Fungal Extracts Research Articles

Isolation, characterization, and screening of secondary metabolites from endophytic fungi isolated from Nigerian Piliostigma thonningii for antimicrobial activities

Piliostigma thonningii leaves are used in Nigeria folk medicine for the treatment and management of diverse ailments. This study was carried out to investigate the antimicrobial activity of the secondary metabolites produced from endophytic fungi isolated from the leaves of Piliostigma thonningii. The isolation of endophytic fungi was carried out according to the standard procedures. The fungi were subjected to solid-state fermentation on rice medium and the secondary metabolites extracted using ethyl acetate. The fungal crude extracts were screened for antimicrobial activity against selected clinically important microbes using the agar well diffusion method. The fungus with the best antimicrobial activity was molecularly characterized and its secondary metabolites profiled using Gas Chromatography - Mass Spectroscopy to establish the correlation between the observed activity and its phytochemical composition. The fungal extracts showed antimicrobial activity with inhibitory zone diameter ranging from 2.00 to 9.00 mm. The secondary metabolites of Aspergillus fumigatus (the most bioactive endophyte) contain 50 compounds with several of them having established antimicrobial activity. The results of this study suggest that Aspergillus fumigatus an endophytic fungus associated with P. thonningii could be a promising source of novel bioactive compounds with pharmaceutical, agricultural and industrial importance. Keywords: Antimicrobial, Endophytic fungi, GC-MS, Piliostigma thonningii

Molecular and Morphological Assessment of the Impact of Gas Flares on the Fungal Abundance and Diversity in soils of Niger Delta Area, Nigeria

Fungal abundance and diversity in soils of three communities flow stations (ID, IR and OB) owned by an unnamed oil exploration firm operating in the Niger Delta area for about five decades were determined using nucleic acid analytical methods. Top soil (0-15 cm) samples were collected from mini pits using sterile bottles at 50, 100 and 150 meters from the flare barrier of each community flow station and soil samples from the control was taken at 2.5 kilometers during the dry and wet seasons. The fungal properties were determined first using the cultural method of serial dilution method which revealed the presence of the following fungi; Aspergillus sp, and penicillium chrysogenum at 50 m away from flare in all the three flow stations during the dry seasons and in the wet season Aspergillus sp, penicillium chrysogenum, Mucor sp., yeast cells, A. niger, and Rhizopus sp. At 100 m away from flare, Mucor sp, A. niger and rhizopus were isolated in all three-flow station in the dry season and in the wet season, Yeast cells, A. niger, Aspegillus sp. and Rhizopus were isolated. P. chrysogenum, Aspergillus sp. and yeast cells were isolated at 150 m away from flare in the dry season and in the same distance, yeast cells, A. niger aggregate, A. niger and P. chrysogenum were isolated. At the control site, during the dry season, A. niger, P. chrysogenum, Aspergillus sp., Rhizopus sp. and Botryodiplodia threobome were isolated in the dry and A. niger, P. chrysogenum and yeast in the wet season. Fungal DNA was extracted using Norgen fungal genomic DNA extraction kits for the molecular analysis to establish the true characteristics and species identity of the isolates earlier identified with cultural methods. This revealed the presence of the following fungi upon sequence blast on NCBI database; Aspergillus fumigatus (Aspergillus fumigatus brown 2 (abr2) gene, complete cds strain), Aspergillus fumigatus (Aspergillus fumigates strain IHM 15988 pigment biosynthesis protein), Fusarium phyllophilum , Fusarium graminearum, Aspergillus oryzae (a strain of Aspergillus niger) Aspergillus oryzae (niger). Findings from this work have shown that molecular technique gave the exact identity of fungal species isolated from study area. All six (6) molecularly identified fungi were isolated from the three-study flow station and in both seasons. The Aspergillus group was dominant as a result of their ability to adapt to the flare environment

Enhancing circular economy: eco-friendly starch extraction and modification using fungal crude enzymatic extract from cocoa shell waste

Enhancing circular economy: eco-friendly starch extraction and modification using fungal crude enzymatic extract from cocoa shell waste

Wound healing and coagulant activity of crude extract metabolites from fungal endophytes

