OH Scavenging Ability Research Articles

Antioksidativna aktivnost biopolimernih filmova na bazi uljane pogače tikve golice dobijenih različitim postupkom filtracije

In this work, pumpkin seed oil cake that remains after process of cold pressed oil extraction, was used for the production of composite biopolymer based packaging films. During the production of films, four degrees of filtration were applied. The obtained composite biopolymer films were analyzed for antioxidant activity using three different antioxidant activity assays: the ability to capture free radicals, including •DPPH radical and hydroxyl radical, •OH, as well as reduction power assay of the analyzed films. By comparing the antioxidant activity of the films obtained with different degrees of filtration, it can be concluded that the films obtained by finer filtration (smaller diameter of the filter pore) exhibit greater ability to capture •DPPH radicals, as well as higher reducing power, while the ability to capture hydroxyl radicals showed different trend. Films obtained from the coarser filtered fractions (higher diameter of the filtrate medium) showed greater •OH scavenging ability.

Drying alters the phenolic constituents, antioxidant properties, α-amylase, and α-glucosidase inhibitory properties of Moringa (Moringa oleifera) leaf.

Moringa oleifera leaf is a popular green leafy vegetable which has found its usefulness in the preparation of traditional stews and soups. Like most green leafy vegetable which are not around year‐round, the leaf is usually dried and pulverized for storage and easier handling, and despite the popularity of this processing technique, there is dearth of information on how drying affects the health‐promoting properties of the leaves. Hence, this study sought to investigate the effect of some drying methods (freeze‐drying, sun, air and oven drying) on the phytoconstituents, antioxidant properties, and biological activities of moringa leaf. This study revealed that drying methods significantly altered the phytoconstituents (phenolics, flavonoids, vitamin C, tannin, saponin, phytate, oxalate, alkaloid, cardenolides, and cardiac glycosides), antioxidant capacities (reducing power, Fe2+chelating, ABTS •+, DPPH, and • OH scavenging abilities), and enzyme inhibitory (α‐amylase and α‐glucosidase) effects of the leaf, with freeze‐drying being the most promising method for preserving the nutraceutical properties of moringa leaf. However, for practical application, the order of preference of the drying methods which ensures adequate retention of phytoconstituents and possibly biological activities of the leaf as observed in this study is freeze‐drying > air drying > sun drying > oven drying, in the order of decreasing magnitude.

Preparation of the controlled acid hydrolysates from pumpkin polysaccharides and their antioxidant and antidiabetic evaluation

Pumpkin polysaccharides (PPe) have various biological activities. This research was to optimize the acid hydrolysis process of PPe with OH scavenging ability based on central composite design (CCD), and to explore the antioxidant and antidiabetic activities of the acid hydrolysates (PPe-H). A rat model of type 2 diabetes mellitus (T2DM) using high-fat diet and low-dose streptozotocin were established to assess the bioactivities. Both PPe and PPe-H could distinctly reduce fasting blood glucose level, prevent the weight loss in T2DM rats, and exhibited the remarkable ability to enhance the activities of the antioxidant enzymes (CAT and GR, p < 0.01, p < 0.01) and the level of GSH (p < 0.05, p < 0.01). Besides, PPe-H could significantly decrease the level of MDA (p < 0.05). Furthermore, PPe-H could cause an evident improvement to glucose stimulated GLP-1 secretion from 0 min to 30 min (p < 0.05). PPe and PPe-H were both the heteropolysaccharide and composed of rhamnose, arabinose, glucose and galactose, their molecular weight were 104.27 kDa and 37.58 kDa, respectively. The potential antidiabetic mechanism of PPe-H might be related to stimulating the secretion of endogenous GLP-1, decreasing oxidative damages, and then slowing down the process of diabetes.

Simultaneous Fenton-like Ion Delivery and Glutathione Depletion by MnO2 -Based Nanoagent to Enhance Chemodynamic Therapy.

