γ-Oryzanol from Rice Bran Antagonizes Glutamate-Induced Excitotoxicity in an In Vitro Model of Differentiated HT-22 Cells.

The excessive activation of glutamate in the brain is a factor in the development of vascular dementia. γ-Oryzanol is a natural compound that has been shown to enhance brain function, but more research is needed to determine its potential as a treatment for vascular dementia. This study investigated if γ-oryzanol can delay or improve glutamate neurotoxicity in an in vitro model of differentiated HT-22 cells and explored its neuroprotective mechanisms. The differentiated HT-22 cells were treated with 0.1 mmol/L glutamate for 24 h then given γ-oryzanol at appropriate concentrations or memantine (10 µmol/L) for another 24 h. Glutamate produced reactive oxygen species and depleted glutathione in the cells, which reduced their viability. Mitochondrial dysfunction was also observed, including the inhibition of mitochondrial respiratory chain complex I activity, the collapse of mitochondrial transmembrane potential, and the reduction of intracellular ATP levels in the HT-22 cells. Calcium influx triggered by glutamate subsequently activated type II calcium/calmodulin-dependent protein kinase (CaMKII) in the HT-22 cells. The activation of CaMKII-ASK1-JNK MAP kinase cascade, decreased Bcl-2/Bax ratio, and increased Apaf-1-dependent caspase-9 activation were also observed due to glutamate induction, which were associated with increased DNA fragmentation. These events were attenuated when the cells were treated with γ-oryzanol (0.4 mmol/L) or the N-methyl-D-aspartate receptor antagonist memantine. The results suggest that γ-oryzanol has potent neuroprotective properties against glutamate excitotoxicity in differentiated HT-22 cells. Therefore, γ-oryzanol could be a promising candidate for the development of therapies for glutamate excitotoxicity-associated neurodegenerative diseases, including vascular dementia.

Hispidin in the Medicinal Fungus Protects Dopaminergic Neurons from JNK Activation-Regulated Mitochondrial-Dependent Apoptosis in an MPP+-Induced In Vitro Model of Parkinson's Disease.

Degenerative diseases of the brain include Parkinson's disease (PD), which is associated with moveable signs and is still incurable. Hispidin belongs to polyphenol and originates primarily from the medicinal fungi Inonotus and Phellinus, with distinct biological effects. In the study, MES23.5 cells were induced by 1-methyl-4-phenylpyridinium (MPP+) to build a cell model of PD in order to detect the protective effect of hispdin and to specify the underlying mechanism. Pretreatment of MES23.5 cells with 1 h of hispdin at appropriate concentrations, followed by incubation of 24 h with 2 µmol/L MPP+ to induce cell damage. MPP+ resulted in reactive oxygen species production that diminished cell viability and dopamine content. Mitochondrial dysfunction in MS23.5 cells exposed to MPP+ was observed, indicated by inhibition of activity in the mitochondrial respiratory chain complex I, the collapse of potential in mitochondrial transmembrane, and the liberation of mitochondrial cytochrome c. Enabling C-Jun N-terminal kinase (JNK), reducing Bcl-2/Bax, and enhancing caspase-9/caspase-3/PARP cleavage were also seen by MPP+ induction associated with increased DNA fragmentation. All of the events mentioned above associated with MPP+-mediated mitochondrial-dependent caspases cascades were attenuated under cells pretreatment with hispidin (20 µmol/L); similar results were obtained during cell pretreatment with pan-JNK inhibitor JNK-IN-8 (1 µmol/L) or JNK3 inhibitor SR3576 (25 µmol/L). The findings show that hispidin has neuroprotection against MPP+-induced mitochondrial dysfunction and cellular apoptosis and suggest that hispidin can be seen as an assist in preventing PD.

p-Hydroxybenzyl Alcohol Antagonized the ROS-Dependent JNK/Jun/Caspase-3 Pathway to Produce Neuroprotection in a Cellular Model of Parkinson's Disease.

