RESUMEN
OBJECTIVE: To study the secondary metabolites and their cytotoxic activities of an endophytic fungus Alternaria sp. Ly81 cultivated on Maytenus hookeri. METHODS: Column chromatography by RP-18, Sephadex LH - 20 and silica gel was used to isolate and purify the chemical constituents, and their structures were identified by spectroscopic analysis. Cytotoxic activities were evaluated by MTT method. RESULTS: Nine compounds were isolated and identified as tricycloalternarene 2a(1), tricycloalternarene 1a(2), tricycloalternarene 1b(3), tricycloalternarene 2b(4), tricycloalternarene 3b(5), tricycloalternarene 4b(6), tricycloalternarene 5b(7), tricycloalternarene-H(8) and tricycloalternarene F(9). CONCLUSION: Compounds 1 - 9 were isolated from the Alternaria sp. Ly81 for the first time. The absolute configuration of compound 1 is elucidated by Mosher's method. Compound 3 shows strong inhibitory activity against Lewis lung carcinoma cells 3LL.