Aspergillus fumigatus CY018, an endophytic fungus in Cynodon dactylon as a versatile producer of new and bioactive metabolites

Bioactive Alkaloids as Secondary Metabolites from Plant Endophytic Aspergillus Genus

Alkaloids represent a large family of natural products with diverse structures and bioactivities. These compounds and their derivatives have been widely used in clinics to treat various diseases. The endophytic Aspergillus is a filamentous fungus renowned for its extraordinary ability to produce active natural products of high therapeutic value and economic importance. This review is the first to focus on Aspergillus-derived alkaloids. Through an extensive literature review and data analysis, 263 alkaloids are categorized according to their structural features into those containing cytochalasans, diketopiperazine alkaloids, quinazoline alkaloids, quinoline alkaloids, indole alkaloids, pyrrolidine alkaloids, and others. These metabolites exhibited diverse biological activities, such as antibacterial activity, cytotoxicity, anti-inflammatory activity, and α-glucosidase, ACE, and DPPH inhibitory activities. The bioactivity, structural diversity, and occurrence of these alkaloids are reviewed in detail.

Box-Behnken design optimization of xylanase and cellulase production by Aspergillus fumigatus on Stipa tenacissima biomass

Optimization of xylanase and cellulase production by a newly isolated Aspergillus fumigatus strain grown on Stipa tenacissima (alfa grass) biomass without pretreatment was carried out using a Box-Behnken design. First, the polysaccharides of dried and ground alfa grass were characterized using chemical methods (strong and diluted acid). The effect of substrate particle size on xylanase and carboxymethylcellulase (CMCase) production by the selected and identified strain was then investigated. Thereafter, experiments were statistically planned with a Box-Behnken design to optimize initial pH, cultivation temperature, moisture content, and incubation period using alfa as sole carbon source. The effect of these parameters on the two enzyme production was evaluated using the response surface method. Analysis of variance was also carried out, and production of the enzymes was expressed using a mathematical equation depending on the influencing factors. The effects of individual, interaction, and square terms on production of both enzymes were represented using the nonlinear regression equations with significant R² and P-values. Xylanase and CMCase production levels were enhanced by 25% and 27%, respectively. Thus, this study demonstrated for the first time the potential of alfa as a raw material to produce enzymes without any pretreatment. A set of parameter combinations was found to be effective for the production of xylanase and CMCase by A. fumigatus in an alfa-based solid-state fermentation.

Physcion, a novel anthraquinone derivative against Chlamydia psittaci infection

Physcion, a natural anthraquinone derivative, has been reported to exert remarkable antibacterial activities against Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa. However, it is not fully illustrated as anti-Chlamydia substance. In the present study, minimum inhibitory concentration(MIC)values for physcion against Chlamydia psittaci(C.psittaci) 6BC, C.psittaci SBL and C.psittaci HJ were 128 μg/mL,256 μg/mL and 128 μg/mL while minimum bactericidal concentration (MBC) values were 256 μg/mL,512 μg/mL and 256 μg/mL,respectively. Moreover, Chlamydial adhesion to Hela 229 cells was blocked in a dose-dependent manner and RB-to-EB differentiation was inhibited by physcion from 28 to 48 hpi.Post treatment,upregulation of LC3-II was in a dose-dependent manner, indicating physcion activated autophagy and bacterial clearance.To validate clinical efficacy,49 SPF chickens aged 21days were divided into 5 groups and infected intra-laryngeally with 0.2 mL of 1 × 10⁷ IFU/mL C.psittaci 6 BCE.Three days later, birds received orally with serial doses of physcion (4 mg/kg to 9 mg/kg), or 3 mg/kg of doxycycline for 6 days.Chickens with difficulty in breathing were alleviated significantly with increasing concentrations of physicon.Postmortem,lesions of air sacs were reduced significantly in a dose-dependent manner.More importantly,birds with 9 mg/kg of physcion could alleviate lesions of air sacs and lungs, and reduce bacterial loads in spleens, which was comparable to doxycycline treatment. Based on above evidences, physcion is a promising cost-effective natural drug by blocking Chlamydial adhesions to host cells, RB-to-EB differentiation and activating bacterial autophagy and it will be a good alternative to doxycycline combating virulent C.psittaci infection, contributing to eradication of Chlamydial transmission from animals to human beings.

Nitrogen fixation of Cyndon dactylon: A possible strategy coping with long-term flooding in the Three Gorges Reservoir

The Three Gorges Reservoir (TGR) is one of the largest hydropower projects around the world which greatly alters the ecological function of the original ecosystem. The riparian zone of TGR is subject to a frequent fluctuation of water level, leading to severe nitrogen loss by leaching. Cyndon dactylon, a perennial stress tolerant plant, is one of the dominant plant species in the riparian zone of TGR. The underlying mechanism that C. dactylon can survive the nitrogen limitation has been under debate. In this study, we sampled the plant tissues of C. dactylon and the surrounding soils across different water levels and seasons in the riparian zone of TGR to explore the possible strategy for them to mining nitrogen. Our study found that the C. dactylon in the TGR riparian zone had endophytic nitrogen-fixing bacteria, particularly enriched in the plant foliage. The abundance of endophytic nitrogen-fixing bacteria was significantly negatively correlated with soil ammonia, nitrate, and organic matter, and significantly positively correlated with total phosphorous and moisture content. The endophytic nitrogen-fixing bacteria in C. dactylon were highly diverse, with Proteobacteria as the main dominant genera. The mutual cooperation mode among bacterial species made the endophytic nitrogen-fixing bacteria community of C. dactylon more resilient to environmental pressure, thus more readily adapting to conditions of repeated long-term flooding in the riparian zone of the TGR.

