The Association between Oxidative Balance Score and Urinary Levels of 8-Hydroxydeoxyguanosine among Japanese Adults.

The oxidative balance score (OBS), wherein higher OBSs indicate lower oxidative stress, was designed to assess a composite measure of multiple pro-oxidant and antioxidant effects on an individual's oxidative stress status. This study aimed to evaluate whether OBSs were inversely associated with urinary levels of 8-hydroxydeoxyguanosine (8-OHdG)-an oxidative stress marker-among Japanese adults. This cross-sectional study was based on data obtained during 2010-2012. Overall, 7552 participants from the J-MICC Study Saga who answered a self-administered food frequency questionnaire were recruited for the final analysis. OBSs were calculated from 11 pro-oxidant and antioxidant lifestyle factors, including dietary intake, physical activity, and alcohol and smoking status. Urinary 8-OHdG values were corrected by creatinine level (ng/mg creatinine). Our findings revealed a higher total OBS was significantly associated with lower urinary 8-OHdG/creatinine levels after adjustment for covariates in men and women (p for trend < 0.01 in both sexes). We performed a multiple regression analysis of the association between OBSs and urinary 8-OHdG/creatinine levels stratified by age, body mass index (BMI), and menopausal status and found consistent negative associations in most groups for both sexes. No significant differences in the 60-64 age group for women (standardized ß = -0.09, p = 0.13) or BMI < 18.5 kg/m2 for men (standardized ß = -0.18, p = 0.17) were observed. A higher OBS had a strong inverse association with urinary 8-OHdG/creatinine levels in men and women among Japanese adults. The OBS might be a useful tool for evaluating the roles of oxidative stress-related lifestyle factors, including diet.

Formation of the mutagenic DNA lesion 1,N2-ethenoguanine induced by heated cooking oil and identification of causative agents.

BACKGROUND: The DNA-damaging compounds in heated cooking oil were identified as guanosine adducts. Heated vegetable oil was subjected to deep-frying conditions at 170 °C for 45 min, reacted with isopropylidene guanosine (ipG) at pH 7.4, and the resulting compounds were separated by high-performance liquid chromatography (HPLC). RESULTS: Two adducts, 8-hydroxy-ipG and 1,N2-etheno-ipG, were identified in the reaction mixture. One of the major components in heated cooking oil, 2,4-heptadienal (HDE), efficiently produced etheno-ipG from ipG in the presence of tBuOOH. An oxidized HDE solution was fractionated using HPLC to identify causative agents, and each fraction was tested for etheno-ipG formation. In addition to the known lipid peroxidation product, 4,5-epoxy-2-heptenal, two unknown polar components with potent etheno-ipG formation activity were discovered. Based on Mass and UV spectra, their structures were identified as 6-oxo- and 6-hydroxy-2,4-HDE. Similarly, 6-oxo- and 6-hydroxy-2,4- decadienal (DDE) were formed from 2,4-DDE. Significant amounts of 6-oxo- and 6-hydroxy-2,4-alkadienal were detected in the heated cooking oil. These compounds induced the formation of 1,N2-ethenoguanine in nucleosides and DNA, especially in the presence of tBuOOH. Moreover, the formation of 6-oxo- and 6-OH-HDE from 2,4-HDE was accelerated in the presence of hemin and tBuOOH. CONCLUSION: The results suggest that these compounds are not only generated during the oil heating process but also produced from 2,4-alkadienal through digestion under normal physiological conditions, especially after ingesting heme- and alkyl-OOH-containing diets. Moreover, these compounds can be formed within cells under oxidative stress, potentially linking them to gastrointestinal carcinogenesis.

Free radical-mediated acetaldehyde formation by model reactions of dietary components: effects of meat, wine, cooking oil and coffee.