Bleeding from a wound as a result of physical injury is a life-threatening condition. In pursuing new drug structures, the effect of crude fungal extracts fungal isolated from Jatropha multifida on wound healing and coagulation of mouse whole blood was investigated. Jatropha multifida leaves were sterilized, cut into small segments, and then incubated in Potato Dextrose Agar for seven days. Four isolates were purified and their morphologies were characterized. Identification of isolates was confirmed by a molecular protocol. Two crude extracts from Phlebiopsis gigantea (OK021602) and Phyllosticta sp (OK021603), which exhibited higher phytochemicals composition, were selected and evaluated using wound excision and coagulation of mouse whole blood, by administering 30 µg/mL, 50 µg/mL and 70 µg/mL crude extracts respectively. The percentage of wound healing in mice was higher (p<0.05) for the crude extracts of Phlebiopsis gigantea (OK021602) as compared to that of Phyllosticta sp (OK021603). The highest percentages of wound contraction were 99% at 70 µg/mL, and 53% at 70 µg/mL for Phlebiopsis gigantea (OK021602) and Phyllosticta sp (OK021603), respectively as compared to the control group which had 42% wound contraction at day 15 post-treatment. The results of the present study clearly indicate that Jatropha multifida leaves harbor endophytic fungi that produce pharmacologically important bioactive secondary metabolites with wound and hemostatic effects; therefore, further exploration is inevitable, particularly for the purification and identification of specific chemical structures of bioactive compounds.

Bioactive nanoparticles derived from marine brown seaweeds and their biological applications: a review.

The biosynthesis of novel nanoparticles with varied morphologies, which has good implications for their biological capabilities, has attracted increasing attention in the field of nanotechnology. Bioactive compounds present in the extract of fungi, bacteria, plants and algae are responsible for nanoparticle synthesis. In comparison to other biological resources, brown seaweeds can also be useful to convert metal ions to metal nanoparticles because of the presence of richer bioactive chemicals. Carbohydrates, proteins, polysaccharides, vitamins, enzymes, pigments, and secondary metabolites in brown seaweeds act as natural reducing, capping, and stabilizing agents in the nanoparticle's synthesis. There are around 2000 species of seaweed that dominate marine resources, but only a few have been reported for nanoparticle synthesis. The presence of bioactive chemicals in the biosynthesized metal nanoparticles confers biological activity. The biosynthesized metal and non-metal nanoparticles from brown seaweeds possess different biological activities because of their different physiochemical properties. Compared with terrestrial resources, marine resources are not much explored for nanoparticle synthesis. To confirm their morphology, characterization methods are used, such as absorption spectrophotometer, X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. This review attempts to include the vital role of brown seaweed in the synthesis of metal and non-metal nanoparticles, as well as the method of synthesis and biological applications such as anticancer, antibacterial, antioxidant, anti-diabetic, and other functions.

Assessment of Fungal Lytic Enzymatic Extracts Produced Under Submerged Fermentation as Enhancers of Entomopathogens’ Biological Activity

The application of enzymes in agricultural fields has been little explored. One potential application of fungal lytic enzymes (chitinases, lipases, and proteases) is as an additive to current biopesticides to increase their efficacy and reduce the time of mortality. For this, a screening of lytic overproducer fungi under submerged fermentation with a chemical-defined medium was performed. Then, the enzymatic crude extract (ECE) was concentrated and partially characterized. This characterization consisted of measuring the enzymatic activity (lipase, protease and, chitinase) and determining the enzyme stability after storage at temperatures of − 80, − 20 and, 4 °C. And lastly, the application of these concentrated enzymatic crude extracts (C-ECE) as an enhancer of spores-based fungal biopesticide was proven. Beauveria were not as good producers of lytic enzymes as the strains from Trichoderma and Metarhizium. The isolate M. robertsii Mt015 was selected for the co-production of chitinases and proteases; and the isolate T. harzianum Th180 for co-production of chitinases, lipases, and proteases. The C-ECE of Mt015 had a protease activity of 18.6 ± 1.1 U ml−1, chitinase activity of 0.28 ± 0.01 U ml−1, and no lipase activity. Meanwhile, the C-ECE of Th180 reached a chitinase activity of 0.75 U ml−1, lipase activity of 0.32 U ml−1, and protease activity of 0.24 U ml−1. Finally, an enhancing effect of the enzymatic extracts of M. robertsii (66.7%) and T. harzianum (43.5%) on the efficacy of B. bassiana Bv064 against Diatraea saccharalis larvae was observed. This work demonstrates the non-species-specific enhancing effect of enzymatic extracts on the insecticidal activity of conidial-based biopesticides, which constitutes a contribution to the improvement of biological control agents’ performance.

