Flavoglaucin, a metabolite ofEurotium chevalieri, its antioxidation and synergism with tocopherol

Metabolomic profiling of Medicago sativa-derived fungal endophytes and evaluation of their biological activities

This study aimed to discover the potential of Medicago sativa-derived fungal endophytes as a prospective source of bioactive metabolites. In the present study, three different strains of fungal endophyte Aspergillus terreus were isolated from leaves L, roots T and stems St of Medicago sativa to explore their biological and chemical diversity. These isolated fungi were exposed to different fermentation conditions by adding various chemical elicitors to their solid fermentation media. According to LC-HRESIMS-based metabolomics and multivariate analysis, each chemical treatment had a different effect on the chemical profiles of the fungi. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) proposed several compounds with anticancer action against MCF-7 (a human breast cancer cell line) and MDA-MB-231 (a human epithelial breast cancer cell line).

Wild Mushrooms: Potential Natural Sources of Antioxidant and Anti-Quorum Sensing Bioactive Compounds for Medical Applications

Objective

This study was aimed at determining the antioxidant, anti-quorum sensing, and in vitro cytotoxic activities of five wild mushroom extracts.

Methods

Wild mushrooms of Auricularia auricula-judae, Termitomyces umkowaani, Trametes elegans, Trametes versicolor, and Microporus xanthopus were collected from Arabuko-Sokoke and Kakamega National Forests, in Kenya. Specimens were identified and extracted using chloroform (CHL), 70% ethanol (Eth), and hot water (HW) solvents. Antioxidant and cytotoxic activities of the extracts were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Vero cell lines, respectively, while anti-quorum sensing activities were tested against Chromobacterium violaceum. All data were compared using relevant descriptive and inferential statistics at a significance level of p ≤ 0.05.

Results

A total of 35 wild mushrooms were collected, identified, and classified into 14 genera. Among screened mycochemicals, fatty acids, flavonoids, polyphenols, and saponins were detected at higher concentrations. The highest free radical scavenging activities of A. auricula-judae, T. umkowaani, T. elegans, and T. versicolor were observed in 70% Eth extract with the percentage values of 76.40 ± 0.12%, 68.40 ± 0.01%, 62.40 ± 0.07%, and 66.40 ± 0.04%, respectively, whereas the HW extract of Microporus xanthopus showed free radical scavenging activity at 65.90 ± 0.02%. None of the extracts, at the tested concentrations (up to 1000 µg/mL), had shown cytotoxic activity against the Vero cell line. The HW extract of T. umkowaani and the 70% Eth extract of T. versicolor showed a statistically significant difference in the inhibitory activity of violacein production against C. violaceum at the concentration of 200 µg/mL.

Conclusions

The antioxidant activity of wild mushrooms can help to tackle the diseases caused by free radicals. The anti-quorum sensing potential of wild mushrooms could also provide future alternatives to conventional drug therapies cost-effectively. Further detailed chemistry of the bioactive compounds and their possible mechanisms of action responsible for the observed antioxidant and anti-quorum sensing activities are needed.

A Review of the Chemistry and Biological Activities of Natural Colorants, Dyes, and Pigments: Challenges, and Opportunities for Food, Cosmetics, and Pharmaceutical Application

Natural pigments are important sources for the screening of bioactive lead compounds. This article reviewed the chemistry and therapeutic potentials of over 570 colored molecules from plants, fungi, bacteria, insects, algae, and marine sources. Moreover, related biological activities, advanced extraction, and identification approaches were reviewed. A variety of biological activities, including cytotoxicity against cancer cells, antioxidant, anti-inflammatory, wound healing, anti-microbial, antiviral, and anti-protozoal activities, have been reported for different pigments. Considering their structural backbone, they were classified as naphthoquinones, carotenoids, flavonoids, xanthones, anthocyanins, benzotropolones, alkaloids, terpenoids, isoprenoids, and non-isoprenoids. Alkaloid pigments were mostly isolated from bacteria and marine sources, while flavonoids were mostly found in plants and mushrooms. Colored quinones and xanthones were mostly extracted from plants and fungi, while colored polyketides and terpenoids are often found in marine sources and fungi. Carotenoids are mostly distributed among bacteria, followed by fungi and plants. The pigments isolated from insects have different structures, but among them, carotenoids and quinone/xanthone are the most important. Considering good manufacturing practices, the current permitted natural colorants are: Carotenoids (canthaxanthin, β-carotene, β-apo-8'-carotenal, annatto, astaxanthin) and their sources, lycopene, anthocyanins, betanin, chlorophyllins, spirulina extract, carmine and cochineal extract, henna, riboflavin, pyrogallol, logwood extract, guaiazulene, turmeric, and soy leghemoglobin.

