Dioscorealide B suppresses LPS-induced nitric oxide production and inflammatory cytokine expression in RAW 264.7 macrophages: The inhibition of NF-kappaB and ERK1/2 activation.

Dioscorealide B (DB), a naphthofuranoxepin has been purified from an ethanolic extract of the rhizome of Dioscorea membranacea Pierre ex Prain & Burkill which has been used to treat inflammation and cancer in Thai Traditional Medicine. Previously, DB has been reported to have anti-inflammatory activities through reducing nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production in lipopolysaccharides (LPS)-induced RAW 264.7 macrophage cells. In this study, the mechanisms of DB on LPS-induced NO production and cytokine expression through the activation of nuclear factor-kappaB (NF-kappaB) and ERK1/2 are demonstrated in RAW 264.7 cells. Through measurement with Griess's reagent, DB reduced NO level with an IC(50) value of 2.85 +/- 0.62 microM that was due to the significant suppression of LPS-induced iNOS mRNA expression as well as IL-1beta, IL-6, and IL-10 mRNA at a concentration of 6 microM. At the signal transduction level, DB significantly inhibited NF-kappaB binding activity, as determined using pNFkappaB-Luciferase reporter system, which action resulted from the prevention of IkappaBalpha degradation. In addition, DB in the range of 1.5-6 microM significantly suppressed the activation of the ERK1/2 protein. In conclusion, the molecular mechanisms of DB on the inhibition of NO production and mRNA expression of iNOS, IL-1beta, IL-6, and IL-10 were due to the inhibition of the upstream kinases activation, which further alleviated the NF-kappaB and MAPK/ERK signaling pathway in LPS-induced RAW264.7 macrophage cells.

Adriamycin-mediated nitration of manganese superoxide dismutase in the central nervous system: insight into the mechanism of chemobrain.

Adriamycin (ADR), a potent anti-tumor agent, produces reactive oxygen species (ROS) in cardiac tissue. Treatment with ADR is dose-limited by cardiotoxicity. However, the effect of ADR in the other tissues, including the brain, is unclear because ADR does not pass the blood-brain barrier. Some cancer patients receiving ADR treatment develop a transient memory loss, inability to handle complex tasks etc., often referred to by patients as chemobrain. We previously demonstrated that ADR causes CNS toxicity, in part, via systemic release of cytokines and subsequent generation of reactive oxygen and nitrogen species (RONS) in the brain. Here, we demonstrate that treatment with ADR led to an increased circulating level of tumor necrosis factor-alpha in wild-type mice and in mice deficient in the inducible form of nitric oxide (iNOSKO). However, the decline in mitochondrial respiration and mitochondrial protein nitration after ADR treatment was observed only in wild-type mice, not in the iNOSKO mice. Importantly, the activity of a major mitochondrial antioxidant enzyme, manganese superoxide dismutase (MnSOD), was reduced and the protein was nitrated. Together, these results suggest that NO is an important mediator, coupling the effect of ADR with cytokine production and subsequent activation of iNOS expression. We also identified the mitochondrion as an important target of ADR-induced NO-mediated CNS injury.

Adriamycin-induced, TNF-alpha-mediated central nervous system toxicity.

The clinical effectiveness of adriamycin (ADR), a potent chemotherapeutic, is known to be limited by severe cardiotoxic side effects. However, the effect of ADR on brain tissue is not well understood. It is generally thought that ADR is not toxic to the brain because ADR does not pass the blood-brain barrier. The present study demonstrates that ADR autofluorescence was detected only in areas of the brain located outside the blood-brain barrier, but a strong tumor necrosis factor (TNF) alpha immunoreactivity was detected in the cortex and hippocampus of ADR-treated mice. Systemic injection of ADR led to a decline in brain mitochondrial respiration via complex I substrate shortly after ADR treatment (P < 0.05). Cytochrome c release, increased caspase 3 activity, and TUNEL-positive cell death all were suggestive of apoptosis in brain following systemic ADR treatment. The levels of the known pro-apoptotic proteins, p53 and Bax, were increased in brain mitochondria at 3 h following ADR treatment and declined by 48 h. In contrast, the anti-apoptotic protein, Bcl-xL, was increased later at 6 h post-ADR treatment and was sustained throughout 72 h. Furthermore, p53 migrated to mitochondria and interacted with Bcl-xL, supporting the hypothesis that mitochondria are targets of ADR-induced CNS injury. Neutralizing antibodies against circulating TNF completely abolished both the increased TNF in the brain and the observed mitochondrial injury in brain tissues. These results are consistent with the notion that TNF is an important mediator by which ADR induces central nervous system (CNS) injury. This study, the first to provide direct biochemical evidence of ADR toxicity to the brain, revealed novel mechanisms of ADR-induced CNS injury and suggests a potential therapeutic intervention against circulating TNF-induced CNS effects.

Aldehyde dehydrogenase 2 genotypes, alcohol flushing symptoms and drinking patterns in Thai men.

The drinking behavior, alcohol-induced facial flushing and ALDH2 genotypes were determined in 283 Thai men comprising 85 who were alcohol-dependent, 62 hazardous/harmful drinkers and 136 non-drinkers or infrequent drinkers. A structured interview questionnaire, containing the 'tri-level' method and the Alcohol-Use Disorders and Associated Disabilities Schedule, was used to determine the quantity of drinking and the number of alcohol-related adverse experiences. The study revealed the mutant ALDH2*2 allele in 44 (15.5%) subjects. The risks of being alcohol-dependent and of having hazardous/harmful drinking were lower in individuals with heterozygous ALDH2*1/*2, compared with homozygous ALDH2*1/*1 [relative probability ratios (95% CI) 0.14 (0.05-0.41) and 0.23 (0.08-0.61), respectively]. Eighty percent of those who were heterozygous and 28% of those who were homozygous ALDH2*1 reported flush symptoms after drinking alcohol. Twenty-nine percent of homozygous ALDH2*1 individuals, but only 9% of heterozygous subjects, drank almost everyday (24-30 days/month). Similarly, higher percentages of people drinking beyond the safety limit (>60 g/day) and having alcohol-related problems were observed in homozygous ALDH2*1 compared with heterozygous individuals: 32% vs. 5% and 27% vs. 12%, respectively. Overall, the study supports the role of the mutant ALDH2*2 allele in preventing high alcohol consumption and the development of alcohol dependence in a Thai population.