Yuzu (Citrus junos Tanaka) Peel Attenuates Dextran Sulfate Sodium-induced Murine Experimental Colitis.

Ulcerative colitis is a well-known inflammatory bowel disease. Although there are drugs that are effective against this disease, the prevention and attenuation of ulcerative colitis by food rich in functional ingredients without side effects is desired because some drugs have side effects. In this study, we investigated the effects of yuzu (Citrus junos Tanaka), a citrus fruit native to northeast Asia, on a mouse dextran sulfate sodium (DSS)-induced colitis model. Mice given drinking water containing DSS showed significant weight loss, colon shortening, diarrhea, and visible fecal blood. In contrast, mice fed a diet containing 5% yuzu peel for 14 d before receiving DSS showed significant attenuation of these phenotypes. To clarify the mechanism underlying the attenuation, we investigated the anti-inflammatory and antioxidant effects of yuzu peel. We found that yuzu peel extract suppressed tumor necrosis factor-α (TNF-α) production in lipopolysaccharide (LPS)-stimulated mice and murine macrophage cell line through suppression of nuclear factor-κB (NF-κB) activation. In addition, we confirmed that yuzu peel extract had a moderate antioxidant effect. These results suggest that yuzu peel attenuates the pathologies of DSS-induced colitis by coordinately suppressing inflammation and oxidative stress against lipids in vivo.

Ascorbic acid prevents zinc oxide nanoparticle-induced intracellular oxidative stress and inflammatory responses.

Exposure to zinc oxide nanoparticles (ZnO NPs) promotes acute pulmonary toxicity through oxidative stress and inflammation. Furthermore, dissolved zinc from ZnO NPs induces the formation of intracellular reactive oxygen species (ROS). We previously reported that supplemental ascorbic acid (AA) inhibits ZnO NP-induced acute pulmonary toxicity in a rat model; however, the mechanism of this action remains unclear. Therefore, we investigated the effects of AA on ZnO NP-induced cytotoxicity in human lung carcinoma A549 cells. AA was found to suppress intracellular production of ROS, and thus reduce the subsequent inflammation of ZnO NPs. However, intracellular Zn2+ concentrations were higher in AA-treated cells than in AA-untreated cells. AA was found to react with Zn2+ but not with the ZnO NPs themselves. These results suggest the possibility that AA-chelated extracellular Zn2+ and the Zn-AA complex was readily taken up into cell. Even if the intracellular Zn2+ level was high, cytotoxicity might be reduced because the Zn-AA complex was stable. Co-treatment of AA to A549 inhibited ROS production and subsequent intracellular inflammatory responses. These results are consistent with those previously reported from an in vivo model. Thus, two possibilities can be considered about the cytotoxicity-reducing the effect of AA: antioxidant efficacy and chelating effect.

Antioxidative and Antidiabetic Effects of Natural Polyphenols and Isoflavones.

Many polyphenols that contain more than two phenolic hydroxyl groups are natural antioxidants and can provide health benefits to humans. These polyphenols include, for example, oleuropein, hydroxytyrosol, catechin, chlorogenic acids, hesperidin, nobiletin, and isoflavones. These have been studied widely because of their strong radical-scavenging and antioxidative effects. These effects may contribute to the prevention of diseases, such as diabetes. Insulin secretion, insulin resistance, and homeostasis are important factors in the onset of diabetes, a disease that is associated with dysfunction of pancreatic ß-cells. Oxidative stress is thought to contribute to this dysfunction and the effects of antioxidants on the pathogenesis of diabetes have, therefore, been investigated. Here, we summarize the antioxidative effects of polyphenols from the perspective of their radical-scavenging activities as well as their effects on signal transduction pathways. We also describe the preventative effects of polyphenols on diabetes by referring to recent studies including those reported by us. Appropriate analytical approaches for evaluating antioxidants in studies on the prevention of diabetes are comprehensively reviewed.

DHA concentration of red blood cells is inversely associated with markers of lipid peroxidation in men taking DHA supplement.