Antiparasitic Activities of Compounds Isolated from Aspergillus fumigatus Strain Discovered in Northcentral Nigeria

In this study, we explored a fungal strain UIAU-3F identified as Aspergillus fumigatus isolated from soil samples collected from the River Oyun in Kwara State, Nigeria. In order to explore its chemical diversity, the fungal strain UIAU-3F was cultured in three different fermentation media, which resulted in different chemical profiles, evidenced by LC-ESI-MS-based metabolomics and multivariate analysis. The methanolic extract afforded two known compounds, fumitremorgin C (1) and pseurotin D (2). The in vitro antiparasitic assays of 1 against Trypanosoma cruzi and Plasmodium falciparum showed moderate activity with IC50 values of 9.6 µM and 2.3 µM, respectively, while 2 displayed IC50 values > 50 µM. Molecular docking analysis was performed on major protein targets to better understand the potential mechanism of the antitrypanosomal and antiplasmodial activities of the two known compounds.

Copper starvation induces antimicrobial isocyanide integrated into two distinct biosynthetic pathways in fungi

The genomes of many filamentous fungi, such as Aspergillus spp., include diverse biosynthetic gene clusters of unknown function. We previously showed that low copper levels upregulate a gene cluster that includes crmA, encoding a putative isocyanide synthase. Here we show, using untargeted comparative metabolomics, that CrmA generates a valine-derived isocyanide that contributes to two distinct biosynthetic pathways under copper-limiting conditions. Reaction of the isocyanide with an ergot alkaloid precursor results in carbon-carbon bond formation analogous to Strecker amino-acid synthesis, producing a group of alkaloids we term fumivalines. In addition, valine isocyanide contributes to biosynthesis of a family of acylated sugar alcohols, the fumicicolins, which are related to brassicicolin A, a known isocyanide from Alternaria brassicicola. CrmA homologs are found in a wide range of pathogenic and non-pathogenic fungi, some of which produce fumicicolin and fumivaline. Extracts from A. fumigatus wild type (but not crmA-deleted strains), grown under copper starvation, inhibit growth of diverse bacteria and fungi, and synthetic valine isocyanide shows antibacterial activity. CrmA thus contributes to two biosynthetic pathways downstream of trace-metal sensing.

Study on Secondary Metabolites of Endophytic Fungus, Aspergillus fumigatus, from Crocus sativus L. Guided byUHPLC-HRMS/MS-Based Molecular Network

As a traditional Chinese medicine, Crocus sativus Linn has been used for a long time in China. However, the studies on secondary metabolites of its endophytic fungi were not fully sufficient. Thus, the endophytic fungus, Aspergillus fumigatus, collected from the lateral buds of C. sativus, was here investigated. An approach combining UHPLC-HRMS/MS (ultra-high performance liquid chromatography-high resolution mass spectrometry) with molecular network was carried out to construct a molecular network of crude EtOAc extract (CEE) of A. fumigatus, in which 32 chemical compounds were annotated. On the basis of analysis results, a total of 15 known natural compounds were isolated from CEE. Among them, compounds 11 and 12 were isolated for the first time from the genus Aspergillus. Moreover, CEE and compound 7 exhibited moderate inhibitory activity against Erwinia sp. with a MIC value of 100 μg/mL. This study provided a more convenient and rapid approach to investigating the crude extract with complex components of A. fumigatus, which is of great benefit to the further study and utilization of secondary metabolites of the genus Aspergillus.

Production and characterization of a broad-spectrum antimicrobial 5-butyl-2-pyridine carboxylic acid from Aspergillus fumigatus nHF-01

The present study aims at the production optimization, purification, and characterization of a potent broad-spectrum antimicrobial compound (AMC) produced by Aspergillus fumigatus nHF-01 (GenBank Ac. No. MN190286). The culture conditions were optimized for a higher amount of AMC. The AMC was solvent extracted and characterized by UV–Vis, FT–IR, ESI–MS, and ¹H-NMR spectroscopy. The MIC, MBC and mode of action were determined against a set of Gram-positive and Gram-negative human pathogenic bacteria. Its antibiofilm, synergistic and cytotoxic effects were also tested. The putative target site of action was evaluated through in silico molecular docking study. The stain A. fumigatus nHF-01 produced the maximum AMC (5-butyl-2-pyridine carboxylic acid) in 2% MEB (w/v) and 4% YE (w/v) at pH 6.0 and 20 °C temperature with 100 rpm agitation for ten days. It caused complete lethality of the Gram-positive and Gram-negative human pathogenic bacteria at a 129 µg/mL dose by rupture and entire dissolution of cell integrity. It showed moderate antibiofilm activity and had a synergistic activity with streptomycin and additive effects with ciprofloxacin and vancomycin. It targets a respiratory enzyme, Quinol-Fumarate Reductase (1l0v), with the highest binding affinities. It had cytotoxicity against human lung carcinoma A549 cell line and was stable up to 100 °C. Thus, the study revealed that the strain A. fumigatus nHF-01 produces a potent broad-spectrum AMC 5-butyl-2-pyridine carboxylic acid that could be used against human food and topical pathogenic bacteria. This is the first report of such a compound produced from the A. fumigatus.

