One of the most prominent strategies of cancer chemoprevention might be protecting cells or tissues against various carcinogens and carcinogenic metabolites derived from exogenous or endogenous sources. This protection could be achieved through the induction of phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase, NAD(P)H quinone oxidoreductase 1, and heme oxygenase-1, a process that is mediated mainly by the antioxidant response elements (ARE) within the promoter regions of these genes. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a member of the Cap 'n' collar (CNC) family of basic region-leucine zipper transcription factors, plays a key role in ARE-mediated gene expression. Under normal condition, Nrf2 is sequestered in the cytoplasm by an actin-binding protein, Kelch-like ECH associating protein 1 (Keap1), and upon exposure of cells to inducers such as oxidative stress and certain chemopreventive agents, Nrf2 dissociates from Keap1, translocates to the nucleus, binds to AREs, and transactivates phase 2 detoxifying and antioxidant genes. Several upstream signaling pathways including mitogen-activated protein kinases, protein kinase C, phosphatidylinositol 3-kinase, and transmembrane kinase are implicated in the regulation of Nrf2/ARE activity. Furthermore, many natural chemopreventive agents are known to induce Nrf2/ARE-dependent gene expression, also in part by regulating the turnover of the Nrf2 protein itself. This review discusses our current understanding of the Nrf2/ARE pathway as a potential molecular target for cancer chemoprevention, as well as the feasibility of screening natural compounds for activation of this pathway and as potential cancer preventive agents for human use.

Resveratrol, a natural polyphenolic compound, is found in various kinds of fruits, plants, and their commercial products such as red wine. It has been demonstrated to exhibit a variety of health-promoting effects including prevention and/or treatment of cardiovascular diseases, inflammation, diabetes, neurodegeneration, aging, and cancer. Cellular defensive properties of resveratrol can be explained through its ability of either directly neutralizing reactive oxygen species/reactive nitrogen species (ROS/RNS) or indirectly upregulating the expression of cellular defensive genes. As a direct antioxidant agent, resveratrol scavenges diverse ROS/RNS as well as secondary organic radicals with mechanisms of hydrogen atom transfer and sequential proton loss electron transfer, thereby protecting cellular biomolecules from oxidative damage. Resveratrol also enhances the expression of various antioxidant defensive enzymes such as heme oxygenase 1, catalase, glutathione peroxidase, and superoxide dismutase as well as the induction of glutathione level responsible for maintaining the cellular redox balance. Such defenses could be achieved by regulating various signaling pathways including sirtuin 1, nuclear factor-erythroid 2-related factor 2 and nuclear factor jB. This review provides current understanding and information on the role of resveratrol in cellular defense system against oxidative stress.

Isoflavones and their glycosides were isolated from kudzu root, and formononetin-7-O-glucoside (ononin) was identified from the plant for the first time. Among isolated compounds, the antioxidant potency of 5 major compounds was determined using (1) 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging assay, (2) thiocyanate assay in the linoleic acid model system, and (3) lipoxygenase inhibition assay. The study indicates that 5 compounds act as free-radical scavengers and inhibit both linoleic acid peroxidation and lipoxygenase activity. The 3 different assays for determining antioxidant activity revealed that activity in one test did not necessarily correlate with activity in another test. Arachidonic acid release in the intact HL-29 cancer cell, biochanin A, showed strong inhibition of about 70%, at a concentration of 50 M.

The aim of this study was to evaluate the antioxidant mechanisms of red ginseng essential oil (REO) in cells as well as in an animal model. REO was prepared by a supercritical CO2 extraction of waste-products generated after hot water extraction of red ginseng. In HepG2 cells, REO diminished the H2O2-mediated oxidative stress and also restored both the activity and expression of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase. Administration of REO inhibited the phosphorylation of upstream mitogen-activated protein kinases (MAPKs) such as c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38. In mice, the CCl4-mediated elevation of serum aspartate transaminase and alanine transaminase as well as the induction of hepatic lipid peroxidation were decreased by REO administration. REO treatments also resulted in up-regulation of the antioxidant enzyme expression in the liver. Moreover, increased phosphorylations of MAPKs were inhibited after REO administration. Overall, REO seems to protect the liver from oxidative stress through the activation and induction of antioxidant enzymes via inhibition of MAPKs pathways.

Study of the reactivity of 3d transition metal cations in diethylene glycol solutions revealed several key features that made it possible to develop a new method for synthesis of the nanocrystalline transition metal ferrites. The 3-7 nm particles of [MFe2O4]n[O2CR]m, where M = Mn, Fe, Co, Ni, and Zn, ligated on their surface with long-chain carboxylate anions, have been obtained in an isolated yield of 75-90%. The key features are the following. Complexation of the first-row transition metal cations with diethylene glycol at a presence of alkaline hydroxide is sufficient to enable control over the rate of their hydrolysis. The reaction of hydrolysis leads to the formation of metal oxide nanocrystals in colloidal solution. The nanoparticles growth is terminated by an added long-chain carboxylic acid, which binds to their surface and acts as a capping ligand. The isolated nanocrystalline powders are stable against agglomeration and highly soluble in nonpolar organic solvents.

The rhizome of ginger (Zingiber officinale Roscoe) is known to have several bioactive compounds including gingerols and shogaols which possess beneficial health properties such as anti-inflammatory and chemopreventive effects. Based on recent observations that 6-shogaol may have more potent bioactivity than 6-gingerol, we obtained a 6-shogaol-rich extract from ginger and examined its effects on the nuclear factor E2-related factor2 (Nrf2)/antioxidant response element (ARE) pathway in vitro and in vivo. 6-Shogaol-rich extract was produced by extracting ginger powder with 95% ethanol at 80 °C after drying at 80 °C (GEE8080). GEE8080 contained over 6-fold more 6-shogaol compared to the room temperature extract (GEE80RT). In HepG2 cells, GEE8080 displayed much stronger inductions of ARE-reporter gene activity and Nrf2 expression than GEE80RT. GEE8080 stimulated phosphorylations of mitogen-activated protein kinases (MAPKs) such as ERK, JNK, and p38. Moreover, the GEE8080-induced expressions of Nrf2 and HO-1 were attenuated by treatments of SB202190 (a p38 specific inhibitor) and LY294002 (an Akt specific inhibitor). In a mouse model, the GEE8080 decreased the diethylnitrosamine (DEN)-mediated elevations of serum aspartate transaminase and alanine transaminase as well as the DEN-induced hepatic lipid peroxidation. Inductions of Nrf2 and HO-1 by GEE8080 were also confirmed in the mice. In addition, the administration of GEE8080 to the mice also restored the DEN-reduced activity and protein expression of hepatic antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and catalase. In conclusion, GEE8080, a 6-shogaol-rich ginger extract, may enhance antioxidant defense mechanism through the induction of Nrf2 and HO-1 regulated by p38 MAPK and PI3k/Akt pathway in vitro and in vivo.

Neuroinflammatory responses induced by amyloid-beta peptide (Aβ) are important causes in the pathogenesis of Alzheimer's disease (AD). Blockade of Aβ has emerged as a possible therapeutic approach to control the onset of AD. This study investigated the neuroprotective effects and molecular mechanisms of p-coumaric acid (p-CA) and ursolic acid (UA) from Corni fructus against Aβ(25-35)-induced toxicity in PC12 cells. p-CA and UA significantly inhibited the expression of iNOS and COX-2 in Aβ(25-35)-injured PC12 cells. Blockade of nuclear translocation of the p65 subunit of nuclear factor κB (NF-κB) and phosphorylation of IκB-α was also observed after p-CA and UA treatment. For the upstream kinases, UA exclusively reduced ERK1/2, p-38, and JNK phosphorylation, but p-CA suppressed ERK1/2 and JNK phosphorylation. Both compounds comprehensively inhibited NF-κB activity, but possibly with different upstream pathways. The results provide new insight into the pharmacological modes of p-CA and UA and their potential therapeutic application to AD.

In the present study, the anti-inflammatory effect and underlying mechanisms of wild grape seeds procyanidins (WGP) were examined using lipopolysaccharide- (LPS-) stimulated RAW 264.7 cells. We used nitric oxide (NO) and prostaglandin E2 (PGE2) and reactive oxygen species (ROS) assays to examine inhibitory effect of WGP and further investigated the mechanisms of WGP suppressed LPS-mediated genes and upstream expression by Western blot and confocal microscopy analysis. Our data indicate that WGP significantly reduced NO, PGE2, and ROS production and also inhibited the expression of proinflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions. Consistently, WGP significantly reduced LPS-stimulated expression of proinflammatory cytokines such as tumor necrosis factor α (TNF-α) and interleukin- (IL-) 1β. Moreover, WGP prevented nuclear translocation of nuclear factor-κB (NFκB) p65 subunit by reducing inhibitory κB-α (IκBα) and NFκB phosphorylation. Furthermore, we found that WGP inhibited LPS-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK). Taken together, our results demonstrated that WGP exerts potent anti-inflammatory activity through the inhibition of iNOS and COX-2 by regulating NFκB and p38 MAPK pathway.