An increase in the proportion of fatty acids with higher numbers of double bonds is believed to increase lipid peroxidation, which augments the risk for many chronic diseases. (n-3) Polyunsaturated fatty acids provide various health benefits, but there is a concern that they might increase lipid peroxidation. We examined the effects of docosahexaenoic acid [22:6 (n-3)] supplementation on lipid peroxidation markers in plasma and red blood cells (RBC) and their associations with red blood cell and plasma fatty acids. Hypertriglyceridemic men (n = 17 per group) aged 39-66 years participated in a double-blind, randomized, placebo-controlled, parallel study. They received no supplements for the first 8 days and then received 7.5 g/day docosahexaenoic acid oil (3 g/day docosahexaenoic acid) or olive oil (placebo) for 90 days. Fasting blood samples were collected 0, 45, and 91 days after supplementation. Docosahexaenoic acid supplementation did not change plasma or RBC concentrations of lipid peroxidation markers (total hydroxyoctadecadienoic acid, total hydroxyeicosatetraenoic acid, total 8-isoprostaglandin F2α, 7α-hydroxycholesterol, 7ß-hydroxycholesterol) when pre- and post-supplement values were compared. However, the post-supplement docosahexaenoic acid (DHA) concentration was inversely associated with RBC concentrations of ZE-HODE, EE-HODE, t-HODE, and total 8-isoprostaglandin F2α, (p<0.05). RBC concentration of hydroxycholesterol was also inversely associated with DHA but it did not attain significance (p = 0.07). Our results suggest that increased concentration of DHA in RBC lipids reduced lipid peroxidation. This may be another health benefit of DHA in addition to its many other health promoting effects.

Do n-3 polyunsaturated fatty acids increase or decrease lipid peroxidation in humans?

UNLABELLED: Abstract Background: Despite many known health benefits of n-3 polyunsaturated fatty acids (PUFA), there is a concern that their high degree of unsaturation may actually increase oxidative stress, lipid peroxidation (LPO), and chronic inflammatory diseases. METHODS: In this review, we have analyzed results from published human studies regarding the effects of n-3 PUFA supplementation on markers of lipid peroxidation. RESULTS: Of the 22 published human studies, nine found no change, eight a decrease, and five an increase in markers of LPO. These inconsistencies may be due to methods, subject characteristics, dose, duration, fatty acid and antioxidant composition of supplements, and basal diets. METHODS used for analysis seem to be the most significant factor. Six of eight studies with a decrease in LPO determined F2-isoprostanes produced in vivo, and two determined plasma antioxidant capacity or hydroperoxides. n-3 PUFA can serve as scavengers for free radicals and also modulate expression of genes that determine the balance between oxidative and antioxidative status. Recent studies that monitored oxidation products of cholesterol and fatty acids support the hypothesis that n-3 PUFA decrease LPO. Most of the studies showing no change or increase in LPO determined markers that involved ex vivo sample preparation or oxidation (malondialdehyde, low-density lipoprotein oxidation, lipid hydroperoxides). CONCLUSION: A majority of studies do not indicate that n-3 PUFA increased LPO. Future studies need to investigate the effects of dose, duration, and composition of n-3 PUFA with standardized diets and methods on concentrations and types of LPO products produced.

Evaluation of biological activities of a groundnut (Apios americana Medik) extract containing a novel isoflavone.

Groundnut (Apios americana Medik) contains a novel isoflavone, genistein-7-O-gentiobioside. In the present study, we examined the biological activities of an alcohol extract of groundnut containing genistein-7-O-gentiobioside as the main component. Although the groundnut extract by itself did not show antioxidative activity, it drove the antioxidative system in cells. Pretreatment of human breast carcinoma MCF-7 cells for 24 h with the groundnut extract and soybean isoflavone increased gene expression of heme oxygenase-1 (HO-1), a major antioxidative stress enzyme. These groundnut extract-treated cells showed antioxidative activity against free radicals derived from a radical initiator. Pretreatment of cells with 100 µg/mL groundnut extract prevented the depletion of glutathione by the radical initiator; however, treatment with 100 µg/mL of soybean isoflavone injured the cell membrane, indicating that glutathione might be released to the extracellular environment. These results suggest that the groundnut extract had isoflavone-like activity. Like soybean, groundnuts are a good source of isoflavones.

Assessment of antioxidant capacity for scavenging free radicals in vitro: a rational basis and practical application.

With increasing evidence showing the involvement of oxidative stress induced by free radicals in the development of various diseases, the role of radical-scavenging antioxidants has received much attention. Although many randomized controlled clinical trials do not support the beneficial effects of indiscriminate supplementation of antioxidants, more recent studies suggest that antioxidants such as vitamin E may be effective for prevention and treatment of some diseases when given to the right subjects at the right time. Many studies on the antioxidant capacity assessed by various available methods showed inconsistent results and the assessment of antioxidant capacity has been the subject of extensive studies and arguments. This study was performed to elucidate the basic chemistry required for the development of a reliable method for the assessment of antioxidant capacity for radical scavenging in vitro. In this study, the capacity of α-tocopherol and its related compounds, ascorbic acid, and uric acid for scavenging radicals was assessed from their effects on the rate of decay of hydrophilic and lipophilic probes with various reactivities toward free radicals induced by hydrophilic and lipophilic radicals in homogeneous solution and heterogeneous micelle systems. Fluorescein, pyranine, and pyrogallol red were used as hydrophilic probes, and BODIPY and N,N-diphenyl-p-phenylenediamine were used as lipophilic probes. We show that the rate and amount of radical scavenging by antioxidants, termed the antioxidant radical absorbance capacity, could be assessed by an appropriate combination of radical initiator and probe. This method was applied to the assessment of radical-scavenging capacity of human plasma, wine, and green tea powder.

A novel role for α-tocopherol transfer protein (α-TTP) in protecting against chloroquine toxicity.

Chloroquine (CQ) is a widely prescribed anti-malarial agent and is also prescribed to treat autoimmune diseases. Clinical treatment with CQ is often accompanied by serious side effects such as hepatitis and retinopathy. As a weak base, CQ accumulates in intracellular acidic organelles, raises the pH, and induces osmotic swelling and permeabilization of acidic organelles, which account for CQ-induced cytotoxicity. We reported previously that CQ treatment caused α-tocopherol transfer protein (α-TTP), a gene product of familial vitamin E deficiency, to change its location from the cytosol to the surface of acidic organelles. Here we show that α-TTP plays a novel role in protecting against CQ toxicity both in vitro and in vivo. In the presence of CQ, rat hepatoma McARH7777 cells, which do not express α-TTP endogenously, showed more severe cytotoxicity, such as larger vacuolation of acidic organelles and caspase activation, than α-TTP transfectant cells. Similarly, α-TTP knockout mice showed more severe CQ toxicity, such as hepatotoxicity and retinopathy, than wild-type mice. These effects were not ameliorated by vitamin E supplementation. In contrast to bafilomycin A1 treatment, which prevents CQ accumulation in cells by raising the pH of acidic organelles, α-TTP expression prevented CQ accumulation without affecting the pH of acidic organelles. Taken together, our data suggest that α-TTP protects against CQ toxicity by preventing CQ accumulation in acidic organelles through a mechanism distinct from vitamin E transport.

Evaluation of cellular influences of platinum nanoparticles by stable medium dispersion.

Platinum nanoparticles have industrial application, for example in catalysis, and are used in consumer products such as cosmetics and supplements. Therefore, among the many nanoparticles, platinum is one of the more accessible nanoparticles for consumers. Most platinum nanoparticles that are used in cosmetics and supplements which have an anti-oxidant activity are modified particles. However, the cellular influences of pristine platinum nanoparticles are still unclear, although it has been reported that platinum nanoparticles induce oxidative stress. In this study, we investigated the cellular influences induced by pure pristine platinum nanoparticles. Platinum nanoparticles of 100% purity were dispersed in a cell culture medium and stable medium dispersion was obtained. The platinum nanoparticle medium dispersion was applied to two kinds of cultured cells, A549 and HaCaT cells, and the cellular influences were examined. Cell viability (MTT assay), cell proliferation (clonogenic assay), apoptosis induction (caspase-3 activity), intracellular ROS level (DCFH assay), and lipid peroxidation level (DPPP assay) were measured as markers of cellular influences. Transmission electron microscope observation showed cellular uptake of platinum nanoparticles. However, the platinum nanoparticles did not drive any markers. It is known that some metal oxide nanoparticles such as NiO and CuO show severe cytotoxicity via metal ion release. Compared with these toxic nanoparticles, the platinum nanoparticles used in this study did not release platinum ions into the culture media. These results suggest that the physically and chemically inactive cellular influences of platinum nanoparticles are small.

α-Tocopheryl phosphate: uptake, hydrolysis, and antioxidant action in cultured cells and mouse.

α-Tocopheryl phosphate (α-TP), a water-soluble analogue of α-tocopherol, is found in humans, animals, and plants. α-TP is resistant to both acid and alkaline hydrolysis and may exert its own function in this form in vivo. In this study, the uptake, hydrolysis, and antioxidant action of α-TP were measured using α-TP with a deuterated methyl group, CD(3), at position 5 of the chroman ring (α-TP(CD3)). The hydrolysis of α-TP(CD3) was followed by measuring α-tocopherol containing the CD(3) group, α-T(CD3), in comparison to unlabeled α-tocopherol, α-T(CH3). α-TP(CD3) was incubated with cultured cells, and the intracellular α-T(CD3) formed was measured with HPLC-ECD and GC-MS. α-TP(CD3) was also administered to mice for 4 weeks by mixing in the diet, and α-T(CD3) was measured in plasma, liver, brain, heart, and testis to compare with endogenous unlabeled α-T(CH3). It was found that α-TP(CD3) was taken in and hydrolyzed readily to α-T(CD3) in cultured cells and in mice. The hydrolysis of α-TP(CD3) in cell culture medium was not observed. α-TP protected primary cortical neuronal cells from glutamate-induced cytotoxicity, and α-TP given to mice reduced the levels of lipid peroxidation products in plasma and liver. These results suggest that α-TP is readily hydrolyzed in vivo to α-T, which acts as an antioxidant, and that α-TP may be used as a water-soluble α-T precursor in intravenous fluids, in eye drops, or as a dietary supplement.

α-Tocopherol suppresses lipid peroxidation and behavioral and cognitive impairments in the Ts65Dn mouse model of Down syndrome.

It is widely accepted that oxidative stress is involved in the pathogenesis of Down syndrome, but the effectiveness of antioxidant treatment remains inconclusive. We tested whether chronic administration of α-tocopherol ameliorates the cognitive deficits exhibited by Ts65Dn mice, a mouse model of Down syndrome. α-Tocopherol was administered to pregnant Ts65Dn females, from the day of conception throughout the pregnancy, and to pups over their entire lifetime, from birth to the end of the behavioral testing period. Cognitive deficits were confirmed for Ts65Dn mice fed a control diet, revealing reduced anxiety or regardlessness in the elevated-plus maze task test and spatial learning deficits in the Morris water maze test. However, supplementation with α-tocopherol attenuated both cognitive impairments. In addition, we found that levels of 8-iso-prostaglandin F(2α) in brain tissue and hydroxyoctadecadienoic acid and 7-hydroxycholesterol in the plasma of Ts65Dn mice were higher than those of control mice. Supplementation with α-tocopherol decreased levels of lipid peroxidation products in Ts65Dn mice. Furthermore, we found out that α-tocopherol improved hypocellularity in the hippocampal dentate gyrus of Ts65Dn mice. These results imply that α-tocopherol supplementation from an early stage may be an effective treatment for the cognitive deficits associated with Down syndrome.

Assessment of the antioxidant capacity of natural fruit extracts by inhibition of probe decay and plasma lipid peroxidation.

The oxidation of lipids, proteins, and DNA induced by reactive oxygen species has been implicated in the development of various diseases, and the role of antioxidants has received much attention. Free-radical scavenging antioxidants play an important role in the defense network in vivo, and assessment of the capacity of antioxidants has been the subject of extensive studies and controversy, but there is no universal method by which antioxidant capacity can be measured accurately. In the present study, the assessment of the antioxidant capacity of natural fruit extracts was examined for radical scavenging and inhibition of lipid peroxidation. It was found that the capacity of fruit extracts for scavenging of both hydrophilic and lipophilic free radicals and for antioxidation can be assessed from the effect on the probe decay and the inhibition of plasma lipid peroxidation respectively. The importance of these two factors in the assessment of antioxidant capacity is discussed.

Supplementation with lutein or lutein plus green tea extracts does not change oxidative stress in adequately nourished older adults.

Epigallocatechin gallate, a major component of green tea polyphenols, protects against the oxidation of fat-soluble antioxidants including lutein. The current study determined the effect of a relatively high but a dietary achievable dose of lutein or lutein plus green tea extract on antioxidant status. Healthy subjects (50-70 years) were randomly assigned to one of two groups (n=20 in each group): (1) a lutein (12 mg/day) supplemented group or (2) a lutein (12 mg/day) plus green tea extract (200 mg/day) supplemented group. After 2 weeks of run-in period consuming less than two servings of lightly colored fruits and vegetables in their diet, each group was treated for 112 days while on their customary regular diets. Plasma carotenoids including lutein, tocopherols, flavanols and ascorbic acid were analyzed by HPLC-UVD and HPLC-electrochemical detector systems; total antioxidant capacity by fluorometry; lipid peroxidation by malondialdehyde using a HPLC system with a fluorescent detector and by total hydroxyoctadecadienoic acids using a GC/MS. Plasma lutein, total carotenoids and ascorbic acid concentrations of subjects in either the lutein group or the lutein plus green tea extract group were significantly increased (P<.05) at 4 weeks and throughout the 16-week study period. However, no significant changes from baseline in any biomarker of overall antioxidant activity or lipid peroxidation of the subjects were seen in either group. Our results indicate that an increase of antioxidant concentrations within a range that could readily be achieved in a healthful diet does not affect in vivo antioxidant status in normal healthy subjects when sufficient amounts of antioxidants already exist.

Ultrafine NiO particles induce cytotoxicity in vitro by cellular uptake and subsequent Ni(II) release.

Nickel oxide (NiO) is one of the important industrial materials used in electronic substrates and for ceramic engineering. Advancements in industrial technology have enabled the manufacture of ultrafine NiO particles. On the other hand, it is well-known that nickel compounds exert toxic effects. The toxicity of nickel compounds is mainly caused by nickel ions (Ni(2+)). However, the ion release properties of ultrafine NiO particles are still unclear. In the present study, the influences of ultrafine NiO particles on cell viability were examined in vitro to obtain fundamental data for the biological effects of ultrafine green NiO and ultrafine black NiO. Ultrafine NiO particles showed higher cytotoxicities toward human keratinocyte HaCaT cells and human lung carcinoma A549 cells than fine NiO particles and also showed higher solubilities in culture medium (Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum) than fine NiO particles. In particular, the concentration of Ni(2+) released into the culture medium by ultrafine green NiO was 150-fold higher than that released by fine green NiO. The concentrations of Ni(2+) released by both types of NiO particles in an aqueous solution containing amino acids were remarkably higher than those released by NiO particles in water. Moreover, we prepared a uniform and stable dispersion of ultrafine black NiO in culture medium and examined its influence on cell viability in comparison with that of NiCl(2), a soluble nickel compound. A medium exchange after 6 h of exposure resulted in a loss of cytotoxicity in the cells exposed to NiCl(2), whereas cytotoxicity was retained in the cells exposed to NiO. Transmission electron microscope observations revealed uptake of both ultrafine and fine NiO particles into HaCaT cells. Taken together, the present results suggest that the intracellular Ni(2+) release could be an important factor that determines the cytotoxicity of NiO. Ultrafine NiO is more cytotoxic than fine NiO in vitro.

Protein adsorption of ultrafine metal oxide and its influence on cytotoxicity toward cultured cells.

Many investigations about the cellular response by metal oxide nanoparticles in vitro have been reported. However, the influence of the adsorption ability of metal oxide nanoparticles toward cells is unknown. The aim of this study is to understand the influence of adsorption by metal oxide nanoparticles on the cell viability in vitro. The adsorption abilities of six kinds of metal oxide nanoparticles, namely, NiO, ZnO, TiO2, CeO2, SiO2, and Fe2O3, to Dulbecco's modified Eagle's medium supplemented with a 10% fetal bovine serum (DMEM-FBS) component such as serum proteins and Ca2) were estimated. All of the metal oxide nanoparticles adsorbed proteins and Ca2+ in the DMEM-FBS; in particular, TiO2, CeO2, and ZnO showed strong adsorption abilities. Furthermore, the influence of the depletion of medium components by adsorption to metal oxide nanoparticles on cell viability and proliferation was examined. The particles were removed from the dispersion by centrifugation, and the supernatant was applied to the cells. Both the cell viability and the proliferation of human keratinocyte HaCaT cells and human lung carcinoma A549 cells were affected by the supernatant. In particular, cell proliferation was strongly inhibited by the supernatant of TiO2 and CeO2 dispersions. The supernatant showed depletion of serum proteins and Ca2+ by adsorption to metal oxide nanoparticles. When the adsorption effect was blocked by the pretreatment of particles with FBS, the inhibitory effect was lost. However, in NiO and ZnO, which showed ion release, a decrease of inhibitory effect by pretreatment was not shown. Furthermore, the association of the primary particle size and adsorption ability was examined in TiO2. The adsorption ability of TiO2 depended on the primary particle size. The TiO2 nanoparticles were size dependently absorbed with proteins and Ca2+, thereby inducing cytotoxicity. In conclusion, the adsorption ability of metal oxide nanoparticles is an important factor for the estimation of cytotoxicity in vitro for low-toxicity materials.

Evaluation of the antioxidant effects of coffee and its components using the biomarkers hydroxyoctadecadienoic acid and isoprostane.

The association between coffee consumption and its antioxidant effects has not been elucidated in detail. In experimental animals, we used biomarkers to investigate the relationship between coffee consumption and its effects on oxidative stress. We propose a method in which both the free and ester forms of hydroperoxides and ketones as well as the hydroxides of linoleic acid are measured as total hydroxyoctadecadienoic acid (tHODE). Mice were divided into 6 groups: animals in 5 of these groups were fed a vitamin E-depleted diet [VE(-) group], whereas those in the 6(th) (control) group were fed a diet containing 0.002 wt% vitamin E [VE(+) group]. Different VE(-) groups were also administered coffee or drinking water that contained a coffee component-chlorogenic acid, caffeic acid, or caffeine-for 1 month. It was clearly demonstrated that the liver levels of tHODE in the VE(-) groups increased compared to the VE(+) group but that coffee consumption reduced these elevated levels to that of the control. Interestingly, the plasma and liver levels of the HODE stereoisomer ratio (Z,E/E,E), which is a measure of antioxidant capacity in vivo, were highest among the groups studied. These data, together with the values for antioxidant levels in vivo, indicate that the efficacy of antioxidants in vivo can be evaluated reasonably well based on the tHODE level and its stereoisomer ratio, and that the antioxidant capacity of coffee is superior to that of its individual components.

Comprehensive royal jelly (RJ) proteomics using one- and two-dimensional proteomics platforms reveals novel RJ proteins and potential phospho/glycoproteins.

Royal jelly (RJ) is an exclusive food for queen honey bee (Apis mellifera L.) that is synthesized and secreted by young worker bees. RJ is also widely used in medical products, cosmetics, and as health foods. However, little is known about RJ functionality and the total protein components, although recent research is attempting to unravel the RJ proteome. We have embarked on a detailed investigation of the RJ proteome, using a modified protein extraction protocol and two complementary proteomics approaches, one- and two-dimensional gel electrophoresis (1-DGE and 2-DGE) in conjunction with tandem mass spectrometry. Simultaneously, we examined total soluble protein from RJ collected at 24, 48, and 72 h after honey bee larvae deposition twice (in two flower blooming seasons), to check differences, if any, in RJ proteome therein. Both 1- and 2-D gels stained with silver nitrate revealed similar protein profiles among these three time points. However, we observed a clear difference in two bands (ca. MW of 55 and 75 kDa) on 1-D gel between the first and the second collection of RJ. A similar difference was also observed in the 2-D gel. Except for this difference, the protein profiles were similar at the 3 time points. As the RJ from 48 (or sometimes 72) is commercially used, we selected the RJ sample at 48 h for detailed analysis with the first collection. 1-DGE identified 90 and 15 proteins from the first and second selection, respectively; in total, 47 nonredundant proteins were identified. 2-DGE identified 105 proteins comprising 14 nonredundant proteins. In total, 52 nonredundant proteins were identified in this study, and other than the major royal jelly protein family and some other previously identified proteins, 42 novel proteins were identified. Furthermore, we also report potentially post-translationally modified (phosphorylation and glycosylation) RJ proteins based on the Pro-Q diamond/emerald phosphoprotein/glycoprotein gel stains; MRJP 2p and 7p were suggested as potential phosphoproteins. The 2-DGE data were integrated to develop a 2-D gel reference map, and all data are accessible through RJ proteomics portal (http://foodfunc.agr.ibaraki.ac.jp/RJP.html).

