Repurposing non-antimicrobial drugs to treat multi-drug resistant bacterial and fungal infections

281 Pages·2017·6.02 MB·English

Purdue University
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Open Access Dissertations Theses and Dissertations
12-2016
Repurposing non-antimicrobial drugs to treat
multi-drug resistant bacterial and fungal infections
Shankar Thangamani
Purdue University
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Thangamani, Shankar, "Repurposing non-antimicrobial drugs to treat multi-drug resistant bacterial and fungal infections" (2016).
Open Access Dissertations. 1015.
https://docs.lib.purdue.edu/open_access_dissertations/1015
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Graduate School Form
30Updated(cid:20)(cid:21)(cid:18)(cid:21)(cid:25)(cid:18)(cid:21)(cid:19)(cid:20)(cid:24)
PURDUE UNIVERSITY
GRADUATE SCHOOL
Thesis/Dissertation Acceptance
This is to certify that the thesis/dissertation prepared
By ShankarThangamani
Entitled
REPURPOSINGNON-ANTIMICROBIALDRUGSTOTREATMULTI-DRUGRESISTANTBACTERIALANDFUNGAL
INFECTIONS
DoctorofPhilosophy
For the degree of
Is approved by the final examining committee:
Dr.MohamedSeleem
Co-chair
Dr.KenitraHammac
Co-chair
Dr.CynthiaStauffacher
Dr.SureshMittal
To the best of my knowledge and as understood by the student in the Thesis/Dissertation
Agreement, Publication Delay, and Certification Disclaimer (Graduate School Form 32),
this thesis/dissertation adheres to the provisions of Purdue University’s“Policy of
Integrity in Research” and the use of copyright material.
Dr.MohamedSeleemandDr.KenitraHammac
Approved by Major Professor(s):
Dr.SureshMittal 8/22/2016
Approved by:
Head of the Departmental Graduate Program Date

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REPURPOSING NON-ANTIMICROBIAL DRUGS TO TREAT MULTI-DRUG
RESISTANT BACTERIAL AND FUNGAL INFECTIONS

A Dissertation
Submitted to the Faculty
of
Purdue University
by
Shankar Thangamani
In Partial Fulfillment of the
Requirements for the Degree
of
Doctor of Philosophy
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December 2016
Purdue University
West Lafayette, Indiana
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ACKNOWLEDGEMENTS
Firstly, I am grateful to the almighty for providing me this wonderful opportunity,
good health, wellbeing and strength that were necessary to complete my studies.
I like to express my sincere gratitude and appreciation to my major advisors Dr.
Mohamed Seleem and Dr. Kenitra Hammac for their guidance and support during the
graduate training. I thank Dr. Seleem for his confidence in me to work on multiple projects
and his encouragement in all aspects to complete this work. He always been accessible to
discuss data or personal matters. He encouraged and supported me to improve my
presentation skills. Knowledge that I have acquired from his discussions will extend
beyond the lab and into all aspects of my life. I also like to thank Dr. Hammac for her
feedback and support in teaching and ADDL projects.
I would like to thank Dr. Ramesh Vemulapalli for his support and valuable
suggestions throughout my PhD. Without him, I would not be able to complete my studies.
I am also indebted to Dr. Chang Kim for providing me an opportunity to learn and improve
my research skills. I would also like to thank my committee members Dr. Cynthia
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Stauffacher and Dr. Suresh Mittal for their valuable inputs and suggestions.
I also thank Dr. Puliyur .S. Mohakumar (The University of Georgia) and Dr. Ramesh
Selvaraj (The Ohio State University) for inspiring me to pursue my graduate studies.
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I thank all my past and current lab colleagues: Jeeho lee, Myunghoo Kim, Jeongho
Park, Seika Hashimoto-Hill, Jinsam Chang, Jeongho Yoon, Bon-hee Gu, Benjamin Ulrich,
Yaqing Qie, Neha Debral, Haroon Mohamed, Waleed Younis, Maha Ahmed, Mostafa,
Mohamed Fathy, Ahmed Hassan, Hassan Elsayed, Youssef Ahmed for their support and
fun times at Purdue.
I thank all my friends and parents for their love and continuous support. Finally, I
thank my better half Madhu and my kid Megna for their love, patience, emotional support
and sacrifices.

