The present disclosure requires 5-[[4-[2-[5-acetylpyridin-2-yl]ethoxy]phenyl]methyl]-1,3-thiazolidine-2,4-dione or a salt thereof. Central nervous system disorder, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, chronic granulomatous disorder, polycystic ovary syndrome, thyroid carcinoma, thyroid autoimmune disorder, pituitary adenoma, atherosclerosis, hypertension, skin disease, It relates to a method of treating or preventing a disease or disorder selected from the group consisting of inflammatory and autoimmune diseases, inflammatory respiratory diseases, and mitochondrial diseases. The present disclosure also provides 5-[[4-[2-[5-acetylpyridin-2-yl]ethoxy]phenyl]methyl] for use in the manufacture of pharmaceutical compositions or medicaments for the treatment or prevention of mitochondrial diseases. -1,3-thiazolidine-2,4-dione.