BACKGROUND: Alcohol consumption and the ingestion of red meat and oxidized cooking oil are risk factors of gastric and colorectal cancers. We reported that acetaldehyde (AcAld) is generated from Heme/Mb/Meat-Linoleate-EtOH model reaction mixtures, and thus could be a new plausible mechanism for the carcinogenesis (Kasai and Kawai, ACS Omega, 2021). RESULTS: In this study, we investigated the effects of wine and coffee, in addition to meat components, on this reaction. Depending on the conditions, such as pH, reaction time and choice of free hemin, myoglobin (Mb), as well as meat extracts (raw meat, baked meat, salami), wine and coffee enhanced AcAld formation. Polyphenols in red wine and coffee may stimulate AcAld formation by acting as pro-oxidants in the presence of Heme/Mb/Meat. In a model reaction of Mb + EtOH + H2O2, we observed time-dependent AcAld formation. In support of these in vitro data, after the consumption of a red meat-rich diet with red wine, the fecal AcAld level significantly increased as compared to the levels associated with a diet of fish + wine, or red meat without alcohol. CONCLUSIONS: These results suggested that AcAld generation from dietary components may be an important mechanism of gastrointestinal tract carcinogenesis.

New Plausible Mechanism for Gastric and Colorectal Carcinogenesis: Free Radical-Mediated Acetaldehyde Generation in a Heme/Myoglobin-Linoleate-Ethanol Mixture.

Epidemiological studies have revealed that alcohol, red meat, and cooking oil (or linoleate) are risk factors for both gastric and colon cancers. A survey of the mutation spectra of the p53 tumor suppressor gene in these cancers suggested that the types of mutations and the hot spots are similar to those induced by acetaldehyde (AcAld) in an in vitro p53 mutation analysis system. Accordingly, various combinations of possible factors, components, or model compounds were reacted in an emulsion and tested for the generation of AcAld. Efficient AcAld formation was only observed with combinations of three factors, red meat homogenate (or heme/myoglobin), methyl linoleate, and ethanol, but not by any combination of the two. The generated AcAld levels (ca. 500 µM) far exceeded the minimum mutagenic concentration (40-100 µM) obtained using concentrations of meat homogenate (or heme/Mb), linoleate, and ethanol comparable to those in the stomach after an ordinary meal. A mutagenic level of AcAld (75 µM) was also generated with a physiological concentration of ethanol, heme, and linoleate in the colon. As a mechanism, linoleate hydroperoxide formation and its decomposition in the presence of myoglobin (or heme) to generate the OH radical seem to be involved in the ethanol-to-AcAld conversion.

Diurnal and day-to-day variation of urinary oxidative stress marker 8-hydroxy-2'-deoxyguanosine.

The urinary 8-hydroxy-2'-deoxyguanosine levels have been widely used as a biomarker of oxidative stress. The purpose of this study is to investigate the diurnal and day-to-day variations of urinary 8-hydroxy-2'-deoxyguanosine levels. For the diurnal variation, the urine samples were collected at the time of awakening and every 2 h, from 10:00 to 22:00, from 6 healthy participants. For the day-to-day variation, the urine samples were collected at the time of awakening for 35 consecutive days, from 27 healthy participants. As a result, no differences were observed in the diurnal urinary 8-hydroxy-2'-deoxyguanosine levels, and each subject had a characteristic 8-hydroxy-2'-deoxyguanosine level. On the other hand, the daily 8-hydroxy-2'-deoxyguanosine values showed a certain range of variation reflecting lifestyle factors, such as stress status, exercise, sleep time, drinking and diet. In conclusion, urinary 8-hydroxy-2'-deoxyguanosine may be a useful biomarker to control and prevent oxidative stress-related diseases, if the certain range of day-to-day variations of urinary 8-hydroxy-2'-deoxyguanosine is known. Even with only one measurement per year, the baseline urinary 8-hydroxy-2'-deoxyguanosine level could be achieved in a few years by incorporating the 8-hydroxy-2'-deoxyguanosine measurement as part of an annual health check. As the number of subjects was limited, further studies are needed for practical applications.

Pyrimidine Ring-Opened Product from Oxidative DNA Damage of 5-Formyl-2'-deoxyuridine.

After thymidine (dT) was treated with a Fenton-type reagent and further incubated for a long period (6 days) under physiological conditions (37 °C, pH 7.4), a new product, named dT*, was detected by HPLC in addition to the free thymine base and the known oxidative dT damage, 5-formyl-2'-deoxyuridine (f5dU). dT* was found to be formed from f5dU. The structure of dT* was determined to be 3-amino-2-carbamoyl-2-propenal-N3-2'-deoxyriboside, a pyrimidine ring-opened product from f5dU, on the basis of 1H- and 13C NMR analyses and mass spectra. From the model compound 1-methyl-5-formyluracil, a similar ring-opened product was formed after the incubation. dT* was also detected in DNA treated with a Fenton-type reagent or γ-rays, followed by the prolonged incubation. dT* will be a new promising marker of oxidative DNA damage. The possible role of this product in oxy-radical-induced mutagenesis is discussed.