Chemodynamic therapy (CDT) utilizes iron-initiated Fenton chemistry to destroy tumor cells by converting endogenous H2 O2 into the highly toxic hydroxyl radical (. OH). There is a paucity of Fenton-like metal-based CDT agents. Intracellular glutathione (GSH) with . OH scavenging ability greatly reduces CDT efficacy. A self-reinforcing CDT nanoagent based on MnO2 is reported that has both Fenton-like Mn2+ delivery and GSH depletion properties. In the presence of HCO3- , which is abundant in the physiological medium, Mn2+ exerts Fenton-like activity to generate . OH from H2 O2 . Upon uptake of MnO2 -coated mesoporous silica nanoparticles (MS@MnO2 NPs) by cancer cells, the MnO2 shell undergoes a redox reaction with GSH to form glutathione disulfide and Mn2+ , resulting in GSH depletion-enhanced CDT. This, together with the GSH-activated MRI contrast effect and dissociation of MnO2 , allows MS@MnO2 NPs to achieve MRI-monitored chemo-chemodynamic combination therapy.

Simultaneous Fenton‐like Ion Delivery and Glutathione Depletion by MnO2‐Based Nanoagent to Enhance Chemodynamic Therapy

AbstractChemodynamic therapy (CDT) utilizes iron‐initiated Fenton chemistry to destroy tumor cells by converting endogenous H2O2 into the highly toxic hydroxyl radical (.OH). There is a paucity of Fenton‐like metal‐based CDT agents. Intracellular glutathione (GSH) with .OH scavenging ability greatly reduces CDT efficacy. A self‐reinforcing CDT nanoagent based on MnO2 is reported that has both Fenton‐like Mn2+ delivery and GSH depletion properties. In the presence of HCO3−, which is abundant in the physiological medium, Mn2+ exerts Fenton‐like activity to generate .OH from H2O2. Upon uptake of MnO2‐coated mesoporous silica nanoparticles (MS@MnO2 NPs) by cancer cells, the MnO2 shell undergoes a redox reaction with GSH to form glutathione disulfide and Mn2+, resulting in GSH depletion‐enhanced CDT. This, together with the GSH‐activated MRI contrast effect and dissociation of MnO2, allows MS@MnO2 NPs to achieve MRI‐monitored chemo–chemodynamic combination therapy.

Novel Colorimetric Assay of 2,3-Dihydroxybenzoate among Other Isomers as a Selective Indicator of Hydroxyl Radical Damage and Related Antioxidant Activity

ABSTRACTAlthough reactive oxygen species can regulate intracellular signaling pathways, excessive amounts under oxidative stress conditions may cause damage to biomolecules. Hydroxyl radical (•OH) is a most reactive oxidant that can harm DNA, lipids, and proteins. As the direct determination of •OH by highly specialized electron paramagnetic resonance techniques is costly, indirect colorimetric determinations have attracted attention. Salicylic acid has been used both as an in vitro and in vivo probes to detect •OH, itself being converted to 2,3-, 2,4-, and 2,5-dihydroxybenzoic acids (DHBA) and catechol, but since 2,5-DHBA may also be generated enzymatically in the cyctochrome P-450 metabolism, 2,3-DHBA is the real marker of oxidative salicylate damage. This work is focused on the development of a selective hydroxyl radical detection assay by modifying a colorimetric nitrite-molybdate method concerning vic-diol determination of 2,3-DHBA among other DHBA isomers. Salicylic acid was hydroxylated to DHBAs and catechol upon the attack of •OH produced in a Fenton system. An aliquot from the mixture was oxidized with a nitrite-molybdate(VI) reagent to give an intense red product in alkaline medium with maximal absorbance at 510 nm. The assay was selective to only 2,3-DHBA and catechol among all DHBA isomers. The residual salicylic acid, DHBAs, and catechol were measured using high-performance liquid chromatography (HPLC); the spectrophotometrically measured contents of 2,3-DHBA and catechol were compared with HPLC results. Antioxidants, when present, caused a reduction in the hydroxylation of salicylate probe producing less 2,3-DHBA and catechol, thereby enabling the development of an indirect antioxidant activity assay for colorimetrically measuring •OH scavenging ability.

Physicochemical and Reactive Oxygen Species Scavenging Properties of Collagen and Collagen Hydrolysates from Farmed Globefish (Fugu rubripes) Bone

ABSTRACTGlobefish (Fugu rubripes) bone collagen (GBC) was isolated and characterized. Electrophoresis and Fourier transform infrared (FTIR) spectra indicated that GBC was high-purity type I collagen with an intact triple-helical structure. Amino acid analysis revealed that GBC contained higher glycine content (364 residues/1,000 residues) than that of other fishery bones, and the imino acid content was 189 residues/1,000 residues. The denaturation temperature (Td) of GBC was 27.1°C. GBC displayed a rapid fibril-forming rate and well-defined fibril morphology in vitro. Globefish bone collagen hydrolysates (GBCH) were optimized by neutral protease through response surface methodology (RSM) with the highest hydroxyl radical (•OH) scavenging capacity. The optimal hydrolysis condition was a reaction temperature of 48.4°C, time of 120 min, and enzyme/substrate ratio of 2520 U/g. Three fractions were collected by ultrafiltration, and the fraction GBCH-III (Mw<1 kDa) possessed the strongest •OH scavenging ability. Reactive oxygen species (ROS) scavenging capacities were evaluated with two model systems: •OH and nitric oxide (NO•). The ROS scavenging capacities increased in a dose-dependent manner. GBCH-III proved to be a more effective •OH scavenger than reduced glutathione (GSH). These findings demonstrated that GBC and GBCH have potential as an alternative source of collagen-derived materials for use in pharmaceutical, nutraceutical, and cosmetic industries.

Constituents and Antioxidant Activity of Bleeding Sap from Various Xinjiang Grapes.

Objective:Wine grape sap or bleeding sap of grapes (GBS) is commonly used in Xinjiang (China) for therapeutic aims. Do variations in composition related to region and variety affect its properties?Methods:GBS samples originating in various parts of Xinjiang (Turpan, Hotan, Kashgar, and Atush) were tested for phenols and polyphenols, polysaccharides, saponin, proteins, individual amino acids, and minerals. Their antioxidant activity was measured using ascorbic acid as reference.Results:Polyphenol content varied from 2.6 to 6.6 mg/L, polysaccharides 18.3–816 mg/L, saponin 6.25–106 mg/L, and protein 3.0–22.4 mg/L. Mineral elements and amino acids ranged from 6.20 to 201.2 mg/L and 0.06–118.7 mg/L, respectively. ·OH scavenging ability varied from 70% to over 90%, higher than Vitamin C. Grapes from Turpan had lower antioxidant activity than other grapes even though the polyphenol content was generally higher.Conclusion:Bleeding sap of Xinjiang grape is rich in amino acids, polysaccharides, polyphenols, and protein. The contents are different according to the origin, related possibly to species, climate, and environment. Antioxidant effects were not correlated with polyphenol content.SUMMARY Antioxidant activity of plants or plant extracts is often associated with polyphenolsBleeding sap of grapes has strong antioxidant propertiesBleeding sap from different grape varieties from different parts of Xinjiang (China) had different polyphenol concentrationsThere was no correlation of polyphenol concentrations with antioxidant activity. Abbreviations used: GBS: Bleeding sap of grapes; PITC: phenyl isothiocyanate.

Starch composition, glycemic indices, phenolic constituents, and antioxidative and antidiabetic properties of some common tropical fruits

BackgroundStudies have supported the protective effect of high fruit consumption in the management of chronic diseases such as diabetes. MethodsThirteen fresh tropical fruits were sourced for and the fruits juices were extracted, freeze dried, and then reconstituted for analysis. The sugar, starch, amylose, and amylopectin contents as well as glycemic indices, antioxidant properties, and the ability of the fruits to inhibit starch-hydrolyzing enzymes were determined. Also, the phenolic constituents of the fruits were characterized using high-performance liquid chromatography coupled with diode array detector. ResultsThe starch, sugar, amylase, and amylopectin contents were 3.01–3.89 g/100 g, 35.34–60.91 g/100 g, 0.84–1.46 g/100 g, and 1.68–2.86 g/100 g, respectively, while the glycemic indices were 28.01–68.34, with African star apple (28.01) having the lowest and watermelon (68.34) the highest. Furthermore, the fruits exhibited high antioxidant properties as exemplified by their DPPH, ABTS+, OH, and NO radical scavenging abilities. Likewise, the fruits also demonstrated α-amylase and α-glucosidase inhibitory property with Soursop (IC50 = 18.52 μg/mL), guava (IC50 = 19.77 μg/mL), and African star apple (IC50 = 20.86 μg/mL) showing the highest inhibitory potential among the 13 fruits. Similarly, the same trend was followed for α-glucosidase inhibitory activity. ConclusionThe fruits' low glycemic indices, strong antioxidant properties, and inhibition of α-amylase and α-glucosidase activities could be possible mechanisms for their use in the management and prevention of type-2 diabetes.

