(2,4-cis)-asimicinone and (2,4-trans)-asimicinone: two novel bioactive ketolactone acetogenins from Asimina triloba (Annonaceae).

Two novel bioactive ketolactone Annonaceous acetogenins, (2,4-cis)-asimicinone (1) and (2,4-trans)-asimicinone (2), have been isolated from Asimina triloba (Annonaceae) by bioactivity directed fractionation. The separation of these two epimeric compounds was achieved by HPLC methods using a Si gel normal phase column eluted with acetone in hexane gradients. The assignments of cis or trans stereochemistry of the ketolactone moieties were made on the bases of 1H-1H COSY and NOESY experiments. 1 and 2 showed selective cytotoxicities against A-549 (human lung cancer) and MCF-7 (human breast cancer) cell lines with ED50 values as low as < 10(-7) micrograms/ml with 2 being the more active isomer.