Reactive oxygen species and their reaction products can damage DNA to form mutagenic lesions. Among the reactive species, lipid peroxidation-derived aldehydes react with nucleobases and form bulky exocyclic adducts. Many types of aldehyde-derived DNA adducts have been characterized, identified and detected in vitro and in vivo, whereas relative quantitative and pathophysiological contributions of each adduct still remain unclear. In recent years, an abundant class of DNA adducts derived from 4-oxo-2-alkenals have been identified, in addition to classic aldehyde-derived adducts. The presence of 4-oxo-2-alkenal-derived DNA adducts associated with age-related diseases has been revealed in rodents and humans. In vitro studies have demonstrated that 4-oxo-2-alkenals, as compared with other classes of lipid peroxidation-derived aldehydes, are highly reactive with nucleobases. It has been generally recognized that 4-oxo-2-alkenals are generated through oxidative degradation of the corresponding 4-hydroperoxy-2-alkenals, homolytic degradation products of polyunsaturated fatty acid hydroperoxides. Our recent results have also shown an alternative pathway for the formation of 4-oxo-2-alkenals, in which 2-alkenals could undergo the metal-catalyzed autoxidation resulting in the formation of the corresponding 4-oxo-2-alkenals. This review summarizes the basis of the formation of lipid peroxidation-derived genotoxic aldehydes and their covalent adduction to nucleobases, especially focusing on the abundance of 4-oxo-2-alkenal-derived DNA adducts.

Isothiocyanates (ITCs), naturally occurring in abundance in cruciferous vegetables, are the most well-studied organosulfur compounds having an electrophilic reactivity. ITCs have been accepted as major ingredients of these vegetables that afford their health promoting potentials. ITCs are able to modulate protein functions related to drug-metabolizing enzymes, transporters, kinases and phosphatases, etc. One of the most important questions about the molecular basis for the health promoting effects of ITCs is how they modulate cellular target proteins. Although the molecular targets of ITCs remains to be validated, dietary modulation of the target proteins via covalent modification by ITCs should be one of the promising strategies for the protection of cells against oxidative and inflammatory damage. This review discusses the plausible target proteins of dietary ITCs with an emphasis on possible involvement of protein modification in their health promoting effects. The fundamental knowledge of ITCs is also included with consideration of the chemistry, intracellular behavior, and metabolism.

Edaravone is a low-molecular-weight antioxidant drug targeting peroxyl radicals among many types of reactive oxygen species. Because of its amphiphilicity, it scavenges both lipid- and water-soluble peroxyl radicals by donating an electron to the radical. Thus, it inhibits the oxidation of lipids by scavenging chain-initiating water-soluble peroxyl radicals and chain-carrying lipid peroxyl radicals. In 2001, it was approved in Japan as a drug to treat acute-phase cerebral infarction, and then in 2015 it was approved for amyotrophic lateral sclerosis (ALS). In 2017, the U.S. Food and Drug Administration also approved edaravone for treatment of patients with ALS. Its mechanism of action was inferred to be scavenging of peroxynitrite. In this review, we focus on the radical-scavenging characteristics of edaravone in comparison with some other antioxidants that have been studied in clinical trials, and we summarize its pharmacological action and clinical efficacy in patients with acute cerebral infarction and ALS.

To clarify the clinical significance of the redox-controlling effects of Kampo, a traditional Japanese herbal medicine, we determined the scavenging activities of various reactive oxygen species in clinically used Kampo formulae using an electron spin resonance-based technique. Formulae containing Rhei Rhizoma (i.e., mashiningan and daiobotanpito) showed high scavenging activity against the alkoxyl radical, and crude extract quantity was significantly correlated with scavenging activity. Hydroxyl radical scavenging activity was positively correlated with the quantity of Zingiberis Rhizoma. Strong hydroxyl radical scavenging activity was also found in formulae containing both Bupleuri Radix and Scutellariae Radix, a widely used anti-inflammatory combination. Formulae containing a clinically common combination of Scutellariae Radix, Coptidis Rhizoma, and Phellodendri Cortex induced high superoxide scavenging activity. Singlet oxygen scavenging activity was high in formulae containing Bupleuri Radix and Glycyrrhizae Radix. In contrast, formulae containing Rehmanniae Radix showed generally low reactive oxygen species scavenging activities, and the quantity of Rehmanniae Radix was negatively correlated with hydroxyl radical and singlet oxygen scavenging activities. These results indicate that the antioxidative effects of Kampo formulae are not uniform but complexly varied against multiple reactive oxygen species. Some formulae have almost no antioxidant effects but may act as pro-oxidants.

Iron transport across the intestinal epithelium is facilitated by the divalent metal transporter 1 (DMT1) on the brush border membrane (BBM). The fluorescent metal sensor calcein, which is hydrophilic, membrane-impermeable and quenched by chelation with iron, was used to test our hypothesis that intestinal iron absorption is through the endocytic processes and is involved in a pathway where BBM-derived vesicles fuse with basolateral membrane (BLM)-derived vesicles. To monitor the flux of iron via transcytosis, Caco-2 cells were employed as a polarized cell layer in Transwell chambers. When calcein was added to the basal chamber along with apo-transferrin (apo-Tf), calcein rapidly underwent endocytosis and co-localized with apo-Tf. Calcein was quenched by adding an iron-ascorbate complex and then restored by adding 2,2'-dipyridyl into the apical chamber. These results were confirmed by live-cell imaging. When hemin from the apical surface and calcein from the basal chamber were added to the Caco-2 cells, internalization of DMT1 and quenching of calcein were not observed until 2 h later. These results indicated that absorbed hemin required processing before hemin-derived iron was available to BLM-derived vesicles. These studies suggest that iron is transported in Caco-2 cells by transcytosis with apical-derived vesicles that are fused to BLM-derived vesicles.

Previously, we showed that 0.5% quercetin simultaneously decreased serum homocysteine and glutathione (GSH) levels in rats. The aim of the present study was to investigate the effects of 0.5% quercetin on GSH metabolism, related enzymes and signal pathways in rats. Rats were fed the control diet and 0.5% quercetin-supplemented diet for 6 weeks. The results showed that quercetin reduced serum and hepatic content of GSH and the ratio of GSH and oxidized glutathione (GSSG), enhanced hepatic activity and mRNA expression of glutathione S-transferase (GST), inhibited hepatic activity and mRNA expression of glutamate cysteine ligase (GCL), and decreased hepatic glutathione reductase (GR) mRNA expression. Levels of phosphorylated p38 and extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinases (MAPKs) increased, while that of nuclear factor E2-like 2 (Nrf2) protein decreased after quercetin treatment. However, no significant hepatotoxicity was noted. We concluded that quercetin treatment altered hepatic GSH metabolism by modulating GSH metabolic enzyme activities and mRNA expression in rats, and p38, ERK1/2 MAPKs, and Nrf2 were involved in modulating GSH metabolism-related enzymes.

Spontaneous preterm birth is often caused by chorioamnionitis. Toll-like receptors (TLRs) have a role in the response of the innate immune system. The role of TLR5 in chorioamnionitis remains unclear: however, TLR5 was reported to have a significantly stronger effect on the induction of interleukin (IL)-6 when compared with other TLRs in amniotic epithelial cells. The aim of this study was to investigate TLR5 expression in placentas with preterm histologic chorioamnionitis (HCA). The expression levels of TLR5 were evaluated in the amnions, chorions, deciduae and villi with and without HCA using immunohistochemistry. The co-localization of IL-6 or IL-8 with TLR5 was examined by immunofluorescence. The production of IL-6 was examined in primary tissue cultured fetal membranes treated with and without the TLR5 agonist. The protein expression of TLR5 was significantly increased in amnions with HCA (p<0.05) and showed a trend toward an increase in chorions with HCA, whereas no significant difference was detected in the villi and decidua. TLR5 co-localized with IL-6 and IL-8 in amnions and chorions. IL-6 showed a significant increase (p<0.05) with the TLR5 agonist. These results suggest that TLR5 plays a role in the pathogenesis of preterm HCA and IL-6 production.

