Isoindolines are essential from the point of view of synthesis and their biological properties, so this work is focused on the synthesis of new isoindolines derived from the following L‐α‐amino acids, aspartic acid (1), arginine (2), glutamic acid (3‐5), serine (6), and lysine (7). All compounds were characterized by 1H and 13C NMR, infrared, and high‐resolution mass spectrometry. In addition, the synthesized compounds were screened to investigate their antiproliferative activities against five human cancer cell lines, A549, U373, MDA‐MB‐231, MCF‐7, and HeLa, as well as on primary cell culture healthy, MGC, EC, and Vero cells lines. All tested compounds exhibited activity against cancer cell lines at mM concentrations. Notably, compounds 6 derived from Ser, and 7 derived from Lys exhibited remarkable effects on the A549 and U373. The IC50 values for these compounds were determined to be 0.001 and 0.007 mM, respectively. These findings indicate a significantly higher potency of compounds 6 and 7 than the other tested compounds. Among the tested compounds, only compound 5 displayed significant cytotoxic activity against the Vero cell line.