Parkinson's disease (PD) is a progressive disorder that affects brain nerve cells responsible for body motion and remains incurable. p-Hydroxybenzyl alcohol (HBA) is the primary phenolic compound in Gastrodiae Rhizoma, known for its therapeutic benefits against neurodegeneration. However, the protective effect of HBA against Parkinson's disease (PD) remains unclear. The objective of this study was to evaluate the neuroprotective effects of HBA in vitro 6-hydroxydopamine (6-OHDA)-induced PD model in SH-SY5Y cells. SH-SY5Y cells were pretreated with various concentrations of HBA for 1 h and incubated with 100 µmol/L 6-OHDA for 24 h to induce cellular lesions. 2,5-Diphenyl-2H-tetrazolium bromide was used to detect cellular viability. 2',7'-dichlorofluorescin oxidation detects reactive oxygen species (ROS). The enzyme-linked immunosorbent assay was used to determine the activities of superoxide dismutase, catalase, and glutathione peroxidase. The cellular mitochondrial function was identified through the collapse of the mitochondrial membrane potential, the release of cytochrome c, and the synthesis of mitochondrial ATP. Expression of pro-and anti-apoptotic factors was measured by Western blot. HBA enhanced cell viability, blocked ROS overproduction, and reduced antioxidant activities induced by 6-OHDA. HBA also reduced mitochondrial dysfunction and cell death caused by 6-OHDA. Moreover, HBA reversed the 6-OHDA-mediated activation of c-Jun N-terminal kinase, the downregulation of the Bcl-2/Bax ratio, the Apaf-1 upregulation and the induction of caspase-9, caspase-3, and PARP cleavage. This study shows that the protective effects of HBA against 6-OHDA-induced cell injury provide the potential preventive effects of HBA, making it a promising preventive agent for PD.

Diosmetin Targeted at Peroxisome Proliferator-Activated Receptor Gamma Alleviates Advanced Glycation End Products Induced Neuronal Injury.

The present study aimed to evaluate the role of diosmetin in alleviating advanced glycation end products (AGEs)-induced Alzheimer's disease (AD)-like pathology and to clarify the action mechanisms. Before stimulation with AGEs (200 µg/mL), SH-SY5Y cells were treated with diosmetin (10 µmol/L), increasing cell viability. The induction of AGEs on the reactive oxygen species overproduction and downregulation of antioxidant enzyme activities, including superoxide dismutase, glutathione peroxidase, and catalase, were ameliorated by diosmetin. Amyloid precursor protein upregulation, accompanied by increased production of amyloid-ß, caused by AGEs, was reversed by diosmetin. In the presence of diosmetin, not only ß-site amyloid precursor protein cleaving enzyme1 expression was lowered, but the protein levels of insulin-degrading enzyme and neprilysin were elevated. Diosmetin protects SH-SY5Y cells from endoplasmic reticulum (ER) stress response to AGEs by suppressing ER stress-induced glucose regulated protein 78, thereby downregulating protein kinase R-like endoplasmic reticulum kinase, eukaryotic initiation factor 2 α, activating transcription factor 4, and C/EBP homologous protein. Diosmetin-pretreated cells had a lower degree of apoptotic DNA fragmentation; this effect may be associated with B-cell lymphoma (Bcl) 2 protein upregulation, Bcl-2-associated X protein downregulation, and decreased activities of caspase-12/-9/-3. The reversion of diosmetin on the AGEs-induced harmful effects was similar to that produced by pioglitazone. The peroxisome proliferator-activated receptor (PPAR)γ antagonist T0070907 (5 µmol/L) abolished the beneficial effects of diosmetin on AGEs-treated SH-SY5Y cells, indicating the involvement of PPARγ. We conclude that diosmetin protects neuroblastoma cells against AGEs-induced ER injury via multiple mechanisms and may be a potential option for AD.

The Citrus Flavonoid Hesperetin Encounters Diabetes-Mediated Alzheimer-Type Neuropathologic Changes through Relieving Advanced Glycation End-Products Inducing Endoplasmic Reticulum Stress.

