The control of oligodendrocyte bioenergetics by interferon-gamma (IFN-γ) and Src homology region 2 domain-containing phosphatase-1 (SHP-1).

Glycolysis and mitochondrial respiration are essential for oligodendrocyte metabolism in both the developing and adult CNS. Based on recent reports on the effects of the proinflammatory cytokine IFN-γ on metabolism and on oligodendrocytes, we addressed whether IFN-γ may affect oligodendrocyte bioenergetics in ways relevant to CNS disease. Oligodendrocytes of mice treated with IFN-γ showed significant reductions in aerobic glycolysis and mitochondrial respiration. As expected, IFN-γ treatment led to the induction of STAT1 in oligodendrocytes indicating active signaling into these cells. To determine the direct effects of IFN-γ on oligodendrocyte metabolism, cultured oligodendrocytes were treated with IFN-γ in vitro, which resulted in suppression of glycolysis similar to oligodendrocytes of animals treated with IFN-γ in vivo. Mice lacking SHP-1, a key regulator of IFN-γ and STAT1 signaling in CNS glia, had high constitutive levels of STAT1 and decreased aerobic glycolysis and mitochondrial respiration rates relative to wild type mouse oligodendrocytes. Together, these data show that IFN-γ and SHP-1 control oligodendrocyte bioenergetics in ways that may relate to the role of this cytokine in CNS disease.

Low molecular-weight gel fraction of Aloe vera exhibits gastroprotection by inducing matrix metalloproteinase-9 inhibitory activity in alcohol-induced acute gastric lesion tissues.

CONTEXT: Aloe has been used for the prevention and cure of various diseases and symptoms including burns, injuries, oedema and pain. OBJECTIVE: This study determines the specific inhibitory activity of matrix metalloproteinase (MMP)-9 induced by the low molecular-weight gel fraction of Aloe vera (L.) Burm.f. (lgfAv) on alcohol-induced acute gastric lesions. MATERIALS AND METHODS: We examined the protective effects of oral (p.o.) administration of lgfAv (molecular weight cutoff <50.0 kDa, 150.0 mg/kg body weight) in a Balb/c mouse model of alcohol-induced acute gastritis for 1 h exposure. By measuring ulcer index, we compared the antiulcerative activity of the fraction. mRNA expression and immunohistochemical analysis of various biomarkers were performed. RESULTS: The lgfAv-treated mice exhibited drastically fewer ulcer lesions than the untreated control mice did. It featured that lgfAv lessened the ulcer lesions than their relevant controls. Moreover, the transcriptional level of MMP-9 was completely alleviated by lgfAv treatment in alcohol-treated gastritis-induced mice. DISCUSSION: The transcriptional level of MMP-9 was significantly alleviated by lgfAv treatment of the model. However, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry experiments revealed that lgfAv treatment in mucosal tissues had the potential to inhibit the mRNA and protein expression levels of MMP-9, respectively. The protein expression of MMP-9 was closely associated with lgfAv-induced gastroprotection against alcohol-induced gastric lesions. CONCLUSIONS: The present findings suggest that lgfAv has the potential to alleviate alcohol-induced acute gastric lesions, which is mediated in part, mainly by the suppression of the mRNA expression of MMP-9.

Phytol induces ROS mediated apoptosis by induction of caspase 9 and 3 through activation of TRAIL, FAS and TNF receptors and inhibits tumor progression factor Glucose 6 phosphate dehydrogenase in lung carcinoma cell line (A549).

A number of drugs as well as lead molecules are isolated from natural sources. Phytol is one of such lead molecule belongs to terpenes group distributed widely in medicinal plants. In the present work, we investigated the cytotoxic behavior of phytol on human lung carcinoma cells (A549). Phytol was found to cause characteristic apoptotic morphological changes and generation of ROS in A549 cells. The mechanism of phytol involved the activation of TRAIL, FAS and TNF-α receptors along with caspase 9 and 3. In silico molecular docking studies revealed that phytol has a good binding affinity with glucose-6-phosphate dehydrogenase (G6PD), which is known to promote tumor proliferation. The ability of phytol to become potential drug candidate has been revealed from the pharmacokinetic study performed in the present study.

