Cyclic heptapeptides from the soil-derived fungus Clonostachys rosea

Asperphenalenones Isolated from the Biocontrol Agent Clonostachys rosea and Their Antimicrobial Activities

Clonostachys rosea is a fungus widely distributed on Earth and has a high capacity to adapt to complex environments in soil, plants, or sea. It is an endophyte that can be used as a potential biocontrol agent to protect plants from pathogenic fungi, nematodes, and insects. However, the spectrum of secondary metabolites produced by C. rosea has only scarcely been studied. In the present study, eight new phenalenones, asperphenalenones F-M (1-8), together with two known derivatives, asperphenalenones E and B (9 and 10), were isolated from the axenic rice culture of this fungus. The structures of the new compounds were elucidated by nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism, and gas chromatography-mass spectrometry analyses. Asperphenalenones J-M (5-8) are unusual phenalenone adducts that are conjugated to diterpenoid glycosides. Asperphenalenones F and H showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus, with minimal inhibitory concentrations of 12.5 and 25 μM, respectively. Asperphenalenone B exhibited low antiviral activity against the human immunodeficiency virus replication. Furthermore, asperphenalenones F and H exhibited low cytotoxicity against Jurkat cells, while all other compounds were devoid of cytotoxicity.

Shifting archetype to nature's hidden gems: from sources, purification to uncover the nutritional potential of bioactive peptides

Contemporary scientific findings revealed that our daily food stuffs are enriched by encrypted bioactive peptides (BPs), evolved by peptide linkage of amino acids or encrypted from the native protein structures. Remarkable to these BPs lies in their potential health benefiting biological activities to serve as nutraceuticals or a lead addition to the development of functional foods. The biological activities of BPs vary depending on the sequence as well as amino acid composition. Existing database records approximately 3000 peptide sequences which possess potential biological activities such as antioxidants, antihypertensive, antithrombotic, anti-adipogenics, anti-microbials, anti-inflammatory, and anti-cancerous. The growing evidences suggest that BPs have very low toxicity, higher accuracy, less tissue accretion, and are easily degraded in the disposed environment. BPs are nowadays evolved as biologically active molecules with potential scope to reduce microbial contamination as well as ward off oxidation of foods, amend diverse range of human diseases to enhance the overall quality of human life. Against the clinical and health perspectives of BPs, this review aimed to elaborate current evolution of nutritional potential of BPs, studies pertaining to overcome limitations with respect to special focus on emerging extraction, protection and delivery tools of BPs. In addition, the nano-delivery mechanism of BP and its clinical significance is detailed. The aim of current review is to augment the research in the field of BPs production, identification, characterisation and to speed up the investigation of the incredible potentials of BPs as potential nutritional and functional food ingredient.

Exploration of Verticillins in High-Grade Serous Ovarian Cancer and Evaluation of Multiple Formulations in Preclinical In Vitro and In Vivo Models

Verticillins are epipolythiodioxopiperazine alkaloids isolated from a fungus with nanomolar anti-tumor activity in high-grade serous ovarian cancer (HGSOC). HGSOC is the fifth leading cause of death in women, and natural products continue to be an inspiration for new drug entities to help tackle chemoresistance. Verticillin D was recently found in a new fungal strain and compared to verticillin A. Both compounds exhibited nanomolar cytotoxic activity against OVCAR4 and OVCAR8 HGSOC cell lines, significantly reduced 2D foci and 3D spheroids, and induced apoptosis. In addition, verticillin A and verticillin D reduced tumor burden in vivo using OVCAR8 xenografts in the peritoneal space as a model. Unfortunately, mice treated with verticillin D displayed signs of liver toxicity. Tolerability studies to optimize verticillin A formulation for in vivo delivery were performed and compared to a semi-synthetic succinate version of verticillin A to monitor bioavailability in athymic nude females. Formulation of verticillins achieved tolerable drug delivery. Thus, formulation studies are effective at improving tolerability and demonstrating efficacy for verticillins.

