Antifungal agent Bifonazole as an antiviral in opposition to SARS-CoV-2

In a current research revealed within the journal Molecular Therapy, researchers recognized Bifonazole, an imidazole-based antifungal agent, to have potent exercise in opposition to extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizing high-throughput screening of small molecules.

SARS-CoV-2 infects host cells by means of interactions of the spike (S) protein receptor-binding area (RBD) and angiotensin-converting enzyme 2 (ACE2) receptors of the host. Subsequently, the S RBD-ACE2 binding web site is a possible goal for the event of anti-SARS-CoV-2 therapies.

Study: Identification of FDA-approved Bifonazole as SARS-CoV-2 blocking agent following a bioreporter drug screen. Image Credit: NIAIDExamine: Identification of FDA-approved Bifonazole as SARS-CoV-2 blocking agent following a bioreporter drug screen. Picture Credit score: NIAID

In regards to the research

Within the current research, researchers explored using small molecules in anti-SARS-CoV-2 therapeutics by figuring out and evaluating the efficacy of small molecules that blocked S RBD-ACE2 interactions.

The workforce used a split-luciferase assay for screening small molecules that inhibit S RBD-ACE2 binding. The assay was primarily based on the NanoLuc Binary Expertise (NanoBiT), wherein the nanoluciferase bioreporter was dissected into two components, i.e., the Small BiT (SmBiT) and Giant BiT (LgBiT), which exhibited sturdy conformational stability and thereby created a super break up reporter for investigating the S RBD-ACE2 interactions. Within the assay, the S RBD-ACE2 binding gave sturdy and steady luminescent nano-luciferase indicators upon including the coelenterazine (CTZ) substrate.

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Human embryonic kidney 293 (HEK 293) cells had been transfected to specific the LgBiT-RBD and SmBiT-ACE2 proteins. Additional, LgBiT-RBD interactions with anti-S RBD antibodies or SmBiT-ACE2 interactions with soluble ACE2 (sACE2) demonstrated aggressive inhibition and impaired the luminescence indicators. A complete of 1,200 Meals and Drug Administration (FDA)-approved drug compounds of the Prestwick library had been screened utilizing two strategies A and B.

In Technique A, the compound library was added to the LgBiT-RBD/SmBiT-ACE2 advanced for figuring out compounds that dissociated the advanced. In Technique B, the library was added to the LgBiT-RBD advanced adopted by including SmBiT-ACE2 to establish compounds that inhibited the S RBD-ACE2 interactions. Hits obtained with bioreporter luminescence ≤ 15 % had been eradicated from the evaluation and compounds with the highest 45 hits had been additional analyzed.

The efficacy of the compounds was assessed in ACE2- and transmembrane serine protease 2 (TMPRSS2)-expressing VeroE6 cells contaminated with SARS-CoV-2 S pseudotyped vesicular-stomatitis virus (VSV) expressing inexperienced fluorescent protein (VSV-GFP-S) or wild kind (wt)VSV-GFP. Subsequently, immunofluorescence imaging and cell viability assessments had been carried out. As well as, the efficacy of Bifonazole in K18-ACE2 mice was assessed.

Graphs denoting % GFP foci for wtVSV and VSV-S throughout all drug concentrations had been plotted to evaluate the specificity of the compounds. As well as, in silico molecular docking evaluation and bimolecular fluorescence complementation (BiFC) assays had been carried out and the SARS-CoV-2 messenger ribonucleic acid (mRNA) ranges had been assessed.


Among the many 1,200 compounds screened, Bifonazole (Prestw-1241) confirmed essentially the most potent aggressive inhibition of SARS-CoV-2 S RBD-ACE2 interactions utilizing each strategies, with a lower of 46% and 51% within the bioreporter indicators utilizing strategies A and B, respectively. In silico molecular docking evaluation confirmed that Bifonazole was sure to the N-terminal small lobe of ACE2 across the K353 residue, which resulted within the prevention of RBD-ACE2 binding.

