Discovery and characterization of novel selective inhibitors of carbonic anhydrase IX

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Oncology

Background:

• Human carbonic anhydrase IX (CA IX) is overexpressed in various tumor types.
• Targeting CA IX is a promising strategy for anticancer drug development.
• A need exists for potent and selective CA IX inhibitors.

Purpose of the Study:

• To design and synthesize novel fluorinated benzenesulfonamides as potential CA IX inhibitors.
• To evaluate the potency and selectivity of these compounds against CA IX.
• To explore structure-activity relationships for optimized anticancer therapeutics.

Main Methods:

• Synthesis of a series of fluorinated benzenesulfonamides with diverse benzene ring substituents.
• In vitro enzymatic assays to determine inhibitory activity against CA IX and CA II.
• Co-crystallization of inhibitors with chimeric CA IX to elucidate binding modes.
• Determination of binding affinities (pM to nM range) and selectivity profiles.

Main Results:

• Several synthesized compounds demonstrated potent and selective inhibition of CA IX.
• Fluorine substitution enhanced affinity by influencing electron withdrawal and pKa.
• Bulky ortho substituents (e.g., cyclooctyl, cyclododecyl) conferred selectivity by interacting with the CA IX active site hydrophobic pocket.
• The most potent inhibitor had an affinity of 50 pM, while the most selective compound showed 10 nM affinity.
• A lead compound achieved a balance with 1 nM affinity and good selectivity.

Conclusions:

• Fluorinated benzenesulfonamides are effective inhibitors of human carbonic anhydrase IX.
• Structural modifications, including fluorine atoms and bulky ortho substituents, are crucial for achieving high affinity and selectivity.
• These novel inhibitors provide a foundation for developing new anticancer therapies targeting CA IX.