Leisure-time physical activity and DNA damage among Japanese workers.

BACKGROUND: It remains unclear whether daily physical activity is associated with DNA damage. This cross-sectional study examined the association between leisure-time physical activity and urinary 8-hydroxydeoxyguanosine (8-OH-dG), a biomarker of oxidative DNA damage, or urinary 7-methylguanine (m7Gua), a biomarker of methylating DNA damage. METHODS: Participants included 501 workers (294 men and 207 women), aged 20-65 years, from municipal offices in Japan. Urinary 8-OH-dG and m7Gua were measured using column-switching HPLC. Physical activity was evaluated using a self-reported questionnaire. The associations between leisure-time physical activity and urinary DNA damage markers were assessed by multiple linear regression analysis, with stratification by occupational physical activity. RESULTS: After adjusting for covariates, leisure-time physical activity showed a suggestive inverse correlation with urinary 8-OH-dG levels (P for trend = 0.06), and a significant inverse association with urinary m7Gua levels (P for trend = 0.03). In analysis stratified by occupation, inverse correlations were observed in sedentary workers (walking < 30 min/day at work: P for trend = 0.06 and = 0.03 for urinary 8-OH-dG and m7Gua, respectively), but not in physically active workers (walking ≥ 30 min/day at work). In analysis for each intensity of leisure-time physical activity, light-intensity exercise was associated with lower levels of urinary 8-OH-dG (P for trend = 0.03), whereas moderate-to-high-intensity exercise was associated with lower levels of urinary m7Gua (P for trend = 0.02). CONCLUSIONS: Our results suggest that high levels of leisure-time physical activity are associated with decreased levels of DNA damage in individuals with low physical activity at work.

Measurement of 8-hydroxyguanine as an oxidative stress biomarker in saliva by HPLC-ECD.

INTRODUCTION: Oxidative stress leads to many kinds of diseases. Currently, urinary 8-hydroxydeoxyguanosine (8-OHdG) is widely measured as an oxidative stress biomarker. There is a specific advantage if saliva can be used as the sample to measure the oxidative stress biomarker, because saliva is much easier to collect than urine. In this study, we investigated the measurement of 8-hydroxyguanine (8-OHGua) as an oxidative stress marker in saliva, by a column switching HPLC system equipped with an electrochemical detector (HPLC-ECD). FINDINGS: The 8-OHGua in saliva could be detected as a single peak by HPLC-ECD. The average level of 8-OHGua in saliva was 3.80 ng/mL in ordinary, non-smoking subjects. The salivary 8-OHGua levels of smokers were significantly higher than those of non-smokers. CONCLUSIONS: Salivary 8-OHGua may be a useful noninvasive and promising oxidative stress biomarker.

Dietary non-enzymatic antioxidant capacity and DNA damage in a working population.

OBJECTIVE: The aim of this study was to investigate the potential links between dietary non-enzymatic antioxidant capacity (NEAC) in overall diet and separately from foods and beverages and markers of DNA damage. METHODS: The participants were 513 employees, 20 to 65 y of age. Urinary levels of 8-hydroxydeoxyguanosine (8-OHdG) and 7-methylguanine (m7 Gua) were measured using column-switching high-performance liquid chromatography. Dietary NEAC was determined from databases of NEAC measurements obtained by different assays: ferric reducing-antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and total radical-trapping antioxidant parameter (TRAP). Dietary NEAC for each participant was calculated by multiplying the estimated NEAC values with the consumed amount and summing up those values, which was ascertained by a validated brief self-administered diet history questionnaire. Multiple-regression analyses were performed to assess the associations between dietary NEAC and 8-OHdG and m7 Gua, with adjustment for potential confounders. RESULTS: No statistically significant associations were found between overall dietary NEAC or NEAC from either foods or beverages and urinary 8-OHdG levels, after adjustment for potential confounders (overall: FRAP, Ptrend = 0.40; ORAC, P = 0.27; TRAP, P = 0.45). Likewise, no association was found between overall dietary NEAC and m7 Gua levels (FRAP, Ptrend = 0.30; ORAC, P = 0.65; TRAP, P = 0.41). However, we did identify significant inverse association between NEAC from foods, as estimated by TRAP, and m7 Gua levels (Ptrend = 0.049). CONCLUSION: Overall, dietary NEAC was not associated with 8-OHdG or m7 Gua levels. In contrast, dietary NEAC from foods but not beverages may be inversely associated with DNA damage caused by methylation.

