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Research Note

In silico analysis suggests repurposing of ibuprofen for prevention and treatment of EBOLA virus disease

[version 1; peer review: 2 approved]
PUBLISHED 01 May 2015
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This article is included in the Emerging Diseases and Outbreaks gateway.

This article is included in the Ebola Virus collection.

Abstract

The large 2014/2015 Ebola virus outbreak in West Africa points out the urgent need to develop new preventive and therapeutic approaches that are effective against Ebola viruses and  can be rapidly utilized. Recently, a simple theoretical criterion for the virtual screening of molecular libraries for candidate inhibitors of Ebola virus infection was proposed. Using this method the ‘drug space’ was screened and 267 approved and 382 experimental drugs as candidates for treatment of the Ebola virus disease (EVD) have been selected. Detailed analysis of these drugs revealed the non-steroidal anti-inflammatory drug ibuprofen as an inexpensive, widely accessible and minimally toxic candidate for prevention and treatment of EVD. Furthermore, the molecular mechanism underlying this possible protective effect of ibuprofen against EVD is suggested in this article.

Keywords

drug space, NSAID, molecular libraries

Introduction

The recent Ebola virus outbreak in West Africa caused (as of April 8, 2015) a total of 25,556 confirmed cases, including 10,587 deaths (World Health Organization, Ebola data and statistics). Although reports of new, confirmed cases of Ebola seemed to decrease in April of 2015 to approximately 30 cases per week, medical and aid organizations are warning that the current crisis is not over. Furthermore, there remains a risk for future epidemics. Therefore, there is an urgent need to develop new preventive and therapeutic approaches that can be rapidly utilized. New drugs for the treatment of EVD should be safe, efficacious, easy to manufacture and inexpensive in order to be successfully deployed in African countries. In contrast to the significant progress recently achieved in development of an effective Ebola virus vaccine1, therapeutic options are still limited2. The main obstacle represents identification of an appropriate therapeutic target, which has been largely hampered by the time and money-consuming development of new drugs, especially for neglected diseases. Furthermore, the registration of newly identified drugs, like favipiravir, for potential usage in EVD patients takes a relatively long period of time, even though it has been shown to be effective in non-human primate models. In order to avoid these obstacles, several approaches for repurposing of approved drugs for the treatment of EVD patients have been proposed in literature37.

Recently, we proposed a relatively simple theoretical criterion for the fast virtual screening of molecular libraries for candidate inhibitors of Ebola virus infection8. Using this criterion, which is based on calculation of the average quasi-valence number (AQVN) and the electron-ion interaction potential (EIIP) - parameters determining long-range interaction between biological molecules913 - we selected 267 approved and 382 experimental drugs as candidates for treatment of EVD. Further detailed analysis of these drugs, including molecular docking, revealed ibuprofen as an inexpensive, widely accessible and minimally toxic candidate for potential prevention and treatment of EVD. The molecular mechanism underlying the possible protective effect of ibuprofen against EVD is suggested.

Material and methods

AQVN and EIIP molecular descriptors

Recently, we proposed a theoretical criterion for selection of candidate inhibitors of Ebola virus infection8. This criterion is based on the calculation of EIIP and AQVN which are determined by following equations:

Z*=1Ni=1mniZi(1)

where:

  • i - Type of the chemical element

  • Zi - Valence of the i-th chemical element

  • ni - Number of the i-th chemical element atoms in the compound

  • m - Number of types of chemical elements in the compond

  • N - Total number of atoms

EIIP=0.25Z*sin(1.04πZ*)2π(2)

The EIIP values calculated according to the equation (2) are in Rydbergs (Ry = 13.6 eV).

The AQVN and EIIP molecular descriptors determine the long-distance (>5Å) intermolecular interactions in biological systems14. This approach showed that molecules which potentially block Ebola virus infection are placed within AQVN range (2.3–2.7) and EIIP range (0.829–0.954 Ry), respectively. Using this theoretical criterion the drug library encompassing 267 approved drugs selected as candidate inhibitors of the Ebola virus infection (Candidate Ebola Drugs Database, CEDD) was established15. This drug library was used for selection of an approved drug, which represents the optimal candidate for prevention and treatment of EVD.

GP1 receptor modelling

The modelling of glycoprotein GP1 from Ebola virus was previously described in 16.

Ligand optimization

Ligands were built in VEGA ZZ17, protonated according to physiological conditions and optimized on semi empirical PM6 level of theory using MOPAC 2009.

