This document examines the structure-activity relationships of inhibitors of plasminogen activator inhibitor-1 (PAI-1). [1] Many effective PAI-1 inhibitors contain gallate or digallate groups. [2] The research synthesized compounds with varying numbers of gallates and positions of hydroxyl groups to determine the effects on PAI-1 inhibition. [3] Results showed that electron-rich carbamate handles and modifying gallate to protocatechuate increased inhibition. Future work will test additional structural modifications and attachments.

1. Examination of the Structure-Activity Relationships of Inhibitors of Plasminogen Activator Inhibitor-1
Structure- Inhibitor-
Karen L. Sanders,1 Hasina Saraha,1 Mark Warnock,2 Jacqueline M. Cale,2 Daniel A. Lawrence,2 and Cory D. Emal1*; (1) Chemistry
Department, Eastern Michigan University, Ypsilanti, 48197; (2) Department of Internal Medicine, University of Michigan Medical
School, Ann Arbor, MI, 48109
Introduction/Background Common Structural Themes Inhibition Results
The inhibition of plasminogen activator-inhibitor-1 (PAI-1) is Many of the compounds displaying PAI-1 inhibition contain gallate or Effect of modifying the gallate to a protocatechuate on PAI-1 inhibition:
anticipated to increase our understanding of various human ailments digallate groups. The focus of our research has been centered on the
including diabetes, stroke, and atherosclerosis, for which high levels of structure-activity relationship of different configurations of polyphenols.
PAI-1 have been associated.(1) PAI-1 prevents certain serine proteases This includes the manipulation of the carbamate handle and the number and
from cleaving peptide bonds and thus is able to regulate various cellular position of the hydroxyl groups on the inhibitory molecules. IC50 = 0.105 µm
processes such as controlling the levels of other intracellular proteins, IC50 = 0.062 µm
such as tissue-type plasminogen activator (tPA) and urokinase-type IC50 = 0.104 µm
plasminogen activator (uPA).(2) Goal: to determine the effect of manipulating the carbamate handle and
the number and position of the hydroxyl groups on the gallate core.
IC50 = 0.029 µm
IC50 = 9.6 µm IC50 = 0.048 µm
Design and Synthesis
Effect of manipulating the carbamate handle on PAI-1 inhibition:
The focus of the reactions depicted in Scheme 1 is the production of IC50 = 4.75 µm IC50 = 0.159 µm
IC50 = 4.69 µm
compounds that investigate the effect of manipulating the carbamate handle
Fibrinolysis: Green arrows indicate a on either a gallate or protocatechuate coupled species. In concert, the effect
stimulatory effect, and red arrows
indicate an inhibitory effect.
on inhibition which the change in either the number or position of the
hydroxyl groups that compose the gallate core was examined. A series of
five-six reactions are required to synthesize the desired compounds. These
reactions were repeated as necessary using different attachments. The last
Therefore, the goal of this research is to inhibit the inhibitor of fibrinolysis, step which entailed the removal of the benzyl protecting groups utilized
IC50 = 0.02 µm
the process which leads to the break down of blood clots. Pd/C 10%. Attempts were made to remove these protecting groups with an IC50 = 0.0108 µm IC50 = 0.022 µm
encapsulated version, Pd Encat 30 Palladium Acetate Microencapsulated in
The complexity of the PAI-1 structure has the potential to possess several
Polyurea Matrix 0.4 mmol Pd/g. It was done with the aim of eliminating
binding sites to a wide variety of inhibitory molecules. Development of
the highly toxic palladium from in vivo studies.(4)
therapeutic agents that act as selective inhibitors of PAI-1 may provide an
approach to treat these ailments. Recent reports have noticed inhibitive
properties in furan-2-one and pyrrolin-2-one derivatives.(3) However, Scheme 1: Synthesis of differing PAI-1 inhibitory molecules IC50 = ? µm
IC50 = ? µm IC50 = 0.027 µm
these known accounts have reported the synthesis of inhibitors that bind to
PAI-1 with a low affinity and fail to inhibit PAI-1 when vitronectin, a
cofactor of PAI-1 is present. Conclusion
Activity towards PAI-1 is very sensitive to the identity of the
carbamate handle. Carbamate handles which are composed of electron-rich
Species result in a increased inhibition of PAI-1. The modification of the gallate
IC50 = 9.6 µm core to a protocatechuate results in a positive increase in the inhibition of the
serpin.
A furan-2-one/pyrrolin-2-one derivative.
A high-throughput screen was conducted by Daniel Lawrence and
Future Directions
- Test the inhibitory effect of electronically larger species attachments.
coworkers at the University of Michigan against a large library of a variety - Synthesize inhibitors with asymmetric gallate attachments.
of organic compounds. Some of these compounds proved to be effective - Incorporate R-NH2 attachments.
PAI-1 inhibitors. Many of these compounds contain gallate or digallate
groups. Similar compounds containing related phenolic structures did not Acknowledgements
show inhibitory activity versus PAI-1. Molecules were synthesized - The remaining members of the Emal and Lawrence research groups
containing varying numbers of gallates which proved to be effective PAI-1
inhibitors. Funding from:
- Eastern Michigan University
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- Camille and Henry Dreyfus Foundation
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O O - National Institutes of Health
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References
OH OH 1.) Ren, Y., Himmeldirk, K., Chen, X. J. Med. Chem. 2006, 49, 2829-2837.
2.) Wang et al. Biochemistry. 1996, 35 (51), 16443-16448.
3.) Miyazaki, H.; Ogiku, T.; Hiroshi, S.; Moritani, Y.; Ohtanl, A. Chem. Pharm. Bull. 2009, 57 (9) 979-985.
4.) Cale, J. M.; Li, S.; Warnock, M.; Su, E. J.; North, P. R.; Sanders, K. L.; Puscau, M. M.; Emal, C. D.; Lawrence,
HO OH IC50 = 0.37 µm D. A. Characterization of a Novel Class of Polyphenolic Inhibitors of Plasminogen Activator Inhibitor-1. J.
IC50 = 0.025 µm Bio. Chem. 2010 In Press
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