title: Effect of dihydropyrazines on human hepatoma HepG2 cells: a comparative study using 2,3-dihydro-5,6-dimethylpyrazine and 3-hydro-2,2,5,6-tetramethylpyrazine.
abstract: Dihydropyrazines (DHPs) are glycation products that are nonenzymatically generated in vivo and in food. In this study, we compared the effects of 2,3-dihydro-5,6-dimethylpyrazine (DHP-1), a low toxicity DHP, and 3-hydro-2,2,5,6-tetramethylpyrazine (DHP-3), a high toxicity DHP on the redox indices in HepG2 cells. An apparent increase in intracellular hydrogen peroxide concentration was observed at 24 hr after 1 mM DHP-3 treatment. In addition, DHP-3 exposure significantly increased the mRNA levels of heme oxygenase-1 (HO-1) and glutamate cysteine ligase catalytic subunit (GCLC), which are stress-responsive genes, at 6 hr (HO-1 and GCLC), 12 hr (HO-1 and GCLC) and 24 hr (GCLC) after exposure. These indices, with the exception of the increase in GCLC mRNA after a 6 hr exposure, were not affected by treatment with 1 mM DHP-1. HO-1, GCLC, and nuclear factor erythroid 2-related factor 2 (Nrf2) protein levels also increased at 6 hr (Nrf2), 12 hr (Nrf2, HO-1 and GCLC) and 24 hr (GCLC) after DHP-3 treatment. The increase in HO-1 and Nrf2 protein levels were observed with lower concentration (0.5 mM) of DHP-3, and in agreement with this, antioxidant responsive element-luciferase reporter activity was significantly increased with exposure to at least 0.5 mM DHP-3. These results support our previous report establishing that oxidative stress is in part involved in the effects of DHP on mammalian cells. Additionally, our results suggest that the cell response to DHP-3 exposure was exerted via the activation of the Nrf2-ARE signal pathway.
authors: Faculty of Pharmaceutical Sciences, Sojo University.
authors: Takumi
authors: T
authors: Ishida
authors: Tadatoshi
authors: T
authors: Yamaguchi
authors: Shinji
authors: S
authors: Takechi
mesh_terms: D061745:Antioxidant Response Elements; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000633:toxicity*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics*; D011719:Pyrazines / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: C000598210:2,3-dihydro-5,6-dimethylpyrazine; C000598211:3-hydro-2,2,5,6-tetramethylpyrazine; D017127:Glycation End Products, Advanced; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011719:Pyrazines; D012333:RNA, Messenger; D008156:Luciferases; D051547:Heme Oxygenase-1; D005721:Glutamate-Cysteine Ligase