Design and synthesis of quinazoline derivatives as novel JMJD3/HDAC dual-target inhibitors

= 1.1/3.5/4.4/16/8.3 nM), along with significant selectivity over related isoforms including JMJD1B, JMJD2A and HDAC8. The cellular enzymatic inhibition activity was validated in triple-negative breast cancer (TNBC) cell lines MDA-MB-231 and HCC1806, where 6a dose-dependently elevated the levels of H3K27 methylation (me1/me2/me3) and H3 acetylation. The therapeutic potential of these JMJD3/HDAC inhibitors was further evaluated in TNBC cell models, where they exhibited potent antiproliferative activity and induced cell cycle arrest. Compared with previously reported JMJD3/HDAC dual inhibitors, 6a demonstrates superior nanomolar potency against both targets. As a highly potent lead, 6a provides a novel scaffold for dual-target epigenetic drug discovery, a valuable chemical probe for investigating epigenetic crosstalk, and a promising candidate for cancer therapy.