Antiviral activity of puerarin as potent inhibitor of influenza virus neuraminidase.

Puerarin is a major isofiavone compound isolated from the root of Pueraria lobata. It was reported that puerarin had antioxidant, antiinflammatory, antitumor, cholesterol lowering, liver protective, and neuroprotective properties. However, few studies have explored the antiviral effect of puerarin and its target mechanism related to influenza virus. Here, the antiinfluenza activity of puerarin in vitro and in vivo and its mode of action on the potential inhibition of neuraminidase (NA) were investigated. Puerarin displayed an inhibitory effect on A/FM/1/1947(H1N1) (EC50 = 52.06 µM). An indirect immunofluorescence assay indicated that puerarin blocked the nuclear export of viral NP. The inhibition of NA activity confirmed that puerarin can block the release of newly formed virus particles from infected cells. Puerarin (100 and 200 mg/kg/d) exhibited effective antiviral activity in mice, conferring 50% and 70% protection from death against H1N1, reducing virus titers, and effectively alleviating inflammation in the lungs. The molecular docking results showed that puerarin had a strong binding affinity with NA from H1N1. The results of the molecular dynamics simulation revealed that puerarin had higher stable binding at the 150-loop region of the NA protein. These results demonstrated that puerarin acts as a NA blocker to inhibit influenza A virus both in cellular and animal models. Thus, puerarin has potential utility for the treatment of the influenza virus infection.

Geraniin as a potential inhibitor of SARS-CoV-2 3CLpro.

Geraniin is a polyphenolic compound first isolated from Geranium thunbergii. The major protease (Mpro), namely 3 C-like protease (3CLpro), of coronaviruses is considered an attractive drug target as it is essential for the processing and maturation of viral polyproteins. Thus, our primary goal is to explore the efficiency of geraniin on 3CLpro of SARS-CoV-2 using the computational biology strategy. In this work, we studied the anti-coronavirus effect of geraniin in vitro and its potential inhibitory mode against the 3CLpro of SARS-CoV-2. We found that geraniin inhibited HCoV-OC43 coronavirus-infected cells during the attachment and penetration phases. Molecular docking and dynamics simulations exhibited that geraniin had a strong binding affinity and high stable binding to 3CLpro of SARS-CoV-2. Geraniin showed a strong inhibitory activity on coronavirus and may be a potential inhibitor of SARS-CoV-2 3CLpro.

A potential antiviral activity of Esculentoside A against binding interactions of SARS-COV-2 spike protein and angiotensin converting enzyme 2 (ACE2).

The recent emergence of the novel coronavirus (SARS-CoV-2) has resulted in a devastating pandemic with global concern. However, to date, there are no regimens to prevent and treat SARS-CoV-2 virus. There is an urgent need to identify novel leads with anti-viral properties that impede viral pathogenesis in the host system. Esculentoside A (EsA), a saponin isolated from the root of Phytolacca esculenta, is known to exhibit diverse pharmacological properties, especially anti-inflammatory activity. To our knowledge, SARS-CoV-2 uses angiotensin converting enzyme 2 (ACE2) to enter host cells. This is mediated through the proteins of SARS-CoV-2, especially the spike glycoprotein receptor binding domain. Thus, our primary goal is to prevent virus replication and binding to the host, which allows us to explore the efficiency of EsA on key surface drug target proteins using the computational biology paradigm approach. Here, the anti-coronavirus activity of EsA in vitro and its potential mode of inhibitory action on the S-protein of SARS-CoV-2 were investigated. We found that EsA inhibited the HCoV-OC43 coronavirus during the attachment and penetration stage. Molecular docking results showed that EsA had a strong binding affinity with the spike glycoprotein from SARS-CoV-2. The results of the molecular dynamics simulation revealed that EsA had higher stable binding with the spike protein. These results demonstrated that Esculentoside A can act as a spike protein blocker to inhibit SARS-CoV-2. Considering the poor bioavailability and low toxicity of EsA, it is suitable as novel lead for the inhibitor against binding interactions of SARS-CoV-2 of S-protein and ACE2.