Molecular docking

Ligand and receptor were prepared in VEGA ZZ17. The docking was carried out with Autodock Vina (version 1.1.2.)18. In both cases the whole receptor conformational space was searched, using grid boxes with dimensions 60×60×60 and 30×30×30Å3. The docking was carried out with weighting of hydrophilic interactions, and the corresponding parameter value in the docking configuration was set to -1.20 (compared to default weight: hydrogen = -0.587439). The exhaustiveness was set to 250. The conformations with lowest binding energy values were chosen. The calculations were carried out on the PARADOX Cluster computer.

Results and discussion

We screened the CEDD library15 for optimal candidates for prevention and treatment of EVD. To achieve this end, we used the following criteria: a) high efficacy of binding of drug to the Ebola virus glycoprotein GP1; b) low toxicity and accessibility (nonprescription drugs); and c) low cost. By mining of CEDD using these criteria, we selected ibuprofen as the best candidate. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). Its mode of action, as for other NSAIDs, is not completely understood, but may be related to prostaglandin synthetase inhibition. It achieves this effect on prostaglandin synthesis by inhibiting cyclooxygenase (COX I and II isotypes), an enzyme that is present in at least one isoform most of the tissues of the body and which is responsible for production of not only prostaglandins but also prostacyclins and tromboxane.

Generally, ibuprofen is minimally toxic drug. A meta-analysis of eight placebo-controlled studies showed that application of non-prescription doses of ibuprofen (800–1200 mg/day) over 10 days caused no significant adverse events19. Similar results were obtained in a prospective study of ibuprofen use in healthy volunteers taking the maximum permitted, non-prescription dose of ibuprofen (1200 mg/day) for 10 days20. It was demonstrated that administration of ibuprofen in children is safe. A randomized, community-based study on the safety of ibuprofen in febrile children aged 2 years old (5 or 10 mg/kg) showed that the risk of hospitalization for gastrointestinal bleeding associated with this drug was 17 per 100,00021. It was also shown that fecal blood loss associated with application of prescription doses of ibuprofen (2400 mg/day) did not exceed the normal range22. Even in the case of post-surgical usage for pain control in children undergoing tonsillectomy, ibuprofen administration is considered to be safe and does not increase risk of hemorrhages23. Accordingly, we believe that it would be crucial to better understand the potential risk and benefits of ibuprofen usage in experimental models of EVD. Taken together, these data indicate that ibuprofen could be safely used in nonprescription doses in EVD patients, with potential antiviral effects as well as to alleviate the symptoms.

To assess specificity of ibuprofen as a potential inhibitor of the Ebola virus infection, distribution of all approved NSAIDs in AQVN/EIIP space was analyzed. Results presented in (Table 1 and Figure 1) show that only ibuprofen and its isomer dexibiprofen are located within the domain of the AQVN/EIIP space. Interestingly, most of the experimentally verified inhibitors of the Ebola virus infection are located in the same space (e.g. chloroquine, amodiaquine, brincidofovir, etc)8. This suggests that ibuprofen and dexibuprofen are the only drugs from the NSAID group that potentially have anti-Ebolavirus effects, which should be tested both in vitro and in vivo.

Table 1. AQVN and EIIP molecular descriptors of nonsteroidal anti-inflammatory drugs.

