Drimane sesquiterpenoids from a wetland soil-derived fungus Aspergillus calidoustus TJ403-EL05

Ustusolate E and 11α-Hydroxy-Ustusolate E induce apoptosis in cancer cell lines by regulating the PI3K/AKT/mTOR and p-53 pathways

Cancer represents a significant disease that profoundly impacts human health and longevity. Projections indicate a 47% increase in the global cancer burden by 2040 compared to 2020, accompanied by a further rise in the associated economic burden. Consequently, there is an urgent need to discover and develop new alternative drugs to mitigate the global impact of cancer. Natural products (NPs) play a crucial role in the identification and development of anticancer therapeutics. This study identified ustusolate E (UE) and its analog 11α-hydroxy-ustusolate E (HUE) from strain Aspergilluscalidoustus TJ403-EL05, and examined their antitumor activities and mechanisms of action. The findings demonstrate that both compounds significantly inhibited the proliferation and colony formation of AGS (human gastric cancer cells) and 786-O (human renal clear cell carcinoma cells), induced irreversible DNA damage, blocked the cell cycle at the G2/M phase, and further induced apoptosis in tumor cells. To the best of the authors' knowledge, this is the first report on the anticancer effects of UE and HUE and their underlying mechanisms. The present study suggests that HUE and UE could serve as lead compounds for the development of novel anticancer drugs.

Diversity and Anti-Infectious Components of Cultivable Rhizosphere Fungi Derived from Three Species of Astragalus Plants in Northwestern Yunnan, China

Astragalus, a group of legume plants, has a pronounced rhizosphere effect. Many species of Astragalus with limited resource reserves are distributed in the high-altitude area of northern Yunnan, China. Although some of these plants have high medicinal value, the recognition of them is still at a low level. The aim of this research is to explore the species diversity of cultivable rhizofungi derived from Astragalus acaulis, A. forrestii and A. ernestii growing in a special high-cold environment of northwest Yunnan and discover anti-infective components from these fungi. A total of 93 fungal strains belonging to 38 species in 18 genera were isolated and identified. Antibacterial and antimalarial screening yielded 10 target strains. Among them, the ethyl acetate crude extract of the fermented substrate of the rhizofungus Aspergillus calidoustus AA12 derived from the plant A. acaulis showed broad-spectrum antibacterial activity and the best antimalarial activity. Further chemical investigation led to the first discovery of seven compounds from the species A. calidoustus, including sesterterpine 6-epi-ophiobolin G; three sesquiterpenes, penicisochroman A, pergillin and 7-methyl-2-(1-methylethylethlidene)-furo [3,2-H]isoquinoline-3-one; and three polyketides, trypacidin, 1,2-seco-trypacidin and questin. Among them, the compound 6-epi-ophiobolin G exhibited moderate to strong antibacterial activity against six Gram-positive pathogens with the minimum inhibitory concentration (MIC) ranging from 25 to 6.25 μg/mL and a prominent inhibitory effect on the biofilm of Streptococcus agalactiae at an MIC value of 3.125 μg/mL. This compound also displayed potent antimalarial activity against Plasmodium falciparum strains 3D7 and chloroquine-resistant Dd2 at the half-maximal inhibitory concentration (IC50) values of 3.319 and 4.340 µmol/L at 72 h, respectively. This study contributed to our understanding of the cultivable rhizofungi from characteristic Astragalus plants in special high-cold environments and further increased the library of fungi available for natural anti-infectious product screening.

Atranones and dolabellanes with cardiomyocyte protective activity against cold ischemic injury from a coral-associated fungus Stachybotrys chartarum

Five undescribed atranones, namely atranones V-Z (1-5), three undescribed dolabellane-type diterpenoids, namely stachatranones D-F (7-9), together with four known congeners (6 and 10-12), were obtained from a coral-associated strain of the toxigenic fungus Stachybotrys chartarum. Their structures were elucidated via extensive spectroscopic analyses, mainly including the HRESIMS and NMR data, single-crystal X-ray diffraction analysis, electronic circular dichroism calculation, and [Mo2(OAc)4] induced circular dichroism spectrum. The cardiomyocyte protective activity assay revealed that compound 9 significantly ameliorated cold ischemic injury at 24 h post cold ischemia (CI) in a dose-dependent manner. Moreover, compound 9 prevented CI induced dephosphorylation of phosphatidylinositol-3-kinase and RAC-α serine/threonine-protein kinase at 12 h post CI in a dose-dependent manner. In this work, the undescribed compound 9 could significantly protect cardiomyocytes against cold ischemic injury, highlighting the promising potential to be designed and developed as a novel cardioprotectant in heart transplant medicine.

New pimarane diterpenoids with antibacterial activity from fungus Arthrinium sp. ZS03

A comprehensive chemical study of the endophytic fungus Arthrinium sp. ZS03, associated with Acorus tatarinowii Schott, yielded eleven pimarane diterpenoids (compounds 1-11), including seven novel compounds designated arthrinoids A-G (1-7). The determination of their structures and absolute configurations was achieved through extensive spectroscopic techniques, quantum chemical calculations of electronic circular dichroism (ECD), and single-crystal X-ray diffraction analysis. Furthermore, 7 demonstrated inhibitory activity against Klebsiella pneumoniae, comparable to the reference antibiotic amikacin, with a minimum inhibitory concentration (MIC) of 8 μg·mL-1.