The present study investigates whether hesperetin, a citrus flavonoid, can encounter advanced glycation end-product (AGE)-induced Alzheimer's disease-like pathophysiological changes with the underlying mechanisms. SH-SY5Y cells pretreated with hesperetin before stimulation with AGEs (200 µg/mL) were assessed in the following experiments. Hesperetin (40 µmol/L) elevated the reduced cell viability induced by AGEs. Hesperetin ameliorated reactive oxygen species overproduction and the downregulation of superoxide dismutase, glutathione peroxidase, and catalase, triggered by AGEs. Amyloid precursor protein upregulation, accompanied by the increased production of Aß, caused by AGEs, was reversed by hesperetin. However, hesperetin lowered ß-site APP-cleaving enzyme 1 expression, inducing insulin-degrading and neprilysin expression. In addition, hesperetin downregulated the expressions of the AGEs-induced endoplasmic reticulum (ER) stress proteins, including 78-kDa glucose-regulated protein and C/EBP homologous protein, and lowered the phosphorylation of protein kinase R-like ER kinase and activating transcription factor 4. Hesperetin-pretreated cells had a minor apoptotic DNA fragmentation. Hesperetin is able to upregulate Bcl-2 protein expression, downregulate Bax expression, and decrease caspase-12/-9/-3 activity as well, indicating that it inhibits ER stress-mediated neuronal apoptosis. There is a similar effect between hesperetin and positive rosiglitazone control against Aß aggravation of SH-SY5Y cell injury induced by AGEs. Thus, hesperetin might be a potential agent for treating glycation-induced Aß neurotoxicity.

A Bibenzyl Component Moscatilin Mitigates Glycation-Mediated Damages in an SH-SY5Y Cell Model of Neurodegenerative Diseases through AMPK Activation and RAGE/NF-κB Pathway Suppression.

Moscatilin can protect rat pheochromocytoma cells against methylglyoxal-induced damage. Elimination of the effect of advanced glycation end-products (AGEs) but activation of AMP-activated protein kinase (AMPK) are the potential therapeutic targets for the neurodegenerative diseases. Our study aimed to clarify AMPK signaling's role in the beneficial effects of moscatilin on the diabetic/hyperglycemia-associated neurodegenerative disorders. AGEs-induced injury in SH-SY5Y cells was used as an in vitro neurodegenerative model. AGEs stimulation resulted in cellular viability loss and reactive oxygen species production, and mitochondrial membrane potential collapse. It was observed that the cleaved forms of caspase-9, caspase-3, and poly (ADP-ribose) polymerase increased in SH-SY5Y cells following AGEs exposure. AGEs decreased Bcl-2 but increased Bax and p53 expression and nuclear factor kappa-B activation in SH-SY5Y cells. AGEs also attenuated the phosphorylation level of AMPK. These AGEs-induced detrimental effects were ameliorated by moscatilin, which was similar to the actions of metformin. Compound C, an inhibitor of AMPK, abolished the beneficial effects of moscatilin on the regulation of SH-SY5Y cells' function, indicating the involvement of AMPK. In conclusion, moscatilin offers a promising therapeutic strategy to reduce the neurotoxicity or AMPK dysfunction of AGEs. It provides a potential beneficial effect with AGEs-related neurodegenerative diseases.

The protective effects of moscatilin against methylglyoxal-induced neurotoxicity via the regulation of p38/JNK MAPK pathways in PC12 neuron-like cells.

Methylglyoxal (MGO) is an endogenous toxic compound that plays a vital role in diabetic complications such as diabetic neuropathy. Moscatilin is a bibenzyl component from Dendrobium species, has been shown to possess a wide range of pharmacological activities. To clarify whether moscatilin prevents rat pheochromocytoma cells (PC12 cells) from damage induced by MGO, cells were pre-treated with moscatilin and then stimulated with MGO. Moscatilin inhibited MGO associated cytotoxicity in a concentration (0.1, 0.5, or 1.0 µmol/L)-dependent manner and downregulated the formation of advanced glycation end products and reactive oxygen species. Moscatilin attenuated MGO-induced mitochondrial dysfunction involving the loss of mitochondrial membrane potential and depletion of adenosine triphosphate. MGO induced cell apoptosis via the upregulation of p53, caspases 3 and poly(ADP-ribose)polymerase, enhancement of cytochrome c release, and interruption of the Bax/Bcl-2 balance; these detrimental effects were ameliorated by moscatilin. Furthermore, moscatilin inhibited MGO-induced activation of MAP kinase (MAPK) superfamily, including p38 and c-Jun N-terminal kinases (JNKs). In conclusion, we found that the neuroprotective effect of moscatilin is due to a reduction of MGO-induced damage to mitochondria function through modulating the p38 and JNK stress-activated MAPK cascades pathway. Thus, it might be a potent compound for preventing/counteracting diabetic neuropathy.

