Journal of Clinical Biochemistry and Nutrition Vol. 61(2017) No. 1

Oxidative stress caused by reactive oxygen species is considered a major mediator of tissue and cell injuries in various neuronal conditions, including neurological emergencies and neurodegenerative diseases. Molecular hydrogen is well characterized as a scavenger of hydroxyl radicals and peroxynitrite. Recently, the neuroprotective effects of treatment with molecular hydrogen have been reported in both basic and clinical settings. Here, we review the effects of hydrogen therapy in acute neuronal conditions and neurodegenerative diseases. Hydrogen therapy administered in drinking water may be useful for the prevention of neurodegenerative diseases and for reducing the symptoms of acute neuronal conditions.

Extracellular-superoxide dismutase (EC-SOD or SOD3), which catalyzes the dismutation of superoxide anions into hydrogen peroxide, plays a key role in vascular protection against reactive oxygen species (ROS). The excess generation of ROS is closely involved in the pathogenesis of diabetic retinopathy (DR); therefore, the maintenance of SOD3 expression at high levels is important for the prevention of DR. In the present study, we showed that caffeic acid phenethyl ester (CAPE) increased the expression of SOD3 through the acetylation of histone within the SOD3 promoter region in human retinal endothelial cells (HRECs). Histone acetylation within its promoter was focused on the inhibition of histone deacetylase (HDAC), and we examined the involvement of myocyte enhancer factor 2 (MEF2) and HDAC1 in CAPE-elicited SOD3 expression. Our results demonstrate that SOD3 silencing in basal HRECs is regulated by HDAC1 composed with MEF2A/2D hetero dimers. Moreover, phosphorylation of threonine 312 in MEF2A and dissociation of HDAC1 from SOD3 promoter play pivotal roles in CAPE-elicited SOD3 expression. Overall, our findings provide that CAPE may be one of the seed compounds that maintain redox homeostasis.

Green tea (’Sencha’), made from the leaves of Camellia sinensis, is the most well-researched antioxidant beverage. The major source of its antioxidant activity is polyphenols, consisting mainly of catechins (flavan-3-ols). However, little is known about the physiological effects of green tea aroma, which lacks catechins. In the present study, we performed inhalation experiments with green tea aroma to evaluate its antioxidant activity in mice. As a result, the urinary 8-hydroxydeoxyguanosine levels were significantly decreased in comparison with those of the non-treated group, and the serum antioxidant capacity was significantly increased by the inhalation administration of green tea aroma. Furthermore, the increase in the urinary 8-hydroxydeoxyguanosine levels due to whole-body X-ray irradiation was significantly suppressed by the inhalation of green tea aroma. This is the first study to show the antioxidant activity of green tea aroma in vivo.

Daily intake of vegetables can reduce the risk of cancer and lifestyle-related diseases. However, supplementary intake of β-carotene alone has been reported to increase the risk of lung cancer in male cigarette smokers and people who were exposed to asbestos. The mechanism of the antioxidative properties of carotenoids in vivo, especially under oxidative stress conditions, still remains unclear. To investigate the antioxidant properties of dietary compounds, we examined the effects of chemically modified astaxanthin (Ax-C-8) using a rat model of ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative injury. Ax-C-8 demonstrated lethally toxic effects on the rats in a dose-dependent manner. Following supplementation with Ax-C-8 (0.02%, w/w) for 30 days, the rats were euthanized 1, 4 and 24 h after injection of Fe-NTA. After 4 h, Ax-C-8 pretreatment suppressed the elevation of creatinine and blood urea nitrogen and protected the rats from renal tubular necrosis and the formation of 4-hydroxy-2-nonenal-modified proteins. After 24 h, pretreatment with Ax-C-8 maintained the renal antioxidant enzyme levels and renal tubules. Here, we demonstrate the antioxidant effects of Ax-C-8 against Fe-NTA-induced oxidative injury in rats receiving a regular diet. These data suggest that dietary intake of astaxanthin may be useful for the prevention of renal tubular oxidative damage.

Fucoxanthinol (FuOH), an intestinal metabolite form of fucoxanthin (Fx) isolated from marine algae, is known to possess multiple health benefits, such as prevention of human cancer. However, there is little available information about the effects of FuOH on colorectal cancer stem cells (CCSCs) and their contribution to drug resistance, tumorigenesis and cancer recurrence. In the present study, we investigated the anti-proliferative effect of FuOH on two putative CCSCs, CD44^high/EpCAM^high cells and colonospheres (Csps) formed by HT-29 human colorectal cancer cells, and the suppressive effects of FuOH on the growth of xenografted tumor. FuOH significantly inhibited the growth of CD44^high/EpCAM^high cells and disintegrated Csps and induced many condensed chromatin bodies in the cells in a dose-dependent manner. The IC₅₀ value of FuOH for these changes in Csps was 1.8 µM. FuOH down-regulated pAkt (Ser⁴⁷³), PPARβ/δ and PPARγ in Csps. These proteins play a critical role in cell proliferation, the cell cycle, metastasis and extracellular adhesion. Ten days after the administration of FuOH (5 mg/kg body weight) to the mice every 3 to 4 days significantly suppressed the Csps tumorigenesis when compared to the untreated control mice. Our results suggest that FuOH could be used as a chemopreventive agent against human CCSC.

Astaxanthin is a carotenoid with potent antioxidant and anti-inflammatory activity. To evaluate the anti-inflammatory effect of astaxanthin on skin deterioration, we confirmed its role in epidermal-dermal interactions in vitro. Astaxanthin treatment suppressed ultraviolet B (UVB)-induced inflammatory cytokine secretion in keratinocytes, and matrix metalloproteinase-1 secretion by fibroblasts cultured in UVB-irradiated keratinocyte medium. To verify these findings, we conducted a 16-week clinical study with 65 healthy female participants. Participants were orally administered either a 6 mg or 12 mg dose of astaxanthin or a placebo. Wrinkle parameters and skin moisture content significantly worsened in the placebo group after 16 weeks. However, significant changes did not occur in the astaxanthin groups. Interleukin-1α levels in the stratum corneum significantly increased in the placebo and low-dose groups but not in the high-dose group between weeks 0 and 16. This study was performed in Japan from August to December, when changing environmental factors, such as UV and dryness, exacerbate skin deterioration. In conclusion, our study suggests that long-term prophylactic astaxanthin supplementation may inhibit age-related skin deterioration and maintain skin conditions associated with environmentally induced damage via its anti-inflammatory effect. (UMIN Clinical Trials Registry ID: UMIN000018550)

The increase in oxidative stress that accompanies aging has been implicated in the abnormal advance of aging and in the onset of various systemic diseases. However, the details of what effects the increase in oxidative stress that accompanies aging has on saliva secretion are not known. In this study, naturally aging mice were used to examine the stimulated whole saliva flow rate, saliva and serum oxidative stress, antioxidant level, submandibular gland H-E staining, and immunofluorescence staining to investigate the effect of aging on the volume of saliva secretion and the relationship with oxidative stress, as well as the effect of aging on the structure of salivary gland tissue. The stimulated whole saliva flow rate decreased significantly with age. Also, oxidative stress increased significantly with age. Antioxidant levels, however, decreased significantly with age. Structural changes of the submandibular gland accompanying aging included atrophy of parenchyma cells and fatty degeneration and fibrosis of stroma, and the submandibular gland weight ratio decreased. These results suggest that oxidative stress increases with age, not just systemically but also locally in the submandibular gland, and that oxidative stress causes changes in the structure of the salivary gland and is involved in hyposalivation.

The effect of 1-deoxynojirimycin, a caloric restriction mimetic, was examined in ICR mice with azoxymethane dextran sodium sulfate-induced colorectal cancer. Azoxymethane is a carcinogen (10 mg/kg body weight), and 2% dextran sodium sulfate (w/v) used as a colitis-inducing agent. Mice were separated into 5 groups: a group without colorectal cancer fed a normal diet (CO– group), and groups with colorectal cancer fed a normal diet (CO+ group), a calorie-restricted diet (caloric restriction group), and diets including 0.02% and 0.1% 1-deoxynojirimycin (l-1-deoxynojirimycin and H-1-deoxynojirimycin groups). The tumor incidence and number were reduced significantly in the caloric restriction group compared to the CO+ group, and were also suppressed in a dose-dependent manner by 1-deoxynojirimycin. mRNA for anti-apoptotic Bcl-2 was decreased and that for pro-apoptotic Bax was increased in the carcinoma tissue of CR, l-1-deoxynojirimycin and H-1-deoxynojirimycin groups. These results suggest that caloric restriction and 1-deoxynojirimycin inhibit growth of colorectal cancer by inducing apoptosis in an induced cancer model in mice.

