Study on cytotoxic active constituents in fermentation liquid of endophytic fungus Myrothecium roridum in Trachelospermum jasminoide

  Objective  To study the cytotoxic constituents in fermentation liquid of endophytic fungus Myrothecium roridum in Trachelospermum jasminoide so as to find compounds with novel structure and strong activity and to provide experimental basis for discovery of anticancer leading compounds.

  Methods  Guided by ¹H-NMR magnetic resonance spectrum(¹H-NMR)and thin-layer chromatography(TLC), isolation and purification of the extract of liquid culture were performed through silica gel column chromatography, Sephadex LH-20 gel filtration chromatography and high performance liquid chromatography(HPLC). Structures of compounds were identified by high resolution mass spectrum and nuclear magnetic resonance spectrum and comparison with data of literatures. In vitro cytotoxic activity of compounds to HepG2 cells and Hela cells were evaluated through MTT method and cisplatin was used as positive control. Flow cytometry was used to analyse the effect of compound on the cell cycle of tumor cells and Western blot to detect the expression level ofnegative regulatory protein p27 in a cell cycle.

  Results  Two trichothecene compounds, including 12′-hydroxyroridin E (1) and trichoverritone (2) were isolated from the fermentation broth of M. roridum, which had obvious inhibitory effect on HepG2 and Hela cells. The IC₅₀ values of two compounds were 0.78 and 1.86 μg/mL, 0.05 and 0.13 μg/mL, respectively, and were 4.9 and 2.28 μg/mL, respectively, in cisplatin. Further study indicated that 12′-hydroxyroridin E (1) could induce G2 phase arrest in HepG2 cells and up-regulate the expression level of protein p27.

  Conclusion  12′-hydroxyroridin E (1) could block G2 phase cell cycle in HepG2 cells to inhibit cell proliferation, which is related to the up-regulated expression of protein p27.