(+)- and (-)-trichodermatrione A: a pair of enantiomers with a cyclobutane-containing skeleton from the endophytic fungus Trichoderma sp. EFT2

(±)-trichodermatrione A, a pair of cyclobutane-containing enantiomers with an undescribed tricyclic 6/4/6 skeleton, was isolated from Trichoderma sp. EFT2, an endophytic fungus from Euonymus fortunei (Turcz.) Hand.-Mazz (Celastraceae). The racemates were separated by chiral HPLC with the structures elucidated by a combination of MS, NMR, ECD calculation and X-ray crystallography analyses. (±)- trichodermatrione A and enantiomers were found to be antibacterial against phytopathogenic bacteria Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc).

Antibacterial Effect and Mode of Action of Secondary Metabolites from Fungal Endophyte Associated with Aloe ferox Mill

The constant increase in drug resistance, occurrence of incurable diseases and high medical costs, have necessitated bio-prospecting of fungi as alternative sources of therapeutic compounds. This study aimed at assessing the antibacterial effect and mode of action of secondary metabolites from fungal endophyte associated with Aloe ferox Mill. Endophytic fungus was isolated from the gel of A. ferox and identified by internal transcribed spacer (ITS) rRNA gene sequence analysis. The targets of antibacterial activity were assessed based on minimum inhibitory concentration (MIC) and the effect of the extract on respiratory chain dehydrogenase (RCD) and membrane integrity. Fourier transform-infrared spectrophotometer (FTIR) was employed to ascertain functional groups. The fungus with the most promising antibiotic-production was identified as Aspergillus welwitschiae MK450668.1. Its extract exhibited antibacterial activity with the MIC values of 0.5 and 1 mg/mL against Staphylococcus aureus (ATCC 25925) and Escherichia coli (ATCC 25922). It demonstrated the inhibitory effect on the RCD activity and destruction of membrane integrity on the test bacteria. FTIR spectrum revealed hydroxyl, amine and alkene groups. A. welwitschiae MK450668.1 serves as a potential source of effective compounds to combat the challenge of drug resistance.

The crystal structure of C19H20O8

C19H20O8, triclinic, P 1 ‾ $P\overline{1}$ (no. 2), a = 7.0708(4) Å, b = 8.1261(4) Å, c = 16.1067(6) Å, α = 81.252(4)°, β = 81.500(4)°, γ = 77.890(4)°, V = 887.88(8) Å3, Z = 2, R gt (F) = 0.0418, wR ref(F 2) = 0.1158, T = 150 K.

Alkaloids from endophytic fungus Aspergillus fumigatus HQD24 isolated from the Chinese mangrove plant Rhizophora mucronata

Chemical investigation of endophytic fungus Aspergillus fumigatus HQD24, isolated from the flower of Rhizophora mucronata led to the isolation of eight alkaloids, including pyripyropene A (1), 1,11-dideacetyl-pyripyropene A (2), pyripyropene E (3), chaetominine (4), tryptoquivaline J (5), fumitremorgin C (6), 1-acetyl-β-carboline (7), and nicotinic acid (8). Their structures were unambiguously elucidated on the basis of extensive spectroscopic data and comparison with the data of literature. Compound 2 was known as a synthetic product and isolated as a natural product for the first time. The immunosuppressive and cytotoxic activities of all isolated compounds were evaluated.

Cure lies in nature: medicinal plants and endophytic fungi in curbing cancer

Success of targeted cancer treatment modalities has generated an ambience of plausible cure for cancer. However, cancer remains to be the major cause of mortality across the globe. The emergence of chemoresistance, relapse after treatment and associated adverse effects has posed challenges to the present therapeutic regimes. Thus, investigating new therapeutic agents of natural origin and delineating the underlying mechanism of action is necessary. Since ages and still in continuum, the phytochemicals have been the prime source of identifying bioactive agents against cancer. They have been exploited for isolating targeted specific compounds to modulate the key regulating signaling pathways of cancer pathogenesis and progression. Capsaicin (alkaloid compound in chilli), catechin, epicatechin, epigallocatechin and epigallocatechin-3-gallate (phytochemicals in green tea), lutein (carotenoid found in yellow fruits), Garcinol (phenolic compound present in kokum tree) and many other naturally available compounds are also very valuable to develop the drugs to treat the cancer. An alternate repository of similar chemical diversity exists in the form of endophytic fungi inhabiting the medicinal plants. There is a high diversity of plant associated endophytic fungi in nature which are potent producers of anti-cancer compounds and offers even stronger hope for the discovery of an efficient anti-cancer drug. These fungi provide various bioactive molecules, such as terpenoids, flavonoids, alkaloids, phenolic compounds, quinines, steroids etc. exhibiting anti-cancerous property. The review discusses the relevance of phytochemicals in chemoprevention and as modulators of miRNA. The perspective advocates the imperative role of anti-cancerous secondary metabolites containing repository of endophytic fungi, as an alternative route of drug discovery.

