A series of novel diaryl urea pyrazolopyrimidine derivatives was designed and synthesized. All the synthesized compounds were evaluated for cytotoxic activity by the National Cancer Institute. A significant antiproliferative activity at a 10‐µM dose was shown by four compounds (5c, 5e, 5g, and 5h), and they were accordingly evaluated at five concentrations. They showed a potent and broad‐spectrum antiproliferative activity, with GI50 values between 0.553 and 3.80 µM and TGI values in the range of 2.17–100 µM. These four compounds potently inhibited the vascular endothelial growth factor receptor‐2 (VEGFR‐2) with IC50 values in the nanomolar range. Molecular docking attributed their potent VEGFR‐2 inhibitory activity to their interactions with key amino acids in the VEGFR‐2 active site. Their flow cytometric analysis showed that they exerted their cytotoxic activity by reduction of the cellular proliferation and by induction of cell cycle arrest at the G2/M phase. Additionally, they induced DNA degradation or fragmentation, confirming the role of apoptosis in the cancer cell death and cytotoxicity induced by these compounds.

中文翻译：

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新型吡唑并嘧啶脲衍生物：合成、抗增殖活性、VEGFR-2 抑制以及对细胞周期曲线的影响

设计并合成了一系列新型二芳基脲吡唑并嘧啶衍生物。美国国家癌症研究所评估了所有合成化合物的细胞毒活性。四种化合物（5c、5e、5g 和 5h）在 10 µM 剂量下显示出显着的抗增殖活性，因此在五个浓度下对它们进行了评估。它们显示出有效的广谱抗增殖活性，GI50 值介于 0.553 和 3.80 µM 之间，TGI 值介于 2.17–100 µM 之间。这四种化合物有效抑制血管内皮生长因子受体-2 (VEGFR-2)，IC50 值在纳摩尔范围内。分子对接将其强大的 VEGFR-2 抑制活性归因于它们与 VEGFR-2 活性位点中关键氨基酸的相互作用。他们的流式细胞术分析表明，它们通过减少细胞增殖和诱导细胞周期停滞在 G2/M 期来发挥细胞毒活性。此外，它们诱导 DNA 降解或断裂，证实了细胞凋亡在这些化合物诱导的癌细胞死亡和细胞毒性中的作用。