Dae-Gill Kang

1H-NMR-based metabolomics study of cerebral infarction.

Background and Purpose— Stroke is one of the leading causes of adult disability and death in developing countries. However, early diagnosis is difficult and no reliable biomarker is currently available. Thus, we applied a 1H-NMR metabolomics approach to investigate the altered metabolic pattern in plasma and urine from patients with cerebral infarctions and sought to identify metabolic biomarkers associated with stroke. Methods— Metabolic profiles of plasma and urine from patients with cerebral infarctions, especially small vessel occlusion, were investigated using 1H-NMR spectroscopy coupled with multivariate statistical analysis, such as principal components analysis and orthogonal partial least-squares discriminant analysis. Results— Multivariate statistical analysis showed a significant separation between patients and healthy individuals. The plasma of stroke patients was characterized by the increased excretion of lactate, pyruvate, glycolate, and formate, and by the decreased excretion of glutamine and methanol; the urine of stroke patients was characterized by decreased levels of citrate, hippurate, and glycine. These metabolites detected from plasma and urine of patients with cerebral infarctions were associated with anaerobic glycolysis, folic acid deficiency, and hyperhomocysteinemia. Furthermore, the presence of cerebral infarction in the external validation model was predicted with high accuracy. Conclusions— These data demonstrate that a metabolomics approach may be useful for the effective diagnosis of cerebral infarction and for the further understanding of stroke pathogenesis.

Effects of bulb of Fritillaria ussuriensis maxim. on angiotensin converting enzyme and vascular release of NO/cGMP in rats

The present study was designed to investigate whether the Bulbus Fritillaria shows a hypotensive effect via the angiotensin converting enzyme (ACE) inhibition and elicit NO/cGMP release in rat aortic rings. Intravenous injection of Bulbus Fritillaria water extract lowered the mean arterial pressure of anesthetized rats in a dose-dependent manner. The ACE activities were inhibited significantly by the additions of ethylacetate and butanol extracts from Bulbus Fritillaria, of which IC(50) values were 292 and 320 microg/ml, respectively. Moreover, angiotensin I-induced vasoconstriction was also strongly inhibited by the additions of ethylacetate and butanol extracts from Bulbus Fritillaria. In order to assess whether NO production was induced by Bulbus Fritillaria extracts, we directly measured NO and cGMP production levels from the aortic ring elicited by extracts of Bulbus Fritillaria. Our results showed that the hexane, butanol, and water extracts of Bulbus Fritillaria increased NO and cGMP productions in intact vascular tissue. These findings suggest that Bulbus Fritillaria extracts have a hypotensive effect in rats via the inhibition of ACE activity and direct release of NO/cGMP in the vascular tissue.

Cytoprotective effects of lindenenyl acetate isolated from Lindera strychnifolia on mouse hippocampal HT22 cells.

Oxidative injury contributes to neuronal degeneration in many central nervous system (CNS) diseases, such as Parkinsons disease, Alzheimers disease, epilepsy and ischemia. Inducible heme oxygenase (HO)-1 acts against oxidants that are thought to play a role in the pathogenesis of these diseases. Lindenenyl acetate, isolated by bioassay-guided fractionation of the MeOH extract of the roots of Lindera strychnifolia, showed potent neuroprotective effects on glutamate-induced neurotoxicity by inducing the expression of HO-1 and increasing the activity of HO in mouse hippocampal HT22 cells. Furthermore, lindenenyl acetate caused the nuclear accumulation of nuclear factor-E2-related factor 2 (Nrf2) and increased the promoter activity of antioxidant response elements (ARE) in mouse hippocampal HT22 cells. In addition, we found that treatment of the cells with extracellular signal-regulated kinase (ERK) inhibitor (U0126) reduced lindenenyl acetate-induced HO-1 expression. Lindenenyl acetate also increased ERK phosphorylation. These results suggest that lindenenyl acetate increases cellular resistance to glutamate-induced oxidative injury in mouse hippocampal HT22 cells, presumably through the ERK pathway-Nrf2/ARE-dependent HO-1 expression.

Cudratricusxanthone A Protects Mouse Hippocampal Cells against Glutamate-Induced Neurotoxicity via the Induction of Heme Oxygenase-1

Cudratricusxantone A (CTXA), isolated from the roots of Cudrania tricuspidata Bureau (Moraceae), has potent hepatoprotective, antiproliferative, and monoamine oxidase inhibitory effects. In this study, we examined whether CTXA could protect HT22-immortalized hippocampal cells against glutamate-induced oxidative stress through the induction of heme oxygenase (HO)-1 expression. CTXA induced the expression of HO-1 and increased HO activity dose- and time-dependently. CTXA also suppressed glutamate-induced ROS generation in HT22 cells. Interestingly, treatment of neuronal cells with CTXA enhanced cellular resistance to glutamate oxidative stress. The protective effect of CTXA was abrogated by tin protoporphyrin IX, an HO inhibitor. In addition, treatment with the HO-1 inducer, cobalt protoporphyrin IX, and bilirubin, one of the enzymatic products of HO-1, produced comparable protection. These results demonstrate that CTXA protects neuronal cells from glutamate-induced oxidative stress via the induction of HO-1.

Angiotensin converting enzyme inhibitors from Cuscuta japonica Choisy.

Bioassay-guided fractionation of the EtOAc-soluble extract of Cuscuta japonica afforded 3,5-Di-O-caffeoylquinic acid (1). methyl 3,5-Di-O-caffeoylquinate (2). 3,4-Di-O-caffeoylquinic acid (3). and methyl 3,4-Di-O-caffeoylquinate (4). Purification of these compounds was conducted with the application of various chromatographic methods. The structures of the compounds were elucidated on the basis of MS and NMR data analysis. Compounds 1-4 inhibited the angiotensin I converting enzyme activity in a dose-dependent manner. Compounds 1-4 showed the 50% inhibitory concentration values of 596, 483, 534, and 460 micro M, respectively. The presence of these active components may be responsible, at least in part, for the antihypertensive action of traditional crude drug Cuscuta Semen.