Exploring endophytes for in vitro synthesis of bioactive compounds similar to metabolites produced in vivo by host plants

Endophytes represent microorganisms residing within plant tissues without typically causing any adverse effect to the plants for considerable part of their life cycle and are primarily known for their beneficial role to their host-plant. These microorganisms can in vitro synthesize secondary metabolites similar to metabolites produced in vivo by their host plants. If microorganisms are isolated from certain plants, there is undoubtedly a strong possibility of obtaining beneficial endophytes strains producing host-specific secondary metabolites for their potential applications in sustainable agriculture, pharmaceuticals and other industrial sectors. Few products derived from endophytes are being used for cultivating resilient crops and developing non-toxic feeds for livestock. Our better understanding of the complex relationship between endophytes and their host will immensely improve the possibility to explore their unlimited functionalities. Successful production of host-secondary metabolites by endophytes at commercial scale might progressively eliminate our direct dependence on high-valued vulnerable plants, thus paving a viable way for utilizing plant resources in a sustainable way.

Fungal Endophytes as Efficient Sources of Plant-Derived Bioactive Compounds and Their Prospective Applications in Natural Product Drug Discovery: Insights, Avenues, and Challenges

Fungal endophytes are well-established sources of biologically active natural compounds with many producing pharmacologically valuable specific plant-derived products. This review details typical plant-derived medicinal compounds of several classes, including alkaloids, coumarins, flavonoids, glycosides, lignans, phenylpropanoids, quinones, saponins, terpenoids, and xanthones that are produced by endophytic fungi. This review covers the studies carried out since the first report of taxol biosynthesis by endophytic Taxomyces andreanae in 1993 up to mid-2020. The article also highlights the prospects of endophyte-dependent biosynthesis of such plant-derived pharmacologically active compounds and the bottlenecks in the commercialization of this novel approach in the area of drug discovery. After recent updates in the field of 'omics' and 'one strain many compounds' (OSMAC) approach, fungal endophytes have emerged as strong unconventional source of such prized products.

Identifying candidate Aspergillus pathogenicity factors by annotation frequency

BACKGROUND

Members of the genus Aspergillus display a variety of lifestyles, ranging from saprobic to pathogenic on plants and/or animals. Increased genome sequencing of economically important members of the genus permits effective use of "-omics" comparisons between closely related species and strains to identify candidate genes that may contribute to phenotypes of interest, especially relating to pathogenicity. Protein-coding genes were predicted from 216 genomes of 12 Aspergillus species, and the frequencies of various structural aspects (exon count and length, intron count and length, GC content, and codon usage) and functional annotations (InterPro, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes terms) were compared.

RESULTS

Using principal component analyses, the three sets of functional annotations for each strain were clustered by species. The species clusters appeared to separate by pathogenicity on plants along the first dimensions, which accounted for over 20% of the variance. More annotations for genes encoding pectinases and secondary metabolite biosynthetic enzymes were assigned to phytopathogenic strains from species such as Aspergillus flavus. In contrast, Aspergillus fumigatus strains, which are pathogenic to animals but not plants, were assigned relatively more terms related to phosphate transferases, and carbohydrate and amino-sugar metabolism. Analyses of publicly available RNA-Seq data indicated that one A. fumigatus protein among 17 amino-sugar processing candidates, a hexokinase, was up-regulated during co-culturing with human immune system cells.

CONCLUSION

Genes encoding hexokinases and other proteins of interest may be subject to future manipulations to further refine understanding of Aspergillus pathogenicity factors.

Antimicrobial and antioxidant activities and chemical profiling of Curvularia tsudae endophytic in Cynodon dactylon (L.) Pers

There is a growing body of evidence that endophytic fungal metabolites possess important biological activities. Cynodon dactylon (L.) Pers., a well-known grass species with potential medicinal properties, is under-explored for the diversity of endophytic fungal species and their metabolites. We report here the diversity of endophytic fungi in the culm, leaf and inflorescence of Cynodon dactylon when cultured on moist blotter (MB), potato dextrose agar (PDA) and malt extract agar (MEA). Species richness, Shannon and Simpson diversity and evenness indices showed that PDA followed by MEA supported the growth of the largest number of fungal species. Amongst four fungal species tested, Curvularia tsudae was selected for further studies on antimicrobial and antioxidant activities. The mycelial mat (MM) and culture filtrate (CF) of PD broth grown Curvularia tsudae extracted with ethyl acetate and methanol, respectively, were subjected to antimicrobial assay against five bacterial and four fungal test isolates. Results indicated that the ethyl acetate extract of CF had moderate activity against Enterococcus faecalis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus whereas the methanolic MM extract showed high to moderate activity to Aspergillus flavus, A. niger and Fusarium oxysporum. Cyclic voltammetric analysis of ethyl acetate extract showed very good antioxidant activity and the extract contained coumarins when determined by HPLC. High-resolution orbitrap LC-MS of ethyl acetate extract revealed the presence of metabolites with antimicrobial and antioxidant and other biological activities. Finding of the present study suggested that Curvularia tsudae could be exploited for pharmaceutical applications.

