The addition of chalcone and amine components into indirubin-3′-oxime resulted in 15 new derivatives with high yields. Structures of new derivatives were also elucidated through 1D, 2D-NMR and HR-MS(eSi) spectra and X-ray crystallography. All designed compounds were screened for cytotoxic activity against four human cancer cell lines (HepG2, LU-1, SW480 and HL-60) and one human normal kidney cell line (HEK-293). Compound 6f exhibited the most marked cytotoxicity meanwhile cytotoxicity of compounds 6e, 6h and 6l was more profound toward cancer cell lines than toward normal cell. These new derivatives were further analyzed via molecular docking studies on GSK-3β enzyme. Docking analysis shows that most of the derivatives exhibited potential inhibition activity against GSK-3β with characteristic interacting residues in the binding site. The fast pulling of ligand scheme was then employed to refine the binding affinity and mechanism between ligands and GSK-3β enzyme. the computational results are expected to contribute to predicting enzyme target of the trial inhibitors and their possible interaction, from which the design of new cytotoxic agents could be created in the future. Cancer is ranked second globally as cause of death. The disease originated due to the inability of cells to control growth, often leading to the formation of cancerous tumors or liquid cancer. (i.e. leukemia and lymphoma cancer). Routines for cancer treatment consist of chemotherapy and radiotherapy where the former utilizes molecule-size drugs aiming at eradication and inhibition of cancer tumors. However, this treatment technique has been shown to suffer from several inherent shortcomings including the development of drug resistance, off-target toxicity and limited targeting capabilities 1,2. Glycogen synthase kinase-3 (GSK-3) is defined as a multifunctional serine/threonine protein kinase that regulates the phosphorylation of various cellular targets 3. The function of GSK-3 is essential for the development

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