A Polypyrrole Based Sensor for the Electrochemical Detection of OH Radicals

AbstractPolypyrrole was used as sensitive material in the development of a new device employed for the indirect detection of OH radicals. The polypyrrole film was electrosynthesized on glassy carbon. The modified electrode was exposed to the OH radicals generated by Fenton reaction. As a result of the overoxidation the conductivity of the polymer diminished very much. The overoxidation (%) was directly proportional to the .OH amount that reached the electrode surface. ABTS.+, superoxide and alkylperoxy radicals did not interfere in the determination. The applicability of the device was demonstrated by estimating the .OH scavenging ability of ascorbic acid.

Aqueous Extracts of Roselle (Hibiscus sabdariffa Linn.) Varieties Inhibit α-Amylase and α-Glucosidase Activities In Vitro

This study sought to investigate the inhibitory effect of aqueous extracts of two varieties (red and white) of Hibiscus sabdariffa (Roselle) calyces on carbohydrate hydrolyzing enzymes (α-amylase and α-glucosidase), with the aim of providing the possible mechanism for their antidiabetes properties. Aqueous extracts were prepared (1:100 w/v) and the supernatant used for the analysis. The extracts caused inhibition of α-amylase and α-glucosidase activities in vitro.The IC(50) revealed that the red variety (25.2 μg/mL) exhibited higher α-glucosidase inhibitory activity than the white variety (47.4 μg/mL), while the white variety (90.5 μg/mL) exhibited higher α-amylase inhibitory activity than the red variety (187.9 μg/mL). However, the α-glucosidase inhibitory activities of both calyces were higher than that of their α-amylase. In addition, the red variety possessed higher antioxidant capacity as exemplified by the (•)OH scavenging abilities, Fe(2+) chelating ability, and inhibition of Fe(2+)-induced pancreatic lipid peroxidation in vitro. The enzyme inhibitory activities and antioxidant properties of the roselle extracts agreed with their phenolic content. Hence, inhibition of α-amylase and α-glucosidase, coupled with strong antioxidant properties could be the possible underlying mechanism for the antidiabetes properties of H. sabdariffa calyces; however, the red variety appeared to be more potent.

Quality characteristics and antioxidant activity of hickory-black soybean yogurt

Hickory-black soybean milk and reconstituted milk (about 12 g/100 g solid content) were mixed in the proportion of 2:3 by volume to prepare hickory-black soybean yogurt (HBY). Cow milk yogurt (CMY) with no addition of hickory-black soybean milk was used as the control. Compared with CMY, HBY had higher water holding capacity, fat, crude protein and amino acids, but lower susceptibility to syneresis and ash content, and had no significant difference in the total count of lactic acid bacteria (p > 0.05). Sensory evaluation showed that the appearance and flavor scores of HBY had no significant difference from CMY (p > 0.05), but the texture score was significantly higher (p < 0.05). IC50 values of DPPH, OH scavenging ability, Fe2+ chelating ability and inhibition of lipid peroxidation of HBY were lower (p < 0.05) than those of CMY. These results suggested that the antioxidant activity of HBY was significantly higher than that of CMY.

Fullerene-C&lt;SUB&gt;60&lt;/SUB&gt; Incorporated in Liposome Exerts Persistent Hydroxyl Radical-Scavenging Activity and Cytoprotection in UVA/B-Irradiated Keratinocytes

The aim of this study is to examine antioxidant activity of fullerene-C60 (C60) incorporated in liposome (LpsmFlln, a diameter of 75.6 nm). LpsmFlln is water-soluble, and composed of hydrogenated lecithin of 89.7%, glycine soja sterol of 10% and C60 of 0.3%. Hydroxyl radicals (*OH), generated from UVA- or UVB-irradiated H2O2, were scavenged by LpsmFlln but not by C60-lacking Lpsm as assessed by ESR, showing that the active principle is C60 as scanty as 1/415 weight versus LpsmFlln; the *OH amount (% of non-additive control) was decreased, LpsmFlln-dose-dependently, and for 0.5% LpsmFlln (C60-eq.:16.7 microM) to 34.1% or 78.3% upon irradiation with UVA (12 J/cm2) or UVB (500 mJ/cm2), respectively, showing the superiority for UVA to UVB in terms of the *OH scavenging of LpsmFlln. Cell viability of human skin keratinocytes HaCaT decreased to 41.1% upon UVA-irradiation at 10 J/cm2, but retained to 60.6% with 0.025% LpsmFlln (C60-eq.: 0.84 microM) together with prevention of cell-morphological degeneration, in contrast to scarce effects of C60-lacking Lpsm. The scavenging activity for Fenton reaction-generated *OH, detected by DMPO/ESR, was 96.2% or 72.2% (% of no-additive control) at 1 min and decreased time-dependently to 24.8% or 28.3% at 12 min with 16.7 microM L-ascorbic acid (Asc) or Trolox, respectively, whereas 0.5% LpsmFlln (C60-eq:16.7 microM, the same concentration as for Asc) diminished *OH by 90.9% at 1 min and 91.5% even at 12 min, demonstrating the superiority of LpsmFlln to Asc or Trolox in terms of persistence of *OH-scavenging ability. Repressive efficacy on beta-carotene discoloration (% of control) for 60 min was in the order, based on the same molar or weight concentration: 1.3%:3.34 microM Asc < 25.0%:0.1% Lpsm < 36.3%:0.1% LpsmFlln (C60-eq.:3.34 microM) < 57.2%:3.34 microM Trolox, indicating the preventive effect of LpsmFlln against beta-carotene oxidation. Thus, LpsmFlln was demonstrated for an antioxidant ability characteristic of long-term persistence, and is attributed to fullerene-C60 but scarcely to Lpsm in all the tests examined, and is expected as the skin-protecting agent against oxidative stress.

Antioxidant Capacity Changes of 3 Cultivar Chinese Pomegranate (Punica granatum L.) Juices and Corresponding Wines

This study investigated the antioxidant capacities that included Ferric reducing antioxidant power (FRAP), 1, 1-diphenyl-2-picryl hydrazine (DPPH), ·OH and O(2·)(-)-scavenging abilities, total polyphenols (TP) and total anthocyanins (TA) in pomegranate (Punica granatum L.) juice (PJ) and pomegranate wine (PW). The correlations among them were also analyzed. Both PJ and PW showed significantly high TP and antioxidant capacities, but some differences existed among these cultivars. There was 1596.67 mg/L TP found in sweet PJ, while sour PJ showed the highest titratable acidity of 35.90 g/L and lowest pH value at 2.56. Red PJ was found to have the highest TA (82.26 mg/L) in the 3 cultivars. Sweet PJ showed higher DPPH-scavenging ability and higher FRAP than others. Both PJ and PW exhibited high and relatively stable ·OH-scavenging abilities, in which sour PJ and sour PW had higher O(2·)(-) scavenging capacity than others. Significant positive correlations were observed among TP, DPPH, and FRAP in both PJ and PW. A high correlation between antioxidant capacities and TP indicated that phenolic compounds were major contributors to the high antioxidant activity of PJ and PW.

Creatinine and HMH (5-hydroxy-1-methylhydantoin, NZ-419) as intrinsic hydroxyl radical scavengers

Creatinine (Crn) is one of the main intrinsic hydroxyl radical (•OH) scavengers and an ideal one for healthy or normal mammals, although this fact has not yet become widely accepted. Our results from urinary data estimated that ca. 0.4-0.6% of Crn is used daily to scavenge •OH in normal mammals [ca. 50 μmole and ca. 400 pmole of •OH in healthy subjects and normal rats, respectively]. In human subjects, Crn reacts non-enzymatically with •OH to form creatol (CTL: 5-hydroxycreatinine) and demethylcreatinine (DMC) in a one to one ratio, and CTL partially decomposes to methylguanidine (MG). And so, the scavenged mole of •OH by Crn is nearly equal to their molar total sum (CTL + MG + DMC) or 2 × (CTL + MG). The molar ratio of (scavenged •OH)/Crn in healthy subjects and normal rats are 4.4 and 6.0 mmole/mole, respectively, i.e. almost similar, but in patients with chronic kidney disease (CKD) the ratio increases up to ca. 60 mmole/mole in proportion to the severity of CKD. Since the level of Crn might not be enough to scavenge all •OH, and MG starts accumulating as a uremic toxin, Crn is not really the ideal scavenger. 5-Hydroxy-1-methylhydantoin (HMH, NZ-419), a Crn metabolite, is another antioxidant, having •OH scavenging ability, and has been shown to inhibit the progression of CKD in rats in stead of Crn, if sufficient amounts are given orally.

Inhibitory effect of Lavandula viridis on Fe2+-induced lipid peroxidation, antioxidant and anti-cholinesterase properties

In this research, the total phenolic content of a Lavandula viridis methanol extract was evaluated and the phenolic identification and quantification was assessed. Rosmarinic acid and luteolin-7-O-glucoside were the two major compounds identified by HPLC–DAD (ca. 39 and 13g/kg, respectively). This extract showed a strong antioxidant activity in ORAC (2858.39±70.97μmolTE/gextract) and TEAC (967.18±22.57μmolTE/gextract) assays, as well as Fe2+ chelating and OH scavenging abilities. Furthermore, the extract prevented Fe2+-induced lipid peroxidation, by reducing MDA content in mouse brains (in vitro), and inhibited AChE and BChE activities both in vitro and in vivo. These findings demonstrate that the methanol extract from L. viridis is a potential source of natural antioxidants and cholinesterase inhibitors.

Characterization and in vitro antioxidation of papain hydrolysate from black-bone silky fowl (Gallus gallus domesticus Brisson) muscle and its fractions

Black-bone silky fowl (Gallus gallus domesticus Brisson) (BSF) muscle was hydrolyzed by papain, and the hydrolysate was separated by preparative high performance liquid chromatography (HPLC). The amino acid composition of the BSF hydrolysate (BSFH) and its fractions was determined by HPLC precolumn derivation with 2,4-dinitrofluorobenzene. The molecular weight (MW) distribution of the BSFH and its fractions was measured by a peptide column on an HPLC system. Antioxidant activities of the BSFH and its fractions were studied by testing the reducing power and four radical scavenging systems: superoxide anion (O2−), hydroxyl (·OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radicals. The results demonstrated that the BSFH had strong antioxidant capacity to scavenge O2−, DPPH and ABTS+, and displayed strong reducing power, but revealed less powerful ability to scavenge ·OH. Fraction II of the BSFH exhibited the highest activity in scavenging O2− and DPPH, and reducing power, whereas fraction I displayed the strongest ·OH scavenging ability. Besides Glu, Asp and Gly, the rich amino acids of Ala and Leu played an important role in antioxidant activity. The small-size peptides with MW ranging from approximately 200–6000Da probably contributed to higher antioxidant activity. Results from this study indicated that BSFH and its fractions could be used as food additives and diet nutrients.

Antioxidant and inhibitory effect of red ginger ( Zingiber officinale var. Rubra) and white ginger ( Zingiber officinale Roscoe) on Fe 2+ induced lipid peroxidation in rat brain in vitro

