Effectiveness of Quercetin and Its Derivatives Against SARS CoV2 -In silico Approach

The COVID-19 pandemic that erupted in November 2019 is continuing, with no effective antiviral agent to date. Synthetic antiviral agents have limitations such as a narrow range of therapeutic effectiveness of the activity, toxicity, and resistant viral strains and traditional antiviral medicines at large seem not to have these limitations. Here, some of the existing phytochemicals are cherry-picked for repurposing against the enzyme or protein targets of SARS CoV2, by the principles of structure-based drug design based on molecular docking studies. The most important drug targets of SARS CoV2 namely, Mpro protease (6LU7), RdRp polymerase (7BTF), and Spike glycoprotein of SARS CoV2(6VSB) were employed for docking analysis with chosen phytochemicals and binding affinity was calculated using PRODIGY software and docking sites determined using Chimera software. For docking studies, 160 phytochemicals were selected from a large pool of phytochemicals. Based on the binding affinity values, 61 phytoconstituents were selected for further in-silico screening which resulted in 15 phytochemicals, with higher binding affinity to spike glycoprotein of SARS CoV2. Moreover, Guaijaverin, Quercetin, Quercitrin, Quinic acid, and spiraeoside binds both to the spike glycoprotein of SARS Cov2 and the host receptor of human ACE2. Hence these compounds may serve as two-pronged drug candidates for SARS CoV2. In nutshell, we present a few phytochemical candidates with higher binding affinity to the Spike protein of SARS CoV2, which needs to be further optimized by in vitro studies to minimize the cytotoxicity and increase or retain the binding affinity, towards an effective antiviral drug against COVID 19