C18 dibenzocyclooctadiene lignans from Kadsura philippinensis.

Four new C18 dibenzocyclooctadiene lignans, kadsuphilins A (1) and B (3), 6-epi-gomisin (2), and 1-demethylkadsuphilin A (4), along with eight known related metabolites, were isolated from an EtOAc fraction of an alcoholic extract of the aerial parts of Kadsura philippinensis growing in Taiwan. The structures of 1-4 were elucidated on the basis of spectroscopic analyses, including 2D NMR (HMQC, HMBC, and NOESY) experiments, and by comparison of their spectroscopic data with those of related metabolites. The configurations of the biphenyl and cyclooctadiene moieties were deduced from circular dichroism (CD) and NOESY NMR spectra, respectively. Some of the compounds showed radical-scavenging activity in a DPPH-HPLC method.

The plasma glucose lowering action of Hei-Shug-Pian, the fire-processed product of the root of Aconitum (Aconitum carmichaeli), in streptozotocin-induced diabetic rats.

The anti-hyperglycemic action of Hei-Shug-Pian, the fire-processed product of the root of Aconitum (Aconitum carmichaeli), was investigated in streptozotocin-induced diabetic (STZ-diabetic) rats. At 120 min following oral administration of Hei-Shug-Pian at doses ranging from 12.5 to 50 mg/kg, plasma glucose of STZ-diabetic rats was found to be decreased in a dose-dependent manner. Under treatment conditions wherein plasma glucose was lowered, the uptake of glucose into soleus muscle was increased and the incorporation of glucose into glycogen of hepatocytes was enhanced. The plasma glucose-lowering effect of Hei-Shug-Pian was eliminated by blockade of opioid mu-receptors. Moreover, Hei-Shug-Pian treatment failed to lower plasma glucose in opioid mu-receptor knockout diabetic mice. The findings obtained in this study support the conclusion that Hei-Shug-Pian lowers the plasma glucose concentrations of STZ-diabetic rats through activation of opioid mu-receptors of peripheral tissues, resulting in enhanced glucose utilization.

Comparison of the antinociceptive action of crude Fuzei, the root of Aconitum, and its processed products.

The antinociceptive effects of crude Fuzei, the root of Aconitum carmichaeli and of Fuzei processed by three different methods were determined in mice and rats using the light tail-flick assay. A dose-dependent and significant increase in pain threshold was found at 60 min post treatment, with doses of 20-60 mg/kg crude Fuzei. The analgesic effects of processed Fuzei (20-60 mg/kg) exhibited a dose-dependent inhibition of tail-flick, but the effects were lower than those produced by crude Fuzei in the same tests. The analgesic effect of Yan-Fuzei, the salt baking product, was the most potent of the processed products and was nearly that provided by crude Fuzei. Although the concentrations of aconitine were significantly lower in the processed Fuzei than in the crude Fuzei, a higher oral LD50 was found for all of the processed Fuzei formulations. Moreover, antinociception of crude Fuzei and its processed products was attenuated but not totally blocked by naloxone at doses sufficient to block opioid mu-receptors. Furthermore, the analgesic effect of crude Fuzei and its processed products was decreased in opioid mu-receptor knockout mice, but the effect remained unaltered in mice with opioid mu-receptors, indicating that the analgesic effect of Fuzei is centrally mediated. These results demonstrate that Fuzei processed by salt baking possesses analgesic effects within a large therapeutic range, probably via a mechanism involving central opioid receptors that mediate the antinociception.