Naringenin is a powerful inhibitor of SARS-CoV-2 infection in vitro

Abstract

Schematic representation of TPC2 role, investigated through genetic ablation and drug blocker, in the inhibition of Coronaviruses release into the cells.

Graphical abstract

Fig. 1

Antiviral Activity of Naringenin and of Endo-Lysosomal Two-Pore Channel 2 Knockdown in CoV Infection. Antiviral activity of Nar on HCoVOC43 and HCoV229E: A) Inhibition of HCoVOC43 and HCoV 229E was evaluated respectively at 24 hpi and 48 hpi in Vero E6 cells treated with 62.5 μM Nar. Differences between treated samples (n = 3) and controls (untreated infected cells, n = 3, not shown) were significant (P < 0.001). TPC2 silencing abolishes HCoV229E infection: B) HCoV229E infection inhibition was evaluated at 24-48-72 hpi in Huh7.5 cells pretreated with siRNA to silence TPC2. Differences between treated samples (n = 4, n = 3 at 72 hpi) and controls (untreated infected cells, n = 4, not shown) were significant (P < 0.05 at 24 hpi and P < 0.001 at 48 hpi and 72 hpi); C) Transient inhibition of TPC2 expression after 24 h and 48 h in Huh7.5 cells. Differences between treated samples (siTPC2, n = 3) and controls (scrambled siRNA, n = 3) were significant (P < 0.01 at 24 h and P < 0.001 at 48 h). Antiviral activity of Nar on SARS-CoV-2: D) CPE on infected Vero E6 cells treated with different concentrations of Nar, as indicated. Bright-field microscopy images (72 hpi) of representative CPE of SARS-CoV-2, hCoV-19/Italy/UniSR1/2020 isolate, detected on both infected and uninfected cells, compared to the untreated infected cells (virus control, red square). DMSO had no effect on virus replication (black square); E) Inhibition of infection calculated on CPE detected at 48 and 72 hpi. Differences between treated samples (n = 9) and controls (untreated infected cells, DMSO, n = 6) were significant (P < 0.001 at 250 and 62.5μM of Nar, P < 0.01 and P < 0.05 at 31.5 μM of Nar, respectively at 48 hpi and 72 hpi). All data were expressed as mean ± sem. Student’s t-test was used for statistical comparison between means (*P < 0.05; **P < 0.01; ***P < 0.001).