Phenolic compounds and bioactive extract produced by endophytic fungus Coriolopsis rigida

Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms

The proliferation of harmful cyanobacterial blooms dominated by Microcystis aeruginosa has become an increasingly serious problem in freshwater ecosystems due to climate change and eutrophication. Microcystis-blooms in freshwater generate compounds with unpleasant odors, reduce the levels of dissolved O2, and excrete microcystins into aquatic ecosystems, potentially harming various organisms, including humans. Various chemical and biological approaches have thus been developed to mitigate the impact of the blooms, though issues such as secondary pollution and high economic costs have not been adequately addressed. Red clays and H2O2 are conventional treatment methods that have been employed worldwide for the mitigation of the blooms, while novel approaches, such as the use of plant or microbial metabolites and antagonistic bacteria, have also recently been proposed. Many of these methods rely on the generation of reactive oxygen species, the inhibition of photosynthesis, and/or the disruption of cellular membranes as their mechanisms of action, which may also negatively impact other freshwater microbiota. Nevertheless, the underlying molecular mechanisms of anticyanobacterial chemicals and antagonistic bacteria remain unclear. This review thus discusses both conventional and innovative approaches for the management of M. aeruginosa in freshwater bodies.

Isolation and Identification of Pigment-Producing Endophytic Fungi from the Amazonian Species Fridericia chica

Pigments of fungal origin have aroused increasing interest in the food dye and cosmetic industries since the global demand for natural dyes has grown. Endophytic microorganisms are a source of bioactive compounds, and Amazonian plant species can harbor fungi with a wide range of biotechnological applications. Popularly known in Brazil as crajiru, Fridericia chica is a medicinal plant that produces a red pigment. In this study, a total of 121 fungi were isolated in potato dextrose agar from three plants. We identified nine pigment-producing endophytic fungi isolated from branches and leaves of F. chica. The isolates that showed pigment production in solid media were molecularly identified via multilocus analysis as Aspergillus welwitschiae, A. sydowii, Curvularia sp., Diaporthe cerradensis (two strains), Hypoxylon investiens, Neoscytalidium sp. (two strains) and Penicillium rubens. These isolates were subjected to submerged fermentation in two culture media to obtain metabolic extracts. The extracts obtained were analyzed in terms of their absorbance between 400 and 700 nm. The pigmented extract produced by H. investiens in medium containing yeast extract showed maximum absorbance in the red absorption range (UA700 = 0.550) and significant antioxidant and antimicrobial activity. This isolate can thus be considered a new source of extracellular pigment.

Fungi-derived natural antioxidants

In humans, exogenous antioxidants aid the endogenous antioxidant system to detoxify excess ROS generated during oxidative stress, thereby protecting the body against various diseases and stressful conditions. The majority of natural antioxidants available on the consumer market are plant-based; however, fungi are being recognized as alternative sources of various natural antioxidants such as polysaccharides, pigments, peptides, sterols, phenolics, alkaloids, and flavonoids. In addition, some exogenous antioxidants are exclusively found in fungi. Fungi-derived antioxidants exhibit scavenging activities against DPPH, ABTS, hydroxyl, superoxide, hydrogen peroxide, and nitric oxide radicals in vitro. Furthermore, in vivo models, application of fungal-derived antioxidants increase the level of various antioxidant enzymes, such as catalases, superoxide dismutases, and glutathione peroxidases, and reduce the level of malondialdehyde. Therefore, fungi-derived antioxidants have potential to be used in the food, cosmetic, and pharmaceutical industries. This review summarizes the antioxidant potential of different fungi (mushrooms, yeasts, and molds)-derived natural compounds such as polysaccharides, pigments, peptides, ergothioneine, ergosterol, phenolics, alkaloids, etc.

Anti-Staphylococcal, Anti-Candida, and Free-Radical Scavenging Potential of Soil Fungal Metabolites: A Study Supported by Phenolic Characterization and Molecular Docking Analysis

Staphylococcus and Candida are recognized as causative agents in numerous diseases, and the rise of multidrug-resistant strains emphasizes the need to explore natural sources, such as fungi, for effective antimicrobial agents. This study aims to assess the in vitro anti-staphylococcal and anti-candidal potential of ethyl acetate extracts from various soil-derived fungal isolates. The investigation includes isolating and identifying fungal strains as well as determining their antioxidative activities, characterizing their phenolic substances through HPLC analysis, and conducting in silico molecular docking assessments of the phenolics' binding affinities to the target proteins, Staphylococcus aureus tyrosyl-tRNA synthetase and Candida albicans secreted aspartic protease 2. Out of nine fungal species tested, two highly potent isolates were identified through ITS ribosomal gene sequencing: Aspergillus terreus AUMC 15447 and A. nidulans AUMC 15444. Results indicated that A. terreus AUMC 15447 and A. nidulans AUMC 15444 extracts effectively inhibited S. aureus (concentration range: 25-0.39 mg/mL), with the A. nidulans AUMC 15444 extract demonstrating significant suppression of Candida spp. (concentration range: 3.125-0.39 mg/mL). The A. terreus AUMC 15447 extract exhibited an IC50 of 0.47 mg/mL toward DPPH radical-scavenging activity. HPLC analysis of the fungal extracts, employing 18 standards, revealed varying degrees of detected phenolics in terms of their presence and quantities. Docking investigations highlighted rutin as a potent inhibitor, showing high affinity (-16.43 kcal/mol and -12.35 kcal/mol) for S. aureus tyrosyl-tRNA synthetase and C. albicans secreted aspartic protease 2, respectively. The findings suggest that fungal metabolites, particularly phenolics, hold significant promise for the development of safe medications to combat pathogenic infections.

Two new furanone derivatives from the endophytic fungus Byssochlamys sp. and their cytotoxic activities

Two new furanone derivatives, byssochlanones A-B (1-2) were purified from the endophytic fungus Byssochlamys sp. isolated from the wetland plant, Phragmites australis. Their structures were elucidated on the basis of extensive spectroscopic analyses. Compounds 1-2 represented typical furanone analogues which are not common in natural products. The absolute configuration of compounds 1-2 were identified through quantum-chemical electronic circular dichroism (ECD) calculation compared with their experimental CD. In addition, compounds 1-2 were tested for their cytotoxic activities against HCT-8 and Hela cancer cell lines, and compound 2 showed moderate activity against HCT-8 cells with IC50 value of 21.3 μM.