Factors Affecting the Metabolite Productions in Endophytes: Biotechnological Approaches for Production of Metabolites

Since 1980, many species and different strains from endophytic genera of Phomopsis, Fusarium, Pestaliopsis and Aspergillus have been studied because of their ability to produce medicinal compounds found in their host plants. Some of these medicinal agents such as Taxol, Brefeldine A, Camptothecin and Podophyllotoxin are being produced in large-scale after an optimization process. However, the potential of fungal endophytes to produce host-like medicinal compounds remains largely unexplored.

Antimicrobial Potential of Fungal Endophytes from Moringa oleifera

The present study was aimed to isolate the endophytic fungi having antimicrobial potential from Moringa oleifera. Out of the active isolates, the endophytic fungal isolate DSE 17 obtained from the bark of the plant was selected for further studies and identified as Aspergillus fumigatus. The classical method for optimization strategy revealed inoculum size of four discs in Czapek dox's medium at a temperature of 25 °C and pH 7 with the incubation period of 6 days to be the best. Sucrose as carbon source (1%) and sodium nitrate as nitrogen source (0.2%) were found to be the best for antimicrobial activity. Response surface methodology was effective in optimizing the selected medium components in Plackett-Burman design, i.e. magnesium sulphate, dipotassium phosphate and sodium nitrate, which resulted in increase in antimicrobial activity by 1.7-fold. Chloroform was found to be the best extractant amongst different solvents. The minimum inhibitory concentration (MIC) values of the chloroformic extract ranged from 0.05 to 0.5 mg/ml, and the viable cell count studies revealed it to be bactericidal in its nature. The post-antibiotic effect (PAE) of the chloroformic extracts ranged from 2 to 20 h. Ames mutagenicity testing and MTT assay revealed the crude extract neither cytotoxic nor mutagenic, thus showing it to be biosafe. Thus, the study suggests that endophytes from this miracle plant could be potential source for the production of broad-spectrum antimicrobial compound/s.

Diagnóstico diferencial das doenças neurológicas dos bovinos no estado do Paraná

RESUMO: O objetivo deste trabalho foi identificar as doenças neurológicas que acometeram bovinos no estado do Paraná entre os anos de 2009 e 2015. A investigação aconteceu, preferencialmente, nas propriedades rurais onde os casos ocorreram. Foram registradas as informações sobre a evolução das doenças nos bovinos afetados do rebanho, e os prováveis fatores de risco foram identificados. Todos os procedimentos de exame físico geral e neurológico foram realizados sistematicamente para a caracterização da síndrome neurológica presente. Amostras de sangue e de líquor foram colhidas para a realização de exames laboratoriais. De acordo com o tempo de evolução e com a gravidade dos sinais clínicos observados, os bovinos doentes eram mantidos vivos para acompanhamento da evolução ou da resposta ao tratamento, ou eram submetidos à eutanásia seguida de necropsia. Fragmentos do sistema nervoso e dos demais órgãos foram colhidos para exame histopatológico. O exame de imunofluorescência direta e a prova biológica em camundongos foram realizados em todos os bovinos que morreram, com a finalidade de confirmar ou descartar o diagnóstico de raiva. Métodos laboratoriais específicos das rotinas de virologia, bacteriologia e toxicologia foram empregados, como complementares, para o estabelecimento do diagnóstico diferencial. Foram investigados 236 bovinos com doença neurológica, sendo 85 casos de ocorrência individual e 151 casos distribuídos por surtos que ocorreram em 79 rebanhos. As encefalopatias (180/236; 76,2%) predominaram sobre as mielopatias (27/236; 11,4%). As doenças inflamatórias determinadas por infecções (98/236; 41,5%) e as doenças tóxicas (91/236; 38,6%) foram as principais, enquanto as causas degenerativas (10/236; 4,2%), metabólicas (9/236; 3,8%), físicas (9/236; 3,8%), neoplásicas (4/236; 1,7%), e os defeitos congênitos (1/236; 0,4%) ocorreram menos frequentemente. Os casos inconclusivos somaram 5,9% (14/236). A meningoencefalite por BoHV-5 e a raiva foram as doenças de frequência maior e podem ser consideradas as mais importantes. Dentre as causas tóxicas, as intoxicações por plantas se destacaram (63/91; 69,2%) e foram responsáveis por 26,6% de todos os casos. Destacaram-se ainda a polioencefalomalácia, a meningoencefalite trombótica por Histophilus somni e o botulismo. Essas informações contribuem para que os médicos veterinários adotem condutas mais efetivas de diagnóstico e de prevenção, e são valiosas para o sistema oficial de vigilância epidemiológica do estado.

Epigenetic modifier induced enhancement of fumiquinazoline C production in Aspergillus fumigatus (GA-L7): an endophytic fungus from Grewia asiatica L

Present study relates to the effect of valproic acid, an epigenetic modifier on the metabolic profile of Aspergillus fumigatus (GA-L7), an endophytic fungus isolated from Grewia asiatica L. Seven secondary metabolites were isolated from A. fumigatus (GA-L7) which were identified as: pseurotin A, pseurotin D, pseurotin F2, fumagillin, tryprostatin C, gliotoxin and bis(methylthio)gliotoxin. Addition of valproic acid in the growth medium resulted in the alteration of secondary metabolic profile with an enhanced production of a metabolite, fumiquinazoline C by tenfolds. In order to assess the effect of valproic acid on the biosynthetic pathway of fumiquinazoline C, we studied the expression of the genes involved in its biosynthesis, both in the valproic acid treated and untreated control culture. The results revealed that all the genes i.e. Afua_6g 12040, Afua_6g 12050, Afua_6g 12060, Afua_6g 12070 and Afua_6g 12080, involved in the biosynthesis of fumiquinazoline C were overexpressed significantly by 7.5, 8.8, 3.4, 5.6 and 2.1 folds respectively, resulting in overall enhancement of fumiquinazoline C production by about tenfolds.

Identification and Antifungal Activity of Compounds from the Mangrove Endophytic Fungus Aspergillus clavatus R7

Two new coumarin derivatives, 4,4′-dimethoxy-5,5′-dimethyl-7,7′-oxydicoumarin (1), 7-(γ,γ-dimethylallyloxy)-5-methoxy-4-methylcoumarin (2), a new chromone derivative, (S)-5-hydroxy-2,6-dimethyl-4H-furo[3,4-g]benzopyran-4,8(6H)-dione (5), and a new sterone derivative, 24-hydroxylergosta-4,6,8(14),22-tetraen-3-one (6), along with two known bicoumarins, kotanin (3) and orlandin (4), were isolated from an endophytic fungus Aspergillusclavatus (collection No. R7), isolated from the root of Myoporum bontioides collected from Leizhou Peninsula, China. Their structures were elucidated using 1D- and 2D- NMR spectroscopy, and HRESIMS. The absolute configuration of compound 5 was determined by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Compound 6 significantly inhibited the plant pathogenic fungi Fusarium oxysporum, Colletotrichum musae and Penicillium italicum, compound 5 significantly inhibited Colletotrichum musae, and compounds 1, 3 and 4 greatly inhibited Fusarium oxysporum, showing the antifungal activities higher than those of the positive control, triadimefon.

Fumigaclavine I, a new alkaloid isolated from endophyte Aspergillus terreus

The present study was designed to isolate and purify chemical constituents from solid culture of endophyte Aspergillus terreus LQ, using silica gel column chromatography, gel filtration with Sephadex LH-20, and HPLC. Fumigaclavine I (1), a new alkaloid, was obtained, along with seven known compounds, including fumigaclavine C (2), rhizoctonic acid (3), monomethylsulochrin (4), chaetominine (5), spirotryprostatin A (6), asperfumoid (7), and lumichrome (8). The structure of compound 1 was elucidated by various spectroscopic analyses (UV, MS, 1D and 2D NMR). The in vitro cytotoxicity of compound 1 was determined by MTT assay in human hepatocarcinoma cell line SMMC-7721, showing weaker cytotoxicity, compared with cisplatin, a clinically used cancer chemotherapeutic agent.

Lethality of cytochalasin B and other compounds isolated from fungus Aspergillus sp. (Trichocomaceae) endophyte of Bauhinia guianensis (Fabaceae)

Endophytic fungi are fungi that colonize internal tissues of plants; several biologically active compounds have been isolated from these fungi. There are few studies of compounds isolated from endophytic fungi of Amazon plants. Thus, this study aimed the isolation and structural identification of ergosterol (1), ergosterol peroxide (2), mevalonolactone (3), cytochalasin B (4) and cytochalasin H (5) from Aspergillus sp. EJC 04, an endophytic fungus from Bauhinia guianensis. The cytochalasin B (4) and the diacetate derivative of cytochalasin B (4a) showed high lethality in the brine shrimp assay. This is the first occurrence of cytochalasins in Amazonian endophytic fungi from B. guianensis.

Anti-phytopathogenic activity of sporothriolide, a metabolite from endophyte Nodulisporium sp. A21 in Ginkgo biloba

Phytopathogenic fungi such as Rhizoctonia solani and Sclerotinia sclerotiorum caused multiple plant diseases resulting in severe loss of crop production. Increasing documents endorsed that endophytes are a striking resource pool for numerous metabolites with various bioactivities such as anti-fungal. Here we reported the characterization and anti-phytopathogenic activity of sporothriolide, a metabolite produced by Nodulisporium sp. A21-an endophytic fungus in the leaves of Ginkgo biloba. Among the total twenty-five endophytic fungi isolated from the healthy leaves of G. biloba, the fermentation broth (FB) of the strain A21 was found potently inhibitory activity against R. solani and S. sclerotiorum using mycelia growth inhibition method. A21 was then identified as Nodulisporium sp., the asexual stage of Hypoxylon sp., by microscopic examination and ITS rDNA sequence data comparison. Under the bioassay-guided fractionation, sporothriolide was isolated from the petroleum ether extract of the FB of A21, whose structure was established by integrated interpretation of HR-ESI-MS and (1)H- and (13)C-NMR. Furthermore, the crystal structure of sporothriolide was first reported. In addition, sporothriolide was validated to be potently antifungal against R. solani, S. sclerotiorum and inhibit conidium germination of Magnaporthe oryzae in vitro and in vivo, indicating that it could be used as a lead compound for new fungicide development.

