The depolarization of mitochondrial membrane potential (MMP) in glioma cells upon treatment with various concentrations of morin was examined using the rhodamine 123 staining technique. The 25 and 50 µM/mL morin-treated and untreated control glioma cells were stained with the lipophilic cationic dye rhodamine 123 and incubated in the dark for 30 min. The fluorescence emission of the cells was read using a fluorescence microplate reader at an excitation of 485 nm and an emission of 530 nm. The intensity of the fluorescence was measured.