aurapten and Brain-Ischemia

We have recently shown that 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) and auraptene (AUR) have neuroprotective effects on the central nervous system. HMF, a citrus flavonoid, altered NMDA-type glutamate receptor antagonist MK-801-induced memory dysfunction and schizophrenia-positive symptom-like behavior. HMF also showed a protective effect against ischemia-induced short-term memory dysfunction. In the ischemic brain, HMF induced the following protective effects against brain dysfunction: 1) rescue of neuronal cell death in the hippocampus; 2) increased production of brain-derived neurotrophic factor; 3) stimulation of neurogenesis in the dentate gyrus subgranular zone; 4) activation of the autophosphorylation of calcium-calmodulin-dependent protein kinase II; and 5) suppression of microglial activation. On the other hand, AUR, a citrus coumarin, ameliorated lipopolysaccharide-induced inflammation in the brain as shown by inhibition of microglial activation and inhibition of cyclooxygenase (COX)-2 expression in the hippocampus. AUR also showed antiinflammatory effects on the ischemic brain by inhibiting microglial activation, COX-2 expression, and neuronal cell death in the hippocampus. The peel of kawachibankan (Citrus kawachiensis), a noted citrus product of Ehime prefecture, Japan, contains AUR, HMF, naringin, and narirutin. The dried powder of both the peel and juice had antiinflammatory effects in the mouse hippocampus, suggesting that citrus compounds may be beneficial as neuroprotective agents in the treatment of neurological disorders.

Topics: Animals; Anti-Inflammatory Agents; Brain; Brain Ischemia; Brain-Derived Neurotrophic Factor; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Cell Death; Central Nervous System; Citrus; Coumarins; Cyclooxygenase 2; Disease Models, Animal; Flavones; Food; Hippocampus; Humans; Memory Disorders; Mice; Microglia; Nervous System Diseases; Neurogenesis; Neuroprotective Agents; Phytotherapy; Receptors, N-Methyl-D-Aspartate; Schizophrenia

The peel of Citrus kawachiensis (Kawachi Bankan), a citrus species grown in Ehime, Japan, is abundant in auraptene. Auraptene, a coumarin compound, have been shown to exert anti-inflammatory effects in peripheral tissues, but it was still unclear of the effect in the brain. Hyperglycemia and brain ischemia induce inflammation and oxidative stress and cause massive damage in the brain; therefore, we examined the anti-inflammatory and other effects of the dried peel powder of C. kawachiensis and auraptene in a hyperglycemia and global cerebral ischemia models. The C. kawachiensis treatment inhibited astroglial activation in the hippocampus and the hyperphosphorylation of tau protein in hippocampal neurons, and also relieved the suppression of neurogenesis in the dentate gyrus of the hippocampus in the type 2 diabetic db/db mice. The C. kawachiensis treatment inhibited microglial and astroglial activation, and neuronal cell death in the hippocampus of transient global cerebral ischemia mice. It was suggested that the dried peel powder of C. kawachiensis exerts anti-inflammatory and neuroprotective effects in the brain. We attempted to demonstrate the effect of auraptene in the brains in streptozotocin-induced hyperglycemic mice and transient global cerebral ischemia mice. Auraptene administration showed the similar effects as the peel of C. kawachiensis in the hippocampus of these mice models. These results suggested that auraptene have potential effects as a neuroprotective agent in the peel of C. kawachiensis.

Topics: Animals; Brain Ischemia; Citrus; Coumarins; Hippocampus; Hyperglycemia; Japan; Mice; Mice, Obese; Neuroprotective Agents; Reperfusion Injury

Cerebral ischemia/reperfusion leads to delayed neuronal cell death, resulting in brain damage. Auraptene (AUR) and naringin (NGIN), which exert neuroprotective effects in ischemic brain, are abundant in the peel of Citrus kawachiensis. Although parts of AUR/NGIN are transited from the peel to the juice during the squeezing of this fruit, these amounts in juice might be too low to exert effects. We thus prepared the AUR/NGIN-rich fruit juice of C. kawachiensis by addition of peel paste to the raw juice. The present study revealed that orally administration of the dried powder of this AUR/NGIN-rich fruit juice (2.5 g/kg/d) for 7 d to ischemic mice significantly suppressed the ischemia-induced neuronal cell death in the hippocampus, which was coincidently with the reduction of hyperactivation of microglia and astrocytes. These results suggest that AUR/NGIN-rich juice of C. kawachiensis may possess therapeutic potential for the prevention of neurodegenerative diseases via inhibition of inflammatory processes.

Topics: Animals; Anti-Inflammatory Agents; Brain; Brain Ischemia; Cell Death; Citrus; Coumarins; Flavanones; Fruit and Vegetable Juices; Hippocampus; Mice; Neuroprotective Agents; Phytotherapy; Plant Preparations; Powders

The anti-inflammatory activity of auraptene (AUR), a citrus coumarin, in peripheral tissues is well-known, and we previously demonstrated that AUR exerts anti-inflammatory effects in the ischemic brain; the treatment of mice with AUR for eight days immediately after ischemic surgery suppressed demise and neuronal cell death in the hippocampus, possibly through its anti-inflammatory effects in the brain. We suggested that these effects were at least partly mediated by the suppression of inflammatory mediators derived from astrocytes. The present study showed that (1) AUR, as a pretreatment for five days before and another three days after ischemic surgery, suppressed microglial activation, cyclooxygenase (COX)-2 expression in astrocytes, and COX-2 mRNA expression in the hippocampus; (2) AUR suppressed the lipopolysaccharide-induced expression of COX-2 mRNA and the mRNA of pro-inflammatory cytokines in cultured astrocytes; (3) AUR was still detectable in the brain 60 min after its intraperitoneal administration. These results support our previous suggestion that AUR directly exerts anti-inflammatory effects on the brain.

Topics: Animals; Anti-Inflammatory Agents; Brain; Brain Ischemia; Coumarins; Cyclooxygenase 2; Cytokines; Disease Models, Animal; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Hippocampus; Inflammation Mediators; Male; Mice

Cerebral ischemia causes delayed neuronal cell death in the hippocampus resulting in sequential cognitive impairments. Hyper-activated inflammation following ischemia is one of the etiologies for delayed neuronal cell death. In the present study, using a transient global ischemia mouse model, we showed that auraptene (AUR), a citrus coumarin, effectively inhibited microglia activation, cyclooxygenase-2 expression by astrocytes, and neuronal cell death in the hippocampus following ischemic insults. These results suggest that AUR acts as a neuroprotective agent in the ischemic brain, which may be mediated by suppression of the inflammatory response.

Topics: Animals; Anti-Inflammatory Agents; Astrocytes; Brain Ischemia; Cell Death; Coumarins; Cyclooxygenase 2; Disease Models, Animal; Hippocampus; Inflammation; Male; Mice; Mice, Inbred C57BL; Microglia; Neurons; Neuroprotective Agents