Constituents of the Endophytic Fungus Annulohypoxylon boveri var. microspora BCRC 34012

Abstract A new azaphilone metabolite with a new substitution pattern, named annulohypoxylin (1), together with twelve known compounds, were isolated from the BuOH‐soluble fraction of the 95% EtOH extract of long‐grain rice (Oryza sativa) fermented with the endophytic fungus Annulohypoxylon boveri var. microspora (BCRC 34012). Annulohypoxylin (1) contains a dihydrobenzofuran‐2,4‐dione backbone, 1‐hydroxyoctyl side chain, and one γ‐lactone ring. Its structure was determined on the basis of extensive 1D‐ and 2D‐NMR analyses in combination with HR‐ESI‐MS. The relative configuration of 1 was confirmed by NOESY experiment. Other known compounds were identified by comparing their spectral data with those in the literature. All known compounds were isolated from this species for the first time.