Ayurvedic antiviral agents: Overview of medicinal plants perspective

In recent years, it has been reported that many herbal plants contain antiviral agents which combat a human disease that is caused by pathogenic viruses. The natural products which are obtained from plants as antiviral agents against viruses have gone through researches to check the efficacy and potentials of the herbal products in the prevention of viral disorders. On the basis of randomized controlled studies and in-vivo studies, and in-vitro studies, some agents are utilized all across the globe. Progressively numerous studies on therapy of antivirals have been increased. Though, efficacy remains disputable for antiviral drugs that are employed for viral disorders. The viral diseases are challenging for the health of people around the world cause significant increase in mortality and enhance crises. There are many synthetic antiviral drugs that have a large number of side effects and have narrow therapeutic window range, while in the other hand herbal formulations have minimized side effects. The advantages of herbal formulation over synthetic drugs encourage us to devise and expand new herbal moieties against the emerging viral infections. The medicinal plants contain phytochemicals that have antiviral properties. In this paper, the activity of antiviral agents from medicinal plants which have importance in Ayurveda, are discussed along with their source.

Black tea bioactives as inhibitors of multiple targets of SARS-CoV-2 (3CLpro, PLpro and RdRp): a virtual screening and molecular dynamic simulation study.

The global pandemic due to the novel Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) has taken more than a million lives. Lack of definitive vaccine/drugs against this highly contagious virus has accelerated exploratory research on novel natural and synthetic inhibitors. Tea is a rich source of bioactives and known to have antiviral properties. In this study, an in silico strategy involving ADMET property screening, receptor-ligand docking and molecular dynamic (MD) simulation was employed to screen potential tea bio-active inhibitors against three selected targets (RdRp, 3CLpro and PLpro) of SARS-CoV-2. Among the 70 tea bioactives screened, theaflavin 3,3'-di-gallate (TF3), Procyanidin B2 and Theaflavin 3-gallate (TF2a) exhibited highest binding affinities towards RdRp, 3CLpro/Mpro and PLpro targets of SARS-CoV-2 with low docking scores of -14.92, -11.68 and -10.90 kcal/mol, respectively. All of them showed a substantial number of hydrogen bonds along with other interactions in and around the active sites. Interestingly, the top bioactives in our study showed higher binding affinities compared with known antiviral drugs. Further, the top protein-ligand complexes showed less conformational changes during binding when subjected to MD simulation for 100 nanoseconds. The MMPBSA results revealed that RdRp-TF3, 3CLpro-Procyanidin B2 and PLpro-TF2a complexes were stable with binding free energies of -93.59 ± 43.97, -139.78 ± 16.51 and -96.88 ± 25.39 kJ/mol, respectively. Our results suggest that theaflavin 3,3'-digallate, Theaflavin 3-gallate and Procyanidin B2 found in black tea have the potential to act as inhibitors for selected targets of SARS-CoV-2 and can be considered as drug candidates in future studies against COVID-19.

The potential role of procyanidin as a therapeutic agent against SARS-CoV-2: a text mining, molecular docking and molecular dynamics simulation approach.

A novel coronavirus (SARS-CoV-2) has caused a major outbreak in human all over the world. There are several proteins interplay during the entry and replication of this virus in human. Here, we have used text mining and named entity recognition method to identify co-occurrence of the important COVID 19 genes/proteins in the interaction network based on the frequency of the interaction. Network analysis revealed a set of genes/proteins, highly dense genes/protein clusters and sub-networks of Angiotensin-converting enzyme 2 (ACE2), Helicase, spike (S) protein (trimeric), membrane (M) protein, envelop (E) protein, and the nucleocapsid (N) protein. The isolated proteins are screened against procyanidin-a flavonoid from plants using molecular docking. Further, molecular dynamics simulation of critical proteins such as ACE2, Mpro and spike proteins are performed to elucidate the inhibition mechanism. The strong network of hydrogen bonds and hydrophobic interactions along with van der Waals interactions inhibit receptors, which are essential to the entry and replication of the SARS-CoV-2. The binding energy which largely arises from van der Waals interactions is calculated (ACE2=-50.21 ± 6.3, Mpro=-89.50 ± 6.32 and spike=-23.06 ± 4.39) through molecular mechanics Poisson-Boltzmann surface area also confirm the affinity of procyanidin towards the critical receptors. Communicated by Ramaswamy H. Sarma.