Simple assessment of radical scavenging capacity of beverages.

The radical-scavenging antioxidants play an important role against oxidative stress in the defense system in vivo. The beneficial effects of antioxidants contained in foods and beverages have been well-accepted, and their antioxidant capacity has been assessed by various methods. In the present study, a simple method is proposed in which the total radical scavenging capacity is assessed from the bleaching of pyranine and pyrogallol red induced by free radicals generated from azo initiator. The total content of antioxidants contained in red wine, green tea, and cassis drink and their reactivities toward peroxyl radicals were measured from the lag phase and rate of bleaching using pyranine and pyrogallol red as a probe, respectively. It was found that this method to follow the bleaching of two probes by visible light spectrophotometer is convenient and applicable for assessment of total radical scavenging capacity of both content and activity of the antioxidants contained in beverages.

Cholesterol is more susceptible to oxidation than linoleates in cultured cells under oxidative stress induced by selenium deficiency and free radicals.

Polyunsaturated fatty acids and their esters are known to be susceptible to free-radical mediated oxidation, while cholesterol is more resistant to oxidation. The present study focused on the relative susceptibilities of linoleates and cholesterol in Jurkat cells under oxidative stress induced by selenium deficiency and free radical insult, as assessed by total hydroxyoctadecadienoic acids (tHODE) and total 7-hydroxycholesterol (t7-OHCh) measured after reduction and saponification. It was observed that the levels of tHODE and t7-OHCh significantly increased by both oxidative insults. The increased amounts of t7-OHCh were higher than those of tHODE in both selenium-deficient and free radical-treated cells. These results suggest that, in contrast to plasma oxidation where cholesterol is much more resistant to oxidation than linoleates, cellular cholesterol is more susceptible to oxidation than cellular linoleates.

Evaluation of lipophilic antioxidant efficacy in vivo by the biomarkers hydroxyoctadecadienoic acid and isoprostane.

The evaluation of antioxidant activity in vivo is difficult. In this study, the effects of dietary natural and synthetic antioxidants on the lipid peroxidation in mice were assessed using a biomarker, total hydroxyoctadecadienoic acid (tHODE). Biological samples such as plasma, erythrocytes, and tissues were first reduced and then saponified to convert various oxidation products of linoleates to tHODE. Subsequently, the absolute concentration of tHODE and its stereoisomer ratio, [9- and 13-(Z,E)-HODE)/[9- and 13-(E,E)-HODE], which is a measure of the hydrogen donor capacity of antioxidants, were determined by gas chromatography-mass spectrometry (GC-MS) analyses. These were then compared with total 8-iso-prostaglandin F(2alpha) (t8-iso-PGF(2alpha)) which was also assessed after reduction and saponification. Remarkable increases in tHODE and t8-iso-PGF(2alpha) levels were observed in the plasma, erythrocytes, liver, and brain of mice that were fed an alpha-tocopherol (alphaT)-stripped (E-free) diet for 1 month when compared with those of mice that were fed a standard diet (alphaT = 0.002 wt%). When mice were fed for 1 month on an E-free diet supplemented with a lipophilic antioxidant (0.04 wt%), namely, alphaT, alpha-tocotrienol (alphaT3), gamma-tocopherol (gammaT), or 2,3-dihydro-5-hydroxy-4,6-di-tert-butyl-2,2-dipentylbenzofuran (BO-653), a potent synthetic antioxidant, the increases of tHODE and t8-iso-PGF(2alpha) in the plasma, erythrocytes, liver, and brain were suppressed to the levels lower than those of mice fed a standard diet. The (Z,E/E,E) HODE ratio was decreased in the plasma and erythrocytes of mice fed the E-free diet when compared with that in mice fed the standard diet. This stereo-isomeric ratio was significantly recovered by the addition of alphaT and BO-653. These results show that the tHODE level and the (Z,E/E,E) HODE ratio are useful biomarkers for the assessment of antioxidant capacity in vivo and that the antioxidant capacity decreased in the order: BO-653 > alphaT3 >or= alphaT, gammaT, as assessed by tHODE levels from blood, liver, and brain.