Novel pyrazolo[3,4-d]pyrimidine derivatives: design, synthesis, anticancer evaluation, VEGFR-2 inhibition, and antiangiogenic activity†

A novel series of 12 pyrazolo[3,4-d]pyrimidine derivatives were created and evaluated in vitro for their antiproliferative activity against the NCI 60 human tumor cell line panel. Compounds 12a–d displayed significant antitumor activity against MDA-MB-468 and T-47D (breast cancer cell lines), especially compound 12b, which exhibited the highest anticancer activity against MDA-MB-468 and T-47D cell lines with IC₅₀ values of 3.343 ± 0.13 and 4.792 ± 0.21 μM, respectively compared to staurosporine with IC₅₀ values of 6.358 ± 0.24 and 4.849 ± 0.22 μM. The most potent cytotoxic derivatives 12a–d were studied for their VEGFR-2 inhibitory activity to explore the mechanism of action of these substances. Compound 12b had potent activity against VEGFR-2 with an IC₅₀ value of 0.063 ± 0.003 μM, compared to sunitinib with IC₅₀ = 0.035 ± 0.012 μM. Moreover, there was an excellent reduction in HUVEC migratory potential that resulted in a significant disruption of wound healing patterns by 23% after 72 h of treatment with compound 12b. Cell cycle and apoptosis investigations showed that compound 12b could stop the cell cycle at the S phase and significantly increase total apoptosis in the MDA-MB-468 cell line by 18.98-fold compared to the control. Moreover, compound 12b increased the caspase-3 level in the MDA-MB-468 cell line by 7.32-fold as compared to the control.