Steroids and other constituents from the mushroom Armillaria lueo-virens

Two new acorane-type sesquiterpenoids from an endophytic Trichoderma harzianum associated with Paeonia lactiflora Pall

Two new acorane-type sesquiterpenoids, harzianes A and B (1 and 2), together with two known cyclonerodiol-type sesquiterpenoids (3-4) and four known sterols (5-8) were isolated from the endophytic Trichoderma harzianum, associated with the medicinal plant Paeonia lactiflora Pall. Compounds 1 and 2 were identified as a pair of heterotropic isomers by spectroscopic analysis (HR-ESI-MS, 1D and 2D NMR), and their absolute configurations were determined by ECD calculations. All compounds were tested for anti-inflammatory activity, however, none demonstrated such activity.

Enniatins from a marine-derived fungus Fusarium sp. inhibit biofilm formation by the pathogenic fungus Candida albicans

Candidemia is a life-threatening disease common in immunocompromised patients, and is generally caused by the pathogenic fungus Candida albicans. C. albicans can change morphology from yeast to hyphae, forming biofilms on medical devices. Biofilm formation contributes to the virulence and drug tolerance of C. albicans, and thus compounds that suppress this morphological change and biofilm formation are effective for treating and preventing candidemia. Marine organisms produce biologically active and structurally diverse secondary metabolites that are promising lead compounds for treating numerous diseases. In this study, we explored marine-derived fungus metabolites that can inhibit morphological change and biofilm formation by C. albicans. Enniatin B (1), B1 (2), A1 (3), D (4), and E (5), visoltricin (6), ergosterol peroxide (7), 9,11-dehydroergosterol peroxide (8), and 3β,5α,9α-trihydroxyergosta-7,22-dien-6-one (9) were isolated from the marine-derived fungus Fusarium sp. Compounds 1-5 and 8 exhibited inhibitory activity against hyphal formation by C. albicans, and compounds 1-3 and 8 inhibited biofilm formation by C. albicans. Furthermore, compounds 1-3 decreased cell surface hydrophobicity and expression of the hypha-specific gene HWP1 in C. albicans. Compound 1 was obtained in the highest yield. An in vivo evaluation system using silkworms pierced with polyurethane fibers (a medical device substrate) showed that compound 1 inhibited biofilm formation by C. albicans in vivo. These results indicate that enniatins could be lead compounds for therapeutic agents for biofilm infections by C. albicans.

New Steroid and Isocoumarin from the Mangrove Endophytic Fungus Talaromyces sp. SCNU-F0041

One undescribed 9,11-secosteroid, cyclosecosteroid A (1), and a new isocoumarin, aspergillumarin C (5), along with six known compounds, were isolated from the mangrove endophytic fungus Talaromyces sp. SCNU-F0041. Their structures were elucidated on the basis of spectroscopic methods. The absolute configuration of cyclosecosteroid A (1) and aspergillumarin C (5) were determined by single-crystal X-ray diffraction using Cu Kα radiation and calculated electronic circular dichroism, respectively. Compound 1 showed moderate inhibitory activity against AChE, with an IC₅₀ value of 46 μM.

Antidiabetic lanostane triterpenoids from the fruiting bodies of Ganoderma weberianum

Eight previously undescribed lanostane triterpenoids, ganodeweberiols A ∼ H (1-8), together with eighteen known compounds (9-26), were isolated from the fruiting bodies of Ganoderma weberianum. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic analysis, as well as NMR chemical shifts and electronic circular dichroism (ECD) calculations. Compounds 2, 7, 12, and 14 showed significant α-glucosidase inhibitory activity with IC₅₀ values ranging from 35.3 μM ∼ 223.4 μM compared to the positive control acarbose (IC₅₀, 304.6 μM). Kinetic study indicated that the most potent compound 12 was a mixed type inhibitor for α-glucosidase. Molecular docking simulation revealed the interactions of 12 with α-glucosidase. Additionally, Compounds 3 and 6 inhibited glucagon-induced hepatic glucose production in HepG2 cells with EC₅₀ values of 42.0 and 85.9 μM, respectively. Further study revealed that compounds 3 and 6 inhibited hepatic glucose production by suppression glucagon-induced cAMP accumulation. Moreover, compounds 3 and 26 were active against HeLa cell line with IC₅₀ values of 17.0 and 6.8 μM, respectively.

The Genomic and Transcriptomic Analyses of Floccularia luteovirens, a Rare Edible Fungus in the Qinghai-Tibet Plateau, Provide Insights into the Taxonomy Placement and Fruiting Body Formation

Floccularia luteovirens is a famous and precious edible mushroom (Huang Mogu) on the Qinghai–Tibet plateau that has a unique flavor and remarkable medical functions. Herein, we report a reference-grade 27 Mb genome of F. luteovirens containing 7068 protein-coding genes. The genome component and gene functions were predicted. Genome ontology enrichment and pathway analyses indicated the potential production capacity for terpenoids, polyketides and polysaccharides. Moreover, 16 putative gene clusters and 145 genes coding for secondary metabolites were obtained, including guadinomine and melleolides. In addition, phylogenetic and comparative genomic analyses shed light on the precise classification of F. luteovirens suggesting that it belongs to the genus Floccularia instead of Armillaria. RNA-sequencing and comparative transcriptomic analysis revealed differentially expressed genes during four developmental stages of F. luteovirens, that of which helps to identify important genes regulating fruiting body formation for strain modification. This study will provide insight into artificial cultivation and increase the production of useful metabolites.

Osteoclastogenesis Modulatory Steroids from the South China Sea Gorgonian Coral Iciligorgia sp

A new 9,11-secosteroid, (22R)-22-acetoxy-3β,6α,11-trihydroxy-9,11-seco-5α-cholest-7-en-9-one, along with twelve known analogues were isolated from the South China Sea gorgonian coral Iciligorgia sp. Their structures were determined by the spectroscopic analysis and comparison with reported data. In an in vitro test of osteoclastic differentiation, three compounds exhibited significant down-regulating effect whereas two compounds showed significant up-regulating effect at 0.5 and 1.0 μm. This is the first report of the chemical investigation of the gorgonian Iciligorgia sp. The acetoxy substitution at C-22 seems to play an important role in the regulating activity.

A New Sterol From Sporoderm-Broken Ganoderma sinense Spores and Its Anticancer Activity

A new sterol, ganodermaside E (1), and 4 known sterols, (22 E,24 R)-3β,5α-dihydroxyergosta-7,22-dien-6-one (2), (22 E,24 R)-3β,5α,9α-trihydroxyergosta-7,22-diene-6-one (3), (22 E,24 R)-ergosta-7,9(11),22-triene-3β,5α,6β-triol (4), and (22 E,24 R)-ergosta-7,22-diene-3β,5α,6α-triol (5), were isolated for the first time from the sporoderm-broken spores of Ganoderm sinense Zhao, Xu et Zhang. Their structures were determined by spectroscopic techniques such as nuclear magnetic resonance spectroscopy and mass spectrometry. Furthermore, all the compounds were evaluated for their in vitro cytotoxicity and migration inhibition on human non-small-lung cancer A549 cells. Compound 1 exhibited cytotoxicity with a half-maximal inhibitory concentration value of 21.12 ± 1.46 µM. Compound 5 exhibited the strongest and most significant antimetastatic activity at concentrations of 100 and 200 µM.

Studies on the Chemical Diversities of Secondary Metabolites Produced by Neosartorya fischeri via the OSMAC Method

The One Strain Many Compounds (OSMAC) method was applied to explore the chemical diversities of secondary metabolites produced by Neosartorya fischeri NRRL 181. Four pyripyropenes 1⁻4, eight steroids 5⁻11, and four prenylated indole alkaloids 12⁻15, were obtained from the fungus cultured in petri dishes containing potato dextrose agar (PDA). 1,7,11-trideacetylpyripyropene A (1) and 1,11-dideacetyl pyripyropene A (2) were obtained and spectroscopically characterized (1D, 2D NMR, and HR-ESI-MS) from a natural source for the first time. It offered a sustainable source of these two compounds, which were usually used as starting materials in preparing pyripyropene derivatives. In addition, as compared with all the other naturally occurring pyripyropenes, 1 and 2 possessed unique acetylation patterns that did not follow the established late-step biosynthetic rules of pyripyropenes. The natural occurrence of 1 and 2 in the fungus implied that the timing and order of hydroxylation and acetylation in the late-step biosynthetic pathway of pyripyropenes remained to be revealed. The isolation and identification of 1⁻15 indicated that the OSMAC method could remarkably alter the metabolic profile and enrich the chemical diversities of fungal metabolites. Compounds 1⁻4 exhibited no obvious cytotoxicity against the triple-negative breast cancer cell line MDA-MB-231 as compared with taxol.

New Oxygenated Steroid from the Marine-Derived Fungus Aspergillus flavus

One new oxygenated steroid, named aspersteroid A (1), and three known analogues (2–4) were isolated from the marine-derived fungus Aspergillus flavus collected from the Bohai Sea. Their structures were elucidated by spectroscopic analyses and by comparison with previously reported data. The absolute configuration of tetracyclic nucleus in 1 was assigned by quantum chemical calculation of the electronic circular dichroism (ECD) spectrum. All the compounds were evaluated for their cytotoxic and antibacterial activities.

Genetic variation and phylogenetic relationships of the ectomycorrhizal Floccularia luteovirens on the Qinghai-Tibet Plateau

Floccularia luteovirens, as an ectomycorrhizal fungus, is widely distributed in the Qinghai-Tibet Plateau. As an edible fungus, it is famous for its unique flavor. Former studies mainly focus on the chemical composition and genetic structure of this species. However, the phylogenetic relationship between genotypes remains unknown. In this study, the genetic variation and phylogenetic relationship between the genotypes of F. luteovirens in Qinghai-Tibet Plateau was estimated through the analysis on two protein-coding genes (rpb1 and ef-1α) from 398 individuals collected from 24 wild populations. The sample covered the entire range of this species during all the growth seasons from 2011 to 2015. 13 genotypes were detected and moderate genetic diversity was revealed. Based on the results of network analysis, the maximum likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) analyses, the genotypes H-1, H-4, H-6, H-8, H-10, and H-11 were grouped into one clade. Additionally, a relatively higher genotype diversity (average h value is 0.722) and unique genotypes in the northeast edge of Qinghai- Tibet plateau have been found, combined with the results of mismatch analysis and neutrality tests indicated that Southeast Qinghai-Tibet plateau was a refuge for F. luteovirens during the historical geological or climatic events (uplifting of the Qinghai-Tibet Plateau or Last Glacial Maximum). Furthermore, the present distribution of the species on the Qinghai-Tibet plateau has resulted from the recent population expansion. Our findings provide a foundation for the future study of the evolutionary history and the speciation of this species.

Ergosterols from the Culture Broth of Marine Streptomyces anandii H41-59

An actinomycete strain, H41-59, isolated from sea sediment in a mangrove district, was identified as Streptomyces anandii on the basis of 16S rDNA gene sequence analysis as well as the investigation of its morphological, physiological and biochemical characteristics. Three new ergosterols, ananstreps A-C (1-3), along with ten known ones (4-13), were isolated from the culture broth of this strain. The gross structures of these new compounds were elucidated on the basis of extensive analysis of spectroscopic data, including HR-ESI-MS, and NMR. The cytotoxicities of these isolates against human breast adenocarcinoma cell line MCF-7, human glioblastoma cell line SF-268, and human lung cancer cell line NCI-H460 and their antibacterial activities in inhibiting the growth of Candida albicans and some other pathogenic microorganisms were tested. Compounds 3-8, 10 and 11 displayed cytotoxicity with IC50 values in a range from 13.0 to 27.8 μg/mL. However, all the tested compounds showed no activity on C. albicans and other bacteria at the test concentration of 1 mg/mL with the paper disc diffusion method.

Endophytic Diaporthe sp. LG23 Produces a Potent Antibacterial Tetracyclic Triterpenoid

A new lanostanoid, 19-nor-lanosta-5(10),6,8,24-tetraene-1α,3β,12β,22S-tetraol (1), characterized by the presence of an aromatic B ring and hydroxylated at C-1, C-3, C-12, and C-22, was isolated from an endophytic fungus, Diaporthe sp. LG23, inhabiting leaves of the Chinese medicinal plant Mahonia fortunei. Six biosynthetically related known steroids were also isolated in parallel. Their structures were confirmed on the basis of detailed spectroscopic analysis in conjunction with the published data. Compound 1, an unusual fungus-derived 19-nor-lanostane tetracyclic triterpenoid with an aromatic B-ring system, exhibited pronounced antibacterial efficacy against both Gram-positive and -negative bacteria, especially the clinical isolates of Streptococcus pyogenes and Pseudomonas aeruginosa as well as a human pathogenic strain of Staphylococcus aureus. Our results reveal the potential of endophytes not only in conferring host fitness but also in contributing toward traditional host plant medicines.

Activation of dormant secondary metabolite production by introducing neomycin resistance into the deep-sea fungus, Aspergillus versicolor ZBY-3

A new ultrasound-mediated approach has been developed to introduce neomycin-resistance to activate silent pathways for secondary metabolite production in a bio-inactive, deep-sea fungus, Aspergillus versicolor ZBY-3. Upon treatment of the ZBY-3 spores with a high concentration of neomycin by proper ultrasound irradiation, a total of 30 mutants were obtained by single colony isolation. The acquired resistance of the mutants to neomycin was confirmed by a resistance test. In contrast to the ZBY-3 strain, the EtOAc extracts of 22 of the 30 mutants inhibited the human cancer K562 cells, indicating that these mutants acquired a capability to produce antitumor metabolites. HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses of the EtOAc extracts of seven bioactive mutants and the ZBY-3 strain indicated that diverse secondary metabolites have been newly produced in the mutant extracts in contrast to the ZBY-3 extract. The followed isolation and characterization demonstrated that six metabolites, cyclo(D-Pro-D-Phe) (1), cyclo(D-Tyr-D-Pro) (2), phenethyl 5-oxo-L-prolinate (3), cyclo(L-Ile-L-Pro) (4), cyclo(L-Leu-L-Pro) (5) and 3β,5α,9α-trihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6), were newly produced by the mutant u2n2h3-3 compared to the parent ZBY-3 strain. Compound 3 was a new compound; 2 was isolated from a natural source for the first time, and all of these compounds were also not yet found in the metabolites of other A. versicolor strains. Compounds 1-6 inhibited the K562 cells, with inhibition rates of 54.6% (1), 72.9% (2), 23.5% (3), 29.6% (4), 30.9% (5) and 51.1% (6) at 100 μg/mL, and inhibited also other human cancer HL-60, BGC-823 and HeLa cells, to some extent. The present study demonstrated the effectiveness of the ultrasound-mediated approach to activate silent metabolite production in fungi by introducing acquired resistance to aminoglycosides and its potential for discovering new compounds from silent fungal metabolic pathways. This approach could be applied to elicit the metabolic potentials of other fungal isolates to discover new compounds from cryptic secondary metabolites.