Synthesis of the bis-4-hydroxycoumarin-type compound, 3,3'-[3-(2-hydroxyphenyl)-3-oxopropane-1,1-diyl]bis(4-hydroxy-2H-chromen-2-one), was performed by two alternative pathways, either involving a basic organocatalyzed 1,4-conjugate addition tandem reaction of 4-hydroxycoumarin on chromone-3-carboxylic acid, or a double condensation of 4-hydroxycoumarin on ω-formyl-2'-hydroxyacetophenone. The anti-proliferative effects of the bis-4-hydroxycoumarin-type compound on human K-562 (chronic myeloid leukaemia) and JURKAT (acute T-cell leukaemia) cell lines using trypan blue staining, as well as its involvement in nuclear factor-kappa B (NF-κB) regulation analyzed by luciferase reporter gene assay, gene expression analysis and western blots were analysed. This compound inhibited TNFα-induced NF-κB activation in K-562 (IC50 17.5μM) and JURKAT (IC50 19.0μM) cell lines, after 8h of incubation. Interestingly, it exerted mainly cytostatic effects at low doses on both cell lines tested, whereas it decreased JURKAT cell viability starting at 50μM from 24h of treatment. Importantly, it did not affect the viability of peripheral blood mononuclear cells (PBMCs) from healthy donors, even at concentrations above 100μM.