In vitro activity: Mdivi-1 is a cell-permeable quinazolinone compound that inhibits yeast (Dnm1) and mammalian (Drp1) division DRPs (dynamin-related GTPases) and effectively induces mitochondrial fusion into net-like structures in a reversible manner. Cell-free studies indicate that mdivi-1 blocks Dnm1 ATPase activity (IC50<10 μM) and self-assembly by an allosteric modulation-based mechanism. Mdivi-1 is shown to effectively suppress STS- as well as C8-Bid-induced MOMP (Mitochondrial Outer Membrane Permeabilization) in HeLa cultures and in cell-free murine liver mitochondria preparations, respectively, as assessed by cytochrome C release. In cells, mdivi-1 retards apoptosis by inhibiting mitochondrial outer membrane permeabilization. In principle, mivi-1 represents a class of therapeutics for stroke, myocardial infarction, and neurodegenerative diseases.

Kinase Assay: All GTPase assay reactions are started in a 200 μL volume, of which 150 μL is placed into the well of a 96-well plate. Depletion of NADH, as monitored by reading the A340 of the reaction, is measured every 20 s for a total of 40 min using a SpectraMAX 250 96-well plate reader. Spectrophotometric data are transferred to Excel and the measured steady state depletion of NADH over time is converted to protein activity.

Cell Assay: The most efficacious inhibitor, mdivi-1 attenuates mitochondrial division in yeast and mammalian cells by selectively inhibiting the mitochondrial Drp1-mediated division dynamin. Mdivi-1 potently blocks Bid-activated Bax/Bak-dependent cytochrome c release from mitochondria.