Cytotoxicity of lipid-soluble ginseng extracts is attenuated by plasma membrane redox enzyme NQO1 through maintaining redox homeostasis and delaying apoptosis in human neuroblastoma cells.

Lipid-soluble ginseng extracts (LSGE) is known to inhibit many types of cancer cells through arresting cell cycle and inducing apoptosis. Usually, normal cells are can also be damaged by anti-tumor reagents. The plasma membrane redox system (PMRS) is enhanced to compensate mitochondrial dysfunction and impaired energy metabolism. NADH-quinone oxidoreductase 1 (NQO1), a plasma membrane redox enzyme, is known to be induced by panaxytriol, one of components of lipid-soluble ginseng extracts (LSGE). The objective of this study was determine the mechanisms of NQO1 involved in neuroprotection in response to cytotoxicity induced by LSGE. Exposure of control SH-SY5Y cells to LSGE resulted in dramatic loss of cell viability in a dose-dependent manner. The loss of cell viability was significantly recovered in cells transfected with NQO1. LSGE-induced cell death occurred through apoptosis such as cell shrinkage, chromatin condensation and cleavage of poly (ADP-ribose) polymerase. These apoptotic features were significantly attenuated by overexpression of NQO1. Levels of oxidative/nitrative damage were highly elevated by LSGE in a dose-dependent manner. However, these elevated levels were greatly reduced by overexpression of NQO1. In addition, overexpression of NQO1 attenuated the decrease in mitochondrial complex I activity caused by LSGE. Taken together, these findings suggest that overexpressed NQO1 can protect cells against LSGE-induced cytotoxicity through lowering oxidative/nitrative damage and delaying apoptosis, supporting that stimulation of NQO1 activity could be a therapeutic targets in neurodegeration.

Cistanche tubulosa ethanol extract mediates rat sex hormone levels by induction of testicular steroidgenic enzymes.

CONTEXT: Plants of the genus Cistanche Hoffmg. et Link (Orobanchaceae) are usually used as ethno-medicine in Eastern Asia. Pharmacology studies have shown that Cistanche possesses an androgen-like effect; however, the exact mechanism is unclear. OBJECTIVE: The present study determines the effect of ethanol extract of Cistanche tubulosa (Schenk) R. Wight stem (CTE) on hormone levels and testicular steroidogenic enzymes in rats. MATERIALS AND METHODS: Phenylethanoid glycoside content of CTE was detected by UV spectrophotometry. Rats were fed with different doses of CTE (0.2, 0.4, and 0.8 g/kg) by intragastric administration for 20 d. Sperm parameters were measured by staining and counting method. The level of progesterone and testosterone in serum was quantified by radioimmunoassay. The expression levels of cholesterol side-chain cleavage enzyme (CYP11A1), 17α-hydroxylase/17, 20-lyase (CYP17A1), and a liver metabolic enzyme (CYP3A4) in the microsome were assessed by immunohistochemical staining or/and western blot analysis. RESULTS: The study illustrates that the administration of CTE (0.4 and 0.8 g/kg) increased sperm count (2.3- and 2.7-folds) and sperm motility (1.3- and 1.4-folds) and decreased the abnormal sperm (0.76- and 0.6-folds). The serum level of progesterone and testosterone in rats was also increased by CTE administration (p < 0.05). Results of immunohistochemistry and western blot analysis confirmed that the expression of CYP11A1, CYP17A1, and CYP3A4 was enhanced by CTE (p < 0.05). It was also found that high-dose of CTE can cause mild hepatic edema. CONCLUSION: Our results suggest that the increase in sex hormone levels could be mediated by the induction of testicular steroidogenic enzymes.

HepG2 cells as an in vitro model for evaluation of cytochrome P450 induction by xenobiotics.

Although various in vitro assays have been developed to evaluate the cytochrome P450 (CYP)-inducing potential of drug candidates, there is a continuing need for the development of a reliable model in drug discovery. The objective of the present study was to compare CYP induction by chemicals in HepG2 cells with Huh7, NKNT-3, and reverted NKNT-3 cells. HepG2 cells showed more similarity to human liver than the other cell lines in comparisons of the expression of cellular proteins. In evaluation of basal CYP activity, Huh7 cells exhibited the highest CYP1A2 and CYP3A4 activity, and HepG2 cells showed the highest CYP2B6 activity. The inducibility of CYP1A2, CYP2B6, and CYP3A4 by prototypical inducers was determined using enzyme assay, immunoblot analysis, and real-time PCR. Among the cells tested, HepG2 cells were highly responsive to CYP inducers, such as 3-methylcholanthrene for CYP1A2 and phenobarbital for CYP2B6 and CYP3A4. Moreover, HepG2 cells were responsive to various CYP1A2, CYP2B6, and CYP3A4 inducers as determined using fluorogenic and LC-MS/MS substrates. Thus, HepG2 cells may be comparable to human hepatocytes for the evaluation of CYP induction or slightly less sensitive. These results suggest HepG2 cells as a cell-based model in screening for CYP inducers in drug discovery.

Effects of Alismatis rhizome on rat cytochrome P450 enzymes.

CONTEXT: Alismatis rhizome (RA) (Water Plantain Family, also called "Zexie" in Chinese), one of the commonly used components of traditional Chinese medicines, is derived from the dried rhizomes of Alisma orientalis (Sam.) Juzep. (Alismataceae). OBJECTIVE: This study explores the RA influences on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo. MATERIALS AND METHODS: A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg), chlorzoxazone (20 mg/kg) and midazolam (10 mg/kg), was orally administration to rats treated twice daily with RA (10, 20 and 40 g/kg) for consecutive 14 days. Blood samples (0.2 mL) were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0 (Wenzhou Medical College, Zhejiang, China). RESULTS: In the experiment, there was a statistically significant difference in the t1/2, Cmax, AUC(0-∞) and CL for phenacetin and midazolam, while there was no statistical pharmacokinetics difference for tolbutamide and chlorzoxazone. Our study showed that treatment with multiple doses of RA had an inductive effect on rat CYP1A2 and an inhibitory effect on rat CYP3A4 enzyme activity. However, RA has no inductive or inhibitory effect on the activities of CYP2C9 and CYP2E1. CONCLUSIONS: Caution is needed when RA is co-administration with some CYP1A2 or CYP3A4 substrates in clinic, because it may result in treatment failure and herb-drug interactions.

Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress.

AIMS: Protection of cells from oxidative insult may be possible through direct scavenging of reactive oxygen species, or through stimulation of intracellular antioxidant defense mechanisms by induction of antioxidant gene expression. In this study we investigated the cytoprotective effect of chamomile and elucidated the underlying mechanisms. MAIN METHODS: The cytoprotective effect of chamomile was examined on H(2)O(2)-induced cellular stress in RAW 264.7 murine macrophages. KEY FINDINGS: RAW 264.7 murine macrophages treated with chamomile were protected from cell death caused by H(2)O(2). Treatment with 50µM H(2)O(2) for 6h caused significant increase in cellular stress accompanied by cell death in RAW 264.7 macrophages. Pretreatment with chamomile at 10-20µg/mL for 16h followed by H(2)O(2) treatment protected the macrophages against cell death. Chamomile exposure significantly increased the expression of antioxidant enzymes viz. heme oxygenase-1 (HO-1), peroxiredoxin-1 (Prx-1), and thioredoxin-1 (Trx-1) in a dose-dependent manner, compared with their respective controls. Chamomile increased nuclear translocation of Nrf2 with increased phosphorylated Nrf2 levels, and binding to the antioxidant response element in the nucleus. SIGNIFICANCE: These molecular findings for the first time provide insights into the mechanisms underlying the induction of phase 2 enzymes through the Keap1-Nrf2 signaling pathway by chamomile, and provide evidence that chamomile possesses antioxidant and cytoprotective properties.

Niacin inhibits vascular inflammation via the induction of heme oxygenase-1.

