The combination of Bromelain and Acetylcysteine (BromAc) synergistically inactivates SARS-CoV-2

  1. Javed Akhter
  2. Grégory Quéromès
  3. Krishna Pillai
  4. Vahan Kepenekian
  5. Samina Badar
  6. Ahmed H. Mekkawy
  7. Emilie Frobert
  8. Sarah J Valle
  9. David L. Morris

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Abstract

Background and objectives

SARS-CoV-2 infection is the cause of a worldwide pandemic, currently with limited therapeutic options. Whilst vaccines are at the forefront of the therapeutic initiative, drug repurposing remains a promising approach for SARS-CoV-2 treatment. BromAc (Bromelain & Acetylcysteine) has synergistic action against glycoproteins by the synchronous breakage of glycosidic linkages and disulfide bonds. The spike protein of SARS-CoV-2, formed of glycoprotein and disulfide bridges for stabilization, represents an attractive target as it is essential for binding to the ACE2 receptor in host cells present in nasal mucosa. We sought to determine the effect of BromAc on the Spike and Envelope proteins and its potential to reduce infectivity in host cells.

Design

Recombinant Spike and Envelope proteins were treated by single agent and combination BromAc at 50 and 100 µg/20mg/mL and analyzed by electrophoresis. Ultraviolet analysis of disulfide bond reduction was performed for both Spike and Envelope proteins after treatment with Acetylcysteine. In vitro whole virus culture inactivation of pre-treated wild type and an S1/S2 Spike mutant SARS-CoV-2 with BromAc from 25 to 250 µg/20mg/mL was measured by cytopathic effect, cell lysis assay, and replication capacity by RT-PCR.

Results

Recombinant Spike and Envelope SARS-CoV-2 proteins were fragmented by BromAc at both 50 and 100 µg/20mg/mL whilst single agents had minimal effect. Spike and Envelope protein disulfide bonds were reduced by Acetylcysteine. In vitro whole virus culture of both wild type and Spike mutant SARS-CoV-2 demonstrated a concentration-dependent inactivation from BromAc treatment but not from single agents.

Conclusion

BromAc disintegrates SARS-CoV-2 Spike and Envelope proteins. In vitro tests on whole virus support this finding with inactivation of its replication capacity most strongly at 100 and 250 µg/20mg/mL BromAc, even in Spike mutant virus. Clinical testing through nasal administration in patients with early SARS-CoV-2 infection is imminent.

Author Summary

There is currently no suitable therapeutic treatment for early SARS-CoV-2 aimed to prevent disease progression. BromAc is under clinical development by the authors for mucinous cancers due to its ability to alter complex glycoproteins structure. The potential of BromAc on SARS-CoV-2 Spike and Envelope glycoproteins stabilized by disulfide bonds was examined and found to disintegrate recombinant Spike and Envelope proteins whilst reducing disulfide stabilizer bridges. BromAc also showed an inhibitory effect on wild-type and Spike mutant SARS-CoV-2 by inactivation of its replication capacity in vitro . Hence, BromAc may be an effective therapeutic agent for early SARS-CoV-2 infection, despite mutations, and even have potential as a prophylactic in people at high risk of infection.

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  1. ScreenIT

    SciScore for 10.1101/2020.09.07.286906: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    Vero cells (ATCC©, CCL-81) were seeded at 20,000 cells per well on an E-Plate 16 (ACEA Biosciences, Inc., CA, USA) and incubated with the same media conditions as described previously at 36°C with 5% CO2.
    Vero
    suggested: None
    Software and Algorithms
    SentencesResources
    Tukey multiple comparison tests were used to compare each condition on GraphPad Prism (software version 9.0).
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.09.07.286906 on bioRxiv