Microbial Biotransformation to Obtain New Antifungals

Antifungal drugs belong to few chemical groups and such low diversity limits the therapeutic choices. The urgent need of innovative options has pushed researchers to search new bioactive molecules. Literature regarding the last 15 years reveals that different research groups have used different approaches to achieve such goal. However, the discovery of molecules with different mechanisms of action still demands considerable time and efforts. This review was conceived to present how Pharmaceutical Biotechnology might contribute to the discovery of molecules with antifungal properties by microbial biotransformation procedures. Authors present some aspects of (1) microbial biotransformation of herbal medicines and food; (2) possibility of major and minor molecular amendments in existing molecules by biocatalysis; (3) methodological improvements in processes involving whole cells and immobilized enzymes; (4) potential of endophytic fungi to produce antimicrobials by bioconversions; and (5) in silico research driving to the improvement of molecules. All these issues belong to a new conception of transformation procedures, so-called "green chemistry," which aims the highest possible efficiency with reduced production of waste and the smallest environmental impact.

Fungal endophytes as prolific source of phytochemicals and other bioactive natural products: A review

Endophytic fungi are those that live internally in apparently healthy and asymptomatic hosts. Endophytic fungi appear to be ubiquitous; indeed, no study has yet shown the existence of a plant species without endophytes. High species diversity is another characteristic of endophytic mycobiota which is depicted by the fact that it is quite common for endophyte surveys to find assemblages consisting of more than 30 fungal species per host plant species. Medicinal plants had been used to isolate and characterize directly the bioactive metabolites. However, the discovery of fungal endophytes inside these plants with capacity to produce the same compounds shifted the focus of new drug sources from plants to fungi. Bioactive natural products from endophytic fungi, isolated from different plant species, are attracting considerable attention from natural product chemists and biologists alike which is clearly depicted by the steady increase of publications devoted to this topic during the recent years. This review will highlight the chemical potential of endophytic fungi with focus on the detection of pharmaceutically valuable plant constituents as products of fungal biosynthesis. In addition, it will cover newly discovered endophytic fungi and also new bioactive metabolites reported in recent years from fungal endophytes. It summarizes the up-to-date and comprehensive information on bioactive compounds from endophytic fungi by having done a thorough survey of literature.

Preparative separation and purification of fumigaclavine C from fermented mycelia of Aspergillus fumigatus CY018 by macroporous adsorption resin

In this work, the separation and purification of fumigaclavine C (FC), an ergot alkaloid with strong anti-inflammatory activity from fermented mycelia of Aspergillus fumigatus was systematically evaluated. Among the eight tested resins, the non-polar resin D101 displayed the best adsorption and desorption based on of static adsorption and desorption tests. Adsorption isotherms were constructed on D101 resin and fitted well to the Freundlich model. Dynamic adsorption and desorption tests on a column packed with D101 resin have been investigated for optimization of chromatographic parameters. Under optimized conditions, the contents of FC increased from 7.32% (w/w) in the crude extract to 67.54% in the final product with a recovery yield of 90.35% (w/w) via one run. Furthermore, a lab scale-up separation was carried out, in which the FC content and recovery yield were 65.83% and 90.13%, respectively. These results demonstrated that this adsorption-desorption strategy by using D101 resin was simple and efficient, thus showing potential for large scale purification and preparation of FC in the future.

In Vitro Evaluation of Antagonism of Endophytic Colletotrichum gloeosporioides Against Potent Fungal Pathogens of Camellia sinensis

An endophytic fungus isolated from Camellia sinensis, Assam, Northeastern India was identified as Colletotrichum gloeosporioides on the basis of morphological characteristics and rDNA ITS analysis. This endophytic fungus was evaluated for growth inhibition against tea pathogens Pestalotiopsis theae and Colletotrichum camelliae. One isolate of C. gloeosporioides showed strong antagonistic activity against Pestalotiopsis theae (64 %) and moderate activity against C. camelliae (37 %). Fifty percent cell-free culture filtrate from 5-day-old cultures showed highest antagonistic activity against both the pathogens although the inhibition percent was less as compared to dual culture. In the experiment of volatile compounds none of the isolates of C. gloeosporioides strains showed visible inhibition against P. theae and C. camelliae. The activity of extracellular hydrolytic enzymes chitinase and protease was also high in this culture fluid and measured 10 and 4.3 IU/μl, respectively.

Phylogenetic reconstruction of endophytic fungal isolates using internal transcribed spacer 2 (ITS2) region

Endophytic fungi are inhabitants of plants, living most part of their lifecycle asymptomatically which mainly confer protection and ecological advantages to the host plant. In this present study, 48 endophytic fungi were isolated from the leaves of three medicinal plants and characterized based on ITS2 sequence – secondary structure analysis. ITS2 secondary structures were elucidated with minimum free energy method (MFOLD version 3.1) and consensus structure of each genus was generated by 4SALE. ProfDistS was used to generate ITS2 sequence structure based phylogenetic tree respectively. Our elucidated isolates were belonging to Ascomycetes family, representing 5 orders and 6 genera. Colletotrichum/Glomerella spp., Diaporthae/Phomopsis spp., and Alternaria spp., were predominantly observed while Cochliobolus sp., Cladosporium sp., and Emericella sp., were represented by singletons. The constructed phylogenetic tree has well resolved monophyletic groups with >50% bootstrap value support. Secondary structures based fungal systematics improves not only the stability; it also increases the precision of phylogenetic inference. Above ITS2 based phylogenetic analysis was performed for our 48 isolates along with sequences of known ex-types taken from GenBank which confirms the efficiency of the proposed method. Further, we propose it as superlative marker for reconstructing phylogenetic relationships at different taxonomic levels due to their lesser length.

