Hypericin Inhibit Alpha-Coronavirus Replication by Targeting 3CL Protease

Abstract

The porcine epidemic diarrhea virus (PEDV) is an Alphacoronavirus (α-CoV) that causes high mortality in infected piglets, resulting in serious economic losses in the farming industry. Hypericin is a dianthrone compound that has been shown as an antiviral activity on several viruses. Here, we first evaluated the antiviral effect of hypericin in PEDV and found the viral replication and egression were significantly reduced with hypericin post-treatment. As hypericin has been shown in SARS-CoV-2 that it is bound to viral 3CLpro, we thus established a molecular docking between hypericin and PEDV 3CLpro using different software and found hypericin bound to 3CLpro through two pockets. These binding pockets were further verified by another docking between hypericin and PEDV 3CLpro pocket mutants, and the fluorescence resonance energy transfer (FRET) assay confirmed that hypericin inhibits the PEDV 3CLpro activity. Moreover, the alignments of α-CoV 3CLpro sequences or crystal structure revealed that the pockets mediating hypericin and PEDV 3CLpro binding were highly conserved, especially in transmissible gastroenteritis virus (TGEV). We then validated the anti-TGEV effect of hypericin through viral replication and egression. Overall, our results push forward that hypericin was for the first time shown to have an inhibitory effect on PEDV and TGEV by targeting 3CLpro, and it deserves further attention as not only a pan-anti-α-CoV compound but potentially also as a compound of other coronaviral infections.

In Silico and In Vitro Identification of Pan-Coronaviral Main Protease Inhibitors from a Large Natural Product Library

“…Although hypericin inhibits human immunodeficiency virus (HIV) in vitro and in vivo [ 38 , 39 ], a clinical trial revealed phytotoxicity of orally administered hypericin (0.5 mg/kg daily) without antiretroviral activity in a limited number of patients [ 40 ]. Moreover, hypericin inhibits the replication of α-coronaviruses (PEDV and TGEV) through the inhibition of M pro [ 41 ]. Hypericin inhibits M pro of SARS-CoV-2 with a CC 50 value of 63.6 µM [ 42 ].…”

“…The rest of ORF-1ab encodes nine accessory proteins and four structural proteins, i.e., spike (S), envelope (E), membrane (M), and nucleocapsid (N) [11,12]. The coronavirus main protease (M pro , also termed 3CL pro ) is a cysteine protease with cysteine 145 and histidine 41 in its active site [10]. Its structure is composed of two monomers, and each of them consists of three domains.…”

Hypericum perforatum and Its Ingredients Hypericin and Pseudohypericin Demonstrate an Antiviral Activity against SARS-CoV-2

“…Several reports on potential antiviral activities of the extract or its active ingredients, such as the naphtodianthrone hypericin, were published. In these studies, these antiviral activities were shown against herpes simplex virus type 1 [ 22 ], human cytomegalovirus [ 23 ], hepatitis B virus [ 24 ], influenza A virus [ 25 , 26 ], human immunodeficiency virus type 1 [ 27 ], and animal viruses [ 28 , 29 ], including the infectious bronchitis virus and the porcine epidemic diarrhea virus, as gamma- and alpha- coronaviruses, respectively [ 30 , 31 ].…”

Natural Compound ZINC12899676 Reduces Porcine Epidemic Diarrhea Virus Replication by Inhibiting the Viral NTPase Activity

“…There are some compounds such as salinomycin ( Yuan et al, 2021 ), homoharringtonine ( Dong et al, 2018 ), and A77 1726 ( Li X. et al, 2020 ) preventing PEDV proliferation by affecting the host defense system. Many compounds inhibit PEDV replication by targeting PEDV 3CLpro, such as tomatidine ( Wang et al, 2020 ), hypericin ( Zhang Y et al, 2021 ), quercetin ( Li Z. et al, 2020 ), and GC376 ( Ye et al, 2020 ). PEDV RdRp also can be the target of antiviral drugs ( Xie et al, 2021 ).…”

“…The antiviral drug molnupiravir for the treatment of mild-to-moderate COVID-19 in adults with at least one risk factor for severe illness has been authorized in UK since November 2021 ( Mahase, 2021a ). It has been reported that certain small molecules inhibit PEDV proliferation, but commercial drugs have not been developed yet ( Wang et al, 2020 ; Huan et al, 2021 ; Zhang Y et al, 2021 ).…”