Perceived Stress, Depressive Symptoms, and Oxidative DNA Damage.

OBJECTIVE: Psychosocial stress may influence the risk of disease through its association with oxidative DNA damage. We examined whether perceived stress and depressive symptoms were associated with urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG), with mutual interaction on 8-OHdG. METHODS: This cross-sectional study included 6517 individuals aged 45 to 74 years who participated, between 2010 and 2012, in a follow-up survey of an ongoing cohort study. Perceived stress during the past year was measured using a self-report questionnaire. Depressive symptoms were evaluated using the Zung Self-Rating Depression Scale. Urinary 8-OHdG concentrations were measured using a column switching high-pressure liquid chromatography system coupled to an electrochemical detector. RESULTS: Higher perceived stress was significantly associated with higher 8-OHdG (2.1% increase per one-category increase of stress; ptrend = .025), even after adjusting for sex, age, supplement use, psychosocial factors, psychotropic medication use, smoking, and body mass index. This association was modestly attenuated after further adjustment for physical activity, suggesting possible mediation or confounding by this factor. Depressive symptoms were not significantly associated with 8-OHdG. No significant interaction was detected between perceived stress and depressive symptoms on 8-OHdG. CONCLUSIONS: In a general Japanese population, we found a weak positive association between perceived stress and urinary excretion of 8-OHdG, whereas no association was observed between depressive symptoms and 8-OHdG. Further studies are needed to examine whether the association between perceived stress and 8-OHdG is modified by depressive symptoms.

Comparison of Blueberry (Vaccinium spp.) and Vitamin C via Antioxidative and Epigenetic Effects in Human.

BACKGROUND: Chemopreventive effects and the underlying mechanisms of blueberry (Vaccinium spp.) are not clearly understood in human. We hypothesized blueberry would work via antioxidative and epigenetic modulation, which is similar to vitamin C. METHODS: We performed a pilot and non-inferiority study in healthy young women (n = 12), who consumed vitamin C (1 g/d) or 240 mL of blueberry juice (total polyphenols 300 mg and proanthocyanidin 76 mg/d) for 2 weeks. We analyzed 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) levels in their urine, and global and specific DNA methylation at the NAD(P)H quinone oxidoreductase 1 (NQO1), methylenetetrahydrofolate reductase (MTHFR), or DNA methyltransferase 1 (DNMT1) genes in their blood. RESULTS: Urinary 8-OHdG levels were reduced by blueberry consumption rather than by vitamin C. The methylation (%) of the MTHFR was significantly decreased in blueberry-consumers and the antioxidant-susceptible subgroup, whose urinary MDA levels were decreased by the intervention. We also found a positive correlation between changes of urinary 8-OHdG and of DNA methylation at the MTHFR or the DNMT1 (P < 0.05). However, the genetic polymorphism of the MTHFR (C677T in exon 4) did not affect any above markers. CONCLUSIONS: Blueberry juice shows similar anti-oxidative or anti-premutagenic activity to vitamin C and the potential as a methylation inhibitor for the MTHFR and the DNMT1 in human.

Intensity-specific effect of physical activity on urinary levels of 8-hydroxydeoxyguanosine in middle-aged Japanese.

