections as the pathogen develops resistance towards multiple antibiotics. The recent emergence of community strains of S. aureus harbouring methicillin-resistant (MRSA), vancomycin-intermediate (VISA) and vancomycin-resistant (VRSA) genes associated with increased virulence is challenging. Despite the few significant developments in antibiotic research, successful MRSA therapeutic options are still needed to reduce the use of scanty and expensive second-line treatments. This paper provides an overview of findings from various studies on antibacterial secondary metabolites from basidiomycetes, with a special focus on antistaphylococcal activity.

Immunomodulatory Effects of Edible and Medicinal Mushrooms and Their Bioactive Immunoregulatory Products

Mushrooms have been valued as food and health supplements by humans for centuries. They are rich in dietary fiber, essential amino acids, minerals, and many bioactive compounds, especially those related to human immune system functions. Mushrooms contain diverse immunoregulatory compounds such as terpenes and terpenoids, lectins, fungal immunomodulatory proteins (FIPs) and polysaccharides. The distributions of these compounds differ among mushroom species and their potent immune modulation activities vary depending on their core structures and fraction composition chemical modifications. Here we review the current status of clinical studies on immunomodulatory activities of mushrooms and mushroom products. The potential mechanisms for their activities both in vitro and in vivo were summarized. We describe the approaches that have been used in the development and application of bioactive compounds extracted from mushrooms. These developments have led to the commercialization of a large number of mushroom products. Finally, we discuss the problems in pharmacological applications of mushrooms and mushroom products and highlight a few areas that should be improved before immunomodulatory compounds from mushrooms can be widely used as therapeutic agents.

In Depth Natural Product Discovery from the Basidiomycetes Stereum Species

Natural metabolites from microorganisms play significant roles in the discovery of drugs, both for disease treatments in humans, and applications in agriculture. The Basidiomycetes Stereum genus has been a source of such bioactive compounds. Here we report on the structures and activities of secondary metabolites from Stereum. Their structural types include sesquiterpenoids, polyketides, vibralactones, triterpenoids, sterols, carboxylic acids and saccharides. Most of them showed biological activities including cytotoxic, antibacterial, antifungal, antiviral, radical scavenging activity, autophagy inducing activity, inhibiting pancreatic lipase against malarial parasite, nematocidal and so on. The syntheses of some metabolites have been studied. In this review, 238 secondary metabolites from 10 known species and various unidentified species of Stereum were summarized over the last seven decades.

Vib-PT, an Aromatic Prenyltransferase Involved in the Biosynthesis of Vibralactone from Stereum vibrans

Vibralactone, a hybrid compound derived from phenols and a prenyl group, is a strong pancreatic lipase inhibitor with a rare fused bicyclic β-lactone skeleton. Recently, a researcher reported a vibralactone derivative (compound C1) that caused inhibition of pancreatic lipase with a half-maximal inhibitory concentration of 14 nM determined by structure-based optimization, suggesting a potential candidate as a new antiobesity treatment. In the present study, we sought to identify the main gene encoding prenyltransferase in Stereum vibrans, which is responsible for the prenylation of phenol leading to vibralactone synthesis. Two RNA silencing transformants of the identified gene (vib-PT) were obtained through Agrobacterium tumefaciens-mediated transformation. Compared to wild-type strains, the transformants showed a decrease in vib-PT expression ranging from 11.0 to 56.0% at 5, 10, and 15 days in reverse transcription-quantitative PCR analysis, along with a reduction in primary vibralactone production of 37 to 64% at 15 and 21 days, respectively, as determined using ultra-high-performance liquid chromatography-mass spectrometry analysis. A soluble and enzymatically active fusion Vib-PT protein was obtained by expressing vib-PT in Escherichia coli, and the enzyme's optimal reaction conditions and catalytic efficiency (K_m /k _cat) were determined. In vitro experiments established that Vib-PT catalyzed the C-prenylation at C-3 of 4-hydroxy-benzaldehyde and the O-prenylation at the 4-hydroxy of 4-hydroxy-benzenemethanol in the presence of dimethylallyl diphosphate. Moreover, Vib-PT shows promiscuity toward aromatic compounds and prenyl donors.IMPORTANCE Vibralactone is a lead compound with a novel skeleton structure that shows strong inhibitory activity against pancreatic lipase. Vibralactone is not encoded by the genome directly but rather is synthesized from phenol, followed by prenylation and other enzyme reactions. Here, we used an RNA silencing approach to identify and characterize a prenyltransferase in a basidiomycete species that is responsible for the synthesis of vibralactone. The identified gene, vib-PT, was expressed in Escherichia coli to obtain a soluble and enzymatically active fusion Vib-PT protein. In vitro characterization of the enzyme demonstrated the catalytic mechanism of prenylation and broad substrate range for different aromatic acceptors and prenyl donors. These characteristics highlight the possibility of Vib-PT to generate prenylated derivatives of aromatics and other compounds as improved bioactive agents or potential prodrugs.