BACKGROUND: Heme oxygenase-1 (HO-1) is a cytoprotective protein whose expression is consistently associated with therapeutic benefits in a number of pathological conditions such as atherosclerotic vascular disease and inflammation. Niacin is a pleiotropic drug that slows the progression of coronary artery disease and increases serum levels of the HO-1 enzymatic product bilirubin. This study asks if the cardioprotective properties of niacin involve the induction of HO-1. METHODS AND RESULTS: New Zealand White rabbits received chow or chow supplemented with 0.6% (wt/wt) niacin for 2 weeks. Acute vascular inflammation was induced in the animals by placing a nonocclusive silastic collar around the left common carotid artery. At 24 hours after collar implantation, serum bilirubin and vascular, liver, and spleen HO-1 messenger RNA levels were significantly increased. Vascular inflammation was decreased in the niacin-supplemented animals compared with control. Treatment of the animals with tin protoporphyrin-IX, a global HO inhibitor, or HO-1 small interfering RNA to knock down carotid artery HO-1 attenuated the ability of niacin to inhibit vascular inflammation. Treatment of cultured human coronary artery endothelial cells with niacin increased HO-1 expression by activating the nuclear factor-E2-related factor 2/p38 mitogen-activated protein kinase signaling pathway and inhibiting tumor necrosis factor α-induced endothelial inflammation. The antiinflammatory effects of niacin in human coronary artery endothelial cells were mimicked by bilirubin and abolished by incubation with tin protoporphyrin-IX and knock down of nuclear factor-E2-related factor 2. CONCLUSIONS: Niacin activates HO-1 in vivo and in vitro. Induction of HO-1 may be partly responsible for the vascular protective properties of niacin.

Genistein induces breast cancer-associated aromatase and stimulates estrogen-dependent tumor cell growth in in vitro breast cancer model.

In breast cancer, the interaction between estrogen-producing breast adipose fibroblasts (BAFs) and estrogen-dependent epithelial tumor cells is pivotal. Local estrogen production is catalyzed by aromatase, which is differentially regulated in disease-free and tumorigenic breast tissue. The use of aromatase inhibitors to block local estrogen production has proven effective in treatment of estrogen-dependent breast cancer. However, a major problem during breast cancer treatment is the sudden onset of menopause and many women seek for alternative medicines, such as the soy isoflavone genistein. In this study, we show that genistein can induce estrogen-dependent MCF-7 tumor cell growth and increase breast cancer-associated aromatase expression and activity in vitro. We have previously developed an in vitro breast cancer model where the positive feedback loop between primary BAFs and estrogen-dependent MCF-7 tumor cells is operational, thereby representing a more natural in vitro model for breast cancer. In this model, genistein could negate the growth inhibitory action of the aromatase inhibitor fadrozole at physiologically relevant concentrations. These data suggest that soy-based supplements might affect the efficacy of breast cancer treatment with aromatase inhibitors. Considering the high number of breast cancer patients using soy supplements to treat menopausal symptoms, the increasing risk for adverse interactions with breast cancer treatment is of major concern and should be considered with care.

Induction of cytochromes P450 1A1 and 1A2 by tanshinones in human HepG2 hepatoma cell line.

Diterpenoid tanshinones including tanshinone IIA (TIIA), cryptotanshinone (CTS), tanshinone I (TI) and dihydrotanshinone I (DHTI) are the major bioactive components from Danshen. The major aim of our present study was to investigate the induction potential of these four main components of tanshinones (TIIA, CTS, TI, and DHTI) on the expression of CYP1A1 and CYP1A2 in HepG2 cells. Our results showed that all of these four tanshinones caused a significant time- and concentration-dependent increase in the amount of CYP1A1/2 expression in HepG2 cells. These induction effects were further characterized through transcriptional regulation: the induction of CYP1A1/2 mRNA level by tanshinones was completely blocked by the transcription inhibitor actinomycin D; the expression of CYP1A1/2 heterogeneous nuclear RNA was induced by tanshinone treatment; and CYP1A1 mRNA stability was not influenced by these tanshinones. Interestingly, tanshinones plus B[a]P produced additive/synergistic effect on CYP1A1/2 induction. In addition, the tanshinone-induced CYP1A1/2 expression was abolished by the aryl hydrocarbon receptor (AhR) antagonist resveratrol, suggesting an AhR dependent transcription mechanism. In the reporter gene assay, while TI and DHTI significantly induced AhR-dependent luciferase activity, TIIA and CTS failed to induce this activity. Collectively, the tanshinones could induce CYP1A1 and CYP1A2 expression through transcriptional activation mechanism and exert differential effects on activating AhR in HepG2 cells. Our findings suggest that rational administration of tanshinones should be considered with respect to their effect on AhR and CYP1A1/2 expression.

