Three new antitumor annonaceous acetogenins from the seeds of Annona squamosa.

Two new annonaceous acetogenins squamocin P (2) and annosquatin III (3) and one new ACG precursor dieporeticenin B (1) along with five known precursors (4-8) were isolated from the seeds of Annona squamosa. Their structures were ascertained by chemical methods and various spectral evidences. These compounds showed inhibitory effects against three multidrug-resistant (MDR) cancer cell lines. Compound 2 and 3 displayed selective cytotoxicity against SMMC 7721/T (IC 0.435 and 1.79 μM) and MCF-7/ADR (IC values 3.34 and 4.04 μM).