In Silico Screening of Potential Phytocompounds from Several Herbs against SARS-CoV-2 Indian Delta Variant B.1.617.2 to Inhibit the Spike Glycoprotein Trimer

In October 2020, the SARS-CoV-2 B.1.617 lineage was discovered in India. It has since become a prominent variant in several Indian regions and 156 countries, including the United States of America. The lineage B.1.617.2 is termed the delta variant, harboring diverse spike mutations in the N-terminal domain (NTD) and the receptor-binding domain (RBD), which may heighten its immune evasion potentiality and cause it to be more transmissible than other variants. As a result, it has sparked substantial scientific investigation into the development of effective vaccinations and anti-viral drugs. Several efforts have been made to examine ancient medicinal herbs known for their health benefits and immune-boosting action against SARS-CoV-2, including repurposing existing FDA-approved anti-viral drugs. No efficient anti-viral drugs are available against the SARS-CoV-2 Indian delta variant B.1.617.2. In this study, efforts were made to shed light on the potential of 603 phytocompounds from 22 plant species to inhibit the Indian delta variant B.1.617.2. We also compared these compounds with the standard drug ceftriaxone, which was already suggested as a beneficial drug in COVID-19 treatment;these compounds were compared with other FDA-approved drugs: remdesivir, chloroquine, hydroxy-chloroquine, lopinavir, and ritonavir. From the analysis, the identified phytocompounds acteoside (-7.3 kcal/mol) and verbascoside (-7.1 kcal/mol), from the plants Clerodendrum serratum and Houttuynia cordata, evidenced a strong inhibitory effect against the mutated NTD (MT-NTD). In addition, the phytocompounds kanzonol V (-6.8 kcal/mol), progeldanamycin (-6.4 kcal/mol), and rhodoxanthin (-7.5 kcal/mol), from the plant Houttuynia cordata, manifested significant prohibition against RBD. Nevertheless, the standard drug, ceftriaxone, signals less inhibitory effect against MT-NTD and RBD with binding affinities of -6.3 kcal/mol and -6.5 kcal/mol, respectively. In this study, we also emphasized the pharmacological properties of the plants, which contain the screened phytocompounds. Our research could be used as a lead for future drug design to develop anti-viral drugs, as well as for preening the Siddha formulation to control the Indian delta variant B.1.617.2 and other future SARS-CoV-2 variants.

Oleanolic acid and ursolic acid

According to the World Health Organization (WHO), more than 70% of worldwide mortality rates can be attributed to noncommunicable diseases (NCDs) and these figures are going to be more alarming after the Covid-19 outbreak. The careful examination of in-vitro tests, in-vivo studies, and clinical models undertaken establish that the intake of fruits/vegetables rich in bioactives can reduce the risk of NCD. Oleanolic acid (OA) and its isomer ursolic acid (UA) fall under the ubiquitous class of pentacyclic triterpenoid bioactives mainly present in medicinal plants, herbs, fruit, and vegetables. In addition to antioxidant, antiinflammatory, and anticancer activities, the diet rich in OA and UA may regulate the human immune system. The protective role and clinically useful activities of OA and UA motivated us to highlight various features, points, and critical concerns regarding biogenesis, extraction, isolation, or purification of these valuable bioactives. Moreover, this chapter consolidates and expands stories of clinical trials undertaken during the last couple of decades to evaluate the biological activities and toxicities of these triterpenoids. © 2021 Elsevier Inc.

Syzygium aromaticum as a possible source of SARS-CoV-2 main protease inhibitors: evidence from a computational investigation

SARS-CoV-2, a new and fast circulating coronavirus strain, infected over 214 countries and territories worldwide and caused global health emergencies. The absence of appropriate medicines and vaccinations has further complicated the condition. SARS-CoV-2 main protease (Mpro) is crucial for its propagation, and it is considered a striking target. This study used several computational approaches to determine the probable antagonist of SARS-CoV-2 Mpro from bioactive phytochemicals of Syzygium aromaticum. A total of 20 compounds were screened through in silico approach. The molecular dynamics simulation studies were then carried out for further insights. We found crategolic acid, oleanolic acid, and kaempferol have considerable binding affinity and important molecular contacts with catalytic pocket residues, His41-Cys145. The pharmacological properties through ADMET analysis also showed that these compounds could be used as safe drug candidates. The molecular dynamics simulation study further confirmed these compound's stability with Mpro. However, further detailed in-vitro and in-vivo analyses are compulsory to evaluate the real potentiality of identified compounds.

Strong Inhibitory Activity and Action Modes of Synthetic Maslinic Acid Derivative on Highly Pathogenic Coronaviruses: COVID-19 Drug Candidate.

In late December 2019, a novel coronavirus, namely severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), escaped the animal-human interface and emerged as an ongoing global pandemic with severe flu-like illness, commonly known as coronavirus disease 2019 (COVID-19). In this study, a molecular docking study was carried out for seventeen (17) structural analogues prepared from natural maslinic and oleanolic acids, screened against SARS-CoV-2 main protease. Furthermore, we experimentally validated the virtual data by measuring the half-maximal cytotoxic and inhibitory concentrations of each compound. Interestingly, the chlorinated isoxazole linked maslinic acid (compound 17) showed promising antiviral activity at micromolar non-toxic concentrations. Thoughtfully, we showed that compound 17 mainly impairs the viral replication of SARS-CoV-2. Furthermore, a very promising SAR study for the examined compounds was concluded, which could be used by medicinal chemists in the near future for the design and synthesis of potential anti-SARS-CoV-2 candidates. Our results could be very promising for performing further additional in vitro and in vivo studies on the tested compound (17) before further licensing for COVID-19 treatment.

Anti-COVID drugs: repurposing existing drugs or search for new complex entities, strategies and perspectives.

At the end of 2019, a novel virus causing severe acute respiratory syndrome to spread globally. There are currently no effective drugs targeting SARS-CoV-2. In this study, based on the analysis of numerous references and selected methods of computational chemistry, the strategy of integrative structural modification of small molecules with antiviral activity into potential active complex molecules has been presented. Proposed molecules have been designed based on the structure of triterpene oleanolic acid and complemented by structures characteristic of selected anti-COVID therapy assisted drugs. Their pharmaceutical molecular parameters and the preliminary bioactivity were calculated and predicted. The results of the above analyses show that among the designed complex substances there are potential antiviral agents directed mainly on SARS-CoV-2.

Identification of phytochemical inhibitors against main protease of COVID-19 using molecular modeling approaches.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel corona virus that causes corona virus disease 2019 (COVID-19). The COVID-19 rapidly spread across the nations with high mortality rate even as very little is known to contain the virus at present. In the current study, we report novel natural metabolites namely, ursolic acid, carvacrol and oleanolic acid as the potential inhibitors against main protease (Mpro) of COVID-19 by using integrated molecular modeling approaches. From a combination of molecular docking and molecular dynamic (MD) simulations, we found three ligands bound to protease during 50 ns of MD simulations. Furthermore, the molecular mechanic/generalized/Born/Poisson-Boltzmann surface area (MM/G/P/BSA) free energy calculations showed that these chemical molecules have stable and favourable energies causing strong binding with binding site of Mpro protein. All these three molecules, namely, ursolic acid, carvacrol and oleanolic acid, have passed the ADME (Absorption, Distribution, Metabolism, and Excretion) property as well as Lipinski's rule of five. The study provides a basic foundation and suggests that the three phytochemicals, viz. ursolic acid, carvacrol and oleanolic acid could serve as potential inhibitors in regulating the Mpro protein's function and controlling viral replication. Communicated by Ramaswamy H. Sarma.