cDNA cloning and induction of tyrosine hydroxylase gene from the diamondback moth, Plutella xylostella.

We cloned a full-length tyrosine hydroxylase cDNA from the integument of the diamondback moth, Plutella xylostella. In the phylogenetic tree, tyrosine hydroxylase (PxTH) clustered with the other lepidopteran THs. Serine residues in the PxTH sequence, namely Ser(24), Ser(31), Ser(35), Ser(53), and Ser(65), were predicted to be the target sites for phosphorylation based on PROSITE analysis. In particular, Ser(35) of PxTH is highly conserved across a broad phylogenetic range of animal taxa including rat and human. Western blot analysis using both PxTH-Ab1 and PxTH-Ab2 polyclonal antibodies verified the expression of PxTH in all life cycle stages of P. xylostella, namely the larval, pupal, and adult stages. To examine the possible immune function of PxTH in P. xylostella, PxTH gene expression was investigated by RT-PCR and western blotting analysis after challenging P. xylostella with bacteria. PxTH expression was elevated 1 h post-infection and was continued till 12 h of post-infection relative to control larvae injected with sterile water.

Docosahexaenoic acid suppresses neuroinflammatory responses and induces heme oxygenase-1 expression in BV-2 microglia: implications of antidepressant effects for ω-3 fatty acids.

Accumulating evidence suggests that the pathophysiology of depression might be associated with neuroinflammation, which could be attenuated by pharmacological treatment for depression. Omega-3 polyunsaturated fatty acids (PUFAs) are anti-inflammatory and exert antidepressant effects. The aim of this study was to identify the molecular mechanisms through which docosahexaenoic acid (DHA), the main omega-3 PUFA in the brain, modulates oxidative reactions and inflammatory cytokine production in microglial and neuronal cells. The results of this study showed that DHA reduced expressions of tumor necrosis factor-α, interleukin-6, nitric oxide synthase, and cyclo-oxygenase-2, induced by interferon-γ, and induced upregulation of heme oxygenase-1 (HO-1) in BV-2 microglia. The inhibitory effect of DHA on nitric oxide production was abolished by HO-1 inhibitor zinc protoporphyrin IX. In addition, DHA caused AKT and ERK activation in a time-dependent manner, and the DHA-induced HO-1 upregulation could be attenuated by PI-3 kinase/AKT and MEK/ERK inhibitors. DHA also increased IKKα/ß phosphorylation, IκBα phosphorylation, and IκBα degradation, whereas both nuclear factor-κB and IκB protease inhibitors could inhibit DHA-induced HO-1 expressions. The other major n-3 PUFA, eicosapentaenoic acid, showed similar effects of DHA on inflammation and HO-1 in repeated key experiments. In connecting with inflammation hypothesis of depression and clinical studies supporting the antidepressant effects of omega-3 PUFAs, this study provides a novel implication of the antidepressant mechanisms of DHA.

Echinacea purpurea significantly induces cytochrome P450 3A activity but does not alter lopinavir-ritonavir exposure in healthy subjects.

