Design, Synthesis, and Antiviral Evaluation of Novel 3,4-Dihydropyrimidin-2(1H)-one Derivatives

The 3,4-dihydropyrimidin-2(1H)-one (DHPM) scaffold possesses diverse biological activities and chemical tunability, allowing structural modifications to modulate antiviral, anticancer, and anti-inflammatory effects. In this study, a series of DHPM derivatives with varied substituents were designed and synthesized, and their structures were characterized by 1H NMR, 13C NMR and HRMS. Their antiviral activities against pseudorabies virus (PRV) and vesicular stomatitis virus (VSV) were evaluated. In vitro assays revealed that several compounds exhibited significant antiviral effects, with 4bf (SI = 243.08 against PRV), 4ce (SI = 196.4 against VSV), and 4be (SI = 124.2 against PRV; SI = 181.1 against VSV) showing the most potent activity. Further studies demonstrated effective inhibition of viral titers, and Western blot and qRT-PCR analyses confirmed downregulation of viral proteins and related genes. Cytotoxicity tests indicated that 4bf, 4ce, and 4be had CC50 values of 270.0, 147.1, and 190.9 μg/mL, respectively, suggesting favorable safety profiles. In vivo experiments showed that 4bf, without affecting normal growth, alleviated PRV-induced pulmonary inflammation and tissue damage, and improved survival in mice. Taken together, DHPM-based compounds demonstrate promising potential as candidate antiviral agents, warranting further development.