1. Strathclyde-Minor Groove Binders (S-MGBs) as Antimicrobial Agents
Dr. Fraser J. Scott
University of Lincoln or

2. Outline The origin of the S-MGB programme
Recent Success of MGB-BP-3 against Gram- positive bacteria
Efforts towards Gram-negative active S-MGBs
Efforts towards TB active S-MGBs
Programme overview

3. Cozzi et al.
Polyamide MGBs
Dervan et al.
Strathclyde

4. Original Design Concept at Strathclyde
Hydrophobic patches
Hydrogen bonding on floor
N-alkyl group on pyrrole 4

5. Very Early Hit Compounds
Head
Het 1
Het 2
Het 3
Tail

6. Target Identification
DNA Footprinting
TyrT - a standard, naturally occurring oligonucleotide commonly used in footprinting.
MS1 and MS2 - synthetic oligonucleotides designed to contain all possible 4mers - ideal for studying binding of MGBs of this size.
Prof Keith Fox, University of Southampton

7. Target Identification
N-alkyl pyrroles read AT
Thiazotropsin A can read GC

8. Target Identification3´
GCTGA
TCAGC5´
5’CGACTAGTCG3´
Canonical DNA with AT rich sequence showing minor groove shaded to show electrostatic potential (red = negative)
Structure of DNA 2:1 thiazotropsin A complex calculated from NMR data. Note wider minor groove. 8

9. Anti-Gram-Positive S-MGBs

10. Recent Success of MGB-BP-3 against Gram-positive bacteria
Amide: planar, H-bond donor and acceptor, hydrolysable.
Alkene: planar, non-polar, stable to hydrolysis.
One hydrogen bond lost.
Tm measurements show that loss of a hydrogen bond does not weaken binding to DNA oligos in this group of compounds.
MGB-BP-3 10

11. Current status
MGB Biopharma has taken MGB-BP-3 to successful completion of Phase I clinical trials for oral treatment of C. diff infections.
“Differentiation of MGB-BP-3 in Clostridium difficile Infection
Broad in vitro activity confirmed against Clostridium difficile
 Rapid killing effect seen for MGB-BP-3 against C. diff strains, including hyper-virulent NAP1/027; activity superior to vancomycin
Superior activity to vancomycin confirmed in vivo
MGB-BP-3 is superior to vancomycin in suppressing sporulation in all C. difficile strains tested
MGB-BP-3 is active against vancomycin resistant enterococci (VRE)”

12. Current status
MGB Biopharma is nearly ready to enter phase I with IV treatments against other Gram-positives.
“Final formulation optimisation and up-scaling has been successfully completed, and pivotal proof of concept and ADME studies assessing IV MGB-BP-3 against Staphylococcus aureus (including MRSA), Streptococcus pyogenes and pneumoniae are complete.”

13. Selectivite Toxicity?
S. Aureus
HS27 Cells

14. Selective Toxicity S. aureus without MGB-BP3 Brightfield under UV
S. aureus with MGB-BP3
Brightfield under UV
B16FOluc cells with MGB-BP3
Brightfield under UV
B16FOluc cells with Hoechst dye
Brightfield under UV

15. Selective Toxicity
Primary hepatocytes after 24 h with a highly fluorescent MGB that has antibacterial activity

16. Anti-Gram-Negative S-MGBs

17. Entry to Cells Brightfield Fluorescence Bacillus cereus
Staphylococcus aureus
Listeria monocytogenes 17 17

18. Entry to Cells Brightfield Fluorescence Pseudomonas aerugenosa
Salmonella enteriditis
Escherichia coli 18 18

19. Entry to Cells Brightfield Fluorescence E. coli Spheroplast
E. coli intact cells 19 19

20. The Role of Efflux Organism MIC80 (µM) MIC80 with EPI (µM)
P. Aeruginosa
>100
1.36
E. coli
0.78
Efflux pump inhibitor (EPI) PAβN.

21. Anti-Mycobacterium Tuberculosis S-MGBs

22. Journey to high activity …
Reto Guler, University of Cape Town
Journey to high activity …
12.5 mM
25 mM
25 mM
25 mM
3.1 mM
0.2 mM M. Tuberculosis
>100 mM HEK293T (IC50)
Different S-MGB Series

23. Other Targets for S-MGBs

24. Trypanosoma congolense (cattle)
Antiparasitics 1: Sleeping Sickness
Michael Barrett – University of Glasgow
Swiss Tropical and Public Health Institute
Trypanosoma brucei (human)
Trypanosoma congolense (cattle)
IC50 = 390 nM
IC50 = 14 nM
IC50 = 110 nM
IC50 = 7 nM

25. Antiparasitics 2: Malaria
Victoria Avery, Griffith University, Australia
Plasmodium falciparum
IC50 = 39, 38 nM, selectivity > 500
IC50 = 103, 241 nM, selectivity >200
Two strains, chloroquine sensitive and chloroquine insensitive studied.
Selectivity and activity against insensitive strain important.
cf. chloroquine IC50 = 11.3, 177 nM, selectivity > 105 for sensitive cells.
Pyrimethamine IC50 = 8.45, na, selectivity = 955 for sensitive cells.

26. Anticancer: human melanoma cell line
Chris Carter, University of Strathclyde
IC50 = 140 nM
cf. gemcitabine = 1089 nM

27. Acknowledgements Chemistry Biology Colin Suckling Elizabeth Ellis
Abedawn Khalaf
Iain Hunter
Roger Waigh
Gordon Ford
Simon Mackay
Curtis Gemmell
Colin Gibson
Nick Tucker
David Breen
Leena Nieminen
Nahoum Anthony
Namita Upadhyay
John Parkinson
Chris Carter
Judith Huggan
Helen Grant
Gavin Donoghue
Katherine Henderson
Claire Bourdin
Keith Fox (Southampton)
Gail Wilson
Michael Barrett (Glasgow)
Angus Wilson
Federica Giordani (Glasgow)
Andrew MacDonald
Reto Guler (Cape Town)
Ross Carleton
Ryan Nichol
Funding
Synergy Fund
Scottish Enterprise Proof of Concept
Leucovorin Royalties, Strathclyde
BBSRC
MSD-SULSA
Rosetrees Trust
Carnegie Foundation