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Objectives: Hypoxia is a common pathological phenomenon, usually caused by insufficient oxygen supply or inability to use oxygen effectively. Hydroxylated and methoxylated flavonoids have significant anti-hypoxia activity. This study aims to explore the synthesis, antioxidant and anti-hypoxia activities of 6-hydroxygenistein (6-OHG) and its methoxylated derivatives., Methods: The 6-OHG and its methoxylated derivatives, including 4',6,7-trimethoxy-5-hydroxyisoflavone (compound 3), 4',5,6,7-tetramethoxyisoflavone (compound 4), 4',6-imethoxy-5,7-dihydroxyisoflavone (compound 6), and 4'-methoxy-5,6,7-trihydroxyisoflavone (compound 7), were synthesized by methylation, bromination, methoxylation, and demethylation using biochanin A as raw material. The structure of these products were characterized by 1 hydrogen-nuclear magnetic resonance spectroscopy ( 1 H-NMR) and mass spectrometry (MS). The purity of these compounds was detected by high pressure chromatography (HPLC). The antioxidant activity in vitro was investigated by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) free radical scavenging assay. PC12 cells were divided into a normal group, a hypoxia model group, rutin (1×10 -9 -1×10 -5 mol/L) groups, and target compounds (1×10 -9 -1×10 -5 mol/L) groups under normal and hypoxic conditions. Cell viability was detected by cell counting kit-8 (CCK-8) assay, the target compounds with excellent anti-hypoxia activity and the drug concentration at the maximum anti-hypoxia activity were screened. PC12 cells were treated with the optimal concentration of the target compound or rutin with excellent anti-hypoxia activity, and the cell morphology was observed under light microscope. The apoptotic rate was determined by flow cytometry, and the expressions of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were detected by Western blotting., Results: The structure of 6-OHG and its 4 methylated derivatives were correct, and the purity was all more than 97%. When the concentration was 4 mmol/L, the DPPH free radical removal rates of chemical compounds 7 and 6-OHG were 81.16% and 86.94%, respectively, which were higher than those of rutin, the positive control. The removal rates of chemical compounds 3, 4, and 6 were all lower than 20%. Compared with the normal group, the cell viability of the hypoxia model group was significantly decreased ( P <0.01). Compared with the hypoxia model group, compounds 3, 4, and 6 had no significant effect on cell viability under hypoxic conditions. At all experimental concentrations, the cell viability of the 6-OHG group was significantly higher than that of the hypoxia model group (all P <0.05). The cell viability of compound 7 group at 1×10 -7 and 1×10 -6 mol/L was significantly higher than that of the hypoxia model group (both P <0.05). The anti-hypoxia activity of 6-OHG and compound 7 was excellent, and the optimal drug concentration was 1×10 -6 and 1×10 -7 mol/L. After PC12 cells was treated with 6-OHG (1×10 -6 mol/L) and compound 7 (1×10 -7 mol/L), the cell damage was reduced, the apoptotic rate was significantly decreased ( P <0.01), and the protein expression levels of HIF-1α and VEGF were significantly decreased in comparison with the hypoxia model group (both P <0.01)., Conclusions: The optimized synthesis route can increase the yield of 6-OHG and obtain 4 derivatives by methylation and selective demethylation. 6-OHG and compound 7 have excellent antioxidant and anti-hypoxia activities, which are related to the structure of the A-ring ortho-triphenol hydroxyl group in the molecule.

Aims: Hypobaric hypoxia (HH), linked to oxidative stress, impairs cardiac function. We synthesized a novel nitronyl nitroxide radical, an HPN derivative (HEPN) and investigated the protective effects of HEPN and HPN against HH-induced heart injury in mice and the underlying mechanisms of action., Main Methods: Mice were administered with HPN (200 mg/kg) or HEPN (200 mg/kg) 30 min before exposed to HH. The cardiac function was measured. Serum AST, CK, LDH and cTnI were estimated. Heart tissue oxidase activity, SOD, CAT, GSH-Px, ROS and MDA were estimated. ATP content, Na + /K + -ATPase and Ca 2+ /Mg 2+ -ATPase activity was measured. The expression of HIF-1, VEGF, Nrf2, HO-1, Bax, Bcl-2, Caspase-3 was estimated., Key Findings: Results showed that pretreatment with HEPN or HPN led to a dramatic decrease in the activity of biochemical markers AST, CK, LDH and cTnI in murine serum. They increased the activity of SOD, CAT and GSH-Px and reduced the level of ROS and MDA in the hearts of mice. HEPN and HPN could increase the expression of Nrf2 and OH-1. They could maintain the ATPase activity. The Bax and Caspase-3 expression as well as the ratio of Bax/Bcl-2 were significantly downregulated and the Bcl-2 expression was upregulated by HPN or HEPN compared to the HH group. They may attenuate the HH-induced oxidant stress via free radical scavenging activity., Significance: The present study showed that the nitronyl nitroxide radical HEPN and HPN may be potential therapeutic agents for treatment of HH-induced cardiac dysfunction., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2019. Published by Elsevier Inc.)

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.

7,8,3',4',5'-Pentahydroxyisoflavone (8,3',5'-trihydroxydaidzein) and 6,7,8,3',4',5'-hexahydroxyisoflavone (6,8,3',5'-tetrahydroxydaidzein) are synthesized via a simple and effective method using commercially available daidzein as a raw material. Their structures are confirmed using spectroscopic analyses (infrared, nuclear magnetic resonance, and mass spectrometry), and their purities are determined by high-performance liquid chromatography. The antioxidant capacities are investigated by utilizing 1,1-diphenyl-2-picryl-hydrazyl radical scavenging, superoxide radical scavenging, nitric oxide radical scavenging, reducing power, and phosphomolybdenum assays. The antihypoxia activity is examined using a hypoxia-induced PC12 cell injury model. The antioxidant and antihypoxia abilities of 8,3',5'-trihydroxydaidzein and 6,8,3',5'-tetrahydroxydaidzein are greatly improved in comparison with daidzein. These results indicate that 8,3',5'-trihydroxydaidzein and 6,8,3',5'-tetrahydroxydaidzein are excellent antioxidant agents and can be used for alleviating injury induced by hypoxia. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Flavones are a group of plant secondary metabolites with multiple biological properties. In the present study, 5,6,7,8-tetrahydroxyflavone (5,6,7,8-THF) was synthesized and characterized. In vitro antioxidant study, the effect of 5,6,7,8-THF on total antioxidant activity, reducing power, DPPH radical scavenging, ABTS radical scavenging, superoxide radical scavenging, hydroxyl radical scavenging, nitric oxide radical scavenging, and ferrous chelating activities was examined. According to the results, 5,6,7,8-THF showed excellent free radical scavenging effect and reducing power but weak the ferrous chelating activity. In conclusion, 5,6,7,8-THF can be regarded as an excellent source of antioxidants. [ABSTRACT FROM AUTHOR]

Abstract: Epimedium (Berberidaceae), is a genus of about 52 species in the family Berberidaceae, which also known as Rowdy Lamb Herb, Xianlinpi, Barrenwort, Bishop''s Hat, Fairy Wings, Horny Goat Weed, and Yangheye or Yin Yang Huo (Chinese: ▪). Many plants have been proven to possess efficacy on sexual dysfunction and osteoporosis in traditional Chinese medicine (TCM). The paper reviews the ethnopharmacology, the biological activities and the correlated chemical compounds of Epimedium species. More than 260 compounds have been isolated; among them prenyl-flavonoids are the major constituents and also important chemotaxonomic markers. Modern pharmacology studies and clinical practice demonstrated that Epimedium and its active compounds possess wide pharmacological actions, especially in strengthening yang, hormone regulation, anti-osteoporosis, immunological function modulation, anti-oxidation and anti-tumor, anti-aging, anti-atherosclerosis and anti-depressant activities. Currently, effective monomeric compounds or active parts have been screened for pharmacological activity from Epimedium in vivo and in vitro. [Copyright &y& Elsevier]