The cyclodextrin family has been found to be promising and cost-effective antiviral agents against SARS-CoV-2.


In a recent study published in bioRxiv* Preprint server Researchers have identified β-cyclodextrins (β-CDs) as a safe and cost-effective drug against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with a broad spectrum of activity.

Study: β-Cyclodextrins as affordable antivirals for the treatment of coronavirus infection.  Image credit: 3DJustincase/Shutterstock
Stady: β-Cyclodextrins as affordable antivirals for the treatment of coronavirus infection. Image credit: 3DJustincase/Shutterstock

COVID-19 (coronavirus disease 2019) has resulted in significant global morbidity and mortality. There is no approved SARS-CoV-2 antibody agent that is economical, easy to use, or can provide universal prevention of COVID-19 in individuals at high risk of disease severity outcomes. Developing large-scale, economical, and safe therapies at the onset of a new variant of SARS-CoV-2 could greatly reduce the transmission of SARS-CoV-2.

about studying

In this study, researchers identify β-cyclodextrins (β-CDs) as cost-effective and broad-spectrum therapeutic agents for COVID-19 that are safe for human administration.

The team recruited 116 drugs that had previously been used to treat diseases or had proven effective against SARS-CoV-2 in preclinical trials. Molecular modeling was performed to classify 44 compounds that showed the greatest efficacy against several α-CoVs and CoVs, for example, SARS-CoV-2 and human CoV 229E (HCoV-229E). The drugs were identified by virology, computational chemistry, transmission electron microscopy (TEM), and cell biology techniques.

The compounds’ antiviral mechanisms were explored by TEM results and the ability to block entry of SARS-CoV-2 pseudoviruses into angiotensin-converting enzyme 2 (ACE2)-expressing human embryonic kidney (HEK)-293T cells. Protein Data Bank (PDB) structures have been revised, protonation states have been identified, restricted miniaturization has been performed, and networks have been generated. Furthermore, six original and modified dextrins were tested.

Binding energies were calculated based on the generalized molecular mechanics/born surface area analysis (MMGBSA), the results of which were analyzed to classify the compounds based on their antiviral potency. Furthermore, molecular dynamics (MD) simulations were performed to evaluate the stability of the compounds. HCoV-229E was propagated into MRC-5 cells (MRC cell lineage 5), and thereafter, the cells were subjected to indirect immunofluorescence (IF) analysis using anti-HCoV-229E nucleocapsid (N) protein antibody.

Moreover, MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-Diphenyltetrazolium bromide) for assessment of cell viability and antivirals effectiveness The selected compounds were evaluated based on the results of the IF. SARS-CoV-2 variants whose genetic sequences were uploaded into the GISAID (Global Initiative on Sharing All Influenza Data) database were isolated from Nasopharyngeal swab samples into Vero E6 cells, and the supernatants were subjected to genomic sequencing.

SARS-CoV-2 spike (S) reporter pseudoviruses expressing human immunodeficiency virus 1 (HIV-1) were generated. Photometer assays and transfection experiments were performed. The p24gag virus content was measured using enzyme-linked immunosorbent assays (ELISA), after which the virus was titrated in HEK-293T cells overexpressing ACE2. In addition, pseudomonas virus entry inhibition assays were performed, and SARS-CoV-2 replication was evaluated using Calu-3 cells (a human lung cancer cell line). SARS-CoV-2 major protease (Mpro) inhibition assays and cell membranes of Calu-3 cells were subjected to lipid analysis after MBCD (methyl-b-CD) treatment.

consequences

Four compounds, U18666A, OSW-1, phytol and hydroxypropyl-β-cyclodextrin (HβCD), showed antiviral activity against HCoV-229E and SARS-CoV-2 in MRC-5 cells and Vero E6 cells, respectively. U18666A and HβCD blocked viral fusion; However, only HβCD showed inhibition of SARS-CoV-2 replication in Calu-3 cells. The original and modified cyclodextrins assay confirmed the strong inhibition of SARS-CoV-2 by c-cyclodextrins in Calu-3 cells.

OSW-1 is efficiently installed in Active Mforefront Site with the largest binding energy of all tested molecules. b-CD and OSW-1 localized in the motivational pocket of M.forefront, While vitol and U1866A were localized in the central pocket of NPC1. OSW-1 and b CD were stable with mean RMSD (root mean square deviation) differences of ca. 2Å and the values ​​were a multiple of vitol and U18666A.

The half-maximal inhibitory concentration (IC50) values ​​for U18666A, OSW-1, HβCD and phytol were 2.6 μM, 0.5 nM, 4.3 mM and 19 μM, respectively. Cyclodextrins inhibit SARS-CoV-2 replication by interfering with viral fusion via cholesterol depletion. HβCDs, MbCDs, and b-CDs inhibit SARS-CoV-2 strain D614G and BA.1 stress on Calu-3 cells.

TEM results of SARS-CoV-2-infected Vero E6 cells showed that U18666A and OSW-1 affect SARS-CoV-2 morphogenesis by inhibiting double membrane vesicle (DMV) assembly and function. Treatment with high doses of U18666A resulted in hypertrophy of lysosomes and Golgi cisternae. Treatments with low-dose phytol altered DMVs to a limited extent with little effect on SARS-CoV-2 aggregation and transmission, whereas pronounced cytopathic effects were visualized with high-dose phytol.

HβCD treatment at a concentration of 0.2 mM altered the inner membrane of DMVs, with large clusters of distorted SARS-CoV-2 particles observed within the vacuoles. At a concentration of 20 mM HβCD, all SARS-CoV-2 structures were reduced with few altered DMVs.

Overall, the results of the study highlighted β-cyclodextrins as promising therapeutic agents against SARS-CoV-2 and other potential pneumococcal viral organisms.

*Important note

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, directing clinical practice/health-related behaviour, or treated as hard information.



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