orientin and Alzheimer-Disease

Alzheimer's disease (AD) is the most common cause of dementia and is characterized by the presence of β-amyloid (Aβ) plaques and defective autophagy in the brain, which is believed to cause neuronal dysfunction. By using APP/PS1 transgenic AD mice, we investigated the influence of orientin (Ori) on cognitive function and its underlying mechanisms in AD models. Our data indicated that Ori improved spatial learning and memory in APP/PS1 mice, possibly through decreasing brain Aβ deposition and attenuating autophagy impairment. Ori decreased the LC3-II/I ratio, p62 and cathepsin D (Ctsd) protein levels and the number of autolysosomes, whereas the protein levels of Ulk1 and Beclin-1 were no different between the control and treatment groups, indicating increased autolysosome clearance and thus a decreased Aβ burden in the brain. Our results showed that Ori could enhance autolysosome clearance, decrease brain Aβ deposition and improve learning and memory in AD mice.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Autophagosomes; Autophagy-Related Protein-1 Homolog; Beclin-1; Brain; Cathepsin D; Cognition; Female; Flavonoids; Glucosides; Mice; Microtubule-Associated Proteins; Presenilin-1; Sequestosome-1 Protein

β-Amyloid (Aβ)-mediated neurotoxicity plays a critical role in the pathogenesis of Alzheimer's disease (AD), possibly including Aβ-induced mitochondrial dysfunction and oxidative stress. Previous studies have demonstrated that orientin (Ori) possesses antioxidation capabilities in vitro. Therefore, current study is to demonstrate that Ori can activate Nrf2/HO-1 signaling and alleviate apoptosis induced by Aβ1-42, and ameliorate cognitive deficits in AD mice.. AD models were made by injecting Aβ1-42 into the bilateral hippocampus of mice. The mice were randomly assigned to three groups: the normal mice and Aβ1-42-induced AD mice with saline, and Aβ1-42-induced AD mice with Ori (5mg/kg), and were injected intraperitoneally once a day for 15 days. After the Morris Water Maze (MWM) test, mice were sacrificed and brains were harvested for biochemical analysis.. Results indicated that Ori could ameliorate cognitive deficits in AD mice. Levels of oxidative stress, indicated by production of reactive oxygen species (ROS), 3-nitrotyrosine (3-NT), 4-hydroxy-nonenal (4-HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), were significantly decreased after Ori treatment. In addition, the current study showed that Ori could attenuate mitochondrial dysfunction induced by Aβ1-42, and subsequently inhibited the mitochondrial apoptotic pathway. Ori induced the nuclear translocation of Nrf2, which enhanced the expression of HO-1 and activation of the redox signaling pathway.. Ori might alleviate cognitive deficits and oxidative stress in AD mice, which might be a potential therapeutic drug for AD.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apoptosis; Cognition Disorders; Flavonoids; Free Radical Scavengers; Glucosides; Heme Oxygenase-1; Male; Maze Learning; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; NF-E2-Related Factor 2; Oxidative Stress; Peptide Fragments; Reactive Oxygen Species; Signal Transduction

To investigate the effect of C-glycosylation at different positions of luteolin, the structure-activity relationships of luteolin and a pair of isomeric C-glycosylated derivatives orientin and isoorientin, were evaluated. We investigated the effects of C-glycosylation on the antioxidant, anti-Alzheimer's disease (AD), anti-diabetic and anti-inflammatory effects of luteolin and its two C-glycosides via in vitro assays of peroxynitrite (ONOO(-)), total reactive oxygen species (ROS), nitric oxide (NO), 1,1-diphenyl-2-picrylhydraxyl (DPPH), aldose reductase, protein tyrosine phosphatase 1B (PTP1B), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-site amyloid precursor cleaving enzyme 1 (BACE1), and cellular assays of NO production and inducible nitric oxide synthase (iNOS)/cyclooxygenase-2 expression in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Of the three compounds, isoorientin showed the highest scavenging activity against DPPH, NO, and ONOO(-), while luteolin was the most potent inhibitor of ROS generation. In addition, luteolin showed the most potent anti-AD activity as determined by its inhibition of AChE, BChE, and BACE1. With respect to anti-diabetic effects, luteolin exerted the strongest inhibitory activity against PTP1B and rat lens aldose reductase. Luteolin also inhibited NO production and iNOS protein expression in LPS-stimulated macrophages, while orientin and isoorientin were inactive at the same concentrations. The effects of C-glycosylation at different positions of luteolin may be closely linked to the intensity and modulation of antioxidant, anti-AD, anti-diabetic, and anti-inflammatory effects of luteolin and its C-glycosylated derivatives.

Topics: Aldehyde Reductase; Alzheimer Disease; Amyloid Precursor Protein Secretases; Animals; Anti-Inflammatory Agents; Antioxidants; Aspartic Acid Endopeptidases; Biphenyl Compounds; Cell Survival; Cells, Cultured; Cholinesterase Inhibitors; Cyclooxygenase 2 Inhibitors; Flavonoids; Glucosides; Glycosylation; Hypoglycemic Agents; In Vitro Techniques; Luteolin; Nitric Oxide; Nitric Oxide Synthase Type II; Peroxynitrous Acid; Picrates; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Rats; Reactive Oxygen Species; Structure-Activity Relationship