Endophytic Fungi from the Four Staple Crops and Their Secondary Metabolites.

Endophytic fungi are present in every plant, and crops are no exception. There are more than 50,000 edible plant species on the planet, but only 15 crops provide 90 percent of the global energy intake, and "the big four"-wheat, rice, maize and potato-are staples for about 5 billion people. Not only do the four staple crops contribute to global food security, but the endophytic fungi within their plant tissues are complex ecosystems that have been under scrutiny. This review presents an outline of the endophytic fungi and their secondary metabolites in four staple crops: wheat, rice, maize and potato. A total of 292 endophytic fungi were identified from the four major crops, with wheat having the highest number of 157 endophytic fungi. Potato endophytic fungi had the highest number of secondary metabolites, totaling 204 compounds, compared with only 23 secondary metabolites from the other three crops containing endophytic fungi. Some of the compounds are those with specific structural and pharmacological activities, which may be beneficial to agrochemistry and medicinal chemistry.

Chromones from the endophytic fungus Bipolaris eleusines.

Eight previously undescribed chromones eleusineketones A-H (1-8), as well as eight known compounds (9-16), were isolated from the endophytic fungus Bipolaris eleusines. These planar structures were created using an in-depth analysis of their spectral data, which included 1D, 2D, and HRESIMS data. Furthermore, the absolute configurations of compounds 1, 2, and 6 were determined by spectroscopic analysis and quantum chemical computational approaches, and compound 5 was determined by single-crystal X-ray diffraction analysis. The cytotoxic activity assay revealed that compounds 1 and 5 both inhibited MDA-MB-231 cells with IC50 values of 14.48 µM and 17.99 µM, respectively.

The antifungal properties of terpenoids from the endophytic fungus Bipolaris eleusines.

A series of terpenoids (1-17), comprising six new compounds designated bipolariterpenes A-F (1-6) and eleven recognized compounds (7-17), were isolated from the wheat culture of the potato endophytic fungus Bipolaris eleusines. Their structures and stereochemistry were clarified by HRESIMS, NMR, DP4 + probability analyses, and computations for electronic circular dichroism (ECD). All compounds are made up of six meroterpenoids, four sesterterpenes and seven sesquiterpenes. Among them, four sesterterpenes (4, 5, 10, 11) were investigated for their antifungal, antibacterial and cytotoxic properties, and six meroterpenoids (1-3, 7-9) were evaluated for their antifungal properties. The compounds 7, 9, and 10 had substantial antifungal activity against Epidermophyton floccosum at a concentration of 100 µM. No antibacterial and cytotoxic activities were observed.

Six Unprecedented Cytochalasin Derivatives from the Potato Endophytic Fungus Xylaria curta E10 and Their Cytotoxicity.

Six previously undescribed cytochalasins, Curtachalasins X1-X6 (1-6), together with six known compounds (7-12) were isolated from the endophytic fungus Xylaria curta E10 harbored in the plant Solanum tuberosum. The structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. The absolute configurations of Curtachalasins X1-X6 were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) spectra. In bioassays, Curtachalasin X1 (1) and X5 (5) showed cytotoxic activity against the MCF-7 cell line with IC50 values of 2.03 µM and 0.85 µM, respectively.

Oblongolides from endophytic fungus Phoma bellidis Neerg. harbored in Tricyrtis maculata (D. Don) J.F.Macbr.

Five previously undescribed oblongolides, namely phomaones A-E, along with four known compounds, were isolated from the endophytic fungus Phoma bellidis Neerg.. Their structures and absolute configurations were determined by extensive experimental spectroscopic methods as well as single crystal X-ray diffractions, ECD calculations and GIAO 13C NMR calculations. Phomaone A represent the first example of oblongolides with glycol directly linked by two C-C bonds, and its biosynthetic pathway were proposed. The cytotoxicity of obtained compounds was evaluated against human cancer cell lines MCF-7, DU145, and SW480. All compounds except phomaone A showed the cytotoxicity against MCF-7 with IC50 value ranging from 12.45 to 49.84 µM.