Resveratrol Inhibits HCoV-229E and SARS-CoV-2 Coronavirus Replication In Vitro

Abstract

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in China at the end of 2019 causing a large global outbreak. As treatments are of the utmost importance, drug repurposing embodies a rich and rapid drug discovery landscape, where candidate drug compounds could be identified and optimized. To this end, we tested seven compounds for their ability to reduce replication of human coronavirus (HCoV)-229E, another member of the coronavirus family. Among these seven drugs tested, four of them, namely rapamycin, disulfiram, loperamide and valproic acid, were highly cytotoxic and did not warrant further testing. In contrast, we observed a reduction of the viral titer by 80% with resveratrol (50% effective concentration (EC50) = 4.6 µM) and lopinavir/ritonavir (EC50 = 8.8 µM) and by 60% with chloroquine (EC50 = 5 µM) with very limited cytotoxicity. Among these three drugs, resveratrol was less cytotoxic (cytotoxic concentration 50 (CC50) = 210 µM) than lopinavir/ritonavir (CC50 = 102 µM) and chloroquine (CC50 = 67 µM). Thus, among the seven drugs tested against HCoV-229E, resveratrol demonstrated the optimal antiviral response with low cytotoxicity with a selectivity index (SI) of 45.65. Similarly, among the three drugs with an anti-HCoV-229E activity, namely lopinavir/ritonavir, chloroquine and resveratrol, only the latter showed a reduction of the viral titer on SARS-CoV-2 with reduced cytotoxicity. This opens the door to further evaluation to fight Covid-19.

Keywords: HCoV-229E; SARS-CoV-2; coronavirus; resveratrol; viral inhibition.

Figure 1

Inhibition of replication of high HCoV-229E viral load (Red), measured by plaque forming unit (PFU) assay, coupled with MTT toxicity assay (Blue) for Lopinavir/Ritonavir (A), Chloroquine (B), Resveratrol (C), Disulfiram (D), Loperamide (E), Rapamycin (F) and valproic acid (VPA) (G). Cells were treated by compounds at the time of infection with HCoV-229E (1 multiplicity of infection (MOI)). PFU and MTT assays were performed after 48 h. Uninfected cells were used for normalization of MTT assay. Untreated cells infected with HCoV-229E were used for normalization of PFU assay.

Figure 2

Inhibition of replication of low HCoV-229E viral load (0.01 MOI) by drugs. (A) No pretreatment (Blue) or 3-h pretreatment of cells (Red). (B) Combination of drugs. The cells were treated with Lopinavir/Ritonavir (LR), Chloroquine (Ch), Resveratrol (Re) or left untreated (UT) for 48 h. The viral replication was measured by PFU assay.

Figure 3

Inhibition of replication of high HCoV-229E viral load (1 MOI) by Resveratrol (A), Lopinavir/Ritonavir (B) and Chloroquine (C) in pre-treated (3 h, Red) or post-treated (4 h, Blue) MRC5 cells. Viral replication was measured by PFU assay after 48 h.

Figure 4

(A) Toxicity assay for Lopinavir/Ritonavir, Chloroquine and Resveratrol in Vero E6 cells, after 48 h. (B) Inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication in Vero E6 cells treated with Resveratrol as measured by qRT-PCR after 48 h. * Cytotoxicity impaired the evaluation of the anti-SARS-CoV-2 effect of Lopinavir/Ritonavir and Chloroquine.