Secondary Metabolites Produced by the Blue-Cheese Ripening Mold Penicillium roqueforti; Biosynthesis and Regulation Mechanisms

Filamentous fungi are an important source of natural products. The mold Penicillium roqueforti, which is well-known for being responsible for the characteristic texture, blue-green spots, and aroma of the so-called blue-veined cheeses (French Bleu, Roquefort, Gorgonzola, Stilton, Cabrales, and Valdeón, among others), is able to synthesize different secondary metabolites, including andrastins and mycophenolic acid, as well as several mycotoxins, such as Roquefortines C and D, PR-toxin and eremofortins, Isofumigaclavines A and B, festuclavine, and Annullatins D and F. This review provides a detailed description of the biosynthetic gene clusters and pathways of the main secondary metabolites produced by P. roqueforti, as well as an overview of the regulatory mechanisms controlling secondary metabolism in this filamentous fungus.

Bispyrrolidinoindoline Epi(poly)thiodioxopiperazines (BPI-ETPs) and Simplified Mimetics: Structural Characterization, Bioactivities, and Total Synthesis

Within the 2,5-dioxopiperazine-containing natural products generated by "head-to-tail" cyclization of peptides, those derived from tryptophan allow further structural diversification due to the rich chemical reactivity of the indole heterocycle, which can generate tetracyclic fragments of hexahydropyrrolo[2,3-b]indole or pyrrolidinoindoline skeleton fused to the 2,5-dioxopiperazine. Even more complex are the dimeric bispyrrolidinoindoline epi(poly)thiodioxopiperazines (BPI-ETPs), since they feature transannular (poly)sulfide bridges connecting C3 and C6 of their 2,5-dioxopiperazine rings. Homo- and heterodimers composed of diastereomeric epi(poly)thiodioxopiperazines increase the complexity of the family. Furthermore, putative biogenetically generated downstream metabolites with C11 and C11'-hydroxylated cores, as well as deoxygenated and/or oxidized side chain counterparts, have also been described. The isolation of these complex polycyclic tryptophan-derived alkaloids from the classical sources, their structural characterization, the description of the relevant biological activities and putative biogenetic routes, and the synthetic efforts to generate and confirm their structures and also to prepare and further evaluate structurally simple analogs will be reported.

Chemical synthesis in competition with global genome mining and heterologous expression for the preparation of dimeric tryptophan-derived 2,5-dioxopiperazines

Covering: up to the end of 2021Within the 2,5-dioxopiperazines-containing natural products, those generated from tryptophan allow further structural diversification due to the rich chemical reactivity of the indole heterocycle. The great variety of natural products, ranging from simple dimeric bispyrrolidinoindoline dioxopiperazines and tryptophan-derived dioxopiperazine/pyrrolidinoindoline dioxopiperazine analogs to complex polycyclic downstream metabolites containing transannular connections between the subunits, will be covered. These natural products are constructed by Nature using hybrid polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) assembly lines. Mining of microbial genome sequences has more recently allowed the study of the metabolic routes and the discovery of their hidden biosynthetic potential. The competition (ideally, also the combined efforts) between their isolation from the cultures of the producing microorganisms after global genome mining and heterologous expression and the synthetic campaigns, has more recently allowed the successful generation and structural confirmation of these natural products. Their biological activities as well as their proposed biogenetic routes and computational studies on biogenesis will also be covered.