Bioprospecting endophytic fungi for bioactive metabolites with seed germination promoting potentials

There is an urgent need for new bioactive molecules with unique mechanisms of action and chemistry to address the issue of incorrect use of chemical fertilizers and pesticides, which hurts both the environment and the health of humans. In light of this, research was done for this work to isolate, identify, and evaluate the germination-promoting potential of various plant species’ fungal endophytes. Zea mays L. (maize) seed germination was examined using spore suspension of 75 different endophytic strains that were identified. Three promising strains were identified through screening to possess the ability mentioned above. These strains Alternaria alternate, Aspergilus flavus, and Aspergillus terreus were isolated from the stem of Tecoma stans, Delonix regia, and Ricinus communis, respectively. The ability of the three endophytic fungal strains to produce siderophore and indole acetic acid (IAA) was also examined. Compared to both Aspergillus flavus as well as Aspergillus terreus, Alternaria alternata recorded the greatest rates of IAA, according to the data that was gathered. On CAS agar versus blue media, all three strains failed to produce siderophores. Moreover, the antioxidant and antifungal potentials of extracts from these fungi were tested against different plant pathogens. The obtained results indicated the antioxidant and antifungal activities of the three fungal strains. GC-Mass studies were carried out to determine the principal components in extracts of all three strains of fungi. The three strains’ fungus extracts included both well-known and previously unidentified bioactive compounds. These results may aid in the development of novel plant growth promoters by suggesting three different fungal strains as sources of compounds that may improve seed germination. According to the study that has been given, as unexplored sources of bioactive compounds, fungal endophytes have great potential.

A scoping review of the effects of mushroom and fungus extracts in rodent models of depression and tests of antidepressant activity.

One of the most important developments in psychopharmacology in the past decade has been the emergence of novel treatments for mood disorders, such as psilocybin for treatment-resistant depression. Psilocybin is most commonly found in different species of mushroom; however, the literature on mushroom and fungus extracts with potential antidepressant activity extends well beyond just psilocybin-containing mushrooms, and includes both psychedelic and non-psychedelic species. In the current review, we systematically review the preclinical literature on mushroom and fungus extracts, and their effects of animal models of depression and tests of antidepressant activity. The PICO structure, PRISMA checklist and the Cochrane Handbook for systematic reviews of intervention were used to guide the search strategy. A scoping search was conducted in electronic databases PubMed, CINAHL, Embase and Web of Science. The literature search identified 50 relevant and suitable published studies. These included 19 different species of mushrooms, as well as seven different species of other fungi. Nearly all studies reported antidepressant-like effects of treatment with extracts. Treatments were most commonly delivered orally, in both acute and chronically administered studies to predominantly male rodents. Multiple animal models of depression were used, the most common being unpredictable chronic mild stress, while the tail suspension test and forced swim test were most frequently used as standalone antidepressant screens. Details on each experiment with mushroom and fungus species are discussed in detail, while an evaluation is provided of the strengths and weaknesses of these studies.

Comparative Cytotoxicity Evaluation of Heat-Assisted vs Cold Water Extractions of Six Medicinal Fungi against Breast and Lung Cancer Cells.