Spironolactone and furosemide, which are used to treat ascites associated with decompensated cirrhosis, are ineffective in treating refractory ascites. Hence, combination therapy with tolvaptan, a vasopressin V2 receptor antagonist, has been approved in Japan. Tolvaptan monotherapy and combination therapy with furosemide inhibit fibrosis in cardiac remodeling; hence, we examined these therapies in a rat cirrhotic model, including their usefulness in inhibiting hepatic fibrosis. In the present study, we used a model of hepatic fibrosis induced by a choline-deficient l-amino-acid-defined diet + diethylnitrosamine. Rats were divided into a low-dose furosemide group (15 mg/kg/day), a high-dose furosemide group (100 mg/kg/day), a tolvaptan monotherapy group (10 mg/kg/day), a low-dose furosemide/tolvaptan combination therapy group, and a control group which received neither furosemide nor tolvaptan; we then assessed diuretic effects and hepatic fibrosis. The tolvaptan monotherapy group and the furosemide/tolvaptan combination therapy group demonstrated significantly higher urine volume than the control group and the low-dose furosemide group. In addition, tolvaptan monotherapy and low-dose furosemide/tolvaptan combination therapy were found to inhibit hepatic fibrosis and yield a hepatoprotective effect by an antioxidative mechanism. The results of the present study suggest that tolvaptan monotherapy and low-dose furosemide/tolvaptan combination therapy are highly effective for hepatoprotection and diuresis.

The present study was conducted to assess the association between serum ferritin and 25-hydroxyvitamin D [25(OH)D] and metabolic syndrome (MetS) in Korean women. The data of a total of 9,256 adults (6,960 women without MetS and 2,296 women with MetS) aged ≥20 years from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES V) (2010–2012) were analyzed. A covariance test adjusted for covariates was performed for serum ferritin levels in relation to vitamin D (vitamin D deficiency, 25(OH)D <10.0 ng/ml; vitamin D insufficiency, 25(OH)D ≥10.0, <20.0 ng/ml; vitamin D sufficiency, 25(OH)D ≥20.0 ng/ml). The key study results were as follows: First, in women without MetS, after adjusting for related variables (smoking, alcohol drinking, regular exercise, current menstruation, hormonal contraceptives, hormone-replacement therapy, SBP, DBP, BMI, WM, TC, TGs, HDL-C, FPG, AST, ALT, and age), vitamin D was positively associated with serum ferritin levels (p<0.001). Second, in women with MetS, after adjusting for related variables (except age), vitamin D was positively associated with serum ferritin levels (p = 0.041). However, when further adjusted for age, vitamin D was not associated with serum ferritin levels (p = 0.293). In conclusion, vitamin D was positively associated with serum ferritin levels in women without MetS but not in women with MetS.

Chronic knee joint pain is common in the elderly and associated with poor quality of life. This study, an open-label clinical trial, aimed to examine how the intake on a daily basis of maslinic acid-containing product (30 mg maslinic acid) on 29 elderly residents (mean 70.7 ± 10.1 years) of Nakajima Island, Ehime, Japan. Study participants consumed 10 g jelly containing maslinic acid daily for 16 weeks and at 0 (baseline), 4, 8, 12 and 16 weeks, assessed for health-related quality of life (Short Form-8) and knee pain score (Japanese Knee Osteoarthritis Measure). After 16 weeks, the physical quality of life, more specifically, the level of Bodily Pain and Physical Component Summary, but not mental quality of life, was significantly improved by maslinic acid intake. Furthermore, maslinic acid intake significantly decreased the Japanese Knee Osteoarthritis Measure at week 8 and tended to decrease Visual Analogue Scale score at weeks 4 and 16. These results suggest that consumption of maslinic acid has a protective effect against chronic knee pain in elderly residents in a community where knee pain causes high quality of life burden.

Dietary acid load is important information, however, survey of food intake needs time and skill. Therefore, it is difficult to survey food intake from all patients. It remains to be elucidated the association between dietary acid load and urinary pH in patients with type 2 diabetes. In this cross-sectional study of 173 patients, we investigated the relationship between urinary pH and dietary acid load, assessed with potential renal acid load. Habitual food and nutrient intake was assessed by a self-administered diet history questionnaire. Urinary pH was negatively correlated with potential renal acid load (r = –0.24, p = 0.002). Multivariate regression analysis revealed that potential renal acid load (standardized regression coefficient = –0.21, p = 0.036) was associated with urinary pH after adjusting for covariates. In addition, according to the receiver operator characteristic analysis, the optimal cut-off point of urinary pH for high dietary acid load, defined as potential renal acid load over 7.0 mEq/day was 5.7 (area under the receiver operator characteristic curve 0.63 (95% CI 0.54–0.71), sensitivity = 0.56, specificity = 0.70, p = 0.004). Urinary pH was associated with dietary acid load in patients with type 2 diabetes. We suggest that urinary pH can be a practical screening marker for dietary acid load in patients with type 2 diabetes.