Multiway resolution of spectrochromatographic measurements for the quantification of echinuline in marine-derived fungi Aspergillus chevalieri using parallel factor analysis

A multiway resolution of incomplete chromatographic separation was presented for spectrochromatographic quantification of echinuline in marine-derived fungi Aspergillus chevalieri. Two-dimensional spectrochromatographic maps of calibration, validation and real samples were recorded as a function of time and wavelength using UPLC-PDA instrument under non-optimized chromatographic conditions, which gave rise to co-elution of echinuline and the constituents of sample matrix. A three-way array was obtained by concatenating the data matrices of the spectrochromatographic maps. Then, parallel factor analysis was applied to the multiway array to extract the individual contribution of echinuline in three modes (time, wavelength and sample). While time and wavelength profiles were used for the characterization of echinuline, the sample profile was used for its quantitative determination of the analyte in validation set and in real samples. Validity of the analytical method was evaluated by analyzing the validation set, which consist of test samples, standard addition samples, intra-day and inter-day samples. The proposed multiway analysis method was then applied to marine-derived fungi extracts and echinuline content was found to be 31.9 µg/g based on the average of ten assay results. The assay results provided by PARAFAC model were statistically compared with those obtained by a newly developed classical UPLC method, which ensured the complete separation of echinuline in a run time of nine minutes. The assay results were found to be comparable due to the fact that there was no significant difference between the analysis results (F = 1.63, Fcrit = 3.17; t = 0.69, tcrit = 2.11) at the significance level of 95%). Consequently, the PARAFAC method permitted the accurate determination of echinuline in fungal extracts despite the partial chromatographic separation with a run time of only three minutes.

Edible Mushrooms: A Comprehensive Review on Bioactive Compounds with Health Benefits and Processing Aspects

Mushrooms are well-known functional foods due to the presence of a huge quantity of nutraceutical components. These are well recognized for their nutritional importance such as high protein, low fat, and low energy contents. These are rich in minerals such as iron, phosphorus, as well as in vitamins like riboflavin, thiamine, ergosterol, niacin, and ascorbic acid. They also contain bioactive constituents like secondary metabolites (terpenoids, acids, alkaloids, sesquiterpenes, polyphenolic compounds, lactones, sterols, nucleotide analogues, vitamins, and metal chelating agents) and polysaccharides chiefly β-glucans and glycoproteins. Due to the occurrence of biologically active substances, mushrooms can serve as hepatoprotective, immune-potentiating, anti-cancer, anti-viral, and hypocholesterolemic agents. They have great potential to prevent cardiovascular diseases due to their low fat and high fiber contents, as well as being foremost sources of natural antioxidants useful in reducing oxidative damages. However, mushrooms remained underutilized, despite their wide nutritional and bioactive potential. Novel green techniques are being explored for the extraction of bioactive components from edible mushrooms. The current review is intended to deliberate the nutraceutical potential of mushrooms, therapeutic properties, bioactive compounds, health benefits, and processing aspects of edible mushrooms for maintenance, and promotion of a healthy lifestyle.

Dynamic Evolution and Correlation between Metabolites and Microorganisms during Manufacturing Process and Storage of Fu Brick Tea

Fu brick tea (FBT) is one of the major brands of dark tea. Microbial fermentation is considered the key step in the development of the special characteristics of FBT. The systemic corelationship of the microbiome and metabolomics during manufacture of Fu brick tea is not fully understood. In this study, we comprehensively explored the microbiome and metabolite dynamic evolution during the FBT manufacturing processes, and revealed decisive factors for the quality and safety of FBT based on the grouped methods of metabolomics combined with biochemical measurements, microbiome sequencing combined with quantitative polymerase chain reaction (PCR), and multiplex analysis. Both the microbiome and quantitative PCR showed that fungi displayed concentrated distribution characteristics in the primary dark tea samples, while bacterial richness increased during the flowering processes and ripening period. All microorganism species, as well as dominant fungi and bacteria, were identified in the distinct processes periods. A total of 178 metabolites were identified, and 34 of them were characterized as critical metabolites responsible for metabolic changes caused by the corresponding processes. Metabolic analysis showed that most metabolites were decreased during the FBT manufacturing processes, with the exception of gallic acid. Multivariate analysis verified that the critical metabolites were correlated with specific dominant microbial species. All the top fungal species except unclassified_g_ Aspergillus showed positive correlations with six critical metabolites (L-The, epigallocatechin (EGC), Gln, tea polyphenol (TP), tea polysaccharides (TPs) and caffeine). Five of the top bacteria species (Cronobacter, Klebsiella, Pantoea, Pluralibacter, and unclassified_ f_Entero-bacteriaceae) showed positive correlations with epigallocatechins and tea polyphenols, while the other 11 top bacterial species correlated negatively with all the critical metabolites. The content of amino acids, tea polyphenols, tea polysaccharides, and flavonoids was reduced during microbial fermentation. In conclusion, our results reveal that microbial composition is the critical factor in changing the metabolic profile of FBT. This discovery provides a theoretical basis for improving the quality of FBT and enhancing its safety.

