Abstract: A dimeric naphthopyrones were activity-guided isolated by MTT method from the fermentation broth extract of Penicillium oxalicum, a fungus residing in Acrida cinerea. On the basis of spectrl data and physicochemical properties, it was identified as secalonic acid A that isolated for the first time from the endophytic fungus of Penicillium oxalicum. Secalonic acid A showed significant cytotoxicity to several human cancer cell lines such as HepG2,A549,Ca Ski,CNE2,MDA-MB-231 with IC₅₀ values of 1.12, 2.23, 4.16, 20.18, 22.65 μM, but slightly cytotoxicity to normal cell lines such as HaCAT and MDCK with IC₅₀ values greater than 100μM.Flow cytometry assay confirmed that secalonic acid A caused a dose-dependent early apoptotic effect with a highest-level of 40.6%.Furthermore,secalonic acid A triggered a rapid decrease of the mitochondrial membrane potential by 97.3% relatively.These findings suggested that secalonic acid A induced mitochondrialmediated apoptosis in HepG cells.

Key words: Penicillium oxalicum, secalonic acid A;cytotoxicity；apoptosis