Showing papers by "Chun Mao Lin published in 2005"
TL;DR: The results suggest that isovitexin, a food phytochemical contained in dietary rice products, might have biological significance.
Abstract: Isovitexin exhibits potent antioxidant activities. In this study, the activity of nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated RAW264.7 macrophages after incubation with isovitexin was investigated. Isovitexin was able to reduce the production of hydrogen peroxide induced by LPS in mouse macrophage RAW264.7 cells. The cells incubated with isovitexin had markedly reduced LPS-stimulated NO production with an IC (50) value of 58.5 microM. The expression of iNOS was also inhibited when the cells were treated with isovitexin. A transient transfection experiment showed that isovitexin suppressed the iNOS promoter and NF-kappaB-dependent transcriptional activities. It was also found to inhibit IKK kinase activity and prevent the degradation of IkappaBalpha in activated RAW264.7 cells. Additionally, Western blotting analysis revealed that isovitexin prevented the translocation of NF-kappaB from the cytoplasm to the nucleus. Our results indicate that its ROS scavenger and IKK inhibitory activities also contribute to the suppression of ROS-mediated NF-kappaB activity. These results suggest that isovitexin, a food phytochemical contained in dietary rice products, might have biological significance.
81 citations
TL;DR: The results suggest that suppression of ROS‐mediated COX‐2 expression by isovitexin is beneficial in reducing inflammation and carcinogenesis.
Abstract: Isovitexin, isolated from rice hull of Oryza sativa, has been characterized as a potent antioxidant. Its antioxidant activity, determined on the basis of inhibition of lipid peroxidation by the Fenton reaction, was comparable with that of alpha-tocopherol, a well-established antioxidant. Isovitexin was able to reduce the amount of hydrogen peroxide production induced by lipopolysaccharide (LPS) in mouse macrophage RAW264.7 cells. In this study, we assessed its effects on the production of tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2), and the expression of cyclooxygenase-2 (COX-2) in LPS-activated RAW 264.7 macrophages. Isovitexin inhibited the release of TNF-alpha, a proinflammatory cytokine, upon LPS activation with a 50% inhibitory concentration (IC50) of 78.6 microM. Isovitexin markedly reduced LPS-stimulated PGE2 production in a concentration-dependent manner, with an IC50 of 80.0 microM. The expression of COX-2 was also inhibited by isovitexin treatment. Our results suggest that suppression of ROS-mediated COX-2 expression by isovitexin is beneficial in reducing inflammation and carcinogenesis.
44 citations
TL;DR: It is demonstrated that NAC blocks the NGF‐induced H2O2/ERK signaling in PC12 cells, which increased intracellular H 2O2 concentration and activated ERK but failed to affect intrace cellular superoxide level.
Abstract: We investigated whether H 2 O 2 , superoxide, and ERK participate in nerve growth factor (NGF)-induced signaling cascades and whether antioxidant N-acetylcysteine (NAC) regulates these NGF-induced responses. PC12 cells werecultured in medium containing NGF or vehicle with or without NAC pretreatment, and the intracellular H 2 O 2 and superoxide levels and the amount of phosphorylated ERK were evaluated by flow cytometry and Western blotting, respectively. We found that NGF increased intracellular H 2 O 2 concentration and activated ERK but failed to affect intracellular superoxide level. Moreover, NAC counteracted these NGF-induced responses. These findings demonstrate that NAC blocks the NGF-induced H 2 O 2 /ERK signaling in PC12 cells.
12 citations
TL;DR: The cell damage induced by oxidative stress was prevented by the plant extract in a concentration‐dependent manner, and the proteolytic cleavage of poly(ADP‐ribose) polymerase during the apoptotic process was also inhibited by AF extract.
Abstract: Anoectochilus formosanus (AF) is a popular folk medicine in Taiwan whose pharmacological effects have been characterized. In this work we investigated the antioxidant properties of an aqueous extract prepared from AF. The AF extract was capable of scavenging H2O2 in a dose-dependent man- ner. We induced oxidative stress in HL-60 cells, either by the addition of hydro- gen peroxide (H2O2) or by the xanthine/xanthine oxidase reaction. Apoptosis caused by oxidative damage was displayed by DNA fragmentation on gel elec- trophoresis, and the apoptotic fraction was quantified with flow cytometry. The cell damage induced by oxidative stress was prevented by the plant extract in a concentration-dependent manner. Furthermore, the proteolytic cleavage of poly(ADP-ribose) polymerase during the apoptotic process was also inhibited by AF extract. Our results provide the basis for determining an AF extract to be an antioxidant.
10 citations