Acetylenic sesquiterpenoids from cultures of the basidiomycete Stereum cf. hirsutum BCC 26597

A new acetylenic sesquiterpenoid, stereyne A (1), and its acetonide derivative, stereyne B (2), were isolated from cultures of the basidiomycete Stereum cf. hirsutum BCC 26597. The structures were elucidated by spectroscopic analysis and a chemical correlation. Their absolute configurations were determined by application of the modified Mosher's method. They represent new structural type of sesquiterpenoids from Stereum.

Linear Triquinane Sesquiterpenoids: Their Isolation, Structures, Biological Activities, and Chemical Synthesis

Linear triquinane sesquiterpenoids represent an important class of natural products. Most of these compounds were isolated from fungi, sponges, and soft corals, and many of them displayed a wide range of biological activities. On account of their structural diversity and complexity, linear triquinane sesquiterpenoids present new challenges for chemical structure identification and total synthesis. 118 linear triquinane sesquiterpenoids were classified into 8 types, named types I–VIII, based on the carbon skeleton and the position of carbon substituents. Their isolation, structure elucidations, biological activities, and chemical synthesis were reviewed. This paper cited 102 articles from 1947 to 2018.

Cerrenins A-C, cerapicane and isohirsutane sesquiterpenoids from the endophytic fungus Cerrena sp

One new cerapicane cerrenin A (1), and two new isohirsutane sesquiterpenoids cerrenins B and C (2 and 3), were isolated from the broth extract of Cerrena sp. A593. Cerrenin A featured a rare cage-like bicyclo[3.2.1]octane skeleton, and cerrenin B represented the rearranged triquinane-type sesquiterpenoid. Their structures were extensively elucidated by NMR spectroscopic analysis with the absolute configuration determined by X-ray crystallography and ECD calculations. The anti-cancer activity for all the compounds were evaluated, and their plausible biosynthetic relationships involving fascinating carbon skeleton rearrangements were also suggested.

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.

A new compound from Stereum insigne CGMCC5.57

Studies of the EtOAc extract of the culture broth and methanol extract of the mycelium of Stereum insigne CGMCC5.57 led to the isolation of one new dihydrobenzofuran (1) and six known compounds (2-7). The structures of compounds were elucidated mainly by HRESIMS experiments, and 1D, 2D NMR spectroscopy analysis. This is the first report about the chemical constitutes of the fungus S. insigne.

Bioactivities and Health Benefits of Mushrooms Mainly from China

Many mushrooms have been used as foods and medicines for a long time. Mushrooms contain polyphenols, polysaccharides, vitamins and minerals. Studies show that mushrooms possess various bioactivities, such as antioxidant, anti-inflammatory, anticancer, immunomodulatory, antimicrobial, hepatoprotective, and antidiabetic properties, therefore, mushrooms have attracted increasing attention in recent years, and could be developed into functional food or medicines for prevention and treatment of several chronic diseases, such as cancer, cardiovascular diseases, diabetes mellitus and neurodegenerative diseases. The present review summarizes the bioactivities and health benefits of mushrooms, and could be useful for full utilization of mushrooms.