Antimicrobial Potential of Metabolites in Fungal Strains Isolated from a Polluted Stream: Annulohypoxylon stygium WL1B5 Produces Metabolites against Extended-Spectrum Beta-Lactamase-Positive Escherichia coli

The emergence of multidrug resistance in bacterial pathogens is a growing public health concern requiring solutions including the discovery of new antimicrobial drugs. Fungi have been used for decades as a source of antimicrobials. Ongoing screenings for newly characterized fungal strains producing antimicrobials include environments that are difficult to access like the deep sea, glaciers, wastewaters and environments polluted due to human activity. In the present study, fungal microorganisms were isolated from water samples taken from a polluted stream in the city of Manaus, AM, Brazil, and screened for antimicrobial effects against Escherichia coli. Using extracts from five isolates (Annulohypoxylon stygium WL1B5, Colletotrichum fructicola WL3B9, Clonostachys rosea WL5B18, Clonostachys rosea WL8B28 and Trichoderma harzianum WL9B49), antimicrobial activity against the reference strains Escherichia coli ATCC 25922 as well as E. coli NCTC 13353, an extended-spectrum beta-lactamase-positive strain, was observed. Inhibition zones ranged from 1 to 35.9 mm and a minimum inhibitory concentration of 400 µg/mL could be demonstrated. Assessments of the metabolites of Annulohypoxylon stygium WL1B5 allowed us to identify nodulisporone and daidzein, which have already been associated with antimicrobial activity. The findings confirm the feasibility of isolating fungal strains from polluted sites producing metabolites that can serve as potential future alternatives for the treatment of multidrug-resistant bacteria.

The Novel Compounds with Biological Activity Derived from Soil Fungi in the Past Decade

The secondary metabolites isolated from soil fungi have received more and more attention, especially new compounds that exhibited good biological activities. In this review, a total of 546 new compounds are included in the relevant literature since 2011. The new compounds are isolated from soil fungi, We divided these compounds into seven categories, including alkaloids, terpenoids, steroids, ketones, phenylpropanoids, quinones, esters, lactones, etc. In addition, the biological activities and structure-activity relationships of these compounds have also been fully discussed. The activities of these compounds are roughly divided into eight categories, including anticancer activity, antimicrobial activity, anti-inflammatory activity, antioxidant activity, antiviral activity, antimalarial activity, immunosuppressive activity and other activities. Since natural products are an important source of new drugs, this review may have a positive guiding effect on drug screening.

NS3 helicase inhibitory potential of the marine sponge Spongia irregularis

In the current study, an investigation of the activity of the total extract of the marine sponge Spongia irregularis and its different fractions against the hepatitis C virus (HCV) was pursued. The results revealed that the ethyl acetate fraction exhibited the highest anti-HCV activity, with an IC50 value of 12.6 ± 0.05 μg ml-1. Chromatographic resolution of the ethyl acetate fraction resulted in the isolation of four known compounds, 1,3,7-trimethylguanine (1), 3,5-dihydroxyfuran-2(5H)-one (2), thymidine (3), and 1H-indazole (4). By using LC-HR-ESI-MS metabolic profiling, compounds 5-14 were also identified in the same fraction. Molecular docking calculations revealed the high binding affinity of compound 14 against the allosteric pocket of HCV NS3-NS4A and the active site of HCV NS3 helicase (-10.1 and -7.4 kcal mol-1, respectively). Molecular dynamics simulations, followed by molecular mechanics-generalized Born surface area energy calculations, demonstrated the structural and energetic stability of compound 14 in complex with HCV targets.