Enhanced production of fumigaclavine C by ultrasound stimulation in a two-stage culture of Aspergillus fumigatus CY018

Stimulation by physical means including ultrasound is important to cell morphology and the product yield. In this work, the effect of ultrasound on the production of fumigaclavine C (FC), a conidiation-associated alkaloid with strong anti-inflammatory activity, was investigated in a newly developed two-stage culture of Aspergillus fumigatus CY018. The optimum ultrasonication conditions consisted of exposing cultures (at 12h of growth phase) to 10-min repeated irradiation (4 times) with a 24-h interval at the fixed power (500 W). Under this condition, FC production reached 118.09 mg/L, which was 89% higher than the control and much higher than previous reported values. Morphological analysis demonstrated that mycelia morphology from ultrasonication was in the form smaller and looser pellets as compared to that of the control. In addition, conidia that is closely related to FC biosynthesis were significantly increased after ultrasound stimulation, with 3 folds of that from the control.

Enhanced production of Fumigaclavine C in liquid culture of Aspergillus fumigatus under a two-stage process

Fumigaclavine C (FC) produced by Aspergillus fumigatus is a conidiation associated ergot alkaloid with strong anti-inflammatory activity. However, its wide application has been severely limited by low FC production from submerged culture. In this work, a novel two-stage culture process by combining shake culture with static culture was proposed to enhance the production of FC. After the process optimization, the FC production reached 62.7 mg/L, which was significantly higher than ever report. For scaling up this new culture process, the gas-liquid interfacial area per unit volume (Agas-liq) was identified as the key factor. The results showed that in a combined stirred-static bioreactor system, a maximum FC production (58.97 mg/L) was obtained at an Agas-liq value of 1.30 cm(2)/mL. These results demonstrated that two-stage culture is an efficient strategy to enhance FC production and the information obtained will be useful to production of this powerful bioactive compound on a large scale.

Flavipin in Chaetomium globosum CDW7, an endophytic fungus from Ginkgo biloba, contributes to antioxidant activity

1,2-Benzenedicarboxaldehyde-3,4,5-trihydroxy-6-methyl (flavipin) was found to be antagonistic against nematodes and fungi. Here we demonstrated that flavipin is a potent antioxidant in vitro and in vivo, which has great potential in the therapy for free radical-associated diseases. Therefore, flavipin-producing bio-source was screened from 80 endophytes in Ginkgo biloba. Seven endophytic fungi were able to synthesize antioxidant substances and identified by ITS rDNA sequences. Among them, Chaetomium globosum CDW7 was a remarkable producer of flavipin. The fermentation parameters of CDW7 were then optimized for high flavipin production. Cultured under the optimal condition (25 °C, 100/250 mL flask, 12 discs/flask, 150 rpm, pH 6.5) for 14 days, CDW7 was able to synthesize flavipin at a production of 315.5 mg/L. In addition, flavipin output was positively correlated to antioxidant activities of crude extracts with a correlation coefficient of 0.8235, indicating that flavipin was the major antioxidant component of CDW7's metabolites. These data demonstrated that CDW7 was a highly yielded bio-source of antioxidant flavipin.

Metabolites from Alternaria fungi and their bioactivities

Alternaria is a cosmopolitan fungal genus widely distributing in soil and organic matter. It includes saprophytic, endophytic and pathogenic species. At least 268 metabolites from Alternaria fungi have been reported in the past few decades. They mainly include nitrogen-containing metabolites, steroids, terpenoids, pyranones, quinones, and phenolics. This review aims to briefly summarize the structurally different metabolites produced by Alternaria fungi, as well as their occurrences, biological activities and functions. Some considerations related to synthesis, biosynthesis, production and applications of the metabolites from Alternaria fungi are also discussed.

Culture condition-dependent metabolite profiling of Aspergillus fumigatus with antifungal activity

Three sections of Aspergillus (five species, 21 strains) were classified according to culture medium-dependent and time-dependent secondary metabolite profile-based chemotaxonomy. Secondary metabolites were analysed by liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS-MS) and multivariate statistical methods. From the Aspergillus sections that were cultured on malt extract agar (MEA) and Czapek yeast extract agar (CYA) for 7, 12, and 16 d, Aspergillus sections Fumigati (A. fumigatus), Nigri (A. niger), and Flavi (A. flavus, A. oryzae, and A. sojae) clustered separately on the basis of the results of the secondary metabolite analyses at 16 d regardless of culture medium. Based on orthogonal projection to latent structures discriminant analysis by partial least squares discriminant analysis (PLS-DA), we identified the secondary metabolites that helped differentiate sections between A. fumigatus and Aspergillus section Flavi to be gliotoxin G, fumigatin oxide, fumigatin, pseurotin A or D, fumiquinazoline D, fumagillin, helvolic acid, 1,2-dihydrohelvolic acid, and 5,8-dihydroxy-9,12-octadecadienoic acid (5,8-diHODE). Among these compounds, fumagillin, helvolic acid, and 1,2-dihydrohelvolic acid of A. fumigatus showed antifungal activities against Malassezia furfur, which is lipophilic yeast that causes epidermal skin disorders.