NSAIDFormulaAQVNEIIP [Ry]
AspirinC9H8O43.2380.1179
DiflunisalC13H8F2O33.0770.0720
Salicylic acidC7H6O33.2500.1202
SalsalateC14H10O53.3100.1296
IbuprofenC13H18O22.4850.0954
DexibuprofenC13H18O22.4850.0954
NaproxenC14H14O32.8390.0169
FenoprofenC15H14O32.8750.0036
KetoprofenC16H14O32.9090.0092
DexketoprofenC16H14O32.9090.0925
FlurbiprofenC15H13FO22.7740.0390
OxaprozinC18H15NO32.9730.0337
LoxoprofenC15H18O32.6670.0693
IndomethacinC19H16ClNO42.9760.0347
TolmetinC15H15NO32.8820.0008
SulindacC20H17FO3S2.9050.0076
EtodolacC17H21NO32.6670.0693
KetorolacC15H13NO33.0000.0439
DiclofenacC14H11Cl2NO22.8670.0067
AceclofenacC16H13Cl2NO43.0000.0439
NabumetoneC15H16O22.6670.0693
PiroxicamC15H13N3O4S3.2770.1251
MeloxicamC14H13N3O4S23.3330.1319
TenoxicamC13H11N3O4S23.4540.1317
DroxicamC16H11N3O5S3.5000.1260
LornoxicamC13H10ClN3O4S23.4540.1317
IsoxicamC14H13N3O5S3.3330.1319
Mefenamic acidC15H15NO22.7880.0345
Meclofenamic acidC14H11Cl2NO22.8670.0067
Flufenamic acidC14H10F3NO22.8670.0067
Tolfenamic acidC14H12ClNO22.8670.0067
CelecoxibC17H14F3N3O2S2.9500.0249
RofecoxibC17H14O4S3.1110.0835
ValdecoxibC16H14N2O3S3.1110.0835
ParecoxibC19H18N2O4S3.0460.0608
LumiracoxibC15H13ClFNO22.7880.0345
EtoricoxibC18H15ClN2O2S2.9740.0342
FirocoxibC17H20O5S2.8840.0003
NimesulideC13H12N2O5S3.3330.1319
ClonixinC13H11ClN2O22.9660.0308
LicofeloneC23H22ClNO22.6940.0626
8d9c3f1f-18fe-48ed-b156-62a0d393e2d4_figure1.gif

Figure 1. Distribution of nonsteroidal anti-inflamatory drugs in the AQVN/EIIP space.

Domain of inhibitors of Ebola virus infection8 is marked in red.

A previous in silico study suggested that Elastin Microfibril Interface Located Proteins (EMILINs) are involved in interaction between GP1 and endothelial extracellular matrix (ECM)16. Docking of ibuprofen to the GP1 model gave conformations which bound to EMILINs binding domain on GP116. The binding site of ibuprofen on GP1 spans the edge of this region and consists of Thr 338, Ser 340, Gln 344 and Ala 41516. The intermolecular interactions between ibuprofen and binding site amino-acids include hydrogen bonds of carboxyl group with Thr 338, Ser 340 and Gln 334. Additional stabilization is provided through aromatic and hydrophobic interaction with Ala 415. This binding site is placed between two loops, which provide the possibility of stabilizing a particular conformation, and therefore possibly blocking receptors. The appropriately high binding energy of -9.0 kcal/mol favors this assumption. The binding conformation is presented in Figure 2. At this stage it can be hypothesized that ibuprofen prevents interaction between Ebola virus and ECM by blocking the interaction between GP1 and EMILIN. There are some literature data that support our current hypothesis. EMILIN-1 is a glycoprotein expressed in the vascular tree that binds to the TGF-β1 precursor and prevents its processing by cellular protease furin24. It was shown that Emilin-1 knockout mice display increased TGF-β1 signaling in the walls of their blood vessels, leading to peripheral vasoconstriction and arterial hypertension25. These matrix-dependent changes in the vascular hemodynamics caused by TGF-β1 and EMILIN-1 are important because they ultimately affect the cardiovascular morbidity and mortality rates. Recently, it was shown that activation of the TGF-β1 signaling pathway by Ebola virus plays an important role in pathogenesis of EVD26. These findings suggest the possibility that binding of GP1 to EMILIN-1 prevents its interaction with TGF-β1, which results in activation of TGF-β1 signaling pathway. Binding of ibuprofen to GP1 could prevent GP1/EMILIN-1 interaction allowing EMILIN-1 to keep control of TGF-β1 signaling pathway.

8d9c3f1f-18fe-48ed-b156-62a0d393e2d4_figure2.gif

Figure 2. Ibuprofen docked to GP1 with marked amino-acid residues.

Green dotted lines: hydrogen bonds; grey: hydrophobic interactions.

In conclusion, presented results should encourage further investigation of ibuprofen and ibuprofen-inspired drugs as inexpensive, low-toxic and wide-accessible candidates for prevention and its usage in the treatment of EVD.

