Xanthohumol Is a Potent Pan-Inhibitor of Coronaviruses Targeting Main Protease.

Coronaviruses cause diseases in humans and livestock. The SARS-CoV-2 is infecting millions of human beings, with high morbidity and mortality worldwide. The main protease (Mpro) of coronavirus plays a pivotal role in viral replication and transcription, which, in theory, is an attractive drug target for antiviral drug development. It has been extensively discussed whether Xanthohumol is able to help COVID-19 patients. Here, we report that Xanthohumol, a small molecule in clinical trials from hops (Humulus lupulus), was a potent pan-inhibitor for various coronaviruses by targeting Mpro, for example, betacoronavirus SARS-CoV-2 (IC50 value of 1.53 µM), and alphacoronavirus PEDV (IC50 value of 7.51 µM). Xanthohumol inhibited Mpro activities in the enzymatical assays, while pretreatment with Xanthohumol restricted the SARS-CoV-2 and PEDV replication in Vero-E6 cells. Therefore, Xanthohumol is a potent pan-inhibitor of coronaviruses and an excellent lead compound for further drug development.

Structural and biochemical characterization of SADS-CoV papain-like protease 2.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel coronavirus that is involved in severe diarrhea disease in piglets, causing considerable agricultural and economic loss in China. The emergence of this new coronavirus increases the importance of understanding SADS-CoV as well as antivirals. Coronaviral proteases, including main proteases and papain-like proteases (PLP), are attractive antiviral targets because of their essential roles in polyprotein processing and thus viral maturation. Here, we describe the biochemical and structural identification of recombinant SADS papain-like protease 2 (PLP2) domain of nsp3. The SADS-CoV PLP2 was shown to cleave nsp1 proteins and also peptides mimicking the nsp2|nsp3 cleavage site and also had deubiquitinating and deISGynating activity by in vitro assays. The crystal structure adopts an architecture resembling that of PLPs from other coronaviruses. We characterize both conserved and unique structural features likely directing the interaction of PLP2 with the substrates, including the tentative mapping of active site and other essential residues. These results provide a foundation for understanding the molecular basis of coronaviral PLPs' catalytic mechanism and for the screening and design of therapeutics to combat infection by SADS coronavirus.

Anti-HCV, nucleotide inhibitors, repurposing against COVID-19.

AIMS: A newly emerged Human Coronavirus (HCoV) is reported two months ago in Wuhan, China (COVID-19). Until today >2700 deaths from the 80,000 confirmed cases reported mainly in China and 40 other countries. Human to human transmission is confirmed for COVID-19 by China a month ago. Based on the World Health Organization (WHO) reports, SARS HCoV is responsible for >8000 cases with confirmed 774 deaths. Additionally, MERS HCoV is responsible for 858 deaths out of about 2500 reported cases. The current study aims to test anti-HCV drugs against COVID-19 RNA dependent RNA polymerase (RdRp). MATERIALS AND METHODS: In this study, sequence analysis, modeling, and docking are used to build a model for Wuhan COVID-19 RdRp. Additionally, the newly emerged Wuhan HCoV RdRp model is targeted by anti-polymerase drugs, including the approved drugs Sofosbuvir and Ribavirin. KEY FINDINGS: The results suggest the effectiveness of Sofosbuvir, IDX-184, Ribavirin, and Remidisvir as potent drugs against the newly emerged HCoV disease. SIGNIFICANCE: The present study presents a perfect model for COVID-19 RdRp enabling its testing in silico against anti-polymerase drugs. Besides, the study presents some drugs that previously proved its efficiency against the newly emerged viral infection.