New Polyketides from Endophytic Diaporthe sp XZ-07

Four new polyketides, namely rel-(2R,3S,4R,5R)-4-ethyltetrahydro-3-methyl-5-propylfuran-2,3-diol (1), methyl 5-[(1R)-1-hydroxyethyl]-gamma-oxofuran-2-butanoate (2), butyl 5-[(1R)-1-hydroxyethyl]-gamma-oxofuran-2-butanoate (3), and 3,4-dihydro-5'-[(1R)-1-hydroxyethyl][2,2'-bifuran]-5(2H)-one (4), together with three known ones, 5-[(1R)-1-hydroxethyl)-gamma-oxofuran-2-butanoic acid (5), phomopsolide B (6), and (2S,3S)-3,6-dihydro-6-oxo-2-[(1E)-2-{(4S,5S)-2,2,5-trimethyl-1,3-dioxolan-4-yl]ethenyl)-2H-pyran-3-yl (2E)-2-methylbut-2-enoate (7), were isolated from the submerged cultures of the endophytic fungal strain Diaporthe sp. XZ-07 of Camptotheca acuminate. The structures of the new compounds were established by 1D- and 2D-NMR and MS data and by Mosher's method. Compound 6 significantly inhibited the growth of human-tumor HeLa cells with an IC50 of 5.7 mu g/ml by the MTT assay (MTT = 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide).