Novel cyclophilin D inhibitors derived from quinoxaline exhibit highly inhibitory activity against rat mitochondrial swelling and Ca2+ uptake/release

Abstract

Aim: To investigate methods for identifying specific cyclophilin D (CypD) inhibitors derived from quinoxaline, thus developing possible lead compounds to inhibit mitochondrial permeability transition (MPT) pore opening. Methods: Kinetic analysis of the CypD/inhibitor interaction was quantitatively performed by using surface plasmon resonance (SPR) and fluorescence titration (FT) techniques. IC 50 values of these inhibitors were determined by PPIase inhibition activity assays. Results: All the equilibrium dissociation constants (K D ) of the seven compounds binding to CypD were below 10 µmol/L. The IC 50 values were all consistent with the SPR and FT results. Compounds GW2, 5, 6, and 7 had high inhibition activities against Ca 2+ -dependent rat liver mitochondrial swelling and Ca 2+ uptake/release. Compound GW5 had binding selectivity for CypD over CypA. Conclusion: The agreement between the measured IC 50 values and the results of SPR and FT suggests that these methods are appropriate and powerful methods for identifying CypD inhibitors. The compounds we screened using these methods (GW1-7) are reasonable CypD inhibitors. Its potent ability to inhibit mitochondrial swelling and the binding selectivity of GW5 indicates that GW5 could potentially be used for inhibiting MPT pore opening.

Mitochondrial permeability transition pore is a potential drug target for neurodegeneration

“…AA also exhibits an additive effect with ubiquinone 0, which inhibits mPTP opening in isolated hepatocytes. As a part of developing novel inhibitors of CypD PPIase activity, Guo, H., et al , has synthesized small molecule quinoxaline derivatives that inhibit mPTP opening [92]. ADP binding to the ANT causes a conformational change thereby inhibiting mPTP opening.…”

Drug-induced Cardiac Mitochondrial Toxicity and Protection: From Doxorubicin to Carvedilol

“…Nonetheless, caution should be taken when inferring the results, since FK-506 also inhibited DOX cardiotoxicity and this compound is not a MPT inhibitor, being in fact an immunosuppressant similarly as CsA [101]. An improved knowledge on this issue could be accomplished if specific MPT inhibitors were used instead [103,104]. Another intriguing aspect is the ex vivo use of CsA on cardiac mitochondria from DOX-treated animals resulted in restoration of respiration to control values, which suggests that the MPT pore or cyclophilin D, the target of CsA in mitochondria, are involved in DOX-induced inhibition of mitochondrial respiration [96].…”

Structure-based identification of small molecule compounds targeting cell cyclophilin A with anti-HIV-1 activity

“…The binding affinity of the selected compounds to cyclophilin A was measured by SPR with a Biacore 3000 instrument (Biacore AB Corporation, Uppsala, Sweden) as previously described (Guo et al, 2005;Thurmond et al, 2001). Briefly, recombinant human cyclophilin A protein (10 µM) was coupled to a carboxylmethylated dextran surface (CM5 chip from Biacore, Inc., Piscataway, NJ) in a buffer containing 10 mM sodium acetate (pH 4.0) using standard amine coupling chemistry following the manufacturer's instructions.…”