Preparation of medicinal fungi for experimental purposes usually involves the extraction and determination of the quality and quantity of bioactive compounds prior to the biological experiment. Water, a common polar solvent, is usually used for traditional preparations for consumption. The application of high temperatures during water extraction can affect the chemical composition and functional properties of the extracts. Therefore, the aim of this study is to compare the differences in composition between extracts obtained with heat-assisted and cold water extractions of six selected species of fungi (Lignosus rhinocerus, Ophiocordyceps sinensis, Inonotus obliquus, Antrodia camphorata, Phellinus linteus and Monascus purpureus) and their cytotoxicity against human lung and breast cancer cells. The extracts obtained with heat-assisted and cold water extraction of six species of fungi were analysed to determine their protein, carbohydrate and phenolic contents. Their cytotoxicity was tested against lung (A549) and breast (MCF-7 and MDA-MB-231) cancer cell lines. The most potent extract was further separated into its protein and non-protein fractions to determine their respective cytotoxicity. The cytotoxicity of the different extracts obtained with heat-assisted and cold water extraction varied. Comparing the two extractions, the cold water extraction resulted in a significantly higher yield of proteins (except M. purpureus) and phenolic compounds (except A. camphorata), while the extracts of I. obliquus and M. purpureus obtained with heat-assisted extraction had a significantly higher carbohydrate mass fraction. Notably, the cold water extract of I. obliquus showed cytotoxicity (IC50=(701±35) µg/mL), which was one of the highest of the extracts tested against A549 cells. The cold water extract of I. obliquus was selected for further studies. Our results showed that cold water extracts generally have higher cytotoxicity against selected human cancer cell lines, with the exception of O. sinensis and A. camphorata extracts. This study reports the advantage of cold water extracts of fungi over those obtained with heat-assisted extraction in terms of cytotoxicity against human cancer cell lines and emphasises the role of extraction conditions, particularly heat, in influencing chemical composition and cytotoxic effects.

Antibacterial activity assay of marine fungal extract Aspergillus terreus (WB 1-2) against Escherichia coli cause of Colibacillosis disease

Antibacterial activity assay of marine fungal extract Aspergillus terreus (WB 1-2) against Escherichia coli cause of Colibacillosis disease

Recycling of printed Xerographic paper using Aspergillus assiutensis enzyme cocktail: an integrated approach to sustainable development.

To overcome the human and animal survivability risk, sustainable development is the only option on earth that can be achieved through the maximum use of renewable environmental resources. Recycling of waste paper is an emerging waste management approach to conserve natural resources. Herein, we studied enzyme-mediated process to recycle the xerographic paper by using the crude fungal extract from indigenously isolated fungi identified asAspergillus assiutensis. The fungal enzyme cocktail has been characterized for the production of multiple enzymes namely cellulase, amylase, xylanase, pectinase, and protease. All these enzymes have pH optima in the acidic range and except cellulase and all the enzymes are stable from 10 to 80C. In the zymogram analysis, pectinase, xylanase, amylase, and cellulase were detected at 68kDa, ~ 54kDa, 38kDa, and 30kDa, respectively. Also, the presence of protease was confirmed by the clear zone at 68, 31, and 16kDa. A 26% decrease in the kappa number and reduction in Hex A of the pulp was observed on the treatment of the pulp with enzyme as compared to the control pulp without any treatment. The physical and chemical properties of the pulp were also improved by enzyme-mediated pulping as compared to the control The physiochemical parameter of the effluent like TDS was reduced (397ppm) significantly in comparison to chemical deinking process and it was within the permissible limit. BOD and alkalinity were reduced when the enzymes and chemical dosage were used in combination. These results indicate that chemi-enzymatic deinking is most promising to reduce or remove the pollution parameters including ink and this approach can be used in the paper and pulp industry for sustainable development.

Withanolides production by the endophytic fungus Penicillium oxalicum associated with Withania somnifera (L.) Dunal.

