A novel alkylated piperazine (3 alpha,5 alpha-diisobutyryl-6 alpha-isopropyl-piperazine-2-one, 1) has been isolated from the n-butanol soluble part of the leaves extract of Arum palaestinum Boiss., the chemical structure and the relative stereochemistry of 1 were elucidated on the basis of 1D and 2D NMR spectroscopic data. Piperazirum showed a significant cytotoxicity against cultured tumor cell lines in vitro. (c) 2007 Published by Elsevier Ltd.