Secondary metabolites from Aspergillus japonicus CAM231, an endophytic fungus associated with Garcinia preussii

Genomics-driven derivatization of the bioactive fungal sesterterpenoid variecolin: Creation of an unnatural analogue with improved anticancer properties

A biosynthetic gene cluster for the bioactive fungal sesterterpenoids variecolin (1) and variecolactone (2) was identified in Aspergillus aculeatus ATCC 16872. Heterologous production of 1 and 2 was achieved in Aspergillus oryzae by expressing the sesterterpene synthase VrcA and the cytochrome P450 VrcB. Intriguingly, the replacement of VrcB with homologous P450s from other fungal terpenoid pathways yielded three new variecolin analogues (5-7). Analysis of the compounds' anticancer activity in vitro and in vivo revealed that although 5 and 1 had comparable activities, 5 was associated with significantly reduced toxic side effects in cancer-bearing mice, indicating its potentially broader therapeutic window. Our study describes the first tests of variecolin and its analogues in animals and demonstrates the utility of synthetic biology for creating molecules with improved biological activities.

Unravelling the Secrets of α-Pyrones from Aspergillus Fungi: A Comprehensive Review of Their Natural Sources, Biosynthesis, and Biological Activities

Aspergillus, one of the most product-rich and genetically robust genera, contains a diverse range of species with potential economic and ecological implications. Chemically, Aspergillus is one of the essential sources of polyketides, alkaloids, diphenyl ethers, diketopiperazines, and other miscellaneous compounds, displaying a variety of pharmacological activities. The α-pyrones are unsaturated six-membered lactones. Although α-pyrone has a small structure, it is responsible for the structural diversity of several natural and synthetic compounds and multiple biological activities. In this review, we have summarized approximately 178 α-pyrone containing metabolites derivatives identified/reported from terrestrial, marine, endophytic, and filamentous Aspergillus species, including their sources, biological properties, and biosynthetic pathways until mid-2023, for the first time. This review is the first to compile and analyze the available data on α-pyrone metabolites from Aspergillus, which could facilitate further research and innovation in this field. Additionally, it offers a valuable source of scaffolds for future bioactive drug development, as some of these metabolites have shown potent antimicrobial, anti-inflammatory, and anticancer effects. Therefore, this review has significant implications for the advancement of natural product chemistry, pharmacology, biotechnology, and medicine.

Asperpyrone, a rare α-pyrone metabolite produced by an endophytic fungus Aspergillus sp. isolated from Garicinia smeathmannii (Planch. & Triana) Oliv

A new α-pyrone, asperpyrone (1) and two known compounds, stigmasterol (2) and 7-hydroxy-3-(2,3-dihydroxybutyl)-1(3H)-Isobenzofuranone (3) were isolated from the solid rice culture of the endophytic fungus Aspergillus sp., an endophytic fungus isolated from the fresh inner tissue of the barks of Garicinia smeathmannii. Their structures were determined by extensive spectral analysis including 1 D and 2 D NMR, HRESIMS and single-crystal X-ray crystallographic analysis. Asperpyrone (1) was tested against an axenic culture of Entamoeba moshkovskii, but did not exhibit any significant amoebicidal activity.

Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher's Method and Chiroptical Approach

Endophytic fungi are one of prolific sources of bioactive natural products with potential application in biomedicine and agriculture. In our continuous search for antimicrobial secondary metabolites from Fusarium oxysporum R1 associated with traditional Chinese medicinal plant Rumex madaio Makino using one strain many compounds (OSMAC) strategy, two diastereomeric polyketides neovasifuranones A (3) and B (4) were obtained from its solid rice medium together with N-(2-phenylethyl)acetamide (1), 1-(3-hydroxy-2-methoxyphenyl)-ethanone (2) and 1,2-seco-trypacidin (5). Their planar structures were unambiguously determined using 1D NMR and MS spectroscopy techniques as well as comparison with the literature data. By a combination of the modified Mosher's reactions and chiroptical methods using time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) and optical rotatory dispersion (ORD), the absolute configurations of compounds 3 and 4 are firstly confirmed and, respectively, characterized as (4S,7S,8R), (4S,7S,8S). Bioassay results indicate that these metabolites 1-5 exhibit weak inhibitory effect on Helicobacter pylori 159 with MIC values of ≥16 μg/mL. An in-depth discussion for enhancement of fungal metabolite diversity is also proposed in this work.

Comprehensive Review of Endophytic Flora from African Medicinal Plants

Many people in different African countries are suffering from different diseases many of which result in serious life threat and public health problems with high risk of infection and mortality. Due to less accessibility and high cost of modern drugs, people of this continent often depend on traditional medicine using medicinal plants to manage the diseases. Africa has large tropical rain forests, which are very rich in medicinal plants. Many of them have been scientifically proven for their medicinal values. These medicinal plants which constitute a large repertoire of endophytes have not been significantly explored for the isolation of these microorganisms and their bioactive secondary metabolites. This review summarizes the research on endophytes isolated from medicinal plants of Africa, their pharmacological potential and some of their biotechnological aspects. Novel compounds reported from endophytes from Africa with their biological activities have also been reviewed. Information documented in this review might serve as starting point for future researches on endophytes in different African countries.

