The phytochemical analysis of the ethyl acetate fraction of Arum palaestinum Boiss. (Araceae) led to the isolation and identification of a new polyhydroxy alkaloid compound; (S)-3,4,5-trihydroxy-1 H-pyrrol-2(5H)-one (1), and other five known compounds; caffeic acid (2), isoorientin (3), luteolin (4) and vicenin 11 (5), as well as the rare compound 3,6,8-trimethoxy, 5,7,3',4'-tetrahydroxy flavone (6). The structural elucidations of all the compounds were based on spectroscopic data (1H- and 13C-NMR, DEPT, HSQC, HMBC and NOE difference techniques) and comparison with literature data. Investigation of the antioxidant activity of the ethyl acetate fraction indicated its strong scavenging capacity for 1,1 -diphenyl-2-picrylhydrazyl (DPPH) radicals (SC50 3.1+/-0.82 microg/mL). Moreover, the treatment of different human cancer cell lines with the ethyl acetate fraction led to dose-dependant suppression in the proliferation of both breast carcinoma cells (MCF-7; IC50 59.09+/-4.1 microg/mL) and lymphoblastic leukemia cells (1301; IC50 53.1+/-2.9 microg/mL); however, it was found to have no effect on the growth of hepatocellular carcinoma cells (Hep G2).