Influenza a Virus Inhibition: Evaluating Computationally Identified Cyproheptadine Through In Vitro Assessment

Abstract

Influenza is still a chronic global health threat, inducing a sustained search for effective antiviral therapeutics. Computational methods have played a pivotal role in developing small molecule therapeutics. In this study, we applied a combined in silico and in vitro approach to explore the potential anti-influenza activity of cyproheptadine, a clinically used histamine H1 receptor antagonist. Virtual screening based on the average quasivalence number (AQVN) and electron-ion interaction potential (EIIP) descriptors suggests similarities between cyproheptadine and several established anti-influenza agents. The subsequent ligand-based pharmacophore screening of a focused H1 antagonist library was aligned with the bioinformatics prediction, and further experimental in vitro evaluation of cyproheptadine demonstrated its anti-influenza activity. These findings provide proof of concept for cyproheptadine's in silico-predicted antiviral potential and underscore the value of integrating computational predictions with experimental validation. The results of the current study provide a preliminary proof of concept for the predicted anti-influenza potential based on computational analysis and emphasize the utility of integrating in silico screening with experimental validation in the early stages of drug repurposing efforts.

Keywords: antiviral; cyproheptadine; drug resistance; influenza; virtual screening.

Figure 1

Schematic presentation of the EIIP/AQVN criterion for the selection of candidate anti-influenza compounds through the virtual screening of molecular libraries (green—NS1 inhibitors; blue—HA inhibitors; navy blue—M2 ion channel inhibitors; red—the AQVN/EIIP domain of histamine H1 receptor antagonists).

Figure 2

Structures of carbinoxamine (a) and chlorpheniramine (b) and the alignment of their conformations with the ligand-based pharmacophore. Cyproheptadine as a compound hit in a virtual screening of a library of antihistaminic compounds. Yellow spheres are hydrophobic features; blue spikes shows the positive ionizable area, and blue circles are aromatic ring features.

Figure 3

Influenza A/CA/07/2009 (H1N1) viral titers at 0, 1, and 2 days post-infection (dpi) after treatment with cyproheptadine with the indicated drug concentrations. Ten micromolar (10 μM) merimepodib was used as a positive control. The results are plotted as the means of triplicate observations, with standard deviations shown.