Bioactive Resorcylic Acid Lactones with Different Ring Systems from Desert Plant Endophytic Fungus Chaetosphaeronema hispidulur

Five new resorcylic acid lactones (RALs) hispidulactones A–E ( 1, 4, 5, 8, and 9 ), a new natural product ( 2 ), and four known ones ( 3, 6, 7, and 10 ) with different ring systems were isolated from the desert plant endophytic fungus Chaetosphaeronema hispidulur . The new compounds were characterized by NMR data, CD spectra, and X-ray experiment. The new natural product ( 2 ) displayed strongly biological effects on the seedlings growth of Arabidopsis thaliana, Digitaria sanguinalis, and Echinochloa crusgalli with a dose-dependent relationship. Compounds 1, 2, and 6 were also tested cytotoxic activities against three cancer cell lines HCT116, Hela, and MCF7 and only did the new natural product ( 2 ) display biological activities with IC 50 values at 54.86 ± 1.52, 4. 90 ± 0.02, and 20.04 ± 4.00 μM, respectively, whereas the IC 50 values of the positive control cis -platinum were 11.36 ± 0.42, 3.54 ± 0.12, and 14.32 ± 1.01 μM, respectively.