Design, synthesis and anticancer activities of novel dual poly(ADP-ribose) polymerase-1/histone deacetylase-1 inhibitors

[Display omitted] •Synergistic inhibition of PARP-1 and HDACs is a potential effective strategy for cancer treatment.•Compound 4 showed comparable potency against PARP-1 and HDAC-1 with olaparib and chidamide respectively.•Compound 4 extended the antitumor spectrum of olaparib.•A few excellent PARP-1 inhibitors and HDAC-1 inhibitors were serendipitously discovered. Currently, synergistic inhibition of poly(ADP-ribose) polymerase-1 (PARP-1) and histone deacetylases (HDACs) has been a potential effective strategy for cancer treatment. Herein, by combining critical pharmacophores in approved drugs olaparib and chidamide, a series of novel 2-fluoro-5-((4-oxo-3,4-dihydrophthalazin-1-yl)methyl)benzoic acid derivatives were designed and synthesized. All efforts led to a good dual PARP-1/HDAC-1 inhibitor, compound 4, with IC50 values of 4.2 and 340 nM against PARP-1 and HDAC-1, which were as potent as olaparib and chidamide respectively. The MTT assay further demonstrated that compound 4 had potent inhibitory activities against BRCA1/2-proficient K562 and MDA-MB-231 cells with GI50 values of 5.6 and 4.3 μM, respectively. Therefore, our results suggested that compound 4 could be a promising dual PARP-1/HDAC-1 inhibitor for further studies. In addition, a few excellent PARP-1 inhibitors such as 7–9 and HDAC-1 inhibitors such as 12 were serendipitously discovered, which also could be further studied in our next work.