Withanolides are steroidal lactones with diverse bioactive potential and their production from plant sources varies with genotype, age, culture conditions, and geographical region. Endophytic fungi serve as an alternative source to produce withanolides, like their host plant, Withania somnifera (L.) Dunal. The present study aimed to isolate endophytic fungi capable of producing withanolides, characterization and investigation of biological activities of these molecules. The methanolic fungal crude extract of one of the fungal isolates WSE16 showed maximum withanolide production (219mg/L). The fungal isolate WSE16 was identified as Penicillium oxalicum based on its morphological and internal transcribed spacer (ITS) sequence analysis and submitted in NCBI (accession number OR888725). The methanolic crude extract of P. oxalicum was further purified by column chromatography, and collected fractions were assessed for the presence of withanolides. Fractions F3 and F4 showed a higher content of withanolides (51.8 and 59.1mg/L, respectively) than other fractions. Fractions F3 and F4 exhibited antibacterial activity against Staphylococcus aureus with an IC50 of 23.52 and 17.39µg/ml, respectively. These fractions also showed antioxidant activity (DPPH assay with IC50 of 39.42 and 38.71µg/ml, superoxide anion scavenging assay with IC50 of 41.10 and 38.84µg/ml, and reducing power assay with IC50 of 42.61 and 41.40µg/ml, respectively) and acetylcholinesterase inhibitory activity (IC50 of 30.34 and 22.05µg/ml, respectively). The withanolides present in fraction 3 and fraction 4 were identified as (20S, 22R)-1a-Acetoxy-27-hydroxywitha-5, 24-dienolide-3b-(O-b-D-glucopyranoside) and withanamide A, respectively, using UV, FTIR, HRMS, and NMR analysis. These results suggest that P. oxalicum, an endophytic fungus isolated from W. somnifera, is a potential source for producing bioactive withanolides.

In vitro Biomedical Application of Endophytic Aspergillus melleus Isolated from Leaves of Premna serratifolia L.

Some microorganisms known as endophytes live in symbiotic relationships in the living tissues of plants without posing a health risk. As a result, they synthesize many metabolites which are helpful for the plants in many ways. So, these metabolites are known to exhibit many biological properties like antioxidant, antidiabetic anti-inflammatory, etc. Currently, many drugs are used to control inflammatory diseases like arthritis and, irritable bowel disease; however, they pose a lot of side effects. The present study was taken up to explore the anti-inflammatory properties along with the phytochemicals present, its quantification, and other in vitro biological activities of the less reported Aspergillus melleus, an endophytic fungus, isolated from Premna serratifolia L., a medicinal plant. The results of the investigation demonstrated the presence of alkaloids, phenols, terpenoids, flavonoids, tannins, cardiac glycosides and amino acids in the methanolic extract of endophytic fungus. It yielded 25.28 µg GAE/g and 19.465 µg GAE/g of total phenolic and flavonoid content, respectively. The results of anti-inflammatory activity showed 84.69+0.82% protein inhibition by BSA and also showed IC50 values of 68.53 µg/mL and 43.34 µg/mL for COX1 and COX 2, respectively. It exhibited 63.91+0.08% of radical scavenging activity by DPPH. The IC50 values of 181.41 µg/mL and 190.62 µg/mL were found for the in vitro antidiabetic activity. This study shows that the endophytic fungus A. melleus has exhibited considerably good results with respect to its in vitro biological activities. Yet, there is a scope for future researchers to isolate the bioactive metabolites to explore for future needs.

Screening and Genomic Analysis of Alkaloid-Producing Endophytic Fungus Fusarium solani Strain MC503 from Macleaya cordata.

The extensive harvesting of Macleaya cordata, as a biomedicinal plant and a wild source of quaternary benzo[c]phenanthridine alkaloids, has led to a rapid decline in its population. An alternative approach to the production of these bioactive compounds, which are known for their diverse pharmacological effects, is needed. Production of these compounds using alkaloid-producing endophytic fungi is a promising potential approach. In this research, we isolated an alkaloid-producing endophytic fungus, strain MC503, from the roots of Macleaya cordata. Genomic analysis was conducted to elucidate its metabolic pathways and identify the potential genes responsible for alkaloid biosynthesis. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses revealed the presence and quantified the content of sanguinarine (536.87 μg/L) and chelerythrine (393.31 μg/L) in the fungal fermentation extract. Based on our analysis of the morphological and micromorphological characteristics and the ITS region of the nuclear ribosomal DNA of the alkaloid-producing endophyte, it was identified as Fusarium solani strain MC503. To the best of our knowledge, there is no existing report on Fusarium solani from Macleaya cordata or other medicinal plants that produce sanguinarine and chelerythrine simultaneously. These findings provide valuable insights into the capability of Fusarium solani to carry out isoquinoline alkaloid biosynthesis and lay the foundation for further exploration of its potential applications in pharmaceuticals.