Data availability

F1000Research: Dataset 2. Approved and experimental drugs selected as candidate for treatment of EVD, 10.5256/f1000research.6110.d4287715

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Veljkovic V, Goeijenbier M, Glisic S et al. In silico analysis suggests repurposing of ibuprofen for prevention and treatment of EBOLA virus disease [version 1; peer review: 2 approved]. F1000Research 2015, 4:104 (https://doi.org/10.12688/f1000research.6436.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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ApprovedThe paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions
Version 1
VERSION 1
PUBLISHED 01 May 2015
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Reviewer Report 23 Jun 2015
Ayub Darji, Centre for Research into Animal Health (CReSA), Autonomous University of Barcelona, Barcelona, Spain 
Approved
VIEWS 26
Current manuscript by Veljkovic et al., deals with the identification of inhibitors against Ebola virus infection. Authors took advantage of existing approved and experimental drugs and, based on in silico analysis, proposed ibuprofen as a potential candidate for prevention and treartment ... Continue reading
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CITE
HOW TO CITE THIS REPORT
Darji A. Reviewer Report For: In silico analysis suggests repurposing of ibuprofen for prevention and treatment of EBOLA virus disease [version 1; peer review: 2 approved]. F1000Research 2015, 4:104 (https://doi.org/10.5256/f1000research.6904.r8796)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 24 Aug 2015
    Veljko Veljkovic, Center for Multidisciplinary Research, Institute of Nuclear Sciences Vinca, University of Belgrade, Mihajla Petrovica 12-14, 11001 Belgrade, Serbia
    24 Aug 2015
    Author Response
    It was previously suggested that Elastin Microfibril Interface Located Proteins (EMILINs) are involved in interaction between GP and endothelial extracellular matrix (ECM) (Veljkovic et al. 2015) The binding site of ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 24 Aug 2015
    Veljko Veljkovic, Center for Multidisciplinary Research, Institute of Nuclear Sciences Vinca, University of Belgrade, Mihajla Petrovica 12-14, 11001 Belgrade, Serbia
    24 Aug 2015
    Author Response
    It was previously suggested that Elastin Microfibril Interface Located Proteins (EMILINs) are involved in interaction between GP and endothelial extracellular matrix (ECM) (Veljkovic et al. 2015) The binding site of ... Continue reading
Views
41
Cite
Reviewer Report 05 Jun 2015
Mattia Mori, Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy 
Approved
VIEWS 41
In the work of Velijkovic et al., in silico methods were used with the aim of identifying inhibitors of Ebola virus infection. Particularly, authors focused their investigation on approved and experimental drugs and proposed ibuprofen as a candidate for prevention ... Continue reading
CITE
CITE
HOW TO CITE THIS REPORT
Mori M. Reviewer Report For: In silico analysis suggests repurposing of ibuprofen for prevention and treatment of EBOLA virus disease [version 1; peer review: 2 approved]. F1000Research 2015, 4:104 (https://doi.org/10.5256/f1000research.6904.r8913)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Reader Comment 23 Jun 2015
    Thomas Hoenen, National Institutes of Health, USA
    23 Jun 2015
    Reader Comment
    With respect to reviewer comment #3 it is worth pointing out that Medicines Sans Frontieres, the WHO, the CDC, and other health organizations specifically advise AGAINST the use of Ibuprofen ... Continue reading
  • Author Response 24 Aug 2015
    Veljko Veljkovic, Center for Multidisciplinary Research, Institute of Nuclear Sciences Vinca, University of Belgrade, Mihajla Petrovica 12-14, 11001 Belgrade, Serbia
    24 Aug 2015
    Author Response
    Response to Mattia Mori
     
    1. It was demonstrated that several host proteins interact with GP1. This indicates (i) that more than one receptor/co-receptor is involved in the Ebola virus infection and (ii)
    ... Continue reading
COMMENTS ON THIS REPORT
  • Reader Comment 23 Jun 2015
    Thomas Hoenen, National Institutes of Health, USA
    23 Jun 2015
    Reader Comment
    With respect to reviewer comment #3 it is worth pointing out that Medicines Sans Frontieres, the WHO, the CDC, and other health organizations specifically advise AGAINST the use of Ibuprofen ... Continue reading
  • Author Response 24 Aug 2015
    Veljko Veljkovic, Center for Multidisciplinary Research, Institute of Nuclear Sciences Vinca, University of Belgrade, Mihajla Petrovica 12-14, 11001 Belgrade, Serbia
    24 Aug 2015
    Author Response
    Response to Mattia Mori
     
    1. It was demonstrated that several host proteins interact with GP1. This indicates (i) that more than one receptor/co-receptor is involved in the Ebola virus infection and (ii)
    ... Continue reading

Comments on this article Comments (0)

Version 1
VERSION 1 PUBLISHED 01 May 2015
Comment
Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions
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