This report presents the design and synthesis of quinazolinone-based derivatives as promising SARS-CoV-2
3CL protease inhibitors. Two novel series, namely, febrifugine analogues 4a–i and quinazolinone
conjugated benzimidazoles 9a–c, were successfully synthesized starting from isatoic anhydride. The
synthesized quinazolinone derivatives were evaluated for their cytotoxicity against cancer cell lines and
SARS-CoV-2 3CL inhibitory activity. The results showed that the synthesized compounds did not have
significant toxicity for the non-cancer HEK293 cell line and MCF-7, MDA-MB-231, HEPG2 and
HEPG2.2.15 cancer cell lines. Notably, compound 9b exhibited anti-3CL enzymatic activity in a dosedependent
manner, with the calculated IC50 value of 10.73 ± 1.17 mM. Docking results highlighted the
interaction between 9b and 3CL protease through hydrogen bonding with key amino acids, including
His41, Met49, Cys145, Met165, Arg188, His164, and Glu166, at the active site of the protease.
Pharmacokinetic studies and ADME analyses provide valuable insights into the potential of compound 9b
as a drug candidate. These findings support the new scaffold as a candidate for 3CLpro inhibition and
advanced anti-coronavirus drug research.