In Silico Screening of Natural Products as Potential Inhibitors of SARS-CoV-2 Using Molecular Docking Simulation.

OBJECTIVE: To explore potential natural products against severe acute respiratory syndrome coronavirus (SARS-CoV-2) via the study of structural and non-structural proteins of human coronaviruses. METHODS: In this study, we performed an in-silico survey of 25 potential natural compounds acting against SARS-CoV-2. Molecular docking studies were carried out using compounds against 3-chymotrypsin-like protease (3CLPRO), papain-like protease (PLPRO), RNA-dependent RNA polymerase (RdRp), non-structural protein (nsp), human angiotensin converting enzyme 2 receptor (hACE2R), spike glycoprotein (S protein), abelson murine leukemia viral oncogene homolog 1 (ABL1), calcineurin-nuclear factor of activated T-cells (NFAT) and transmembrane protease serine 2. RESULTS: Among the screened compounds, amentoflavone showed the best binding affinity with the 3CLPRO, RdRp, nsp13, nsp15, hACE2R. ABL1 and calcineurin-NFAT; berbamine with hACE2R and ABL1; cepharanthine with nsp10, nsp14, nsp16, S protein and ABL1; glucogallin with nsp15; and papyriflavonol A with PLPRO protein. Other good interacting compounds were juglanin, betulinic acid, betulonic acid, broussooflavan A, tomentin A, B and E, 7-methoxycryptopleurine, aloe emodin, quercetin, tanshinone I, tylophorine and furruginol, which also showed excellent binding affinity towards a number of target proteins. Most of these compounds showed better binding affinities towards the target proteins than the standard drugs used in this study. CONCLUSION: Natural products or their derivatives may be one of the potential targets to fight against SARS-CoV-2.

COVID-19 Pandemic: Epidemiology, Etiology, Conventional and Non-Conventional Therapies.

Coronavirus disease 2019 (COVID-19), which reported in an outbreak in 2019 in Wuhan, Hubei province, China, is caused by the SARS-CoV-2 virus. The virus belongs to the beta-coronavirus class, along with the Middle East Respiratory Syndrome coronavirus and Severe Acute Respiratory Syndrome coronavirus. Interestingly, the virus binds with angiotensin-converting enzyme-2 found in host cells, through the spike (S) protein that exists on its surface. This binding causes the entry of the virus into cells of the host organism. The actual mechanism used by the COVID-19 virus to induce disease is still speculative. A total of 44,322,504 cases, a 1,173,189 death toll and 32,486,703 recovery cases have been reported in 217 countries globally as of 28 October 2020. Symptoms from the infection of the virus include chest pain, fever, fatigue, nausea, and others. Acute respiratory stress syndrome, arrhythmia, and shock are some of the chronic manifestations recorded in severe COVID-19. Transmission is majorly by individual-to-individual through coughing, sneezing, etc. The lack of knowledge regarding the mechanism of and immune response to the virus has posed a challenge in the development of a novel drug and vaccine. Currently, treatment of the disease involves the use of anti-viral medications such as lopinavir, remdesivir, and other drugs. These drugs show some efficacy in the management of COVID-19. Studies are still on-going for the development of an ideal and novel drug for treatment. In terms of natural product intervention, Traditional Chinese Medicines (TCM) have been employed to alleviate the clinical manifestation and severity of the disease and have shown some efficacy. This review presents an updated detailed overview of COVID-19 and the virus, concerning its structure, epidemiology, symptoms and transmission, immune responses, and current interventions, and highlights the potential of TCM. It is anticipated that this review will further add to the understanding of COVID-19 and the virus, hence opening new research perspectives.