Synthesis and anti-SARS-CoV-2 activity of amino acid modified cephalotaxine derivatives.

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) pandemic has triggered a significant impact on global public health security, it is urgent to develop effective antiviral drugs. Previous studies have found that binding to ACE2 is a key step in the invasion of SARS-CoV-2 into host cells, so virus invasion can be inhibited by blocking ACE2, but there are few reports on this kind of specific inhibitor. Our previous study found that Harringtonine (HT) can inhibit the entry of SARS-CoV-2 spike pseudovirus into ACE2h cells, but its relatively high cytotoxicity limits its further development. Amino acid modification of the active components can increase their solubility and reduce their cytotoxicity. Therefore, in this study, seven new derivatives were synthesized by amino acid modification of its core structure Cephalotaxine. The target compounds were evaluated by cell viability assay and the SARS-CoV-2 spike pseudovirus entry assay. Compound CET-1 significantly inhibited the entry of pseudovirus into ACE2h cells and showed less cytotoxicity than HT. Molecular docking results showed that CET-1 could bind TYR83, an important residue of ACE2, just like HT. In conclusion, our study provided a novel compound with more potential activity and lower toxicity than HT on inhibiting the SARS-CoV-2 spike pseudovirus infection, which makes it possible to be a lead compound as an antiviral drug in the future.

Si M ，An M ，Xia Z ，Mo X ，Lu J ，He H ，Wang C ... -  《-》

Harringtonine metabolites: 5'-de-O-methylharringtonine and cephalotaxine, targeting spike protein and TMPRSS2 to double block membrane fusion of SARS-CoV-2 and its variants.

Gao J ，Hu S ，Ma X ，Zhang Y ，Ren B ，Lei P ，Ma W ，He L ... -  《-》

Discovery of Novel Spike Inhibitors against SARS-CoV-2 Infection.

Tai LT ，Yeh CY ，Chang YJ ，Liu JF ，Hsu KC ，Cheng JC ，Lu CH ... -  《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》

Withanone from Withania somnifera Attenuates SARS-CoV-2 RBD and Host ACE2 Interactions to Rescue Spike Protein Induced Pathologies in Humanized Zebrafish Model.

SARS-CoV-2 engages human ACE2 through its spike (S) protein receptor binding domain (RBD) to enter the host cell. Recent computational studies have reported that withanone and withaferin A, phytochemicals found in Withania somnifera, target viral main protease (MPro) and host transmembrane TMPRSS2, and glucose related protein 78 (GRP78), respectively, implicating their potential as viral entry inhibitors. Absence of specific treatment against SARS-CoV-2 infection has encouraged exploration of phytochemicals as potential antivirals. This study aimed at in silico exploration, along with in vitro and in vivo validation of antiviral efficacy of the phytochemical withanone. Through molecular docking, molecular dynamic (MD) simulation and electrostatic energy calculation the plausible biochemical interactions between withanone and the ACE2-RBD complex were investigated. These in silico observations were biochemically validated by ELISA-based assays. Withanone-enriched extract from W. somnifera was tested for its ability to ameliorate clinically relevant pathological features, modelled in humanized zebrafish through SARS-CoV-2 recombinant spike (S) protein induction. Withanone bound efficiently at the interacting interface of the ACE2-RBD complex and destabilized it energetically. The electrostatic component of binding free energies of the complex was significantly decreased. The two intrachain salt bridge interactions (K31-E35) and the interchain long-range ion-pair (K31-E484), at the ACE2-RBD interface were completely abolished by withanone, in the 50 ns simulation. In vitro binding assay experimentally validated that withanone efficiently inhibited (IC50=0.33 ng/mL) the interaction between ACE2 and RBD, in a dose-dependent manner. A withanone-enriched extract, without any co-extracted withaferin A, was prepared from W. somnifera leaves. This enriched extract was found to be efficient in ameliorating human-like pathological responses induced in humanized zebrafish by SARS-CoV-2 recombinant spike (S) protein. In conclusion, this study provided experimental validation for computational insight into the potential of withanone as a potent inhibitor of SARS-CoV-2 coronavirus entry into the host cells.

Balkrishna A ，Pokhrel S ，Singh H ，Joshi M ，Mulay VP ，Haldar S ，Varshney A ... -  《Drug Design Development and Therapy》

Repositioning of histamine H(1) receptor antagonist: Doxepin inhibits viropexis of SARS-CoV-2 Spike pseudovirus by blocking ACE2.

The spread of the corona virus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been intensifying in the past year, posing a huge threat to global health. There is an urgent need for effective drugs and vaccines to fight the COVID-19, but their advent may not be quite fast. Drug repurposing is a feasible strategy in the current situation, which could greatly shorten drug development time and help to response quickly to the novel virus outbreak. It has been reported that histamine H1 receptor antagonists have broad-spectrum antiviral effects. Therefore, in this study, we aim to screen potential drugs among histamine H1 receptor antagonists that may inhibit SARS-CoV-2 infection. Based on the model of angiotensin-converting enzyme 2 (ACE2) overexpressing HEK293T cell membrane chromatography (CMC), five FDA-approved histamine H1 receptor antagonists were found to have bioaffinity to ACE2. Then we determined the interaction between these drugs and ACE2 by frontal analysis and surface plasmon resonance (SPR), which consistently demonstrated that these hits bind to ACE2 at micromolar levels of affinity. Through the pseudovirus assay, we finally identified that doxepin could inhibit SARS-CoV-2 spike pseudovirus from entering the ACE2-expressing cell, reducing the infection rate to 25.82%. These preliminary results indicate that the histamine H1 receptor antagonist, doxepin, is a viable drug candidate for clinical trials. Therefore, we hope the work timely provides rational help for developing anti-SARS-CoV-2 drugs to control the rapid spread of SARS-CoV-2.

Ge S ，Wang X ，Hou Y ，Lv Y ，Wang C ，He H ... -  《-》