Neurodegerative diseases have been linked to oxidative stress arising from peroxidation of membrane biomolecules and high levels of Fe have been reported to play an important role in neurodegenerative diseases and other brain disorder. Malondialdehyde (MDA) is the end-product of lipid peroxidation and the production of this aldehyde is used as a biomarker to measure the level of oxidative stress in an organism. The present study compares the protective properties of two varieties of ginger [red ginger ( Zingiber officinale var. Rubra) and white ginger ( Zingiber officinale Roscoe)] on Fe 2+ induced lipid peroxidation in rat brain in vitro. Incubation of the brain tissue homogenate in the presence of Fe caused a significant increase in the malondialdehyde (MDA) contents of the brain. However, the aqueous extract from both varieties of ginger caused a significant decrease in the MDA contents of the brain in a dose-dependent manner. However, the aqueous extract of red ginger had a significantly higher inhibitory effect on both Fe 2+-induced lipid peroxidation in the rat brain homogenates than that of white ginger. This higher inhibitory effect of red ginger could be attributed to its significantly higher phytochemical content, Fe 2+ chelating ability, OH scavenging ability and reducing power. However, part of the mechanisms through which the extractable phytochemicals in ginger (red and white) protect the brain may be through their antioxidant activity, Fe 2+ chelating and OH scavenging ability. Therefore, oxidative stress in the brain could be potentially managed/prevented by dietary intake of ginger varieties (red ginger and white ginger rhizomes).

Oestradiol Protects Against the Harmful Effects of Fluoride More by Increasing Thiol Group Levels than Scavenging Hydroxyl Radicals

The aim of the study was to investigate the role of oestrogens in free radical detoxication upon exposure to fluoride. Interactions between xenobiotics and oestrogens need to be investigated, especially as many chemicals interact with the oestrogen receptor. It is still unknown whether free radical-generating xenobiotics can influence the antioxidative ability of oestradiol (E(2)). In an in vitro examination of human placental mitochondria, thiobarbituric active reagent species (TBARS), hydroxyl radical ((*)OH) generation and protein thiol (-SH) groups were detected. 17beta-E(2) was examined in physiological (0.15-0.73 nM) and experimental (1-10 microM) concentrations and sodium fluoride (NaF) in concentrations of 6-24 microM. E(2) in all the concentrations significantly decreased lipid peroxidation measured as the TBARS level, in contrast to NaF, which increased lipid peroxidation. Lipid peroxidation induced by NaF was decreased by E(2). The influence of E(2) on (*)OH generation was not very significant and depended on the E(2 )concentration. The main mechanism of E(2) protection in NaF exposure appeared to be connected with the influence of E(2 )on thiol group levels, not (*)OH scavenging ability. The E(2) in concentrations 0.44-0.73 nM and 1-10 microM significantly increased the levels of -SH groups, in contrast to NaF, which significantly decreased them. E(2) at every concentration reversed the harmful effects of NaF on -SH group levels. No unfavourable interactions in the influence of E(2) and NaF on TBARS production, (*)OH generation, or -SH group levels were observed. The results suggest that postmenopausal women could be more sensitive to NaF-initiated oxidative stress.

Effect of catechins and tannins on hydroxyl radical formation in depleted uranium-hydrogen peroxide systems

The effects of catechins and tannins on the uranyl ion (UO22+)-hydrogen peroxide (H2O2) system were examined using the spin-trapping method. Epigallocatechin (EGC), having low •OH-scavenging ability, significantly enhanced and accelerated the hydroxyl radical (•OH) formation in the UO22+–H2O2 solution. Epigallocatechin gallate (EGCG), having high •OH-scavenging ability, fairly enhanced and accelerated hydroxyl radical (•OH) formation in the UO22+–H2O2 solution. These results indicate that the enhancement and acceleration of •OH formation are caused by the reduction of UO22+ to UO2+ by EGC and EGCG. The effects of tannins on •OH formation in the UO22+–H2O2 solution varied with tannins. Mimosa (MMT) and quebracho (QBT) tannins enhanced and accelerated •OH formation, while chestnut (CNT), mylobaran (MBT) and Chinese gallo- (CGT) tannins heavily depressed it. In the solution containing persimmon (PST) and gambir (GBT) tannins, the depression of •OH formation caused by the strong coupling with UO22+ ion should be added to the enhancement caused by the reduction of UO22+ to UO2+. MBT indicated the highest ability to scavenge •OH in the UV-irradiated H2O2 solution, and MMT, the lowest. In summary, MMT and QBT, classified as condensed tannins, have very high abilities to reduce UO22+ to UO2+, similarly to catechins such as EGC and EGCG, while MBT, a hydrolysable tannin, has higher abilities to scavenge •OH.