Antibiotics from Extremophilic Micromycetes

Extremophilic microorganisms, which are capable of functioning normally at extremely high or low temperatures, pressure, and in other environmental conditions, have been in the focus of microbiologists' attention for several decades due to the biotechnological potential of enzymes inherent in extremophiles. These enzymes (also called extremozymes) are used in the production of food and detergents and other industries. At the same time, the inhabitants of extreme econiches remained almost unexplored for a long time in terms of the chemistry of natural compounds. In recent years, the emergence of new antibiotic-resistant strains of pathogens, which affect humans and animals has become a global problem. The problem is compounded by a strong slowdown in the development of new antibiotics. In search of new active substances and scaffolds for medical chemistry, researchers turn to unexplored natural sources. In recent years, there has been a sharp increase in the number of studies on secondary metabolites produced by extremophiles. From the discovery of penicillin to the present day, micromycetes, along with actinobacteria, are one of the most productive sources of antibiotic compounds for medicine and agriculture. Many authors consider extremophilic micromycetes as a promising source of small molecules with an unusual mechanism of action or significant structural novelty. This review summarizes the latest (for 2018-2019) experimental data on antibiotic compounds, which are produced by extremophilic micromycetes with various types of adaptation. Active metabolites are classified by the type of structure and biosynthetic origin. The data on the biological activity of the isolated metabolites are summarized.

Marine Fungus Aspergillus chevalieri TM2-S6 Extract Protects Skin Fibroblasts from Oxidative Stress

The strain Aspergillus chevalieri TM2-S6 was isolated from the sponge Axinella and identified according to internal transcribed spacer (ITS) molecular sequence homology with Aspergillus species from the section Restricti. The strain was cultivated 9 days on potato dextrose broth (PDB), and the medium evaluated as antioxidant on primary normal human dermal fibroblasts (NHDF). The cultivation broth was submitted to sterile filtration, lyophilized and used without any further processing to give the Aspergillus chevalieri TM2-S6 cultivation broth ingredient named ACBB. ACCB contains two main compounds: tetrahydroauroglaucin and flavoglaucin. Under oxidative stress, ACCB showed a significant promotion of cell viability. To elucidate the mechanism of action, the impact on a panel of hundreds of genes involved in fibroblast physiology was evaluated. Thus, ACCB stimulates cell proliferation (VEGFA, TGFB3), antioxidant response (GPX1, SOD1, NRF2), and extracellular matrix organization (COL1A1, COL3A1, CD44, MMP14). ACCD also reduced aging (SIRT1, SIRT2, FOXO3). These findings indicate that Aspergillus chevalieri TM2-S6 cultivation broth exhibits significant in vitro skin protection of human fibroblasts under oxidative stress, making it a potential cosmetic ingredient.

Purification, characterization, and hypoglycemic properties of eurocristatine from Eurotium cristatum spores in Fuzhuan brick tea

Fuzhuan brick tea (FBT) is a Chinese dark tea that is famous for its significant health benefits, in which Eurotium cristatum (E. cristatum) strains play a vital role in its postfermentation process. In this study, eurocristatine with hypoglycemic activity was discovered for the first time and purified from the spores of E. cristatum growing in FBT. Eurocristatine (98%) was obtained by D-101 macroporous resin-based column chromatography and preparative high performance liquid chromatography (HPLC) with a C18 column as the stationary phase and 35% acetonitrile in ultrapure water as the mobile phase. Hypoglycemic activity in a Hep-G2 cell hypoglycemic model was used as a screening indicator during purification. The chemical structure of eurocristatine was characterized by ESI/MS, 1H NMR and 13C NMR analyses. The antidiabetic effects of eurocristatine were verified in high-fat diet/streptozocin-induced type 2 diabetes mellitus (T2DM) rats. The results showed that eurocristatine significantly reduced fasting blood glucose. Our study demonstrated that eurocristatine, as a newly discovered hypoglycemic active substance, could be considered a potential candidate for the treatment of diabetes and its complications.

