Neuroprotective effects of Hypericum perforatum on trauma induced by hydrogen peroxide in PC12 cells.

The standard extracts of Hypericum perforatum L. (SEHP), a well-known medicinal plant, are used for the treatment of depression, exhibited upgrading and significant protective effects on the trauma of PC12 cells induced by 200 microM H2O2 in a dose-dependent manner within 24-hour treatment. Cell viability was assessed by the MTT method, and in situ cellular hydrogen peroxide (H2O2)-induced oxidative stress was examined by measurement of reactive oxygen species (ROS) formation using CDCFH procedures. Intra- and extra-cellular ROS levels decreased significantly to 71.9% and 50.0% of the control at a moderate concentration of 20 microg/ml, respectively, suggesting that SEHP could easily enter the cells and play important roles in reducing ROS levels. Our results were proved by detection of DNA fragmentation and inspection of cell morphology of PC12 cells. SEHP can obviously block DNA fragmentation and prevent the cells from shrinking and turning round of H2O2-induced apoptosis in PC12 cells at concentrations of 10 approximately 100 microg/ml. This data suggests SEHP may be a candidate for application in neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease.

The protective effect of ascorbic acid derivative on PC12 cells: involvement of its ROS scavenging ability.

L-ascorbic acid 2-phosphate-6-palmitate (Asc2P6P) was synthesized and its effect on the damage of PC12 cells induced by H2O2 was investigated. 200 microM H2O2 in a treatment period of 4 hours in our experiment resulted in substantial cell loss. With the increasing concentration of antioxidants, such H2O2-induced cytotoxicity was significantly prevented and the corresponding intracellular and extracellular ROS levels decreased concurrently by pre-treatment with Asc2P6P and Asc. It was found that Asc2P6P was superior to L-ascorbic acid in its protective role and showed a dose-dependent manner during a 24-hour treatment. The higher potency of Asc2P6P's protective role on PC12 cells was correlated with its more effective ROS scavenging ability. HPLC assay demonstrated that Asc2P6P could easily enter the cells and be converted into Asc persistently, which contributed to its distinguished role in protecting PC12 cells against H2O2-induced cytotoxicity.

Enhancement of fibrinolytic activity of bovine aortic endothelial cells by ginsenoside Rb2.

AIM: The effect of ginsenoside Rb2 purified from Panax ginseng on fibrinolytic activity of bovine aortic endothelial cells (BAEC) was investigated. METHODS: Cellular plasminogen activator (PA) level of the lysates was measured by the chromogenic substrate S-2403. Fibrin underlay technique was carried out to observe fibrinolysis by growing endothelial cells in the culture medium. Cell viability was then determined by measurement of the activity of mitochondrial dehydrogenase. The ability of Rb2 of potentiating cellular PA activity was investigated by measuring the amounts of PA and PA inhibitor-1 (PAI-1) in the culture medium using zymography and reverse zymography. Changes in the expression of urokinase-type PA (uPA), uPA receptor, and PAI-1 mRNA in BAEC after treatment with Rb2 were analyzed by Northern blot. RESULTS: Rb2 enhanced cellular PA activity in a concentration-and time-dependent manner. Treatment of BAEC with Rb2 10 mg/L for 9 h resulted in a 3.5-fold increase of PA activity without a marked cytotoxic effect, as shown by LDH levels in culture. Increased PA levels caused the increase in surface plasmin levels as observed by fibrin underlay technique. Rb2 greatly or moderately increased the amount of urokinase-type PA (uPA) or its inhibitor (PAI-1), present in the culture medium, whereas saponin did not influence mRNA levels of uPA, its surface receptor, and PAI-1, suggesting that Rb2 may stimulate the secretion of uPA without enhancing its gene expression. The enhancement of PA levels by retinoic acid alone, a stimulator of PA synthesis, was potentiated by the simultaneous addition of ginsenoside Rb2 1 mg/L. Therefore, Rb2 might exert a strong synergism in the synthesis of cellular PA in BAEC. CONCLUSION: Ginsenoside Rb2 enhanced the PA activity levels in BAEC as well as the surface plasmin activity of BAEC. Rb2 may stimulate the secretion of uPA without enhancing the gene expression of uPA, uPA receptor (uPAR), and PAI-1.

[Protective effects of Cleistocalyx operculatus on lipid peroxidation and trauma of neuronal cells].

OBJECTIVE: To observe the protective effects of Cleistocalyx operculatus on lipid peroxidation in rat liver microsomes and on the trauma of PC12 cells induced by H2O2. METHOD: The mouse liver homogenate lipid peroxidation assay and PC12 Cell culture and Cell viability (MTT assay) were applied. RESULT: Cleistocalyx operculatus showed strong protective effects on lipid peroxidation in rat liver microsomes in a dose-dependent manner and exhibited potent protective effects on the trauma of PC12 cells induced by H2O2 (200 micromol x L(-1)) when the concentration reached 1.00 g x L(-1). CONCLUSION: Cleistocalyx operculatus may be used as antioxidant to prevent or delay the pathogenesis of neural cell diseases.

[Study on the mechanism of inhibition of tumor cell motility by ascorbic acid derivatives].

Our previous study shows that tumor invasion is inhibited by 2-O-phosphorylated ascorbate-6-O-palmitylester (Asc2P6Plm). In the present study, the mechanism underlying the inhibitory effect of Asc2P6Plm on invasion of human fibrosarcoma cells HT-1080 was attempted to be analysed. Migratory ability of the tumor cells was shown to be inhibited in a dose-dependent manner by treatment with Asc2P6Plm at 50-300 micromol/L for 1 hr. Hydroxyl radicals in homogenates of Asc2P6Plm-treated HT-1080 cells were markedly diminished relative to those of non-treated cells as evaluated by electron spin resonance method using the spin-trapping agent DMPO. F-actin was localized in the vicinity of the cell membrane abundantly in nontreated cells, but was diminished in a time-dependent manner in Asc2P6Plm-treated cells as shown with the F-actin-directed agent NBD-phallacidin. The cell adhesion-controlling molecule RhoA increased time-dependently in the cell nucleus of Asc2P6Plm-treated cells as shown by Western blots. Thus the inhibition of tumor invasion by Asc2P6Plm was shown to be attributed to decreases in both the cell migratory ability and the F-actin localization near the cell membrane, which may result from an increase in RhoA in the cell nucleus and reduction of intracellular ROS that is achieved by enrichment of intracellular Asc derived from Asc2P6Plm.