ABSTRACT
One new compound ()-2,3-dihydroxybutyl 2-hydroxy-3,5,6-trimethylbenzoate (1) and six known compounds xylariphthalide A (2), convolvulol (3), cis-4-hydroxy-6-deoxytalone (4), phomoxydienes B (5), 5,6-dihydroxy-2,3,6-trimethylcyclohex-2-enone (6), trans-cyclo-(D-tryptophanyl-L-tyrosyl) (7) were isolated from Diaporthe sp., an endophytic fungus hosted in the leaves of the toxic Chinese folk medicine Tylophora ouata, using the combination methods of silica gel column chromatography, medium-pressure ODS column chromatography and RP-preparative HPLC. The structure of compound 1 was elucidated by NMR and MS data analyses. The absolute configurations were established according to the ¹H-NMR data and exciton chirality method. Compound 1 inhibited the activation of human lung fibroblasts MRC-5 cells by 64.0% at 10 μmol·L⁻¹. The MTT assay showed that compounds 2 and 4 displayed cytotoxic activity against human tumor cell lines BGC-823 cells with IC₅₀ values of 1.5 and 8.6 μmol·L⁻¹, respectively.