Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach

Endophytic fungi are one of prolific sources of bioactive natural products with potential application in biomedicine and agriculture. In our continuous search for antimicrobial secondary metabolites from Fusarium oxysporum R1 associated with traditional Chinese medicinal plant Rumex madaio Makino using one strain many compounds (OSMAC) strategy, two diastereomeric polyketides neovasifuranones A (3) and B (4) were obtained from its solid rice medium together with N-(2-phenylethyl)acetamide (1), 1-(3-hydroxy-2-methoxyphenyl)-ethanone (2) and 1,2-seco-trypacidin (5). Their planar structures were unambiguously determined using 1D NMR and MS spectroscopy techniques as well as comparison with the literature data. By a combination of the modified Mosher’s reactions and chiroptical methods using time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) and optical rotatory dispersion (ORD), the absolute configurations of compounds 3 and 4 are firstly confirmed and, respectively, characterized as (4S,7S,8R), (4S,7S,8S). Bioassay results indicate that these metabolites 1–5 exhibit weak inhibitory effect on Helicobacter pylori 159 with MIC values of ≥16 μg/mL. An in-depth discussion for enhancement of fungal metabolite diversity is also proposed in this work.

Apoptotic Activity of New Oxisterigmatocystin Derivatives from the Marine-Derived Fungus Aspergillus nomius NC06

Sponge-derived fungi have recently attracted attention as an important source of interesting bioactive compounds. Aspergillus nomius NC06 was isolated from the marine sponge Neopetrosia chaliniformis. This fungus was cultured on rice medium and yielded four compounds including three new oxisterigmatocystins, namely, J, K, and L (1, 2, and 3), and one known compound, aspergillicin A (4). Structures of the compounds were elucidated by 1D and 2D NMR spectroscopy and by high-resolution mass spectrometry. The isolated compounds were tested for cytotoxic activity against HT 29 colon cancer cells, where compounds 1, 2, and 4 exhibited IC50 values of 1.21, 2.23, and 5.62 µg/mL, respectively. Under the fluorescence microscope by using a double staining method, HT 29 cells were observed to be viable, apoptotic, and necrotic after treatment with the cytotoxic compounds 1, 2, and 4. The result shows that compounds 1 and 2 were able to induce apoptosis and cell death in HT 29 cells.

Production of bacterial cellulose biopolymers in media containing rice and corn hydrolysate as carbon sources

Bacterial cellulose (BC) is a promising option for ecologically viable processes. In this work, BC was produced using starch hydrolysate (rice and corn flakes) as carbon sources. The starch was hydrolyzed by fungus for glucose production. A maximum yield of 2.80 ± 0.43 g/L of BC was obtained with the hydrolyzed rice medium. Moreover, BC produced in the rice and corn media had crystallinity of around 50%. Fourier-transform infrared spectrometry confirmed the functional groups in BC as well as the absence of contaminants from production process. The thermogravimetric analysis revealed that the polymers formed with alternative media had greater thermal stability. Scanning electron microscopy revealed a morphological structure with the random arrangement of nanofibrils in a non-uniform manner distributed in the weave of both polymeric films. The biofilms produced in different media had similar properties to those of films obtained with a conventional medium, revealing that the polymeric characteristics are not modified.

New Antiproliferative Compounds against Glioma Cells from the Marine-Sourced Fungus Penicillium sp. ZZ1750

Seven novel compounds, namely peniresorcinosides A–E (1–5), penidifarnesylin A (6), and penipyridinone A (7), together with the 11 known ones 8–17, were isolated from a culture of the marine-associated fungus Penicillium sp. ZZ1750 in rice medium. The structures of the new compounds were established based on their high-resolution electrospray ionization mass spectroscopy (HRESIMS) data, extensive nuclear magnetic resonance (NMR) spectroscopic analyses, chemical degradation, Mosher’s method, 13C-NMR calculations, electronic circular dichroism (ECD) calculations, and single crystal X-ray diffraction. Peniresorcinosides A (1) and B (2) are rare glycosylated alkylresorcinols and exhibited potent antiglioma activity, with IC50 values of 4.0 and 5.6 µM for U87MG cells and 14.1 and 9.8 µM for U251 cells, respectively.

Optimal Liquid Spawn Conditions and Grain Medium Enhanced Hispidin Production by Phellinus linteus in Solid-State Fermentation

This study aimed to screen a highest hispidin production of strain from 12 strains of Phellinus, and to evaluate the effects of liquid spawn conditions and grain medium on this strain’s hispidin production levels after solid-state fermentation. Results showed that the P. linteus 04 led to the highest hispidin production, this strain was then selected to elucidate the optimal liquid spawn conditions and grain medium for hispidin production. Various liquid spawn conditions were evaluated, and the highest hispidin yield, specific productivity of hispidin, and total content of hispidin were found to be optimal at 1 week of liquid spawn age, cultured with potato dextrose borth, and using 10 % inoculum rate, with each condition resulting to 0.350, 0.325, and 0.328 mg/g dry weight of mycelium, 0.352, 0.251, and 0.249 µg/mg week− 1 specific productivity, 57.90, 60.23, and 61.77 mg/kg dry weight of brown rice medium, respectively. These liquid spawn conditions were then used to determine the appropriate grain medium for hispidin production. The highest hispidin yield and total content of hispidin were observed in pearl barley which resulted in 1.107 mg/g dry weight of mycelium and 199.76 mg/kg dry weight of pearl barley, which led to results that were 4.73-fold and 5.35-fold higher than those of control (brown rice medium). Overall, this study shows that P. linteus hispidin production can be enhanced by solid-state fermentation using optimal liquid spawn conditions and the appropriate grain medium.

Media and strain studies for the scaled production of cis-enone resorcylic acid lactones as feedstocks for semisynthesis

Resorcylic acid lactones (RALs) with a cis-enone moiety, represented by hypothemycin (1) and (5Z)-7-oxozeaenol (2), are fungal secondary metabolites with irreversible inhibitory activity against protein kinases, with particularly selective activity for inhibition of TAK1 (transforming growth factor beta-activated kinase 1). Gram-scale quantities of these compounds were needed as feedstock for semi-synthesizing RAL-analogues in a step-economical fashion. To do so, this study had three primary goals: identifying fungi that biosynthesized 1 and 2, enhancing their production by optimizing the fermentation conditions on the lab scale, and developing straight forward purification processes. After evaluating 536 fungal extracts via an in-house dereplication protocol, three strains were identified as producing cis-enone RALs (i.e., MSX78495, MSX63935, MSX45109). Screening these fungal strains on three grain-based media revealed enhanced production of 1 by strain MSX78495 on oatmeal medium, while rice medium increased the biosynthesis of 2 by strain MSX63935. Furthermore, the purification processes were improved, moving away from HPLC purification to utilizing two to four cycles of resuspension and centrifugation in small volumes of organic solvents, generating gram-scale quantities of these metabolites readily. In addition, studying the chemistry profiles of strains MSX78495 and MSX63935 resulted in the isolation of ten other RALs (3-12), two radicinin analogues (13-14), and six benzopyranones (15-20), with 19 and 20 being newly described chlorinated benzopyranones.

Antimicrobial and Cytotoxic Potential of Crude Extracts from Culturable Fungal Endophytes Associated with the Mangrove Species Rhizophora stylosa and R. mucronata in the South China Sea

Our research evaluated the antimicrobial and cytotoxic activities of crude extracts of endophytic fungi from R. stylosa and R. mucronate. 46 fungal isolates were cultured on the four different mediums, namely Dextrose Agar (PDA), Czapek’s Agar (CZA), Rice Medium (RM) and Grain Medium (GM), and harvested by ethyl acetate solvent at 40 days. The extracts were tested for antimicrobial activity by the microdilution method against Gram-negative bacteria Pseudomons adaceae (PA), Gram-positive bacteria Enterococcus faecalis (EF), Methicillin-resistant Staphylococcus aureus (MRSA) and pathogenic fungus Monilia albican (MA). Cytotoxic activity of the extracts was evaluated by MTT assay using human lung cancer cells A549, human cervical carcinoma cells Hela, and human hepatocellular cells HepG2. The results showed that rice medium could promote the secretion of antimicrobial and anti-tumor secondary metabolites of endophytic fungi in comparison with the other cultivation media. 17 strains (68%) from R. stylosa exhibited inhibition effects on indicators, especially N. protearum HHL46 which could inhibit the growth of four microbes with the MIC values reaching 0.0625 mg/mL. 15 strains (71.4%) from R. mucronata displayed activities against human pathogenic microbes, especially Pestalotiopsis sp. HQD6 and N. protearum HQD5 which could resist the growth of four microbial with MIC values ranging from 0.015 to 1 mg/mL. In cytotoxic assay, the extracts of 10 strains (40%), 9 strains (40%) and 13 strains (52%) from R. stylosa and 13 strains (61.9%), 10 stains (47.6%) and 10 stains (47.6%) in R. mucronata displayed the cytotoxicity against A549, Hela and HepG2 cancer cells with cells viability value ≤50%, respectively. Neopestalotiopsis protearum HHL46, Phomopsis longicolla HHL50, Botryosphaeria fusispora HQD83, Fusarium verticillioides HQD48 and Pestalotiopsis sp. HQD6 displayed significant antitumor activity with IC50 values below the 20 μg/mL. These results highlighted the antimicrobial and anti-tumor potential of endophytic fungi from R. stylosa and R. mucronata and the possibility to be exploited for their antimicrobial and cytotoxic agents.

