Annulohpoxylotol A and B, new sesquiterpenoids from the endophytic fungus Annulohypoxylon truncatum, are natural NF-κB inhibitors

Two sesquiterpenoids, annulohpoxylotol A and B, were isolated along with five sterols from an ethyl acetate extract of cultures of the endophytic fungus Annulohypoxylon truncatum growing on leaves of Zizania caduciflora. The structures of the isolated compounds were established using one-dimensional (1D) and two-dimensional (2D)-NMR and mass spectrometry. The nuclear factor-kappa B (NF-kappa B) inhibitory activities of the isolated compounds stimulated with tumor necrosis factor-alpha (TNF-alpha) were measured using a luciferase reporter system. Annulohpoxylotol A (1) significantly inhibited NF-kappa B activation in a dose-dependent manner, with an IC50 of 7.11 mu M, whereas annulohpoxylotol B (2) and ergone (7) moderately inhibited NF-kappa B transcriptional activity, with IC50 values of 19.24 and 17.51 mu M, respectively.