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Cyclotheonamide derivatives: synthesis and thrombin inhibition. Exploration of specific structure-function issues
B E Maryanoff1, H C Zhang, M N Greco
1R.W. Johnson Pharmaceutical Research Institute, Spring House, PA 19477, USA.
Bioorganic & Medicinal Chemistry
|August 1, 1995
Summary
Researchers synthesized macrocyclic pentapeptide analogues of cyclotheonamide A to study alpha-thrombin inhibition. Structure-activity relationships were less predictable than expected, impacting drug design strategies.
Area of Science:
- Medicinal Chemistry
- Biochemistry
- Natural Product Synthesis
Background:
- Cyclotheonamide A (CtA) is a natural product with potential therapeutic applications.
- Alpha-thrombin is a key serine protease involved in blood coagulation and thrombosis.
- Understanding CtA's interaction with alpha-thrombin can guide the development of anticoagulants.
Purpose of the Study:
- To synthesize novel macrocyclic pentapeptide analogues of CtA.
- To evaluate the inhibitory activity of these analogues against alpha-thrombin.
- To investigate structure-activity relationships (SAR) to optimize thrombin inhibition.
Main Methods:
- Convergent [3 + 2] synthetic strategy to prepare CtA analogues (5-9).
- Enzymatic assays to determine Michaelis-Menten and slow-binding kinetics of inhibition.
- Systematic structural modifications to probe interactions with the alpha-thrombin active site.
Main Results:
- Synthesis of five novel CtA analogues with modifications at key positions.
- Characterization of the kinetic parameters for alpha-thrombin inhibition by CtA, CtB, and analogues.
- Exploration of the S3 subsite and the role of the hydroxyphenyl group revealed complex SAR.
Conclusions:
- The structure-activity relationship for cyclotheonamide analogues inhibiting alpha-thrombin is complex and not easily predictable.
- Modifications aimed at exploiting specific thrombin subsites or interactions did not yield straightforward improvements in inhibition.
- Further research is needed to fully elucidate the SAR for developing potent and selective alpha-thrombin inhibitors based on the cyclotheonamide scaffold.