In this study, we investigated the relationship between age-related changes in renal α-Klotho gene expression, vitamin D metabolism and the responsiveness of dietary phosphate in 1, 2 and 13 month-old mice fed a high phosphate (phosphate 1.2%) diet or low phosphate (phosphate 0.02%) diet for 5 days. We found that 1,25-dihydroxyvitamin D levels in plasma were significantly lower in the high phosphate group than the low phosphate group for 1 and 2 month-old mice, but not 13 month-old mice. In addition, in the high phosphate group plasma 1,25-dihydroxyvitamin D levels were decreased in 2 month-old mice relative to 1 month-old mice, but 13 month-old mice had higher levels than 2 month-old mice. In fact, plasma 1,25-dihydroxyvitamin D levels showed a significant correlation with vitamin D metabolism gene Cyp27b1 and Cyp24a1 mRNA expression in the high phosphate group. Interestingly, renal α-Klotho mRNA and protein levels were significant change with age. Furthermore, α-Klotho mRNA expression showed a significant negative correlation with plasma 1,25-dihydroxyvitamin D levels in the high phosphate group. Our results suggest that age-related alterations in renal α-Klotho expression could affect the responsiveness of dietary phosphate to vitamin D metabolism.

Chronic oxidative stress impairs regular defecation. Sulforaphane (SFN) enhances anti-oxidant systems, ameliorating oxidative injury. SFN inhibits overgrowth of anaerobic microflora and protects small intestine from oxidative injury. We assessed whether daily intake of SFN-rich broccoli sprouts (BS) improves defecation in humans. Forty-eight subjects, with a constipation scoring system (CSS) >2 points, were assigned to either the BS group (n = 24) or the alfalfa sprouts (AS) group (n = 24), and were requested to eat 20 g daily of raw BS or AS, respectively, for 4 weeks. BS contains 4.4 mg/g sulforaphane glucosinolates (SGS), while AS contains no SGS. CSS-based questionnaires were performed to evaluate bowel habit. Stool samples were collected to evaluate intestinal microflora using a terminal restriction fragment length polymorphism flora analysis. Intervention with BS, but not AS, caused a significant decrease in the duration of attempted defecation and the total CSS score. Intervention with BS decreased the percentage of Bifidobacterium in the stool. These results suggest that daily intake of BS improves bowel habit in human subjects. Since BS treatment enhance antioxidant enzyme activities, these effects of BS appear to relate with the SFN-mediated modulation of the intestinal motility during exposure to oxidative stress. (UMIN Clinical Trial Registration Number: UMIN-000021207)

Inflammation is associated with chronic disease. High-sensitivity C-reactive protein (hs-CRP) is a predictor of chronic disease. The dietary inflammatory index (DII) is used to determine the overall inflammatory potential of diet. A cross-sectional analysis of Health Examinee cohort data (2012–2014) from Korea was performed. Subjects were 40–79 years of age (8,332 males; 19,754 females). The DII was used to analyze the relationship between subject characteristics, nutrient intake, and the hs-CRP. Additionally, the relationship between DII and hs-CRP as a predictor of chronic disease was examined. The DII was divided into 4 quartile: Q1 = −7.21 to −1.88 (median: −3.020), Q2 = −1.87 to −0.02 (median: −0.410), Q3 = −0.01 to 1.87 (median = 0.870) and Q4 = 1.88 to 7.34 (median = 3.040). For each group, the carbohydrate/protein/fat intake ratio was Q1 = 66.7:16.6:19.2, Q2 = 67.2:15.6:18.7, Q3 = 67.3:15.1:18.4 and Q4 = 67.3:14.0:17.9. The odds of elevated hs-CRP were 1.241 times higher in participants with the most proinflammatory diets than those with the most anti-inflammatory diets [hs-CRP; odds ratio (95% confidence interval) for Q4 vs Q1: 1.241 (1.071, 1.438); p for trend = 0.002]. An association was found between a high DII and high levels of hs-CRP. The DII may be applied to measure the association between diet and chronic diseases.

