Benzopyrans from Curvularia sp., an endophytic fungus associated with Ocotea corymbosa (Lauraceae)

Benzopyrans ( 2) and ( 4) were produced by an endophytic fungus Curvularia sp. associated to Ocotea corymbosa, a native plant of Brazilian Cerrado. The structures of the derivatives were established on the basis of comprehensive spectroscopic analysis, mainly using 1D and 2D NMR experiments. Analyses of biological activities were carried out on a human cervix tumor cell line aimed at evaluation of potential effects on a mammalian cell line proliferation. Only 2 showed a significant activity. An isolate of Curvularia sp. was obtained from the leaves of Ocotea corymbosa, a native plant of the Brazilian Cerrado. The ethyl acetate extract from culture of this fungus afforded two benzopyran derivatives: (2′ S)-2-(propan-2′-ol)-5-hydroxy-benzopyran-4-one ( 2) and 2,3-dihydro-2-methyl-benzopyran-4,5-diol ( 4); and two known benzopyrans: 2-methyl-5-methoxy-benzopyran-4-one ( 1) and (2 R)-2,3-dihydro-2-methyl-5-methoxy-benzopyran-4-one ( 3). The structures of 2 and 4 were established on the basis of comprehensive spectroscopic analysis, mainly using 1D and 2D NMR experiments. The benzopyrans 1 and 2 showed weak in vitro antifungal activity against Cladosporium sphaerospermum and C. cladosporioides. Analyses of the biological activities were also carried out on HeLa (human cervix tumor) and CHO (Chinese hamster ovary) cells, aiming to evaluate their potential effects on mammalian cell line proliferation. Results from both cell lines indicated that compound 2 was able to induce cell proliferation: 70% on HeLa cells and 25% on CHO cells.