MOLECULAR NETWORKING-BASED DEREPLICATION OF AMBUIC ACID DERIVATIVES FROM THE MARINE FUNGUS PESTALOTIOPSIS SP. 4A11

Ambuic acid (AA) is a highly-modified cyclohexenone and known as a promising inhibitor of quorum sensing in methicillinresistant Staphylococcus aureus, and is thus a candidate as an antivirulence drug. This molecule is mainly produced by the species of Pestalotiopsis and, since its discovery twenty years ago, only a restricted amount of AA-derivatives have been described. Despite being a promising subject, methods for the analysis of modified AA-analogues via mass spectrometry remain unexplored. In order to adress this question, the marine fungus Pestalotiopsis sp. 4A11 associated with the ascidian Didemnum perlucidum was grown in a solid rice medium and its crude extract was chemically studied. From this extract, AA and 10-hydroxy ambuic acid (10-HAA) were isolated and identified using NMR spectroscopy with the aim of obtaining model compounds for the MS analysis. These served as reference compounds (seeds) to guide the dereplication of other AA-analogues via LC-MS/MS-based molecular networking. Based on the manual interpretation of the fragmentation pathways of the seeds and related compounds observed in the networks, six AA-derivatives were dereplicated in the extract. Furthermore, three analogues with unprecedented chemical formulas were proposed as putative unprecedented AA-derivatives. The fragmentation annotation proposed represents a fast and feasible method for characterizing AA-derivatives.

Chemical Profiles and Bio-Activities of Different Extracts of Terfezia Species and their Other Associated Fungi

Background: Desert truffles (Terfezia species) are known by their vital nutritional benefits as they are considered as rich sources of vitamins, fatty acid, minerals and proteins. Methods: The chemical constituents of the different solvent extracts of Terfezia species were isolated and identified by column chromatography, spectroscopic and GC-MS analyses. Also, the ethyl acetate and acetone extracts of different fungal isolates, associated Terfezia, after grown on rice medium were screened for their antimicrobial, anticancer and antioxidant activities via disc agar plate, micro culture tetrazolium (MTT) and 2,2-azino-di-[3-ethylbenzo-thiazolin-sulphonate] (ABTS) assays, respectively. The promising fugal strains were molecularly identified by 18SrRNA tool. Results: Bio-guided separation of methylene chloride, ethyl acetate and n-butanol fractions of Terfezia species led to identification of nine compounds namely; (R)-4,8-dihydroxy-7-hydroxymethyl-6- methoxy isochroman-1-one (1), 4-deoxy-4α-phorbal-12-(2,3-dimethyl)butyrate-13-isobutyrate (2), oxyphylline B (3), terfezien A (4), latilagascene D (5), amaiouine (6), senbusine acetate (7), terfezien B (8) and marinoquinoline D (9). Moreover, sixteen compounds were identified in the n-hexane extract via GC-MS analysis, accounting for 93.69% of the total detected components in the extract. While, twenty five components were detected in the methylene chloride extract, representing 43.86% from total detected components in the extract. Eight fungal strains were isolated from Terfezia sp., powder by serial dilution methods and these fungi were cultivated on solid rice medium. Also, their ethyl acetate and acetone extracts were subjected to biological studies including antimicrobial, antioxidant and anticancer activities. The three potent fungal strains (1M, 4M and 8M) were identified by the molecular technique 18SrRNA as Aspergillus niger 1M-EGY-IQ, Penicillium crustosum 4M-EGY-IQ, and Fusarium proliferatum 8M-EGY-IQ for 1M, 4M and 8M, respectively. Conclusion: Terfezia sp., comprise a rich source of bioactive compounds and could be considered as an interesting candidate for the treatment of infectious diseases.