The beneficial effects of dietary calcium intake on high-sensitivity C-reactive protein levels, a risk factor of cardiovascular disease, have not been fully elucidated. This study investigated the associations between dietary calcium intake and serum high-sensitivity C-reactive protein levels in the general Japanese population. We analyzed the data of 2,019 subjects (1,194 men and 825 women) aged 35 to 69 years in a cross-sectional study of the Japan Multi-Institutional Collaborative Cohort Study. Nutrients intake including calcium were estimated using a validated food-frequency questionnaire. Analysis using a general linear model revealed that dietary calcium intake was inversely associated with serum high-sensitivity C-reactive protein levels (p for trend <0.001) after adjustment for age, sex, research group, leisure-time physical activity, smoking habit, drinking habit, dietary intakes (energy, dietary fiber, saturated fatty acids and vitamin D) and menopausal status. The association was slightly attenuated after additional adjustment for body mass index; however, remained significant (p for trend = 0.008). There were no significant interactions between dietary calcium intakes and sex, body mass index, or vitamin D intake for high-sensitivity C-reactive protein levels. This study have demonstrated that dietary calcium intake was inversely associated with serum high-sensitivity C-reactive protein levels in the general population.

The present study was conducted to assess the association between 25-hydroxyvitamin D [25(OH)D], estimated glomerular filtration rate (eGFR) and urine microalbumin/creatinine ratio (uACR) in Korean adults. Data on 4,948 adults aged ≥20 years from the Korean National Health and Nutrition Examination Survey V-3 (2012) were analyzed. After adjusting for the related variables (except age), the odds ratios (ORs) of vitamin D deficiency with the normal group as a reference were significantly higher in the decreased eGFR plus elevated uACR group [3.089 (95% CI, 1.722–5.544)], but not in the elevated uACR [1.247 (95% CI, 0.986–1.577)] and decreased eGFR group [1.303 (95% CI, 0.789–2.152)]. However, when further adjusting for age, the ORs of vitamin D deficiency with the normal group as a reference were significantly higher in the elevated uACR group [1.312 (95% CI, 1.035–1.662)], decreased eGFR group [1.761 (95% CI, 1.062–2.919)] and the decreased eGFR plus elevated uACR group [3.549 (95% CI, 1.975–6.365)]. In conclusion, vitamin D deficiency was positively associated with the elevated uACR and decreased eGFR. In addition, vitamin D level decreased greatly when decreased eGFR and elevated uACR appeared simultaneously.

Proton pump inhibitors (PPIs) are widely used to treat gastro-esophageal reflux and prevent gastric ulcers, and have been considered as low risk. However, recent studies have identified possible associations between PPI use and gut microbiota, suggesting that PPIs use increases the risk of enteric infections, including Clostridium difficile infection. To investigate gut microbiota in Japanese PPIs users, we conducted 16S metagenomics analysis of fecal samples collected from PPI users and healthy adults. In total, 36 PPI users and 36 PPI non-users (as control subjects) matched by age and sex were recruited and fecal samples were obtained to analyze the gut microbiome using 16S rRNA gene sequencing. There were significant differences in the microbial structure between PPI non-users and PPI users. In contrast, the analysis of α-diversity revealed no significant differences between PPI non-users and PPI users. When comparing in genus level between these two groups, the genera Streptococcus was significantly abundant and the genera Faecalibacterium was significantly decreased in PPI users. Our findings indicate a probable association between PPI use and the alternation of microbiota. These alterations might provide a mechanism by which PPIs predispose enteric infection such as Clostridium difficile infection.