Fungi as a Potential Source of Pigments: Harnessing Filamentous Fungi

The growing concern over the harmful effects of synthetic colorants on both the consumer and the environment has raised a strong interest in natural coloring alternatives. As a result the worldwide demand for colorants of natural origin is rapidly increasing in the food, cosmetic and textile sectors. Natural colorants have the capacity to be used for a variety of industrial applications, for instance, as dyes for textile and non-textile substrates such as leather, paper, within paints and coatings, in cosmetics, and in food additives. Currently, pigments and colorants produced through plants and microbes are the primary source exploited by modern industries. Among the other non-conventional sources, filamentous fungi particularly ascomycetous and basidiomycetous fungi (mushrooms), and lichens (symbiotic association of a fungus with a green alga or cyanobacterium) are known to produce an extraordinary range of colors including several chemical classes of pigments such as melanins, azaphilones, flavins, phenazines, and quinines. This review seeks to emphasize the opportunity afforded by pigments naturally found in fungi as a viable green alternative to current sources. This review presents a comprehensive discussion on the capacity of fungal resources such as endophytes, halophytes, and fungi obtained from a range or sources such as soil, sediments, mangroves, and marine environments. A key driver of the interest in fungi as a source of pigments stems from environmental factors and discussion here will extend on the advancement of greener extraction techniques used for the extraction of intracellular and extracellular pigments. The search for compounds of interest requires a multidisciplinary approach and techniques such as metabolomics, metabolic engineering and biotechnological approaches that have potential to deal with various challenges faced by pigment industry.

Bio-Guided Fractionation of Prenylated Benzaldehyde Derivatives as Potent Antimicrobial and Antibiofilm from Ammi majus L. Fruits-Associated Aspergillus amstelodami

Ammi majus L.; Family Apiaceae; is a plant indigenous to Egypt. Its fruits contain bioactive compounds such as furanocoumarins and flavonoids of important biological activities. An endophytic fungus was isolated from the fruits and identified as Aspergillus amstelodami (MK215708) by morphology, microscopical characterization, and molecular identification. To our knowledge this is the first time an endophytic fungus has been isolated from the fruits. The antimicrobial activity of the Ammi majus ethanol fruits extract (AME) and fungal ethyl acetate extract (FEA) were investigated, where the FEA showed higher antimicrobial activity, against all the tested standard strains. Phytochemical investigation of the FEA extract yielded five prenylated benzaldehyde derivative compounds isolated for the first time from this species: Dihydroauroglaucin (1), tetrahydroauroglaucin (2), 2-(3,6-dihydroxyhepta-1,4-dien-1-yl)-3,6-dihydroxy-5-(dimethylallyl)benzaldehyde (3), isotetrahydroauroglaucin )4), and flavoglaucin (5). Structure elucidation was carried out using (1H- and 13C-NMR). Fractions and the major isolated compound 1 were evaluated for their antimicrobial and antibiofilm activity. Compound 1 showed high antimicrobial activity against Escherichia coli with minimum inhibitory concentration (MIC) = 1.95 µg/mL, Streptococcus mutans (MIC = 1.95 µg/mL), and Staphylococcus aureus (MIC = 3.9 µg/mL). It exhibited high antibiofilm activity with minimum biofilm inhibitory concentration (MBIC) = 7.81 µg/mL against Staphylococcus aureus and Escherichia coli biofilms and MBIC = 15.63 µg/mL against Streptococcus mutans and Candida albicans and moderate activity (MBIC = 31.25 µg/mL) against Pseudomonas aeruginosa biofilm. This reveals that dihydroauroglaucin, a prenylated benzaldehyde derivative, has a broad spectrum antimicrobial activity. In conclusion, it was observed that the MICs of the FEA are much lower than that of the AME against all susceptible strains, confirming that the antimicrobial activity of Ammi majus may be due to the ability of its endophytic fungi to produce effective secondary metabolites.

