The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV–2) has emerged as a virus ofgrave concern due to its ability to cause the severe and life-threatening diseasecalledcoronavirus disease 2019 (COVID–19) with high mortality rate worldwide . World Health Organization (WHO) declared COVID–19 as a pandemic disease on 11 March 2020 . As per “situation report–63”released by WHO on 23 March 2020, more than300,000 cases and 14510deaths have been confirmed globally.ByJanuary 12, 2020 the Chinese authorities had released the whole genome sequence of SARS-CoV–2 which has been hallmark for researchers worldwide to quickly identify and develop the potential candidates by using computational methods and other therapeutic techniques . First publication along with other recent studies on current outbreak revealed that SARS-CoV–2 is a member of the coronavirus family and shared 96% similarity with previously identified genome of SARS-CoV that had emerged in China in November, 2002 .
Based on recent studies, this virus has a complex genomic organization consisting of single stranded-positive sense RNA which codes for several structural and non-structural proteins (nsps) including envelope protein (E) gene, spike protein (S) gene, membrane protein (M) gene, nucleocapsid protein (N) gene, replicase complex (orf1ab) gene along with 3’ and 5’-untranslated region (UTR) [5, 6]. As per study carried out by K. Anand et al. in 2003, coronaviruses make small polypeptide chains during transcription by proteolytic enzymes such as papain-like protease (PLpro) and 3-chymotrypsin-like protease (3CLpro) to form several types of non-structural proteins which are responsible for viral replication . Additionally, unique spike protein (S) has also been found to have a strong affinity with the human ACE2 receptor . Thus, both main protease and spike protein complexed with human ACE2 receptor might be important targets to discover and develop vaccines and other therapeutic agents to control this new CoV.
Since the first reported case of COVID 19 on 31 December 2019, no specific medication is available to prevent or kill the SARS-CoV–2 so far. Preliminary treatment of COVID–19 depends upon the severity of infection which ranges from mild to strong including, if necessary administration of oxygen, maintaining the body fluids and administration of antibiotics and antiviral drugs to combat co-infections because of numerous types of bacteria and virus . Recent studies suggested the use of remdisivir and chloroquine along with HIV–1 protease inhibitors like lopinavir and ritonavir as therapeutic agents for the treatment of COVID–19 . Moreover, Xu et al. identified four tested drugs nelfinavir, praziquantel, perampanel and pitavestatin as potential candidates against SARS-CoV–2 using computational methods. Therefore, three approaches need to be urgently pursued, namely vaccines, post exposure prophylaxis and therapeutic agents that target virus-encoded functions, replication, infection as well as the respiratory symptoms in humans that exacerbate the disease.
In the last decade, dietary moleculesfrom edible herbs and vegetables have ofgreat interest amongresearchers worldwide because of their diversified and complex structures having health benefits with no or minimal side-effects . These dietary molecules may be developed as herbal medicines or therapeutic agents in the prevention and treatment of current COVID–19 disease. In previous studies, numerous dietary molecules such as curcumin, savinin and betulinic acid have been found to show inhibition of SARS-CoV in the range of 3–10 μM concentrations . Recently, kaempferol, quercetin, luteolin–7-glucoside, demethoxycurcumin, naringenin, apigenin–7-glucoside, oleuropein, curcumin, catechin, and epicatechin-gallate have been identified as significant anti-COVID–19 agents with the help of molecular docking study . Seeing this terrible and deadly crisis, as yet, it is urgent and timely need to evaluate and develop more potent and reliable anti-COVID–19agents which are easy to reach us. In this study, we evaluated 18 dietary moleculesnamely epigallocatechin gallate (EGCG), piperine, apigenin, curcumin, gingerol-, beta glucan, resveratrol, myricetin, quercetin, genistein, diadzein, alliin, allicin, sulphoraphane, phycocyanobillin, ferulic acid and alpha lipoic acid by using molecular docking study. Our findings will provide valuable information to explore and develop dietary moleculesas novel anti-COVID–19 agents in the future.