Physical activity (PA) is recommended to both promote and maintain health and prevent cancer by improving the body's DNA repair system, which is considered a mechanism of cancer prevention. However, associations between PA and urinary levels of 8-hydroxydeoxyguanosine (8-OH-dG), which reflects DNA damage, are unclear. This cross-sectional study included 2370 men and 4052 women aged 45-74 years enrolled between 2010 and 2012. Habitual PA was assessed by single-axis accelerometer and urinary 8-OH-dG levels by automated HPLC. Multiple linear regression analysis was used to examine the relationship between log-transformed urinary 8-OH-dG and total PA (TPA) and PA of moderate/vigorous intensity (MVPA; ≥3 metabolic equivalents), with adjustment for age, body mass index, energy intake, alcohol consumption, smoking status, daily coffee drinking, menopause status (in women), and TPA (for MVPA). On multivariate adjustment, urinary 8-OH-dG levels were inversely correlated with TPA (ß = -0.020, P < 0.01) in women, and this correlation was not changed by PA intensity. Conversely, urinary 8-OH-dG levels were inversely correlated with MVPA (ß = -0.022, P < 0.05) in men, although the correlation with TPA was non-significant. This inverse correlation was clearer in current smokers than in never or former smokers, although the interaction between smoking status and MVPA on urinary 8-OH-dG levels was non-significant. In conclusion, greater TPA in women and greater MVPA in men were correlated with reduction in urinary 8-OH-dG, suggesting sex-specific effects of MVPA and TPA on protection from oxidative DNA damage. Increasing PA may mediate reduction in oxidative stress.

What causes human cancer? Approaches from the chemistry of DNA damage.

To prevent human cancers, environmental mutagens must be identified. A common mechanism of carcinogenesis is DNA damage, and thus it is quite possible that environmental mutagens can be trapped as adducts by DNA components. It is also important to identify new types of DNA damaging reactions and clarify their mechanisms. In this paper, I will provide typical examples of our efforts to identify DNA damage by environmental agents, from chemistry-based studies. 1) Oxidative DNA damage: 8-Hydroxydeoxyguanosine (8-OHdG, 8-oxodG) was discovered during a structural study of DNA modifications caused in vitro by heating glucose, which was used as a model of cooked foods. We found that various oxygen radical-forming agents induced the formation of 8-OHdG in DNA, in vitro and in vivo. Analyses of the urinary 8-OHdG levels are useful to assess the extent of oxidative DNA damage in a human population. 2) Lipid peroxide-derived DNA adducts: We searched for mutagens that react with deoxynucleosides, in model systems of lipid peroxidation. The reaction mixtures were analyzed by high performance liquid chromatography (HPLC), and we discovered various lipid peroxide-derived mutagens, including new mutagens. Some of these adducts were detected in human DNA. These mutagens may be involved in lipid peroxide-related cancers. 3) Methylation of cytosine by free radicals: Methylation of the cytosine C-5 position is an important mechanism of carcinogenesis, in addition to gene mutations. However, the actual mechanisms of de novo methylation in relation to environmental agents are not clear. We found that cytosine C-5 methylation occurred by a free radical mechanism. The possible role of this radical-induced DNA methylation in carcinogenesis will be discussed, in relation to the presently accepted concept of cancer epigenetics. In these studies, chemical analyses of the adducts formed in model reactions led to the discoveries of new mutagens and important types of DNA modifications, which seem to be involved in human carcinogenesis.

Coffee intake is associated with lower levels of oxidative DNA damage and decreasing body iron storage in healthy women.

Habitual coffee drinking has been linked to a lower risk for some forms of cancer, but the mechanism remains elusive. Coffee may decrease oxidative DNA damage, an important pathway to carcinogenesis. We examined the association between coffee consumption and urinary 8-hydroxydeoxyguanosine (8-OHdG) concentrations, a biomarker of systemic oxidative DNA damage and repair, in 507 healthy subjects (298 men and 209 women aged 21-67 yr) while adjusting for age, sex, smoking status, body mass index, job type, and fasting blood glucose in multivariable regression models. The association with green tea consumption was also assessed. Urinary 8-OHdG concentrations tended to decrease with coffee consumption in women (trend P = 0.046), with women drinking 2-3 cups of coffee per day showing the lowest mean of urinary 8-OHdG concentrations. This association was largely attenuated after further adjustment for serum ferritin concentrations, a marker of body iron storage (trend P = 0.96). Green tea consumption was not associated with urinary 8-OHdG concentrations. Coffee drinking may be associated with decreased systemic oxidative DNA damage through decreasing body iron storage in women.

Somatic cell mutations caused by 365 nm LED-UVA due to DNA double-strand breaks through oxidative damage.

Evidence is accumulating indicating that UVA (320-400 nm ultraviolet light) plays an important role in photo-carcinogenesis. UVA is thought to produce reactive oxygen species in irradiated cells through photo-activation of inherent photosensitizers, and was recently reported to cause DNA double-strand breaks (DSBs) in exposed cells. We have investigated the involvement of UVA in mutations and DNA damage in somatic cells using Drosophila melanogaster larvae. Using the Okazaki Large Spectrograph, we previously observed that longer wavelength UVA (>330 nm) was more mutagenic in post-replication repair-deficient D. melanogaster (mei-41) than in the nucleotide excision repair-deficient strain (mei-9). LED-light has recently been developed as a high-dose-rate UVA source. LED-UVA light (365 nm) was also more mutagenic in mei-41 than in mei-9. The mei-41 gene was shown to be an orthologue of the human ATR gene, which is involved in the repair of DSBs through phosphorylation of histone H2AX. In order to estimate the extent to which oxidative damage contributes to mutation, we established a new D. melanogaster strain (urate-null mutant) that is sensitive to oxidative damage and has a marker to detect somatic cell mutations. When somatic cell mutations were examined using this strain, LED-UVA was mutagenic in the urate-null strain at doses that were non-mutagenic in the urate-positive strain. In an effort to investigate the generation of DSBs, we examined the presence of phosphorylated histone H2AvD (H2AX D. melanogaster homologue). At high doses of LED-UVA (>800 kJ m(-2)), levels of phosphorylated H2AvD (γ-H2AvD) increased significantly in the urate-null strain. Moreover, the level of γ-H2AvD increased in the excision repair-deficient strain but not in the ATR-deficient strain following UVA-irradiation. These results supported the notion that the generation of γ-H2AvD was mediated by the function of the mei-41 gene. It was reported that ATR functions on DSB repair in D. melanogaster. Taken together, we propose a possible pathway for UVA-induced mutation, whereby DNA double-strand breaks resulting from oxidative stress might be responsible for UVA-induced mutation in somatic cells of D. melanogaster larvae.

Urinary 1-hydroxypyrene and 8-hydroxydeoxyguanosine levels among coke-oven workers for 2 consecutive days.

OBJECTIVES: This study evaluated the levels of exposure to polycyclic aromatic hydrocarbons (PAHs) and their relationship with oxidative DNA damage among Vietnamese coke-oven workers. METHODS: We collected urine from 36 coke-oven workers (exposed group) at the beginning and end of the shift on 2 consecutive days. We also collected urine from 78 medical staff (control group). Information was collected by questionnaire about smoking status, drinking habit, and working position. Urinary 1-hydroxypyrene (1-OHP) and 8-hydroxydeoxyguanosine (8-OH-dG) were measured using HPLC. All statistical analyses were performed with SPSS version 19. RESULTS: Urinary 1-OHP was significantly higher in the coke-oven workers than in the control group (p<0.05). Top-oven workers had the highest levels of internal exposure to PAHs, followed by side-oven and then bottom-oven workers (5.41, 4.41 and 1.35 ng/mg creatinine, respectively, at the end of the shift on day 2). Urinary 8-OH-dG was significantly higher in top- and side-oven workers at the end of the shift on day 2 (4.63 and 5.88 ng/mg creatinine, respectively) than in the control group (3.85 ng/mg creatinine). Based on a multi-regression analysis, smoking status had a significant effect on urinary 8-OH-dG (p=0.049). Urinary 1-OHP tended to have a positive correlation with urinary 8-OH-dG (p=0.070). CONCLUSIONS: Vietnamese coke-oven workers were exposed to PAHs during their work shift. Urinary 1-OHP exceeded the recommended limit, and elevated oxidative DNA damage occurred in top- and side-oven workers on the second day of work. A tendency for positive correlation was found between urinary 1-OHP and urinary 8-OH-dG.

Identification of octenal-related dA and dC adducts formed by reactions with a hemin-ω-6-fat peroxidation model system.

Deoxynucleosides were reacted in a lipid peroxidation model system, emulsified hemin-ethyl linoleate, and the adducts thus produced were analyzed by HPLC. Substantial amounts of stable adducts were detected in the dA- and dC-reaction mixtures. The structures of the major dA and dC adducts, other than the known 4-oxo-2-nonenal adducts, were determined to be etheno-type adducts, with a C6 side chain bearing an α-hydroxyl-group. These results suggested that the substance involved in adduct formation is 2,3-epoxyoctanal. This compound showed mutagenicity in Salmonella strains TA 100 and TA 104 without the S-9 mix. In addition, based on the structure of a minor dC adduct, another possibly involved mutagen, 4-oxo-2-octenal, was proposed. These mutagens may be formed during storage and cooking of food, or during digestion, and may be involved in human cancers.

Magnetic nanoparticles of Fe3O4 enhance docetaxel-induced prostate cancer cell death.

Docetaxel (DTX) is one of the most important anticancer drugs; however, the severity of its adverse effects detracts from its practical use in the clinic. Magnetic nanoparticles of Fe3O4 (MgNPs-Fe3O4) can enhance the delivery and efficacy of anticancer drugs. We investigated the effects of MgNPs-Fe3O4 or DTX alone, and in combination with prostate cancer cell growth in vitro, as well as with the mechanism underlying the cytotoxic effects. MgNPs-Fe3O4 caused dose-dependent increases in reactive oxygen species levels in DU145, PC-3, and LNCaP cells; 8-hydroxydeoxyguanosine levels were also elevated. MgNPs-Fe3O4 alone reduced the viability of LNCaP and PC-3 cells; however, MgNPs-Fe3O4 enhanced the cytotoxic effect of a low dose of DTX in all three cell lines. MgNPs-Fe3O4 also augmented the percentage of DU145 cells undergoing apoptosis following treatment with low dose DTX. Expression of nuclear transcription factor κB in DU145 was not affected by MgNPs-Fe3O4 or DTX alone; however, combined treatment suppressed nuclear transcription factor κB expression. These findings offer the possibility that MgNPs-Fe3O4-low dose DTX combination therapy may be effective in treating prostate cancer with limited adverse effects.

Effects of Fe3O4 Magnetic Nanoparticles on A549 Cells.

Fe3O4 magnetic nanoparticles (MgNPs-Fe3O4) are widely used in medical applications, including magnetic resonance imaging, drug delivery, and in hyperthermia. However, the same properties that aid their utility in the clinic may potentially induce toxicity. Therefore, the purpose of this study was to investigate the cytotoxicity and genotoxicity of MgNPs-Fe3O4 in A549 human lung epithelial cells. MgNPs-Fe3O4 caused cell membrane damage, as assessed by the release of lactate dehydrogenase (LDH), only at a high concentration (100 µg/mL); a lower concentration (10 µg/mL) increased the production of reactive oxygen species, increased oxidative damage to DNA, and decreased the level of reduced glutathione. MgNPs-Fe3O4 caused a dose-dependent increase in the CD44+ fraction of A549 cells. MgNPs-Fe3O4 induced the expression of heme oxygenase-1 at a concentration of 1 µg/mL, and in a dose-dependent manner. Despite these effects, MgNPs-Fe3O4 had minimal effect on cell viability and elicited only a small increase in the number of cells undergoing apoptosis. Together, these data suggest that MgNPs-Fe3O4 exert little or no cytotoxicity until a high exposure level (100 µg/mL) is reached. This dissociation between elevated indices of cell damage and a small effect on cell viability warrants further study.

8-hydroxyguanine in urine and serum as an oxidative stress marker: effects of diabetes and aging.

8-Hydroxydeoxyguanosine (8-OH-dG) is the most extensively analyzed oxidative stress marker. Recently, 8-hydroxyguanine (free base: 8-OH-Gua) has been recognized as an oxidative stress marker. To verify the usefulness of 8-OH-Gua, the 8-OH-dG and 8-OH-Gua levels in the urine and the 8-OH-Gua levels in the serum of type 2 diabetic model animals, db/db mice, were measured as oxidative stress markers by a column switching HPLC-system coupled to an electrochemical detector. The urinary 8-OH-Gua and 8-OH-dG levels in db/db mice (7-26 weeks old) were significantly higher than those in control (db/m+) mice. The 8-OH-Gua levels in the serum of the db/db mice were also about 2-fold higher than those in the control mice at 26 weeks of age. In addition, the urinary levels of 8-OH-dG and 8-OH-Gua increased with age (9-26 weeks). A significant positive correlation was obtained between the 8-OH-dG and 8-OH-Gua levels in urine. Although no difference was observed in the 8-OH-dG levels in the liver and kidney DNA between the diabetic and control mice, these results suggested that urinary 8-OH-dG and free base 8-OH-Gua in urine or serum may be good biomarkers of oxidative stress.