Bifonazole considerably diminished the pseudotyped VSV-S-GFP contaminated cells [half-maximal inhibitory concentration (IC50) = 30 to 40 µM, without toxicity up to 100 µM] and wtVSV-GFP contaminated cells (IC50 = 60 to 70 µM). When administered intranasally, Bifonazole led to a 40% discount in lethality in VSV S-challenged K18-ACE2 mice with related advantages post-challenge with stay SARS-CoV-2.

The specificity graphs of Bifonazole confirmed an upward pattern from 20 to 67 μM, indicative of the compound’s potential for VSV-S inhibition. Bifonazole additionally diminished SARS-CoV-2 mRNA ranges, diminished viral burden within the median tissue tradition infectious dose (TCID50) assay, and diminished immunofluorescence staining for SARS-CoV-2 S. Cytotoxicity assays confirmed no influence of Bifonazole on cell viability, as noticed within the VeroE6-hTMPRSS2 cells on the doses examined. Furthermore, Bifonazole demonstrated considerably diminished the luminescence of mutant RBD bioreporters, indicative of considerable inhibition of SARS-CoV-2 variants (particularly Omicron) that bind with ACE2 by Bifonzaole.

The BiFC assay confirmed a dose-dependent lower within the fusion of TMPRSS2/ACE2-expressing cells and S-expressing human embryonic kidney (HEK293T) cells on Bifonazole therapy. Related results had been noticed on utilizing S of SARS-CoV with 45% and 22% inhibition of the SARS-CoV S RBD-ACE2 interactions utilizing strategies A and B, respectively. This indicated that Bifonazole additionally possessed antiviral exercise in opposition to SARS-CoV.

Among the many different compounds, nicardipine and ethynylestradiol considerably diminished bioreporter indicators with comparable bioreporter impairment between Bifonazole and nicardipine (IC50 = 1.9 µM), cisapride (IC50 = 16.5 µM), and ethynylestradiol (IC50 = 2.6 µM). Nicardipine and ethynylestradiol inhibited wtVSV-GFP (IC50 = 15 to twenty µM) extra effectively than VSV-S-GFP (IC50  = 25 to 70 µM). Cisapride didn’t have an effect on VSV an infection and was poisonous at >20 µM doses. The specificity curves for nicardipine and ethynylestradiol confirmed a downward pattern, indicating enhanced wtVSV inhibition and decrease S specificity.

Within the drug screening, different imidazole antifungals (econazole, ketoconazole, clotrimazole, oxiconazole nitrate) and an imidazole anti-inflammatory agent, tribenoside, blocked the S RBD-ACE2 interactions. Econazole (IC50 = 2.3 µM) and ketoconazole (IC50 = 14.5 µM) confirmed bioreporter impairment and upward traits within the specificity curves, albeit at excessive concentrations of 60 to 80 μM, respectively.


Total, the research findings highlighted the promising potential of Bifonazole as an anti-SARS-CoV-2 therapeutic agent with excessive efficiency and specificity for SARS-CoV-2 inhibition by competitively binding to ACE2 and subsequently blocking the S RBD-ACE2 interactions.

Journal reference:
  • Taha Z, Arulanandam R, Maznyi G, Godbout E, Carter-Timofte ME, Kurmasheva N, Reinert LS, Chen A, Crupi MJF, Boulton S, Laroche G, Phan A, Rezaei R, Alluqmani N, Jirovec A, Acal A, Brown EEF, Singaravelu R, Petryk J, Idorn M, Potts KG, Todesco H, John C, Mahoney DJ, Ilkow CS, Giguère P, Alain T, Côté M, Paludan SR, Olagnier D, Bell JC, Azad T, Diallo J-S, Identification of FDA-approved Bifonazole as SARS-CoV-2 blocking agent following a bioreporter drug display screen, Molecular Remedy (2022), DOI:,



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