Seven undescribed cytochalasins, multirostratins K – Q (2–8), together with one known analogue, cytochalasin Z3 (1), were isolated from the culture of Phoma multirostrata XJ-2-1, an endophytic fungus obtained from the root of Parasenecio albus. Their structures with absolute configurations were determined by 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), electronic circular dichroism (ECD), single-crystal X-ray crystallography, and chemical methods. The structure of ascochalasin was revised from Δ13 to Δ21 by detailed analysis of the NMR data and by comparison with the data for 7. In a TRAIL (tumor necrosis factor related apoptosis inducing ligand)-resistance-overcoming experiment, co-treatment of 2 or 6 with TRAIL reduced the cell viability of A549 cells by 30.3% and 27.5% at 10 µM, respectively.
Nine new ( 1 – 9 ) and four known ( 10 – 13 ) [13]cytochalasins, along with three known 24-oxa[14]cytochalasins ( 14 – 16 ), were isolated from the culture of Phoma multirostrata XJ-2-1, an endophytic fungus obtained from the fibrous root of Parasenecio albus . Their structures were elucidated by interpretation of the nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS). The absolute configurations were assigned by single-crystal X-ray crystallography, modified Mosher′s method, and by analysis of their experimental electronic circular dichroism (ECD) spectra. Compound 6 could induce cell cycle arrest at G2-phase in CT26 and A549 cells, and displayed moderate cytotoxicity against CT26 and A549 cell lines with IC 50 values of 6.03 and 5.04 μM, respectively. Co-treatment of 7 – 9 , 13 and 16 with tumor necrosis factor related apoptosis inducing ligand (TRAIL) could significantly decrease the cell viability of A549, which revealed that cytochalasins could possibly be a new group of TRAIL sensitizers in lung cancer therapy.
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