Green synthesis and characterization of silver anchored ZnO nanoparticle as the antimicrobial reinforcement for polylactide films

AbstractThe aqueous extract of endophytic fungi (Periconia sp.) was effectively used as a reducing agent to anchor Ag nanoparticles on the ZnO surface. The XRD, UV‐Vis, SEM‐EDX and TEM analyses were performed to ensure the formation of AgNP@ZnO architecture. TEM analysis confirmed that the 4–20 nm sized Ag nanoparticles were anchored evenly on the surface of ZnO with 16–78 nm in size. The antimicrobial study showed the superior performance of AgNP@ZnO functional nanoparticles than the pristine ZnO against pathogenic bacteria Staphylococcus aureus (gram‐positive) and Escherichia coli (gram‐negative). Hence, AgNP@ZnO functional particles were effectively explored as antimicrobial reinforcement for fabricating composite films using polylactic acid (PLA) as a matrix. The obtained nanocomposite films showed excellent antibacterial activity, which increases with increasing AgNP@ZnO loading.

Bioprospecting Antibacterial Properties of Fungi Isolated from Kakinada Sea Coast and Eucalyptus Foliage

Background: Fungi produce a wide range of secondary metabolites with bactericidal or bacteriostatic properties. In search of novel antibacterial compounds recently, many fungi of marine and plant origin have been studied for their antimicrobial properties. Aims: This work aimed to study bio-prospect marine and endophytic fungi for their antibacterial properties. objective: To determine the antibacterial properties of ethyl acetate extracts of fungal isolates. Methods: Intensive microbiological methods were followed for isolation, differential growth, and qualitative screening of enzyme production. The isolates were characterised and identified based on morpho-taxonomy, 18S rRNA gene sequencing, and phylogenetic analysis of the tar-get genes. The antimicrobial activity of fungal ethyl acetate extracts against S. aureus, B. sub-tilis, and E. coli was evaluated using a well-diffusion method, and MIC was determined by the microdilution method. Cell lysis was observed through Transmission Electron Microscopy. Results: A BLAST search of 18S rRNA gene sequences of the marine isolates GSBT S13 and GSBT S14 showed 99.3 % sequence similarity with A. glaucus for both isolates and that of endophyte GSBT E3 showed 99.7 % sequence similarity with B. pinkertoniae. Cellulase pro-duction was comparatively higher in GSBT E3 and lipase from GSBT S13 and GSBT S14. Ethyl acetate extracts of GSBT S14 and GSBT E3 showed a clear zone of inhibition by the well-diffusion method, further confirmed by electron microscopy. HR-TEM showed that the ethyl acetate extracts of the isolates appeared to damage the cell membrane, leading to cell shrinkage and death in E. coli and S. aureus. Conclusion: GSBT S13 and GSBT S14 exhibited extracellular amylase, cellulase, and lipase activities. Ethyl acetate extracts of both GSBT S14 and B. pinkertoniae GSBT E3 showed better antibacterial properties against S. aureus.

Graphiumisides A-D, Monoterpene Glycosides from an Animal-Derived Endophytic Fungus Graphium sp. GD-11.

Four new monoterpene rhamnosides, graphiumisides A-D (1-4), along with four known steroid compounds (5-8) were isolated from the fermentation extract of animal-derived endophytic fungus, Graphium sp. GD-11. The chemical structures of all compounds were elucidated using 1D and 2D NMR, HRESIMS spectroscopic analyses, and other spectroscopic methods. Compounds 1-4 exhibit a distinctive structure connected by one p-menthane type monoterpene and one L-rhamnose. This is the first report of monoterpene glycosides from Graphium sp. All compounds (1-8) were tested for cytotoxic activities against four cancer cell lines (HepG2, SMMC7721, SW480, and A549), and only compound 1 showed weak anti-tumor activity against SMMC7721 cells.

Using molecular fine structure to identify optimal methods of extracting fungal glycogen

Glycogen is a highly branched glucose polymer that is an energy storage material in fungi and animals. Extraction of glycogen from its source in a way that minimizes its molecular degradation is essential to investigate its native structure. In this study, the following extraction methods were compared: sucrose gradient density ultracentrifugation, thermal alkali, hot alcohol and hot water extractions. Molecular-size and chain-length distributions of glycogen were measured by size-exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis, respectively. These two fine-structure features are the most likely structural characteristics to be degraded during extraction. The results show that the thermal alkali, hot alcohol and hot water extractions degrade glycogen molecular size and/or chain-length distributions, and that sucrose gradient density ultracentrifugation with neither high temperature nor alkaline treatment is the most suitable method for fungal glycogen extraction.

