Norwogonin attenuates hypoxia-induced oxidative stress and apoptosis in PC12 cells.

BACKGROUND: Norwogonin is a natural flavone with three phenolic hydroxyl groups in skeletal structure and has excellent antioxidant activity. However, the neuroprotective effect of norwogonin remains unclear. Here, we investigated the protective capacity of norwogonin against oxidative damage elicited by hypoxia in PC12 cells. METHODS: The cell viability and apoptosis were examined by MTT assay and Annexin V-FITC/PI staining, respectively. Reactive oxygen species (ROS) content was measured using DCFH-DA assay. Lactate dehydrogenase (LDH), malondialdehyde (MDA) and antioxidant enzyme levels were determined using commercial kits. The expression of related genes and proteins was measured by real-time quantitative PCR and Western blotting, respectively. RESULTS: We found that norwogonin alleviated hypoxia-induced injury in PC12 cells by increasing the cell viability, reducing LDH release, and ameliorating the changes of cell morphology. Norwogonin also acted as an antioxidant by scavenging ROS, reducing MDA production, maintaining the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and decreasing the expression levels of HIF-1α and VEGF. In addition, norwogonin prevented cell apoptosis via inhibiting the expression levels of caspase-3, cytochrome c and Bax, while increasing the expression levels of Bcl-2 and the ratio of Bcl-2/Bax. CONCLUSIONS: Norwogonin attenuates hypoxia-induced injury in PC12 cells by quenching ROS, maintaining the activities of antioxidant enzymes, and inhibiting mitochondrial apoptosis pathway.

Antioxidant potential, total phenolic and total flavonoid contents of Rhododendron anthopogonoides and its protective effect on hypoxia-induced injury in PC12 cells.

BACKGROUND: Rhododendron anthopogonoides Maxim, a kind of traditional Tibetan medicine, has been used to remove body heat, body detoxification, cough, asthma, stomachic and swelling, eliminate abundant phlegm and inflammatory for a long time. In the present study, the total phenols and total flavonoid contents as well as antioxidative properties of the crude extract and solvent fractions of R. anthopogonoides were determined using seven antioxidant assays. Additionally, the protective effect of the extracts on hypoxia-induced injury in PC12 cells was also investigated. METHODS: The content of total flavonoid and total phenolic was determined by the aluminum colorimetric method and Folin-Ciocalteu assay, respectively. In vitro antioxidant study, the effect of the crude extract and solvent fractions on total antioxidant activity, reducing power, DPPH radical scavenging, ABTS radical scavenging, superoxide radical scavenging, hydroxyl radical scavenging and nitric oxide radical scavenging were examined. The correlation between the phenolic and flavonoid content of the extracts and their antioxidant properties also analyzed. Furthermore, the protective effect of extracts on hypoxia-induced damage on PC12 cells was investigated by cell viability, lactate dehydrogenase (LDH) release, malondialdehyde (MDA) production and the activities of antioxidant enzymes. RESULTS: Our results showed that ethyl acetate and n-butanol fractions had higher content of phenolics and flavonoid compounds than other fractions. Except ABTS radical assay, n-butanol fraction exhibited the strongest antioxidant activity. While the hexane fraction showed the lowest antioxidant activity. Ethyl acetate also presented excellent antioxidant activity, which was just lower than n-butanol fraction. Significant correlation between the phenolic, flavonoid content of the extract and fractions with antioxidant assay excluding ABTS, OH scavenging assay was observed. Moreover, ethyl acetate and n-butanol fractions showed protective effect in PC12 cell under hypoxia condition, while crude extract and water fraction had no protective effect. In contrast, hexane fraction exhibited strong cytoprotective effect. Further study indicated that pretreatment of PC12 cells with ethyl acetate and n-butanol fractions, prior to hypoxia exposure, significantly increased the survival of cells and the activities of SOD, CAT, GSH-Px and T-AOC, as well as reduced the level of LDH and MDA. The gathered data demonstrated that ethyl acetate and n-butanol fractions were able to protect PC12 cells against hypoxia induced injury through direct free radical scavenging and modulation of endogenous antioxidant enzymes. CONCLUSION: These findings suggested that ethyl acetate and n-butanol fractions of R. anthopogonoides had significant antioxidant activity and could prevent PC12 cells against hypoxia-induced injury. So it might be regarded as an excellent source of antioxidants and had great potential to explore as therapeutic agent for preventing hypoxia related sickness in future.

[Protective effect and action mechanism of petroleum ether extracts from Saussurea involucrate on brain tissues of hypoxia rats].

OBJECTIVE: To investigate the protective effect and action mechanism of petroleum ether extracts from Saussurea involucrate on brain tissues of hypoxia rats under constant pressure and closed conditions. METHOD: The PESI dosage-dependent experiment for hypoxia rats was conducted under constant pressure and closed conditions by intraperitoneally injecting 125, 250, 500 mg x kg(-1) to finalize that the optimum dosage is the high dose of PESI. Afterwards, 90 Wistar rats were randomly divided into the hypoxic model group, the acetazolamide 250 mg x kg(-1) group and the PESI high dose group. Each group was further divided into three subgroups according to different hypoxia times, with 10 rats in each subgroup. Under the same hypoxia and administration conditions, the rats were sacrificed after 0, 3, 6 h respectively. Their brain samples were collected for common pathological observation and immunohistochemical staining of HIF-1alpha. Real-time RT-PCR was used to detect HIF-1alpha, EPO, HO-1 and Caspase-3 gene expressions. And the Western blot assay was adopted to detect HIF-1alpha protein expression. RESULT: The brain tissues of the hypoxia model group were severely damaged with the increase in the hypoxia time. The acetazolamide group and the PESI high does group were damaged in a much lower degree. According to the gene expression and the Western blot assay, high dose of PESI could inhibit HIF-1alpha expression. According to the pure gene expression test, high dose of PESI could increase EPO and HO-1 mRNA expressions, but inhibit Caspase-3 mRNA expression. CONCLUSION: PESI's protective mechanism for brain tissues of hypoxia rats under constant pressure and closed conditions may be related to its effects in inhibiting HIF-1alpha expression, increasing EPO expression and resisting cell apoptosis.

[Effect of ethanol extract from Saussurea involucrata on biochemical indicators of simulated high-altitude hypoxia induced mice].

OBJECTIVE: To estimate the effect of ethanol extract from Saussurea involucrata (EES) on biochemical indicators of simulated high-altitude hypoxia induced mice and its mechanism. METHODS: The oxidative stress indicator( MDA content, SOD activity) and metabolism parameters (LD content, LDH activity, ATP content, Na+ -K+ -ATPase and Ca2+ -Mg2+ -ATPase activity) in both brain and heart of the simulated high-altitude hypoxia induced mice were detected. RESULTS: Compared with the model group, the ESS group could significantly increase the activity of SOD and LDH and decrease the content of MDA and LD in both brain and heart, the content of ATP and the activity of Na+ -K -ATPase and Ca2+ -Mg2+ -ATPase were also elevated. CONCLUSION: The results demonstrate that EES can increase the antioxidant ability, decrease the injury of free radical and ease the disfunction of energy metabolism caused by hypoxia.