Combating Antimicrobial Resistance in Foodborne Microorganisms

This review addresses an important public health hazard affecting food safety. Antimicrobial agents are used in foods to reduce or eliminate microorganisms that cause disease. Many traditional organic compounds, novel synthetic organic agents, natural products, peptides, and proteins have been extensively studied for their effectiveness as antimicrobial agents against foodborne Campylobacter spp., Escherichia coli, Listeria spp. and Salmonella. However, antimicrobial resistance can develop in microorganisms, enhancing their ability to withstand the inhibiting or killing action of antimicrobial agents. Knowledge gaps still exist with regard to the actual chemical and microbiological mechanisms that must be identified to facilitate the search for new antimicrobial agents. Technical implementation of antimicrobial active packing films and coatings against target microorganisms must also be improved for extended product shelf life. Recent advances in antimicrobial susceptibility testing can provide researchers with new momentum to pursue their quest for a resistance panacea.

Bioactive compounds isolated from submerged fermentations of the Chilean fungus Stereum rameale

Liquid fermentations of the fungus Stereum rameale (N° 2511) yielded extracts with antibacterial activity. The antibacterial activity reached its peak after 216 h of stirring. Bioassay-guided fractionation methods were employed for the isolation of the bioactive metabolites. Three known compounds were identified: MS-3 (1), vibralactone (2) and vibralactone B (3). The three compounds showed antibacterial activity as a function of their concentration. Minimal bactericidal concentrations (MBC) of compound 1 against Gram-positive bacteria were as follows: Bacillus cereus (50 μg/mL), Bacillus subtilis (10 μg/mL) and Staphylococcus aureus (100 μg/mL). Compounds 2 and 3 were active only against Gram-negative bacteria. The MBC of compound 2 against Escherichia coli was 200 μg/mL. Compound 3 inhibited significantly the growth of E. coli and Pseudomonas aeruginosa, with MBC values of 50 and 100 μg/mL, respectively.

Lanostane Triterpenes from the Tibetan Medicinal Mushroom Ganoderma leucocontextum and Their Inhibitory Effects on HMG-CoA Reductase and α-Glucosidase

Sixteen new lanostane triterpenes, ganoleucoins A-P (1-16), together with 10 known tripterpenes (17-26), were isolated from the cultivated fruiting bodies of Ganoderma leucocontextum, a new member of the Ganoderma lucidum complex. The structures of the new compounds were elucidated by extensive spectroscopic analysis and chemical transformation. The inhibitory effects of 1-26 on HMG-CoA reductase and α-glucosidase were tested in vitro. Compounds 1, 3, 6, 10-14, 17, 18, 23, 25, and 26 showed much stronger inhibitory activity against HMG-CoA reductase than the positive control atorvastatin. Compounds 13, 14, and 16 presented potent inhibitory activity against α-glucosidase from yeast with IC₅₀ values of 13.6, 2.5, and 5.9 μM, respectively. In addition, the cytotoxicity of 1-26 was evaluated against the K562 and PC-3 cell lines by the MTT assay. Compounds 1, 2, 6, 7, 10, 12, 16, 18, and 25 exhibited cytotoxicity against K562 cells with IC₅₀ values in the range 10-20 μM. Paclitaxel was used as the positive control with an IC₅₀ value of 0.9 μM. This is the first report of secondary metabolites from this medicinal mushroom.

New Furan and Cyclopentenone Derivatives from the Sponge-Associated Fungus Hypocrea Koningii PF04

Two new furan derivatives, hypofurans A and B (1 and 2), and three new cyclopentenone derivatives, hypocrenones A-C (3-5), along with seven known compounds (6-12), were isolated from a marine fungus Hypocrea koningii PF04 associated with the sponge Phakellia fusca. Among them, compounds 10 and 11 were obtained for the first time as natural products. The planar structures of compounds 1-5 were elucidated by analysis of their spectroscopic data. Meanwhile, the absolute configuration of 1 was determined as 2R,3R by the comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. All the isolates were evaluated for their antibacterial and antioxidant activity. Compounds 1, 10, and 12 all showed modest antibacterial activity against Staphylococcus aureus ATCC25923 (MIC, 32 μg/mL). In addition, compounds 1, 10 and 11 exhibited moderate DPPH radical scavenging capacity with IC50 values of 27.4, 16.8, and 61.7 µg/mL, respectively.