Investigation of Antioxidant and Antimicrobial Activities of Different Extracts of Auricularia and Termitomyces Species of Mushrooms

Mushrooms produce a variety of bioactive compounds that are known to have a potential source of antioxidant and antimicrobial properties. Natural antioxidants can protect against free radicals without any side effects. The purpose of this study was to evaluate the antioxidant and antimicrobial activities of Auricularia and Termitomyces extracts. Specimens of Auricularia and Termitomyces spp. were collected from Kakamega National Reserve Forest in Kenya. Specimens were identified, extracted, and screened for their antioxidant and antimicrobial activities using stable free radical DPPH and colorimetric bioassay methods, respectively. The antimicrobial activity of the extracts was tested against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, MRSA, Candida albicans, and Candida parapsilosis. The maximum scavenging activity of hot water extract of Auricularia spp. was observed at 70.4% with the IC₅₀ value of 40 μg/mL. Of the three extracts of Termitomyces spp., 70% ethanol extract has shown the highest scavenging activity (63%) with the IC₅₀ value of 50 μg/mL. Chloroform and hot water extracts of Auricularia have shown statistically significantly different antifungal activities against C. parapsilosis (df = 2, F = 22.49, p ≤ 0.05). Of all the organisms, S. aureus was highly susceptible to 70% ethanol and hot water extracts of Termitomyces spp. with minimum inhibitory concentration values of 0.67±0.29 mg/mL. S. aureus and E. coli were the most susceptible and resistant bacteria to the hot water extract, respectively. In conclusion, the extracts of Auricularia spp. and Termitomyces spp. have shown promising antimicrobial and antioxidant activities.

Induction of pigment production through media composition, abiotic and biotic factors in two filamentous fungi

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Pigment production and accumulation is dependent of high C:N ratios in F. oxysporum and A. chevaleri.

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Red pigment content of F. oxysporum in terms of Absorbance units per gram of biomass increased in 191% through use of blue light. Different light wavelengths stimulate synthesis of additional pigments in A. chevalieri with highest accumulation in red and UV-light.

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Stimulation of pigment production in co-culture is species – specific, being only accomplished in A. chevalieri. With a rise higher that 500% of a pigment obtained in green light.

In addition to plant-derived, fungal pigments have become an alternative in respect to synthetic ones. Besides Monascus sp., several pigment-producing fungi do not have culture conditions well-established yet. In this research, media composition, light wavelength and co-culture were evaluated, results were reported in Absorbance Units per gram of biomass (AU/Bgr). For Fusarium oxysporum a C:N ratio above 7 was advantageous, using both complex and defined media; blue LED light increased the AU/Bgr value from 18013 to 344; co-culture did not enhance pigment production. In Aspergillus chevalieri a high C:N ratio with glucose as carbon source was ideal. When exposing cultures to light, UV and red light gave the highest pigmentation; moreover, differential UV-VIS spectra in all wavelengths suggested production of additional pigments. Particularly a pigment observed when cultured in green light was also found in co-culture with yeast and there was an improvement of AU/Bgr value of 52549%. This is the first report regarding light effect and co-culture for these fungi, as well as C:N ratio for A. chevalieri.

Fungal community succession and major components change during manufacturing process of Fu brick tea

Fu brick tea is a unique post-fermented tea product which is fermented with microorganism during the manufacturing process. Metabolic analysis showed that most metabolites content were decreased during the manufacturing process of Fu brick tea, except GA (gallic acid). Illumina MiSeq sequencing of ITS gene amplicons was applied to analyze the fungal community succession. The genera Aspergillus, Cyberlindnera and Candida were predominant at the early stage of manufacturing process (from "primary dark tea" to "fermentation for 3 days"), but after the stage of "fermentation for 3 days" only Aspergillus was still dominated, and maintain a relatively constant until to the end of manufacturing process. The effects of metabolites on the structure of the fungal community were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicated that GCG (gallocatechin gallate), EGCG (epigallocatechin gallate) and GA as well as the interactions among them were the most probably ones to influence, or be influenced by the fungal communities during the fermentation process of Fu brick tea. This study revealed fungal succession, metabolite changes and their relationships, provided new insights into the mechanisms for manufacturing process of Fu brick tea.

