title: Nrf2-dependent neuroprotective activity of diterpenoids isolated from Sideritis spp.
abstract: BACKGROUND
  The species of the genus Sideritis are extensively used in the Mediterranean area in folk medicine for their digestive, antimicrobial, anti-inflammatory and antioxidant properties, among others. Moreover, Sideritis species as tea infusions are popularly known for improving memory function and cognitive ability. Diterpenoids are one of the most abundant and important pharmacological interest of the classes of natural products presented in these medicinal plants.
  
  
  OBJECTIVE
  To determine for the first time the neuroprotective effects, based on their antioxidant properties, of the three isolated major diterpenoids andalusol, conchitriol and lagascatriol in an oxidative stress model.
  
  
  METHODS
  H2O2 was used as oxidant inductor and rat adrenal pheochromocytoma PC12 cells as cellular model. Cell viability was measured using MTT and LDH assays, lipid peroxidation was determined by HPLC, GSH and GSSG levels assessed by fluorometric techniques, enzymatic activity and protein expression were determined by spectrofometric techniques and Western blot, respectively.
  
  
  RESULTS
  Pretreatments with the three diterpenoids significantly attenuated H2O2-induced changes in mitochondrial integrity and activity (MTT assay), in cell membrane integrity (LDH assay) and in cell morphology. Moreover, these diterpenoids inhibited intracellular ROS production H2O2-induced, reduced lipid peroxidation and counteracted GSH/GSSG changes. Furthermore, both activities and protein expression of the endogenous antioxidant enzymes (CAT, SOD, GR, GPx and HO-1) were increased. The Nrf2 pathway was involved, at least in part, in the protective effects of these diterpenoids.
  
  
  CONCLUSIONS
  These findings suggest that these natural compounds provide significant antioxidant effects in PC12 under for counteracting the oxidative damage H2O2-induced and their potential role as useful agents for the prevention of those oxidative stress-mediated dementia disorders. Andalusol was the most active compound among the studied diterpenoids.
authors.affiliation: Department of Pharmacology, Faculty of Pharmacy, University Complutense, Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: González-Burgos
authors.forename: M Emilia
authors.initials: ME
authors.lastname: Carretero
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Gómez-Serranillos
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D031365:Sideritis; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004224:Diterpenes; D051267:NF-E2-Related Factor 2; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione