Insights into antiviral activity of chlorpromazine against RNA viruses: Molecular docking, ADME profile, and semi-in vivo study.

Viral entry into the host cell is a limiting step in the viral-related pathogenesis, where many viruses utilize different endocytic pathways, particularly clathrin-mediated endocytosis (CME), in cell invasion. Previously, we reclassified endocytosis inhibitors based on their mode of action, where compounds like phenothiazine derivatives inhibit viral endocytosis through different mechanisms. Also, the multifaceted therapeutic potential of these derivatives, like chlorpromazine (CPZ), is attributed to their endocytosis and non-endocytosis-related effects. Thus, this study was designed to investigate CPZ's antiviral activity against two RNA viruses and to explore how does it interact with structural and regulatory viral proteins. In addition to in silico studies that included molecular interaction and ADME profiling of CPZ, its antiviral activity against infectious bronchitis virus (IBV) and avian influenza virus (N5H1, AIV5) was evaluated by cytotoxicity assay, development of gross lesions in chicken embryos, hemagglutination (HA) assay, and viral replication in chicken embryos by qRT-PCR. The results demonstrated that CPZ interacts with integral IBV proteins, including spike (S), polymerase, and nucleocapsid proteins. Moreover, it interacts with N5H1's polymerase complexes, nucleoprotein (NP), neuraminidase, and hemagglutinin. Furthermore, ADME profiling suggested that CPZ has better physicochemical characteristics and higher oral bioavailability than Remdesivir, due to its molecular flexibility and polarity. In parallel, experimental investigations revealed the cytotoxic effect at high doses and antiviral activity against both viruses, which led to stunted growth and reduced weight, attenuated replication, induced growth lesions in chicken embryos, and decreased the hemagglutinin (HA) titer at early developmental stages. In summary, the study repurposed CPZ as an antiviral agent, as the synergistic use of molecular docking, ADME studies, in vitro, and in vivo antiviral assays suggested its broad antiviral activity against IBV and N5H1.