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TABLE OF CONTENTS
Page
LIST OF TABLES ............................................................................................................ vii
LIST OF FIGURES ......................................................................................................... viii
LIST OF ABBREVIATIONS ............................................................................................ xi
ABSTRACT ..................................................................................................................... xiii
CHAPTER 1. DRUG REPURPOSING FOR THE DEVELOPMENT OF NOVEL
ANTIMICROBIALS ....................................................................................................... xiv
1.1 Introduction ........................................................................................................... 1
1.2 Approved non-antimicrobial drugs with activity against S. aureus ...................... 6
1.2.1 Drugs with activity in a clinical range that can be achieved systemically .... 6
1.2.2 Drugs with activity that cannot be achieved systemically .......................... 12
1.3 Novel uses of approved drugs ............................................................................. 13
1.3.1 Targeting virulence factors and toxins ........................................................ 13
1.3.2 Efflux pump inhibitors ................................................................................ 15
1.3.3 Immuno-modulatory drugs ......................................................................... 16
1.3.4 Anti-biofilm agents ..................................................................................... 21
1.4 Identifying new antibiotic leads from approved drugs which can serve as novel
antibiotics ............................................................................................................ 22
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1.5 Challenges for repurposing non-antibiotic drugs for S. aureus........................... 23
1.6 Conclusion ........................................................................................................... 26
CHAPTER 2. DRUG REPURPOSING FOR BACTERIAL INFECTIONS ............. 28
2.1 Antibacterial activity and mechanism of action of auranofin against multi-drug
resistant bacterial pathogens ................................................................................ 28
2.1.1 Introduction ................................................................................................. 28
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Page
2.1.2 Materials and Methods ................................................................................. 30
2.1.3 Results ......................................................................................................... 37
2.1.4 Discussion ................................................................................................... 54
2.2 Repurposing auranofin for the treatment of cutaneous staphylococcal infections
………………………………………………………………………………….59
2.2.1 Introduction ................................................................................................. 59
2.2.2 Materials and Methods ................................................................................ 61
2.2.3 Results and Discussion ............................................................................... 65
2.2.4 Conclusion .................................................................................................. 75
2.3 Repurposing ebselen for the treatment of staphylococcal infections .................. 75
2.3.1 Introduction ................................................................................................. 75
2.3.2 Materials and Methods ................................................................................ 77
2.3.3 Results ......................................................................................................... 83
2.3.4 Discussion ................................................................................................... 95
2.4 Repurposing clinical molecule ebselen to combat drug resistant pathogens ...... 99
2.4.1 Introduction ................................................................................................. 99
2.4.2 Materials and Methods .............................................................................. 100
2.4.3 Results and Discussion ............................................................................. 106
2.5 Exploring simvastatin, an antihyperlipidemic drug, as a potential topical
antibacterial agent .............................................................................................. 120 v

2.5.1 Introduction ............................................................................................... 120
2.5.2 Materials and Methods .............................................................................. 122
2.5.3 Results ....................................................................................................... 129
2.5.4 Discussion ................................................................................................. 143
2.6 Repurposing celecoxib as a topical antimicrobial agent for staphylococcal skin
infections ........................................................................................................... 151
2.6.1 Introduction ............................................................................................... 151
2.6.2 Materials and Methods .............................................................................. 153
2.6.3 Results ....................................................................................................... 159
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Page
2.6.4 Discussion ................................................................................................. 169
CHAPTER 3. DRUG REPURPOSING FOR FUNGAL INFECTIONS ................. 176
3.1 Repurposing approach identifies auranofin with broad spectrum antifungal
activity that targets Mia40-Erv1 pathway ......................................................... 176
3.1.1 Introduction ............................................................................................... 176
3.1.2 Materials and Methods .............................................................................. 177
3.1.3 Results and Discussion ............................................................................. 184
3.2 Ebselen exerts antifungal activity by regulating glutathione (GSH) and reactive
oxygen species (ROS) production in fungal cells ............................................. 201
3.2.1 Introduction ............................................................................................... 201
3.2.2 Materials and Methods .............................................................................. 203
3.2.3 Results ....................................................................................................... 208
3.2.4 Discussion ................................................................................................. 218
REFERENCES ............................................................................................................... 223
VITA ............................................................................................................................... 254
PUBLICATIONS ............................................................................................................ 259

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LIST OF TABLES
Table .............................................................................................................................. Page
Table 1.1 List of drugs which have been repurposed as anti-infective agents ................... 5
Table 1.2 Approved drugs with activity against S. aureus ................................................. 9
Table 1.3 continued ........................................................................................................... 10
Table 2.1 MICs of auranofin and control antibiotics against Gram-positive bacteria ..... 38
Table 2.2 MICs of auranofin and control antibiotics against Gram-negative bacteria ..... 41
Table 2.3 Minimum Inhibitory Concentration (MIC) of auranofin and control antibiotics
against Staphylococcus aureus and S. epidermidis ........................................................... 66
Table 2.4 MICs of ebselen and antibiotics against clinical isolates of Staphylococcus
strains ................................................................................................................................ 84
Table 2.5 The MIC and MBC of EB against Gram-positive and Gram-negative bacteria
......................................................................................................................................... 108
Table 2.6 Screening statins for antibacterial activity ...................................................... 130
Table 2.7 MIC of simvastatin against a panel of Gram-positive bacteria ....................... 131
Table 2.8 MIC of simvastatin against a panel of Gram-negative bacteria ...................... 132
Table 2.9 MIC of celecoxib against Gram-positive bacteria ......................................... 160
Table 2.10 MIC of celecoxib against Gram-negative bacteria ....................................... 161
Table 2.11 MIC of celecoxib against clinical isolates of Staphylococcus aureus strains
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......................................................................................................................................... 162
Table 3.1 MIC of auranofin and control antifungal drugs against Candida and
Cryptococcus strains ....................................................................................................... 185
Table 3.2. MIC of ebselen and control antifungal drugs against Candida and
Cryptococcus strains ....................................................................................................... 209
Table 3.3 MIC of ebselen and control antifungal drugs against Candida and
Cryptococcus strains with L-reduced glutathione supplementation ............................... 216