STUDY OBJECTIVE: . To determine the influence of Echinacea purpurea on the pharmacokinetics of lopinavir-ritonavir and on cytochrome P450 (CYP) 3A and P-glycoprotein activity by using the probe substrates midazolam and fexofenadine, respectively. DESIGN: Open-label, single-sequence pharmacokinetic study. SETTING: Outpatient clinic in a federal government research center. SUBJECTS: Thirteen healthy volunteers (eight men, five women). INTERVENTION: Subjects received lopinavir 400 mg-ritonavir 100 mg twice/day with meals for 29.5 days. On day 16, subjects received E. purpurea 500 mg 3 times/day for 28 days: 14 days in combination with lopinavir-ritonavir and 14 days of E. purpurea alone. In order to assess CYP3A and P-glycoprotein activity, subjects received single oral doses of midazolam 8 mg and fexofenadine 120 mg, respectively, before and after the 28 days of E. purpurea. MEASUREMENTS AND MAIN RESULTS: On days 15 and 30 of lopinavir-ritonavir administration (before and after E. purpurea administration, respectively), serial blood samples were collected over 12 hours to determine lopinavir and ritonavir concentrations and subsequent pharmacokinetic parameters by using noncompartmental methods. Neither lopinavir nor ritonavir pharmacokinetics were significantly altered by 14 days of E. purpurea coadministration. The post-echinacea: pre-echinacea geometric mean ratios (GMRs) for lopinavir area under the concentration-time curve (AUC) from 0-12 hours and for maximum concentration were 0.96 (90% confidence interval [CI] 0.83-1.10, p=0.82) and 1.00 (90% CI 0.88-1.12, p=0.72), respectively. Conversely, GMRs for midazolam AUC from time zero extrapolated to infinity and oral clearance were 0.73 (90% CI 0.61-0.85, p=0.008) and 1.37 (90% CI 1.10-1.63, p=0.02), respectively. Fexofenadine pharmacokinetics did not significantly differ before and after E. purpurea administration (p>0.05). CONCLUSION: Echinacea purpurea induced CYP3A activity but did not alter lopinavir concentrations, most likely due to the presence of the potent CYP3A inhibitor, ritonavir. Echinacea purpurea is unlikely to alter the pharmacokinetics of ritonavir-boosted protease inhibitors but may cause modest decreases in plasma concentrations of other CYP3A substrates.

In vitro and in vivo induction of cytochrome p450: a survey of the current practices and recommendations: a pharmaceutical research and manufacturers of america perspective.

Cytochrome P450 (P450) induction is one of the factors that can affect the pharmacokinetics of a drug molecule upon multiple dosing, and it can result in pharmacokinetic drug-drug interactions with coadministered drugs causing potential therapeutic failures. In recent years, various in vitro assays have been developed and used routinely to assess the potential for drug-drug interactions due to P450 induction. There is a desire from the pharmaceutical industry and regulatory agencies to harmonize assay methodologies, data interpretation, and the design of clinical drug-drug interaction studies. In this article, a team of 10 scientists from nine Pharmaceutical Research and Manufacturers of America (PhRMA) member companies conducted an anonymous survey among PhRMA companies to query current practices with regards to the conduct of in vitro induction assays, data interpretation, and clinical induction study practices. The results of the survey are presented in this article, along with reviews of current methodologies of in vitro assays and in vivo studies, including modeling efforts in this area. A consensus recommendation regarding common practices for the conduct of P450 induction studies is included.

Matrix metalloproteinases MMP2 and MMP9 are upregulated by noradrenaline in the mouse neuroendocrine hypothalamus.

Magnocellular neurons of the hypothalamic supraoptic nuclei (SON) are involved in the synthesis and release of two major neuropeptides: oxytocin (OT) and arginine-vassopressin (AVP). Neurochemical plasticity in this system is induced by physiological conditions such as lactation, parturition and dehydration, and may be accompanied by reversible structural plasticity affecting neurons, astrocytes and the extracellular matrix (ECM). The noradrenergic system plays a critical role in triggering this chemical plasticity associated with structural plasticity. Matrix metalloproteinases (MMPs) are good candidates for involvement in the ECM remodelling observed in structural plasticity. We investigated the possible regulation of the two gelatinases, MMP2 and MMP9, by noradrenaline (NA) in the mouse neuroendocrine hypothalamus. We looked for the presence, location and activity of MMP2 and MMP9 in the SON, using an ex vivo experimental model of mouse hypothalamic slices incubated for 4 h with 10(-4) m NA. We showed that: (i) immunoreactivity for MMP2 and MMP9 was detected not only in AVP-positive and OT-positive magnocellular neurons, but also in astrocyte processes in control and NA-treated slices; (ii) the number of MMP2- and MMP9-positive cells increased after incubation with NA; (iii) MMP2 and MMP9 displayed markedly higher levels of gelatinolytic activity after NA treatment. These results suggest that both MMP2 and MMP9 are regulated by NA, and could therefore also be involved in structural plasticity within the SON.

