Repurposing of Doxycycline to Hinder the Viral Replication of SARS-CoV-2: From in silico to in vitro Validation

Abstract

Since the rapid spread of coronavirus disease (COVID-19) became a global pandemic, healthcare ministries around the world have recommended specific control methods such as quarantining infected peoples, identifying infections, wearing mask, and practicing hand hygiene. Since no effective treatment for COVID-19 has yet been discovered, a variety of drugs approved by Food and Drug Administration (FDA) have been suggested for repurposing strategy. In the current study, we predicted that doxycycline could interact with the nucleotide triphosphate (NTP) entry channel, and is therefore expected to hinder the viral replication of SARS-CoV-2 RNA-dependent RNA-polymerase (RdRp) through docking analysis. Further, the molecular dynamics results revealed that the RdRp-Doxycycline complex was structurally relatively stable during the dynamic period (100 ns), and its complex maintained close contact with their active catalytic domains of SARS-CoV-2 RdRp. The molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) calculation of binding free energy also showed that the doxycycline has worthy affinities with SARS-CoV-2 RdRp. As expected, doxycycline effectively inhibited the viral replication of IHU strains of SARS-CoV-2 (IHUMI-3 and IHUMI-6), identified from the hospitalized patients in IHU Méditerranée Infection (IHUMI), Marseille, France. Moreover, doxycycline inhibited the viral load in vitro at both on-entry and after viral entry of IHU variants of SARS-CoV-2. The results suggest that doxycycline exhibits strains-dependant antiviral activity against COVID-19. As a result, the current study concludes that doxycycline may be more effective in combination with other drugs for better COVID-19 treatment efficacy.

Doxycycline’s Potential Role in Reducing Thrombosis and Mortality in Critically Ill Patients With COVID-19: A Multicenter Cohort Study

“…24 Besides, the anti-inflammatory, immunomodulatory, and cardio-protective properties of doxycycline may be responsible for MMP gene inhibition, which is related to the severity and mortality of COVID-19. 15,[33][34][35] In addition to the ability of doxycycline to lower the odds of thrombosis, we found a lower percentage of 30-day mortality in the doxycycline group. Also, this difference was statistically significant compared to the other group (P = .04).…”

Fluoxetine pharmacokinetics and tissue distribution quantitatively supports a therapeutic role in COVID-19 at a minimum dose of 20 mg per day

“…Further, of note, the over-the-counter compound famotidine (PEPCID ® ), a histamine type 2 H 2 receptor antagonists, which has been shown to inhibit the human immunodeficiency virus (HIV) ( Bourinbaiar & Fruhstorfer, 1996 ), has also been shown to provide clinical benefit in patients with COVID-19 – particularly COVID-19 pneumonia – and future retrospective studies should evaluate potential synergistic benefit as famotidine is available in both oral and intravenous formulations ( Freedberg et al , 2020 ; Janowitz et al , 2020 ; Mather, Seip & McKay, 2020 ). Lastly, doxycycline has also been shown to provide benefit in patients with COVID-19 pneumonia even in high-risk elderly nursing home patients and achieves therapeutic levels in lungs as found in vitro ( Alam et al , 2020 ; Gendrot et al , 2020 ; Stricker & Fesler, 2020 ; Yates et al , 2020 ; Alexpandi et al , 2022 ).…”

Doxycycline for the prevention of progression of COVID-19 to severe disease requiring intensive care unit (ICU) admission: A randomized, controlled, open-label, parallel group trial (DOXPREVENT.ICU)

“…As an antiviral positive control, the clinical RNA-dependent RNA polymerase (RdRp) inhibitor remdesivir potently blocked SARS-CoV-2 replication and virus-induced cell death ( S1 Fig ). While studies by one laboratory in African green monkey-derived Vero-E6 cells suggested an antiviral effect of doxycycline in vitro [ 20 , 21 ], another report has challenged this conclusion [ 22 ]. Potentially, the non-human origin of Vero-E6 cells may have been a confounder in the evaluation of anti-SARS-CoV-2-specific effects of doxycycline.…”

“…Our in vitro studies showed that neither doxycycline nor tetracycline had an inhibitory effects on different SARS-CoV-2 variants, including five variants of concern evaluated on two established ACE-2-overexpressing human cell lines (S1 Fig) [16]. As an antiviral positive control, the clinical RNA-dependent RNA polymerase (RdRp) inhibitor remdesivir potently blocked SARS-CoV-2 replication and virus-induced cell death (S1 Fig) . While studies by one laboratory in African green monkey-derived Vero-E6 cells suggested an antiviral effect of doxycycline in vitro [20,21], another report has challenged this conclusion [22]. Potentially, the non-human origin of Vero-E6 cells may have been a confounder in the evaluation of anti-SARS-CoV-2-specific effects of doxycycline.…”