Seco-tremulane Sesquiterpenoids from the Cultures of the Medicinal Fungus Irpex lacteus HFG1102

Sesquiterpenoids Specially Produced by Fungi: Structures, Biological Activities, Chemical and Biosynthesis (2015-2020)

Fungi are widely distributed in the terrestrial environment, freshwater, and marine habitat. Only approximately 100,000 of these have been classified although there are about 5.1 million characteristic fungi all over the world. These eukaryotic microbes produce specialized metabolites and participate in a variety of ecological functions, such as quorum detection, chemical defense, allelopathy, and maintenance of symbiosis. Fungi therefore remain an important resource for the screening and discovery of biologically active natural products. Sesquiterpenoids are arguably the richest natural products from plants and micro-organisms. The rearrangement of the 15 high-ductility carbons gave rise to a large number of different skeletons. At the same time, abundant structural variations lead to a diversification of biological activity. This review examines the isolation, structural determination, bioactivities, and synthesis of sesquiterpenoids that were specially produced by fungi over the past five years (2015-2020).

Sesquiterpenoids From the Antarctic Fungus Pseudogymnoascus sp. HSX2#-11

The fungal strains Pseudogymnoascus are a kind of psychrophilic pathogenic fungi that are ubiquitously distributed in Antarctica, while the studies of their secondary metabolites are infrequent. Systematic research of the metabolites of the fungus Pseudogymnoascus sp. HSX2#-11 led to the isolation of six new tremulane sesquiterpenoids pseudotremulanes A-F (1-6), combined with one known analog 11,12-epoxy-12β-hydroxy-1-tremulen-5-one (7), and five known steroids (8-12). The absolute configurations of the new compounds (1-6) were elucidated by their ECD spectra and ECD calculations. Compounds 1-7 were proved to be isomeride structures with the same chemical formula. Compounds 1/2, 3/4, 1/4, and 2/3 were identified as four pairs of epimerides at the locations of C-3, C-3, C-9, and C-9, respectively. Compounds 8 and 9 exhibited cytotoxic activities against human breast cancer (MDA-MB-231), colorectal cancer (HCT116), and hepatoma (HepG2) cell lines. Compounds 9 and 10 also showed antibacterial activities against marine fouling bacteria Aeromonas salmonicida. This is the first time to find terpenoids and steroids in the fungal genus Pseudogymnoascus.

Two new pyridine derivatives and two new furan derivatives from Irpex lacteus

Two undescribed disubstituted pyridine derivatives irpexidines A and B (1 and 2) and two undescribed alkylfuran derivatives irpexins K and L (3 and 4) were isolated from fermentation broth of Irpex lacteus. Their structures were established by extensive spectroscopic methods. The pyridine derivatives from this fungus were reported for the first time. The new compounds were evaluated for their cytotoxicity against Hela cancer cell and inhibitory activity on NO production.

Progress on Terpenoids With Biological Activities Produced by Plant Endophytic Fungi in China Between 2017 and 2019

Plant endophytic fungi are an important part of plant microecosystems and a natural resource for human survival and development. Various bioactive natural products produced by plant endophytic fungi show promising prospects in biopharmacy, agricultural production, and industrial fermentation. Terpenoids, the most numerous and structurally diverse natural products from endophytic fungi, possess a broad range of biological activities and huge potential for drug development. It is critically significant for ecological and economic benefits to develop their activities. This paper utilized literature analysis to summarize 200 terpenoids with biological activities that are derived from plant endophytic fungi in China between 2017 and 2019. Among them, sesquiterpenoids were the most important kind of terpenoids, and Trichoderma and Aspergillus species were main terpenoid-producing plant endophytic fungi. Furthermore, these terpenoids displayed multifarious biological activities, including antimicrobial, antipathogenic, and anti-inflammatory activities, as well as cytotoxicity, antitumor agents, and enzyme inhibition.

Biotransformation of Huperzine A by Irpex lacteus-A fungal endophyte of Huperzia serrata

The biotransformation of huperzine A (hupA), one of the characteristic bioactive constituents of the medicinal plant Huperzia serrata, by a fungal endophyte of the host plant was studied. Two previously undescribed compounds 1-2, along with a known analog 8α,15α-epoxyhuperzine A (3), were isolated and identified. The structures of all the isolates were established by spectroscopic methods including NMR, MS, IR, and UV spectra. In particular, the absolute configurations of 1 and 2 were elucidated by CD spectra comparison and theoretic NOE strength calculation. In the LPS-induced neuro-inflammation injury assay, 1-3 exhibited moderate neuroprotective activity by increasing the viability of U251 cell lines with EC₅₀ values of 35.3 ± 0.9, 32.1 ± 0.9, and 50.3 ± 0.8 nM, respectively.