Small-molecule inhibitor: clioquinol

Name

History: The copper complex of clioquinol was shown to inhibit the chymotrypsin-like activity of the proteasome in breast cancer cells (Daniel et al., 2005). Since some cancers naturally contain high concentrations of copper, it was proposed that clioquinol would form complexes in the tissue, and might have therapeutic value. Binding of copper to clioquinol was found to be required for transportation of the copper complex into human breast cancer cells and for subsequent proteasome-inhibitory, growth-suppressive, and apoptosis-inducing activities (Zhai et al., 2010).
Peptidases inhibited: proteasome catalytic subunit 3
Pharmaceutical relevance: Clioquinol has a long history as a drug, used for a number of conditions including Alzheimer"s disease, and thus has well-known pharmacology and toxicology (Schimmer, 2011). .

CID at PubChem: 2788
Structure
Chemical/biochemical name: 5-chloro-7-iodo-quinolin-8-ol
Formula weight: 305
Related inhibitors: Clioquinol is a metal ionophore that is able to form stable complexes with copper or zinc. It is a halogenated derivative of 8-hydroxyquinoline, which has some of the same properties.