It is known that reactive oxygen species (ROS) have a central role in causing many types of neuronal damage such as Alzheimer's disease, Parkinson's disease, ischemia, etc.
1,2)ROS comprise a group of unstable molecules: super oxide radical (O 2 Ϫ ), hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH) and hypochlorous acid (HOCl), that are generated in all cells as a by-product of cellular metabolism during conversion of molecular oxygen (O 2 ) to water (H 2 O). Additionally, phagocytes generate oxidative bursts of ROS to combat microorganisms. Cells possess endogenous systems (superoxide dismutase, catalase, glutathione peroxide) and diet derived (vitamin C and vitamin E) anti-oxidants to prevent or limit ROS induced tissue damage. H 2 O 2 is often used to investigate the mechanism of ROS-induced cell death, 3) and the mechanism of H 2 O 2 -induced PC12 cell death has been examined. 4,5) Hydroxyl radicals form when it comes in contact with a range of transition metal ions. Oxidative stress occurs during an imbalance between ROS and anti-oxidants. Excess production of ROS may lead to cellular injury through nonspecific modification and disruption of proteins, phospholipids and nucleic acids.6) Critical sites of ROS attack are the cell membrane and the membranes of intracellular organelles. The disruptive effects of ROS involve membrane lipid per-oxidation and membrane protein modification, which may produce alterations in the membrane structure and function including fluidity, permeability, enzyme activity, ion channels, transporter and receptor proteins.7) The role of ROS has been implicated in many human degenerative diseases of aging. Various antioxidants have been found to have some preventive and therapeutic effects on these diseases induced by ROS.8) Therefore, substantial efforts have been made in recent years to identify both natural and synthetic antioxidants. Moutan Cortex Radicis (MCR), the root cortex of Paeonia suffruticosa ANDREWS, is a Chinese herbal medicine widely used as an analgesic, antispasmodic, and anti-inflammatory agent. The drug has also long been used in remedies for female diseases. MCR is reported to inhibit oxidative DNA cleavage 9) and to have a scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and superoxide anion radicals generated by the xanthine-xanthine oxidase system.
10)The chemical components of MCR are known to be paeonol, paeonoside, paeonolide, paeoniflorin, benzoylpaeoniflorin, oxypaeoniflorin, benzoyl-oxy-paeoniflorin, and apiopaeonoside.PC12 cells have been widely used as an in vitro experimental model to study the effects of various neurotoxic agents, including 6-hydroxydopamine, 1-methyl-4-phenylpyridinium (MPP ϩ ), paraquat, and manganese on dopaminergic cells.11,12) PC12 cells are electrically excitable and neurosecretory (dopamine, norepinephrine, and/or acetylcholine), and contain many membrane-bound and cytosolic macromolecules associated with neurons.11)The present study was designed to investigate whether ethanol extract of MCR is capable of...
