HPGDS and Alzheimer disease: On the other hand, metformin reduces MDA and nitrite levels and myeloperoxidase activity, while it also enhances antioxidant status, increasing glutathione, glutathione peroxidase, and catalase and glutathione transferase and SOD activities in various sporadic AD models [167, 168, 170, 175, 177, 178, 181].