Heptacyclosordarianone, a New Polyketide From Sordaria sp., an Endophytic Fungus From Garcinia polyantha

One new polyketide derivative, heptacyclosordarianone (1), together with 2 known compounds, heptacyclosordariolone (2) and sordariol (3), were isolated from an extract of Sordaria sp. AM-71, an endophytic fungus inhabiting Garcinia polyantha. The structures of these compounds were elucidated based on intensive nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry and by comparison with literature data. All compounds were assayed for their antimicrobial and cytotoxic properties. Only compound 2 showed antimicrobial activities against Bacillus subtilis DSMZ 704 , Pseudomonas agarici DSMZ 11810, and Micrococcus luteus DSMZ 1605 with minimum inhibitory concentration values of 9.3, 15.5, and 16.9 µg/mL respectively. None of the isolated compounds showed a significant cytotoxic property.

Natural Polypropionates in 1999-2020: An Overview of Chemical and Biological Diversity

Natural polypropionates (PPs) are a large subgroup of polyketides with diverse structural features and bioactivities. Most of the PPs are discovered from marine organisms including mollusks, fungi and actinomycetes, while some of them are also isolated from terrestrial resources. An increasing number of studies about PPs have been carried out in the past two decades and an updated review is needed. In this current review, we summarize the chemical structures and biological activities of 164 natural PPs reported in 67 research papers from 1999 to 2020. The isolation, structural features and bioactivities of these PPs are discussed in detail. The chemical diversity, bioactive diversity, biodiversity and the relationship between chemical classes and the bioactivities are also concluded.

A new diketopiperazine from an endophytic fungus Aspergillus aculeatus F027

A new diketopiperazine cyclo-(L-Phe-N-ethyl-L-Glu) (1), along with two known diketopiperazines cyclo-(L-Pro-L-Leu) (2) and cyclo-(L-Pro-L-Phe) (3) were isolated from the cultures of an endophytic fungus Aspergillus aculeatus F027. The structures of these compounds were elucidated based on spectroscopic data. The configurations of these compounds were determined by advanced Marfey's analysis. Antibacterial activity of the diketopiperazines against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were also evaluated.Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1677652.

New pyrone and cyclopentenone derivatives from marine-derived fungus Aspergillus sydowii SCSIO 00305

Two new 2-pyrone derivatives sydowiones A-B (1, 2), one new cyclopentenone derivative sydowione C (3), and one new mycotoxin 6-methoxyl austocystin A (4) along with two known analogues paecilpyrone A (5) and austocystin A (6), were isolated from the marine-derived fungus Aspergillus sydowii SCSIO 00305. The structures of 1-4 were elucidated by extensive spectroscopic analysis. The absolute configuration of C-8 in 1 was established by Mosher method, and further confirmed by calculation of the electronic circular dichroism (ECD) spectra. The absolute configuration of C-11 in 3 was also determined by calculation of ECD spectra. The absolute configuration of 6 was determined by a single-crystal X-ray diffraction experiment for the first time. Compounds 1-4 showed moderate toxicity towards brine shrine naupalii with LC₅₀ values of 19.5, 14.3, 8.3 and 2.9 μM, respectively. And 1 and 2 also showed antioxidant activity against 2,2-diphenyl-picrylhydrazyl (DPPH) radicals with IC₅₀ values of 46.0 and 46.6 μM, respectively.[Formula: see text].

Isolation and structure elucidation of a new compound from the fungus Aspergillus flavipes PJ03-11

A new diphenyl ether 3-methylpentyl-2, 4-dichloroasterrate (2), along with a known diphenyl ether butyl 2, 4-dichloroasterrate (1) were isolated from the metabolites of a wetland fungus Aspergillus flavipes. PJ03-11. The structures of 1 and 2 were determined by extensive NMR and HR-ESI-MS experiments. Compounds 1 and 2 showed weak cytotoxic activity, but both of them showed no antimicrobial activity.

New metabolites from the sponge-derived fungus Aspergillus sydowii J05B-7F-4

Two new metabolites, diorcinolic acid (1) and β-d-glucopyranosyl aspergillusene A (8), together with six diphenylethers (2-7), a diketopiperazine (9), a chromone (10) and a xanthone (11) were isolated from the fungus Aspergillus sydowii derived from the marine sponge Stelletta sp. The planar structures and their relative configurations were elucidated by analysing 1D, 2D NMR and HRESIMS data. Compound 8 is the first glycoside of phenolic bisabolane sesquiterpenes. Compounds 1 and 8 exhibited mild cytotoxicity against KB (human nasopharyngeal carcinoma cells), HepG2 (human liver cancer cells) and HCT 116 (human colon cancer cells). All compounds were evaluated for antibacterial activity and their abilities to suppress LPS-induced nitric oxide (NO) production. Compounds 2 and 4-7 showed mild antibacterial activity against human pathogen Staphylococcus aureus and fish pathogens Streptococcus iniae and Vibrio ichthyoenteri, and compounds 4 and 7 weakly suppressed NO production.