Pomegranate peel polyphenols prophylaxis against SARS-CoV-2 main protease by <i>in-silico</i> docking and molecular dynamics study

Pomegranate peel, the waste product generated from pomegranate fruit, has prophylactic properties, such as antimicrobial, anti-malarial, and controls respiratory infections and influenza. Based on the previous literature and need of the hour, molecular docking was performed to evaluate the inhibitory effects of major pomegranate peel polyphenols against COVID-19. Among the 44 studied compounds, 37 polyphenols show interaction with the catalytic dyad of the Mpro protease and 18 polyphenols have a higher binding affinity than that of the Mpro protease inhibitor (N3), indicating their high probability of binding at ACE2: SARS-CoV-2 interface. Furthermore, several polyphenols studied in this work are found to have higher binding affinity as compared to those of hydroxychloroquine, lopinavir, nelfinavir, and curcumin, some of which have been earlier tested against COVID-19. Further, molecular dynamics simulations (200 ns) for Mpro–polyphenols including pelargonidin3-glucoside, quercetin3-O-rhamnoside, cyanidin3-glucoside and punicalin revealed highly stable complexes with less conformational fluctuations and similar degree of compactness. Estimation of total number of intermolecular hydrogen bonds and binding free energy confirmed the stability of these Mpro–polyphenol complexes over Mpro–curcumin complex. Based on the greater binding affinity of polyphenols of pomegranate peel towards Mpro as compared to that of curcumin, pomegranate peel may be considered in any herbal medicinal formulation or may be incorporated into daily diets for prevention of COVID-19. Communicated by Ramaswamy H. Sarma