New apoptosis-inducing sesquiterpenoids from the mycelial culture of Chinese edible fungus Pleurotus cystidiosus

Two new bisabolane-type sesquiterpenoids, pleuroton A (1) and pleuroton B (2), and three clitocybulol derivatives, clitocybulol D (3), clitocybulol E (4), and clitocybulol F (5), were obtained from the mycelial culture of edible fungus Pleurotus cystidiosus O. K. Mill by repeated column chromatography over RP-18, Sephadex LH-20, and silica gel. Their structures were determined according to nuclear magnetic resonance data, high-resolution electron impact mass spectrometry, and circular dichroism spectra. These new sesquiterpenoids exhibited significant cytotoxicity against two human prostate cancer DU-145 and C42B cells in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The median inhibitory concentration (IC50) of compounds 1, 2, 3, 4, and 5 was 174, 28, 233, 162, and 179 nM, respectively, against the DU-145 cell and was 104, 52, 163, 120, and 119 nM, respectively, against the C42B cell. Especially, pleuroton B (2) exhibited the strongest cytotoxity among these sesquiterpenoids, which was confirmed by the colony formation assay. Furthermore, pleuroton B (2) could trigger the apoptosis of DU-145 cells through the detection of apoptosis cells using annexin V-FITC staining by flow cytometry, the observation of condensed nuclei in the apoptosis cells, and the western blot analysis for the expression of apoptosis-related proteins Bcl-2, Bak, and Bax. Analysis of structure-activity relationships of these sesquiterpenoids revealed that the unusual functional moiety of pleuroton B should contribute to its significant bioactivity. These results display the pharmacological potential of P. cystidiosus.

Six New Vibralactone Derivatives from Cultures of the Fungus Boreostereum vibrans

Phytochemical reinvestigation on the cultural broth of Boreostereum vibrans led to the isolation of six new vibralactone derivatives, vibralactone N (1), vibralactone O (2), vibralactone P (3), 10-lactyl vibralactone G (4), (3S*, 4R*)-6-acetoxymethyl-2,2-dimethyl-3,4-dihydro-2H-chromene-3,4-diol (5), vibralactone Q (6). Their structures were elucidated by extensive spectroscopic methods.

Traversing the fungal terpenome

Fungi (Ascomycota and Basidiomycota) are prolific producers of structurally diverse terpenoid compounds. Classes of terpenoids identified in fungi include the sesqui-, di- and triterpenoids. Biosynthetic pathways and enzymes to terpenoids from each of these classes have been described. These typically involve the scaffold generating terpene synthases and cyclases, and scaffold tailoring enzymes such as e.g. cytochrome P450 monoxygenases, NAD(P)+ and flavin dependent oxidoreductases, and various group transferases that generate the final bioactive structures. The biosynthesis of several sesquiterpenoid mycotoxins and bioactive diterpenoids has been well-studied in Ascomycota (e.g. filamentous fungi). Little is known about the terpenoid biosynthetic pathways in Basidiomycota (e.g. mushroom forming fungi), although they produce a huge diversity of terpenoid natural products. Specifically, many trans-humulyl cation derived sesquiterpenoid natural products with potent bioactivities have been isolated. Biosynthetic gene clusters responsible for the production of trans-humulyl cation derived protoilludanes, and other sesquiterpenoids, can be rapidly identified by genome sequencing and bioinformatic methods. Genome mining combined with heterologous biosynthetic pathway refactoring has the potential to facilitate discovery and production of pharmaceutically relevant fungal terpenoids.

Sterhirsutins A and B, two new heterodimeric sesquiterpenes with a new skeleton from the culture of Stereum hirsutum collected in Tibet Plateau

Two new heterodimeric sesquiterpenes, sterhirsutins A (1) and B (2), and two new sesquiterpenes, hirsutic acids D-E (3 and 4), were identified from the culture of Stereum hirsutum. The absolute configurations in 1 and 2 were confirmed by single-crystal X-ray diffraction experiments and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 are likely biosynthesized from a hirsutane-type sesquiterpene and α-humulene by a hetero-Diels-Alder cycloaddition. Compounds 1-4 showed cytotoxicity against K562 and HCT116 cell lines.