An Updated Review on the Secondary Metabolites and Biological Activities of Aspergillus ruber and Aspergillus flavus and Exploring the Cytotoxic Potential of Their Isolated Compounds Using Virtual Screening

The secondary metabolites and biological activities of Aspergillus ruber and Aspergillus flavus were comprehensively reported. About 70 compounds were isolated from both species that belong to different classes using conventional and advanced chromatographic techniques and unambiguously elucidated employing one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) and high resolution mass spectrometry (HRMS). Some of them displayed promising antiviral, anti-inflammatory, and antioxidant activities. In silico studies were conducted on human cyclin-dependent kinase 2 (CDK-2), human DNA topoisomerase II (TOP-2), and matrix metalloprotinase 13 (MMP-13) in an effort to explore the cytotoxic potential of the diverse compounds obtained from both Aspergillus species. 1,6,8-Trihydroxy-4-benzoyloxy-3-methylanthraquinone (23) revealed the most firm fitting with the active pockets of CDK-2 and MMP-13; meanwhile, variecolorin H alkaloid (14) showed the highest fitting within TOP-2 with ∆G equals to −36.51 kcal/mole. Thus, fungal metabolites could offer new drug entities for combating cancer. Relevant data about both Aspergillus species up to August 2020 were gathered from various databases comprising Scifinder (https://scifinder.cas.org/scifinder/login) for secondary metabolite-related studies; meanwhile, for biology-related articles, data were collected from both PubMed (http://www.ncbi.nlm.nih.gov/pubmed/) and Web of Knowledge (http://www.webofknowledge.com) as well.

Metabolites from Clonostachys Fungi and Their Biological Activities

Clonostachys (teleomorph: Bionectria) fungi are well known to produce a variety of secondary metabolites with various biological activities to show their pharmaceutical and agrochemical applications. Up to now, at least 229 secondary metabolites, mainly including 84 nitrogen-containing metabolites, 85 polyketides, 40 terpenoids, and 20 other metabolites, have been reported. Many of these compounds exhibit biological activities, such as cytotoxic, antimicrobial, antileishmanial, antimalarial activities. This mini-review aims to summarize the diversity of the secondary metabolites as well as their occurrences in Clonostachys fungi and biological activities.

Review of Natural Compounds for the Management and Prevention of Lymphoma

Lymphoma is a type of blood cancer that can be categorized into two types-Hodgkin lymphoma (HL) and Non-Hodgkin lymphoma (NHL). A total of 509,590 and 79,990 cases of NHL and HL were newly diagnosed in 2018, respectively. Although conventional therapy has stridden forward over recent decades, its adverse effects are still a hurdle to be solved. Thus, to help researchers develop better lymphoma treatment, this study aims to review the systematic anticancer data for natural products and their compounds. A variety of natural products showed anticancerous effects on lymphoma by regulation of intracellular mechanisms including apoptosis as well as cell cycle arrest. As these results shed light on the potential to substitute conventional therapy with natural products, it may become a promising strategy for lymphoma treatment in the near future.

A Comprehensive Review of Bioactive Peptides from Marine Fungi and Their Biological Significance

Fungal marine microorganisms are a valuable source of bioactive natural products. Fungal secondary metabolites mainly comprise alkaloids, terpenoids, peptides, polyketides, steroids, and lactones. Proteins and peptides from marine fungi show minimal human toxicity and less adverse effects comparable to synthetic drugs. This review summarizes the chemistry and the biological activities of peptides that were isolated and structurally elucidated from marine fungi. Relevant fungal genera including Acremonium, Ascotricha, Aspergillus, Asteromyces, Ceratodictyon, Clonostachys, Emericella, Exserohilum, Microsporum, Metarrhizium, Penicillium, Scytalidium, Simplicillium, Stachylidium, Talaromyces, Trichoderma, as well as Zygosporium were extensively reviewed. About 131 peptides were reported from these 17 genera and their structures were unambiguously determined using 1D and 2D NMR (one and two dimensional nuclear magnetic resonance) techniques in addition to HRMS (high resolution mass spectrometry). Marfey and Mosher reactions were used to confirm the identity of these compounds. About 53% of the isolated peptides exhibited cytotoxic, antimicrobial, and antiviral activity, meanwhile, few of them showed antidiabetic, lipid lowering, and anti-inflammatory activity. However 47% of the isolated peptides showed no activity with respect to the examined biological activity and thus required further in depth biological assessment. In conclusion, when searching for bioactive natural products, it is worth exploring more peptides of fungal origin and assessing their biological activities.