Design, synthesis and biological evaluation of phenylpicolinamide sorafenib derivatives as antitumor agents

Two series of phenylpicolinamide sorafenib derivatives (14a–k, 15a–k) were designed and synthesized. They were evaluated for IC50 values against three cancer cell lines (A549, Hela, and MCF-7) and VEGFR2/KDR, BRAF, and CRAF kinases. Fourteen target compounds showed moderate to excellent cytotoxicity activity against the different cancer cells with potency from the single-digit μM to nanomole range. What’s more, six of them were equal to more potent than sorafenib against one or more cell lines. Most of the compounds showed bad activity against VEGFR2/KDR, BRAF, or CRAF kinases. The most promising compound 15f showed strong antitumor activities against A549 and MCF-7 cell lines with IC50 values of 5.43 ± 0.74 and 0.62 ± 0.21 μM, which were 1.29–6.79-fold more active than sorafenib (6.53 ± 0.82, 4.21 ± 0.62 μM), respectively and it exhibited moderate IC50 (7.1 μM) than 14f (IC50 = 3.1 μM). Structure–activity relationships (SARs) and docking studies indicated that replacement of diarylurea of sorafenib with phenylpicolinamide moiety benefits to the activity. The position of aryl group and the substitutions of aryl group have a great influence on antitumor activity and selectivity. Small volume groups of aryl group such as (substituted) alkyl groups (–CH3, –CF3), halogen atoms (–F) were favorable to the cytotoxicity. Exact action mechanism of target compounds is not quite clear and further study will be carried out to identify the target in near future.