Genistein amino acid derivatives 4a–4d were synthesized and evaluated for their cytotoxic activities against MCF-7, Hela, MGC-803 and HCT-116 cell lines by MTT assays in vitro. The results revealed that compounds 4a–4d showed better activity than the parent compound genistein. Particularly, compound 4b displayed the most significant anticancer activity against MGC-803 with an IC50 value of 12.08 μM. In addition, the mechanisms of interaction between genistein, compounds 4a–4d and BSA were investigated via multi-spectroscopic techniques such...