Abstract: To further explore an efficient strategy for the construction of antitumor fluoroquinolone molecules from antibacterial fluoroquinolone drugs, twelve new title compounds, 1-ethyl-6-fluoro-7-(4-methyl-piperazin-1-yl)-3-(3-substituted-rhodanin-5-ylidene)methyl-quinolon-4(1H)-ones( 6a - 6l ), was designed and synthesized with α, β-unsaturated ketone scaffold and a rhodanine ring as an isostere and fused modified group, respectively, from pefloxacin( 1 ), and their structures were characterized by elemental analysis and spectral data. The in vitro anti-cell proliferative activity of the title compounds against the tested A549, Hep-3B and HL60 cancer cells exhibited more significant potency than parent 1 . In particular, halogenated phenyl title compounds( 6d , 6e , 6f )displayed a comparable activity to comparison doxorubicin against A549 cells and low cytotoxicity against normal Vero cells. Thus, a methylene rhodanine scaffold as a bioisostere of the C-3 carboxylic acid group have shown to be beneficial to improving the antitumor activity.