Serum iron increases with acute induction of hepatic heme oxygenase-1 in mice.

Heme oxygenase (HO)-1 is induced by oxidative stress and protects against oxidant injury. We examined the effect of rapid induction of hepatic HO-1 on serum iron level. Serum iron was approximately doubled within 6 h when HO-1 was induced by phenobarbital treatment of selenium-deficient mice. Blocking heme synthesis with diethyl 1,4-dihydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC) prevented the induction of HO-1 and the rise in serum iron. DDC did not block HO-1 induction by hemin. Inhibition of HO activity by tin protoporphyrin prevented a rise in serum iron that occurred following phorone treatment. These results indicate that heme synthesis or an exogenous source of heme is needed to allow induction of HO-1. Further, they link HO-1 induction with a rise in serum iron, suggesting that the iron resulting from catabolism of heme by HO-1 is released by the liver.

Antioxidant effects of black rice extract through the induction of superoxide dismutase and catalase activities.

Our ex vivo study revealed that BRE had significantly stronger ability to inhibit LDL oxidation than white rice extract (WRE). The purpose of this study was to investigate whether black rice extract (BRE) supplementation might ameliorate oxidative stress and enhance antioxidant enzyme activities in HepG2 cells and in C57BL/6 mice. In the cellular study, superoxide anions (O2*-) and reactive oxygen species (ROS) in the BRE group were significantly suppressed. The BRE group also showed significant increases in superoxide dismutase (SOD) and catalase (CAT) activities by 161.6% and 73.4%, respectively. The major components responsible for the free-radical-scavenging and antioxidative properties might be cyanidin-3-O-glucoside chloride and peonidin-3-O-glucuside chloride. In the animal study, male C57BL/6 mice were divided into three groups (control, BRE, and WRE). Plasma HDL-cholesterol was significantly higher, and thiobarbituric, acid-reactive substances were significantly lower in the BRE group, whereas plasma levels of total cholesterol and triglyceride were not affected by BRE supplementation. Increased hepatic SOD and CAT activities were observed in BRE-treated mice as compared to the control mice. However, no changes were detected for the protein expression of antioxidant enzymes by Western blot analysis. Our data suggest that antioxidative effects exerted by BRE are mediated through decreases in free-radical generation as well as increases in SOD and CAT activities both in vitro and in vivo.

Induction of neutral endopeptidase (NEP) activity of SK-N-SH cells by natural compounds from green tea.

Deposition of amyloid beta-peptide as senile plaques in the brain is one of the neuropathological hallmarks of Alzheimer's disease, which is the most prevalent progressive neurodegenerative disease leading to dementia. Neutral endopeptidase is one of the major beta-amyloid-degrading enzymes in the brain. To examine the influence of different polyphenols and other natural products from green tea extract (from Camellia sinensis, Theaceae), we used the neuroblastoma cell line SK-N-SH and studied the changes in the specific cellular neutral endopeptidase activity after long-term treatment with these substances. We have shown that caffeine leads to an increase in specific cellular neutral endopeptidase activity more than theophylline, theobromine or theanine. We have also shown that the combination of epicatechin, epigallocatechin and epigallocatechingallate with caffeine, theobromine or theophylline induced cellular neutral endopeptidase activity. It is suggested that the enhancement of cellular neutral endopeptidase activity by green tea extract and its natural products might be correlated with an elevated level of intracellular cyclic adenosine monophosphate.