Unveiling the Multifaceted Capabilities of Endophytic Aspergillus flavus Isolated from Annona squamosa Fruit Peels against Staphylococcus Isolates and HCoV 229E-In Vitro and In Silico Investigations.

Recently, there has been a surge towards searching for primitive treatment strategies to discover novel therapeutic approaches against multi-drug-resistant pathogens. Endophytes are considered unexplored yet perpetual sources of several secondary metabolites with therapeutic significance. This study aims to isolate and identify the endophytic fungi from Annona squamosa L. fruit peels using morphological, microscopical, and transcribed spacer (ITS-rDNA) sequence analysis; extract the fungus's secondary metabolites by ethyl acetate; investigate the chemical profile using UPLC/MS; and evaluate the potential antibacterial, antibiofilm, and antiviral activities. An endophytic fungus was isolated and identified as Aspergillus flavus L. from the fruit peels. The UPLC/MS revealed seven compounds with various chemical classes. The antimicrobial activity of the fungal ethyl acetate extract (FEA) was investigated against different Gram-positive and Gram-negative standard strains, in addition to resistant clinical isolates using the agar diffusion method. The CPE-inhibition assay was used to identify the potential antiviral activity of the crude fungal extract against low pathogenic human coronavirus (HCoV 229E). Selective Gram-positive antibacterial and antibiofilm activities were evident, demonstrating pronounced efficacy against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). However, the extract exhibited very weak activity against Gram-negative bacterial strains. The ethyl acetate extract of Aspergillus flavus L exhibited an interesting antiviral activity with a half maximal inhibitory concentration (IC50) value of 27.2 µg/mL against HCoV 229E. Furthermore, in silico virtual molecular docking-coupled dynamics simulation highlighted the promising affinity of the identified metabolite, orienting towards three MRSA biotargets and HCoV 229E main protease as compared to reported reference inhibitors/substrates. Finally, ADME analysis was conducted to evaluate the potential oral bioavailability of the identified metabolites.

Characterization of melanin from Exophiala mesophila with the prospect of potential biotechnological applications.

Fungal melanin is an underexplored natural biomaterial of great biotechnological interest in different areas. This study investigated the physical, chemical, electrochemical, and metal-binding properties of melanin extracted from the metallotolerant black fungus Exophiala mesophila strain IRTA-M2-F10. Specific inhibitory studies with tricyclazole and biochemical profiling of whole cells by synchrotron radiation-based Fourier-transform infrared spectral microscopy (SR-FTIRM) were performed. An optimized extraction protocol was implemented, and purified fungal melanin was characterized using an array of spectrophotometric techniques (UV-Vis, FTIR, and EPR) and by cyclic voltammetry (CV) experiments. The metal-binding capacity of melanin extracts was also assessed by using Cr(VI) as a model heavy metal. Inhibitory studies indicated that 1,8-dihydroxynaphthalene may be the main precursor molecule of E. mesophila melanin (DHN-melanin). The biochemical characterization of fungal melanin extracts were benchmarked against those from two melanins comprising the precursor molecule L-3,4-dihydroxiphenylalanine (DOPA-melanin): extracts from the ink of the cephalopod Sepia officinalis and DOPA-melanin synthesized in the laboratory. The CV results of melanin extracts incubated with and without cell suspensions of the electroconductive bacterium Geobacter sulfurreducens were indicative of novel semiquinone/hydroquinone redox transformations specific for each melanin type. These interactions may play an important role in cation exchange for the adsorption of metals and in microbial interspecies electron transfer processes. The obtained results provided further evidence for the DHN-nature of E. mesophila melanin. The FTIR profiling of melanin extracts exposed to Cr(VI), compared to unexposed melanin, resulted in useful information on the distinct surface-binding properties of fungal melanin. The parameters of the Langmuir and Freundlicht isotherms for the adsorption of Cr(VI) were determined and compared to bibliographic data. Altogether, the inherent properties of fungal melanin suggest its promising potential as a biomaterial for environmental applications.