Cannabidiol inhibits SARS-Cov-2 spike (S) protein-induced cytotoxicity and inflammation through a PPARγ-dependent TLR4/NLRP3/Caspase-1 signaling suppression in Caco-2 cell line.

Given the abundancy of angiotensin converting enzyme 2 (ACE-2) receptors density, beyond the lung, the intestine is considered as an alternative site of infection and replication for severe acute respiratory syndrome by coronavirus type 2 (SARS-CoV-2). Cannabidiol (CBD) has recently been proposed in the management of coronavirus disease 2019 (COVID-19) respiratory symptoms because of its anti-inflammatory and immunomodulatory activity exerted in the lung. In this study, we demonstrated the in vitro PPAR-γ-dependent efficacy of CBD (10-9 -10-7  M) in preventing epithelial damage and hyperinflammatory response triggered by SARS-CoV-2 spike protein (SP) in a Caco-2 cells. Immunoblot analysis revealed that CBD was able to reduce all the analyzed proinflammatory markers triggered by SP incubation, such as tool-like receptor 4 (TLR-4), ACE-2, family members of Ras homologues A-GTPase (RhoA-GTPase), inflammasome complex (NLRP3), and Caspase-1. CBD caused a parallel inhibition of interleukin 1 beta (IL-1ß), IL-6, tumor necrosis factor alpha (TNF-α), and IL-18 by enzyme-linked immunosorbent assay (ELISA) assay. By immunofluorescence analysis, we observed increased expression of tight-junction proteins and restoration of transepithelial electrical resistance (TEER) following CBD treatment, as well as the rescue of fluorescein isothiocyanate (FITC)-dextran permeability induced by SP. Our data indicate, in conclusion, that CBD is a powerful inhibitor of SP protein enterotoxicity in vitro.

Molecular Docking and Molecular Dynamics Aided Virtual Search of OliveNet™ Directory for Secoiridoids to Combat SARS-CoV-2 Infection and Associated Hyperinflammatory Responses.

Molecular docking and molecular dynamics aided virtual search of OliveNet™ directory identified potential secoiridoids that combat SARS-CoV-2 entry, replication, and associated hyperinflammatory responses. OliveNet™ is an active directory of phytochemicals obtained from different parts of the olive tree, Olea europaea (Oleaceae). Olive oil, olive fruits containing phenolics, known for their health benefits, are indispensable in the Mediterranean and Arabian diets. Secoiridoids is the largest group of olive phenols and is exclusive to the olive fruits. Functional food like olive fruits could help prevent and alleviate viral disease at an affordable cost. A systematized virtual search of 932 conformers of 78 secoiridoids utilizing Autodock Vina, followed by precision docking using Idock and Smina indicated that Nüzhenide oleoside (NZO), Oleuropein dimer (OED), and Dihydro oleuropein (DHO) blocked the SARS-CoV-2 spike (S) protein-ACE-2 interface; Demethyloleuropein (DMO), Neo-nüzhenide (NNZ), and Nüzhenide (NZE) blocked the SARS-CoV-2 main protease (Mpro). Molecular dynamics (MD) simulation of the NZO-S-protein-ACE-2 complex by Desmond revealed stability during 50 ns. RMSD of the NZO-S-protein-ACE-2 complex converged at 2.1 Å after 20 ns. During MD, the interaction fractions confirmed multiple interactions of NZO with Lys417, a crucial residue for inhibition of S protein. MD of DMO-Mpro complex proved its stability as the RMSD converged at 1.6 Å. Analysis of interactions during MD confirmed the interaction of Cys145 of Mpro with DMO and, thus, its inhibition. The docking predicted IC50 of NZO and DMO was 11.58 and 6.44 µM, respectively. Molecular docking and dynamics of inhibition of the S protein and Mpro by NZO and DMO correlated well. Docking of the six-hit secoiridoids to IL1R, IL6R, and TNFR1, the receptors of inflammatory cytokines IL1ß, IL6, and TNFα, revealed the anti-inflammatory potential except for DHO. Due to intricate structures, the secoiridoids violated Lipinski's rule of five. However, the drug scores of secoiridoids supported their use as drugs. The ADMET predictions implied that the secoiridoids are non-toxic and pose low oral absorption. Secoiridoids need further optimization and are a suitable lead for the discovery of anti-SARS-CoV-2 therapeutics. For the moment, olive secoiridoids presents an accessible mode of prevention and therapy of SARS-CoV-2 infection.

A perspective on potential target proteins of COVID-19: Comparison with SARS-CoV for designing new small molecules.

SARS-CoV-2 (COVID-19) epidemic has created an unprecedented medical and economic crisis all over the world. SARS-CoV-2 is found to have more contagious character as compared to MERS-CoV and is spreading in a very fast manner all around the globe. It has affected over 31 million people all over the world till date. This virus shares around 80% of genome similarity with SARS-CoV. In this perspective, we have explored three major targets namely; SARS-CoV-2 spike (S) protein, RNA dependent RNA polymerase, and 3CL or Mpro Protease for the inhibition of SARS-CoV-2. These targets have attracted attention of the medicinal chemists working on computer-aided drug design in developing new small molecules that might inhibit these targets for combating COVID-19 disease. Moreover, we have compared the similarity of these target proteins with earlier reported coronavirus (SARS-CoV). We have observed that both the coronaviruses share around 80% similarity in their amino acid sequence. The key amino acid interactions which can play a crucial role in designing new small molecule inhibitors against COVID-19 have been reported in this perspective. Authors believe that this study will help the medicinal chemists to understand the key amino acids essential for interactions at the active site of target proteins in SARS-CoV-2, based on their similarity with earlier reported viruses. In this review, we have also described the lead molecules under various clinical trials for their efficacy against COVID-19.

The inorganic polymer, polyphosphate, blocks binding of SARS-CoV-2 spike protein to ACE2 receptor at physiological concentrations.

Inorganic polyphosphate (polyP) is a morphogenetically active and metabolic energy-delivering physiological polymer that is released from blood platelets. Here, we show that polyP efficiently inhibits the binding of the envelope spike (S)-protein of the coronavirus SARS-CoV-2, the causative agent of COVID-19, to its host cell receptor ACE2 (angiotensin-converting enzyme 2). To stabilize polyP against the polyP-degrading alkaline phosphatase, the soluble polymer was encapsulated in silica/polyP nanoparticles. Applying a binding assay, soluble Na-polyP (sizes of 40 Pi and of 3 Pi units) as well as silica-nanoparticle-associated polyP significantly inhibit the interaction of the S-protein with ACE2 at a concentration of 1 µg/mL, close to the level present in blood. This inhibition is attributed to an interaction of polyP with a basic amino acid stretch on the surface of the receptor binding domain of S-protein. PolyP retains its activity in a flushing solution, opening a new strategy for the prevention and treatment of SARS-CoV-2 infection in the oropharyngeal cavity. The data suggest that supplementation of polyP might contribute to a strengthening of the human innate immunity system in compromised, thrombocytopenic COVID-19 patients.