Design, molecular docking, synthesis and in vitro evaluation of anti-influenza activity of oseltamivir carboxamides and their hybrid molecules with hydroxamic acid

Abstract

Background The influenza virus is a highly contagious respiratory disease that causes seasonal outbreaks and occasionally, unpredictable pandemics with high morbidity and mortality rates. This problem is exacerbated by the lack of drugs with potential antiviral activity against all types of influenza strains, including resistant strains. Therefore, there is an urgent need to develop novel antiviral agents. Methods The synthesis of new oseltamivir carboxamides with amino acids and the subsequent synthesis of hybrid molecules with hydroxamic acid were considered. Two series are presented as series one; oseltamivir carboxamides with L-serine, L-isoleucine, L-phenylalanine, L-tyrosine and series two included hydroxamates of series one. This approach may provide promising candidates with potential anti-influenza activity. The in vitro cytotoxic activity against Madin-Darby Canine Kidney (MDCK), type (NBL-2) - CCL-34 cells using the MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to determine the half maximal inhibitory concentrations (IC50) of the investigated compounds. The percent inhibition of neuraminidase was plotted against concentrations and the IC50 values were calculated by non-linear logistic curve fitting. Results The compounds were subjected to molecular docking using the GOLD suite (version 5.7.1) to predict the binding affinities for neuraminidase (3CL0). The docking scores are presented as PLP fitness and are comparable to those of oseltamivir. Oseltamivir-Phenylalanine recorded the highest docking score (72.23 kcal/mol), while, oseltamivir acid was recorded (56.24 kcal/mol). The ADMET parameters were generated using the Swiss ADME server to predict successful candidates with reasonable oral absorption and safety margins. All compounds are safer than oseltamivir and their IC50 values for neuraminidase inhibition were variable. The hybrids showed a lower percentage of viable cells. Oseltamivir-phenylalanine had the highest inhibitory activity against neuraminidase (3.03 μM), when compared with oseltamivir (67.22 μM). Conclusion Oseltamivir-phenylalanine showed remarkable and very significant activity, and the hybrid molecules were surprisingly less effective on neuraminidase than oseltamivir carboxamides.