Synthesis and biological evaluation of (3/4-(pyrimidin-2-ylamino)benzoyl)-based hydrazine-1-carboxamide/carbothioamide derivatives as novel RXRα antagonists

Abnormal alterations in the expression and biological function of retinoid X receptor alpha (RXRα) have a key role in the development of cancer. Potential modulators of RXRα as anticancer agents are explored in growing numbers of studies. A series of (4/3-(pyrimidin-2-ylamino)benzoyl)hydrazine-1-carboxamide/carbothioamide derivatives are synthesised and evaluated for anticancer activity as RXRα antagonists in this study. Among all synthesised compounds, <b>6A</b> shows strong antagonist activity (half maximal effective concentration (EC₅₀) = 1.68 ± 0.22 µM), potent anti-proliferative activity against human cancer cell lines HepG2 and A549 cells (50% inhibition of cell viability (IC₅₀) values &lt; 10 µM), and low cytotoxic property in normal cells such as LO2 and MRC-5 cells (IC₅₀ values &gt; 100 µM). Further bioassays indicate that <b>6A</b> inhibits 9-cis-RA-induced activity in a dose-dependent manner, and selectively binds to RXRα-=LΒD with submicromolar affinity (Kd = 1.20 × 10⁻⁷ M). <b>6A</b> induces time-and dose-dependent cleavage of poly ADP-ribose polymerase, and significantly stimulates caspase-3 activity, leading to RXRα-dependent apoptosis. Finally, molecular docking studies predict the binding modes for RXRα-LBD and <b>6A</b>. Compound <b>6A</b> with low cytotoxic property in normal cells acts as a selective RXR alpha ligand to promote TNF alpha-mediated apoptosis of cancer cells.