piperine–amino acid ester conjugates (4a–4r) were synthesized under mild conditions and screened for their cytotoxicactivities against a panel of humancancercell lines (IMR-32, MCF-7, PC-3, DU-145, Colo-205, and Hep-2). The parent compound piperine lacked significant activity but the analogues were effective to in all tested humancancercell lines. The introduction of d- and l-amino acid side chain