Design, Synthesis, and Biological Evaluation of Heterocyclic-Fused Pyrimidine Chemotypes Guided by X-ray Crystal Structure with Potential Antitumor and Anti-multidrug Resistance Efficacy Targeting the Colchicine Binding Site

Abstract

Herein, a series of quinazoline and heterocyclic fused pyrimidine analogues were designed and synthesized based on the X-ray co-crystal structure of lead compound <b>3a</b>, showing efficacious antitumor activities. Two analogues, <b>15</b> and <b>27a</b>, exhibited favorable antiproliferative activities, which were more potent than lead compound <b>3a</b> by 10-fold in MCF-7 cells. In addition, <b>15</b> and <b>27a</b> exhibited potent antitumor efficacy and tubulin polymerization inhibition <i>in vitro</i>. <b>15</b> reduced the average tumor volume by 80.30% (2 mg/kg) in the MCF-7 xenograft model and 75.36% (4 mg/kg) in the A2780/T xenograft model, respectively. Most importantly, supported by structural optimization and Mulliken charge calculation, X-ray co-crystal structures of compounds <b>15</b>, <b>27a</b>, and <b>27b</b> in complex with tubulin were resolved. In summary, our research provided the rational design strategy of colchicine binding site inhibitors (CBSIs) based on X-ray crystallography with antiproliferation, antiangiogenesis, and anti-multidrug resistance properties.