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Aspergillus section Aspergillus (formerly the genus Eurotium) includes xerophilic species with uniseriate conidiophores, globose to subglobose vesicles, green conidia and yellow, thin walled eurotium-like ascomata with hyaline, lenticular ascospores. In the present study, a polyphasic approach using morphological characters, extrolites, physiological characters and phylogeny was applied to investigate the taxonomy of this section. Over 500 strains from various culture collections and new isolates obtained from indoor environments and a wide range of substrates all over the world were identified using calmodulin gene sequencing. Of these, 163 isolates were subjected to molecular phylogenetic analyses using sequences of ITS rDNA, partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) genes. Colony characteristics were documented on eight cultivation media, growth parameters at three incubation temperatures were recorded and micromorphology was examined using light microscopy as well as scanning electron microscopy to illustrate and characterize each species. Many specific extrolites were extracted and identified from cultures, including echinulins, epiheveadrides, auroglaucins and anthraquinone bisanthrons, and to be consistent in strains of nearly all species. Other extrolites are species-specific, and thus valuable for identification. Several extrolites show antioxidant effects, which may be nutritionally beneficial in food and beverages. Important mycotoxins in the strict sense, such as sterigmatocystin, aflatoxins, ochratoxins, citrinin were not detected despite previous reports on their production in this section. Adopting a polyphasic approach, 31 species are recognized, including nine new species. ITS is highly conserved in this section and does not distinguish species. All species can be differentiated using CaM or RPB2 sequences. For BenA, Aspergillus brunneus and A. niveoglaucus share identical sequences. Ascospores and conidia morphology, growth rates at different temperatures are most useful characters for phenotypic species identification.

Two benzaldehyde derivatives and their artefacts from a gorgonian-derived Eurotium sp. fungus

Two new benzaldehyde derivatives, named 3'-OH-tetrahydroauroglaucin (1) and(3'S*,4'R*)-6-(3',5-epoxy-4'-hydroxy-1'-heptenyl)-2-hydroxy-3-(3''-methyl-2''-butenyl)benzaldehyde (2), were isolated from a gorgonian-derived Eurotium sp. fungus. Their structures were determined by extensive spectroscopic analysis including NMR and MS spectra. Dissolved 1 in CDCl₃ for several days could be detected its 2H-chromene skeleton derivatives (1a/1b), a pair of enantiomers with opposite configurations at C-3'. Compound 2 was also found to chemically convert to a pair of epimers non-enzymatically. The plausible mechanism to form the 2H-chromene artefacts with racemisation at C-3' undergoing nucleophilic substitution (S_N1) was proposed.

Two sarcoviolins with antioxidative and α-glucosidase inhibitory activity from the edible mushroom Sarcodon leucopus collected in Tibet

Edible mushrooms are known as an important source of natural antioxidants. The ethyl acetate extract of the edible mushroom Sarcodon leucopus (Zangzi mushroom) possesses strong antioxidative activity. Bioactivity-guided isolation afforded 10 compounds from its fruiting bodies, including two new sarcoviolins, sarcoviolin β (1) and episarcoviolin β (2), and one new p-terphenyl derivative (3) along with seven known compounds. The structures of the new compounds were elucidated by spectroscopic methods and comparison with the known compounds. Compounds 1-10 were found to have antioxidant effects in the DPPH scavenging assay, the total antioxidant capacity assay, the reducing power assay, and the lipid peroxidation assay. Further study indicated that they could protect DNA strands from free radical-induced cleavage at 200 μM. Compounds 1-10 also presented strong α-glucosidase inhibitory activity. Of all tested compounds, compound 1 exhibited the strongest inhibitory activity, with an IC50 value of 0.58 μM.

Total synthesis and structural revision of (+)-cristatumin C

Naturally occurring (+)-cristatumin C, a bis-pyrrolidinoindoline diketopiperazine alkaloid isolated from Eurotium cristatum EN-220, is the 2R,3R,11S,15R,2'R,3'R,11'S,15'S enantiomer, as confirmed by total synthesis.

