Secondary metabolites and cytotoxic activities from the endophytic fungus Annulohypoxylon squamulosum

One new dihydrobenzofuran-2,4-dione derivative, designated as annulosquamulin (1), together with 10 known compounds (2–11), were isolated from the n-BuOH-soluble fraction of the 95% EtOH extract of long-grain rice (Oryza sativa) fermented with the endophytic fungus Annulohypoxylon squamulosum (BCRC 34022), derived from the stem bark of medicinal plant Cinnamomum sp. Partial isolated compounds (1–5) were evaluated for their cytotoxicity against the MCF-7, NCI-H460 and SF-268 cell lines using the MTT assay. [Display omitted] ► Eleven compounds were isolated from an endophytic fungus Annulohypoxylon squamulosum. ► Compound 1 was a dihydrobenzofuran-2,4-dione derivative. ► Compounds 1 and 2 were found to possess cytotoxic activities. One new dihydrobenzofuran-2,4-dione derivative, designated as annulosquamulin (1), together with 10 known compounds (2–11), were isolated from the n-BuOH-soluble fraction of the 95% EtOH extract of long-grain rice fermented with the endophytic fungus Annulohypoxylon squamulosum BCRC 34022, derived from the stem bark of medicinal plant Cinnamomum sp. Annulosquamulin (1) comprises one dihydrobenzofuran-2,4-dione skeleton, 1-hydroxydecyl side chain, and one γ-lactone ring. Their structures were elucidated by means of spectroscopic and mass-spectrometric analyses, particularly 1D and 2D NMR spectroscopy as well as HRESIMS. All known isolates except 11, were isolated for the first time from this species. In addition, isolated compounds (1–5) were evaluated for their cytotoxicity against the MCF-7, NCI-H460 and SF-268 cell lines using the MTT assay.