Antimicrobial activity of invertebrate-pathogenic fungi in the genera Akanthomyces and Gibellula

Study on species diversity of Akanthomyces (Cordycipitaceae, Hypocreales) in the Jinyun Mountains, Chongqing, China

Akanthomyces species have only been reported from Guizhou and Qinghai Province, with few reports from other regions in China. In this research, the species diversity of Akanthomyces in the Jinyun Mountains, Chongqing was investigated. Fourteen infected spider specimens were collected and two new species (A.bashanensis and A.beibeiensis) and a known species (A.tiankengensis) were established and described according to a multi-locus phylogenetic analysis and the morphological characteristics. Our results reveal abundant Akanthomyces specimens and three species were found at Jinyun Mountain. Due to its being an important kind of entomopathogenic fungi, further attention needs to be paid to the diversity of other entomopathogenic fungi in Chongqing, China.

Microbial Natural Products with Antiviral Activities, Including Anti-SARS-CoV-2: A Review

The SARS-CoV-2 virus, which caused the COVID-19 infection, was discovered two and a half years ago. It caused a global pandemic, resulting in millions of deaths and substantial damage to the worldwide economy. Currently, only a few vaccines and antiviral drugs are available to combat SARS-CoV-2. However, there has been an increase in virus-related research, including exploring new drugs and their repurposing. Since discovering penicillin, natural products, particularly those derived from microbes, have been viewed as an abundant source of lead compounds for drug discovery. These compounds treat bacterial, fungal, parasitic, and viral infections. This review incorporates evidence from the available research publications on isolated and identified natural products derived from microbes with anti-hepatitis, anti-herpes simplex, anti-HIV, anti-influenza, anti-respiratory syncytial virus, and anti-SARS-CoV-2 properties. About 131 compounds with in vitro antiviral activity and 1 compound with both in vitro and in vivo activity have been isolated from microorganisms, and the mechanism of action for some of these compounds has been described. Recent reports have shown that natural products produced by the microbes, such as aurasperone A, neochinulin A and B, and aspulvinone D, M, and R, have potent in vitro anti-SARS-CoV-2 activity, targeting the main protease (M^pro). In the near and distant future, these molecules could be used to develop antiviral drugs for treating infections and preventing the spread of disease.

Morphological and molecular analyses reveal two new species of Gibellula (Cordycipitaceae, Hypocreales) from China

Gibellulapenicillioides sp. nov. and G.longispora sp. nov., two new species parasitising spiders collected in China, are illustrated and described, based on morphological features and multiloci phylogenetic analysis. The G.penicillioides sp. nov. group is sister to the G.scorpioides group, but form long penicilloid conidiophore producing enlarged fusiform conidia ((7-) 7.5-9 (-10) × 2.5-3.5 μm). G.longispora sp. nov. is sister to G.pigmentosinum, but has slender long conidia (5-7 × 1-2 μm); teleomorph and Granulomanus-synanamorphic conidiogenous cells are absent in these two species. Type specimens of G.penicillioides sp. nov. and G.longispora sp. nov. were deposited in the Anhui Agricultural University (RCEF). In addition, a key to all known species of Gibellula is illustrated.

Phylogeny- and morphology-based recognition of new species in the spider-parasitic genus Gibellula (Hypocreales, Cordycipitaceae) from Thailand

Thailand is known to be a part of what is called the Indo-Burma biodiversity hotspot, hosting a vast array of organisms across its diverse ecosystems. This is reflected by the increasing number of new species described over time, especially fungi. However, a very few fungal species from the specialized spider-parasitic genus Gibellula have ever been reported from this region. A survey of invertebrate-pathogenic fungi in Thailand over several decades has led to the discovery of a number of fungal specimens with affinities to this genus. Integration of morphological traits into multi-locus phylogenetic analysis uncovered four new species: G.cebrennini, G.fusiformispora, G.pigmentosinum, and G.scorpioides. All these appear to be exclusively linked with torrubiella-like sexual morphs with the presence of granulomanus-like asexual morph in G.pigmentosinum and G.cebrennini. A remarkably high host specificity of these new species towards their spider hosts was revealed, and for the first time, evidence is presented for manipulation of host behavior in G.scorpioides.

Akanthopyrones A-D, α-Pyrones Bearing a 4-O-Methyl-β-d-glucopyranose Moiety from the Spider-Associated Ascomycete Akanthomyces novoguineensis

Hypocrealean fungi have proved to be prolific bioactive metabolite producers; they have caught the attention of mycologists throughout the world. However, only a few studies on the insect and spider parasitic genus Akanthomyces have so far been carried out. In this study, we report the isolation, structural elucidation and biological activities of four unprecedented glycosylated α-pyrone derivatives, akanthopyrones A–D (1–4), from a culture of Akanthomyces novoguineensis collected in Thailand. The chemical structures of the akanthopyrones were determined by extensive 1D- and 2D-NMR, and HRMS spectroscopic analysis. Their absolute configurations were determined. Akanthopyrone A (1) exhibited weak antimicrobial activity against Bacillus subtilis DSM10 and cytotoxicity against the HeLa cell line KB-3-1, while akanthopyrone D (4) showed weak activity against Candida tenuis MUCL 29892.

Extraction, identification and antimicrobial activity of a new furanone, grifolaone A, from Grifola frondosa

A furanone (1), (S)-methyl 2-(2-hydroxy-3,4-dimethyl-5-oxo-2,5-dihydrofuran-2-yl)acetate, was isolated from the edible mushroom Grifola frondosa. Mass spectrometry and NMR analyses were used to elucidate the structure of this compound, and its absolute configuration was determined using circular dichroism spectroscopy. Compound 1 exhibited specific antifungal activity against the plant pathogens, Fusarium oxysporum, Gibberella zeae and Piricularia oryzae and the opportunistic human pathogen, Pseudallescheria boydii, resulting in minimum inhibitory concentration values of 2.5, 2.5, 1.25 and 0.15 μg/mL, respectively. In contrast, the furanone showed only weak activity towards Aspergillus spp., Candida albicans and several other fungal strains tested as well as no appreciable antibacterial activity.

Isolation and structural elucidation of novel antimicrobial compounds from maggots of Chrysomyis megacephala Fabricius

The excretions/secretions from the maggot of Chrysomyis megacephala Fabricius are traditionally used to treat serious infections in China. In this study, bioassay-guided fractionation led to the isolation of three novel antibacterial compounds (1-3), including important fluorinated compounds (3 and 5), together with other nine known compounds from 70% methanol extract of C. megacephala. The structures of the new compounds were elucidated by NMR spectroscopic analysis and high-resolution mass spectroscopy. The antibacterial activities of the isolated compounds were evaluated using agar disc diffusion method. New compounds 1 and 2 exhibited moderate activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) of 250 μg mL(- 1). The most active compounds 3 and 5 displayed a broad spectrum of antimicrobial activity with an MIC of 125 μg mL(- 1) against G(+) and G(- ) bacteria. The structure of the above-mentioned novel compounds and their antimicrobial activities are herein reported for the first time from the natural product of insects.