Antioxidant and anti-inflammatory activities of methanol extracts of Tremella fuciformis and its major phenolic acids

Methanol extract subfractions of the edible white jelly mushroom (Tremella fuciformis), were assessed for the following antioxidant properties: ABTS(+) radical scavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and inhibitory activity of human low-density lipoprotein (LDL) oxidation. Among the subfractions tested, the chloroform subfraction exhibited the strongest antioxidant activity, with the highest total phenolic content (66.31 μg CAE/mg extract) and flavonoids content (5.12 μg QE/mg extract). The ABTS(+) radical scavenging activity of the chloroform subfraction was 7.89 μmol trolox/mg extract, which was the highest among all subfractions. This subfraction also showed the highest DPPH radical scavenging activity and inhibitory activity of LDL oxidation. In addition, the chloroform subfraction demonstrated anti-inflammatory activity through inhibition of nitric oxide production and inducible nitric oxide synthase expression in RAW 264.7 cells. Major phenolic acids from the mushroom extract were identified as 4-hydroxybenzoic acid (323 mg/kg dry weight of mushroom), gentisic acid (174 mg/kg dry weight of mushroom), and 4-coumaric acid (30 mg/kg dry weight of mushroom).

Antimicrobial and antiprotozoal activities of secondary metabolites from the fungus Eurotium repens

In this study, we examined in vitro antibacterial, antifungal, antimalarial, and antileishmanial activities of secondary metabolites (1-8) isolated from the fungus Eurotium repens. All compounds showed mild to moderate antibacterial or antifungal or both activities except 7. The activity of compound 6 was the best of the group tested. The in vitro antimalarial evaluation of these compounds revealed that compounds 1-3, 5, and 6 showed antimalarial activities against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum with IC(50) values in the range of 1.1-3.0 μg/ml without showing any cytotoxicity to the mammalian cells. Compound 5 displayed the highest antimalarial activity. Antileishmanial activity against Leishmania donovani promastigotes was observed for compounds 1-6 with IC(50) values ranging from 6.2 to 23 μg/ml. Antileishmanial activity of compounds 5 and 6 (IC(50) values of 7.5 and 6.2 μg/ml, respectively) was more potent than 1-4 (IC(50) values ranging from 19-23 μg/ml). Compounds 7 and 8 did not show any antiprotozoal effect. Preliminary structure and activity relationship studies indicated that antibacterial, antifungal, antimalarial, and antileishmanial activities associated with phenol derivates (1-6) seem to be dependent on the number of double bonds in the side chain, which would be important for lead optimization in the future.

Comparative Chemistry of Aspergillus oryzae (RIB40) and A. flavus (NRRL 3357)

Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus.

Comparison of antioxidant capacities of Ganoderma lucidum (Curtis) P. Karst and Funalia trogii (Berk.) Bondartsev & Singer by using different in vitro methods

The aim of the study was to investigate antioxidant activities of Ganoderma lucidum and Funalia trogii. Ethanol and water crude extracts from G. lucidum and F. trogii were investigated for their antioxidant capacity in some different assays, namely, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, metal chelating activity against ferrous ions, and plasma lipid peroxidation inhibitory. In addition, the amounts of total phenol, ascorbic acid, β-carotene, and lycopene components in the extracts were determined. Among the four mushroom extracts, G. lucidum water extract and G. lucidum ethanol extract showed the highest scavenging activity against DPPH radicals (50% inhibitory concentration = 0.055 ± 0.001 mg/mL). Total phenol was the major antioxidant component found in the mushroom extracts. These results showed that G. lucidum may be used in pharmaceutical applications because of its effective antioxidant properties.

Five sesquiterpenoids from a marine-derived fungus Aspergillus sp. isolated from a gorgonian Dichotella gemmacea

Three new phenolic bisabolane-type sesquiterpenoids: (+)-methyl sydowate (1), 7-deoxy-7,14-didehydrosydonic acid (2), and 7-deoxy-7,8-didehydrosydonic acid (3), together with two known fungal metabolites were isolated from the fermentation broth of a marine-derived fungus Aspergillus sp., which was isolated in turn from a gorgonian Dichotella gemmacea collected from the South China Sea. Their structures were elucidated by combined spectroscopic methods, and the structure of 1 was further confirmed by single-crystal X-ray data.