Deoxyribose Oxidation Research Articles

In vitro Screening of Antioxidant and Anti-inflammatory Activities of Plant Extract Adenanthera pavonina

Adenanthera pavonina (AP) is a medicinal herb used in traditional systems of medicine in Sri Lanka. It is considered a rich source of bioactive compounds as they are able to produce a great variety of secondary metabolites with great anticancer and antioxidant properties. In the present study, the bark of the plant was used and water extract was prepared in order to screen Total Phenolic Content (TPC), Total Flavonoid Content (TFC), Ferric ion reducing power, DPPH radical scavenging capacity, inhibition of lipid peroxidation, inhibition of protein oxidation and inhibition deoxyribose oxidation. Anti-inflammatory activity was screened in vitro using Human Red Blood cell Membrane stability assay (HRBM) and inhibition of protein denaturation assay. All methods were carried out according to the standard protocol. The TPC and TFC were 80.3±0.1 mg GA/g (Gallic Acid/g) and 46.1±0.1 mg EGCG/g (epigallocatechin gallate /g) respectively. The DPPH radical scavenging capacity, inhibition of lipid peroxidation, protein oxidation and deoxyribose oxidation were IC50, 15.8±0.5 (Gallic acid, 4.5±0.3 μg/ml), 46.1±0.5 μg/ml (Ascorbic acid , 58.4±2.2 μg/ml), 72.6±3.1 μg/ml (Ascorbic acid, 51.2±0.1 μg/ml) and 7.4±0.7 μg/ml (Ascorbic acid, 8.7±0.6 μg/ml) respectively. Reducing power of the AO extract increased with the concentration. HRBM and inhibition of BSA denaturation of AO extract were IC50 that 49.7±1.4 μg/ml (Diclofenac sodium, 47.8±2.1 μg/ml) and 29.1±1.5 (Diclofenac sodium 23.8±3.6 μg/ml) respectively. The results of the study suggest that the bioactive molecules present in the AP water extract can be used as a prototype for the development of new drugs or as a source of antioxidants and anti-inflammatory pharmaceutical raw material.
 Keywords: Adenanthera pavonina, Inhibition of lipid peroxidation, Inhibition of protein oxidation, Inhibition deoxyribose oxidation.

Chemical Insights into Oxidative and Nitrative Modifications of DNA.

This review focuses on DNA damage caused by a variety of oxidizing, alkylating, and nitrating species, and it may play an important role in the pathophysiology of inflammation, cancer, and degenerative diseases. Infection and chronic inflammation have been recognized as important factors in carcinogenesis. Under inflammatory conditions, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from inflammatory and epithelial cells, and result in the formation of oxidative and nitrative DNA lesions, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-nitroguanine. Cellular DNA is continuously exposed to a very high level of genotoxic stress caused by physical, chemical, and biological agents, with an estimated 10,000 modifications occurring every hour in the genetic material of each of our cells. This review highlights recent developments in the chemical biology and toxicology of 2'-deoxyribose oxidation products in DNA.

Amidinoquinoxaline-Based Nitrones as Lipophilic Antioxidants.

The potential of nitrones (N-oxides) as therapeutic antioxidants is due to their ability to counteract oxidative stress, mainly attributed to their action as radical scavengers toward C- and O-centered radicals. Among them, nitrones from the amidinoquinoxaline series resulted in interesting derivatives, due to the ease with which it is possible to introduce proper substituents within their structure in order to modulate their lipophilicity. The goal is to obtain lipophilic antioxidants that are able to interact with cell membranes and, at the same time, enough hydrophilic to neutralize those radicals present in a water compartment. In this work, the antioxidant efficacy of a series of amidinoquinoxaline nitrones has been evaluated regarding the oxidation of 2-deoxyribose and lipid peroxidation. The results have been rationalized on the basis of the different possible mechanisms involved, depending on some of their properties, such as lipophilicity, the ability to scavenge free radicals, and to undergo single electron transfer (SET) reactions.

Antioxidant Properties of Casein Phosphopeptides (CPP) and Maillard-Type Conjugated Products.

A casein phosphopeptide (CPP) fraction derived from tryptic hydrolysis of bovine casein was evaluated for antioxidant activity. Conjugations or mixtures of CPP with polysaccharide, galactomannan (Gal), or xyloglucan (Xyl) were prepared to evaluate potential enhancement of CPP antioxidant activity. The effect of calcium was also investigated. The CPP preparation alone was effective at scavenging hydroxyl radicals and sequestering Fe2+ to protect against Fenton reaction-induced deoxyribose oxidation in non-site-specific (up 63.3% inhibition) and site-specific (up 32.1% inhibition) binding assays, respectively. CPP also effectively quenched 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radicals (ABTS•+) to an extent of 67.6% scavenging in an aqueous system. In a soybean lecithin liposome system, CPP exhibited effective protection against peroxyl radical-induced liposomal peroxidation (38.3% of control in terms of rate of propagation). Conjugating CPP with Gal or Xyl polysaccharides using Maillard reaction conditions significantly reduced activity in the Fenton reaction-deoxyribose assays, while exhibiting no effect on the antioxidant activity of native CPP in both the ABTS and liposome assays, respectively. These results represent comparative antioxidant capacity of the native CPP and associated conjugates in phases that varied in relative hydrophilic and hydrophobic character. We conclude that CPP has the potential to act as both a primary and secondary antioxidant by displaying transition metal ion sequestering activity and free radical quenching activity. Improvements in antioxidant activity of CPP by Maillard-type conjugation with Xyl or Gal were relatively small and model-specific.

Antioxidant activity of different species and varieties of turmeric (Curcuma spp): Isolation of active compounds

There are >80 species of turmeric (Curcuma spp.) and some species have multiple varieties, for example, Curcuma longa (C. longa) has 70 varieties. They could be different in their chemical properties and biological activities. Therefore, we compared antioxidant activity, total phenolic and flavonoid content of different species and varieties of turmeric namely C. longa [variety: Ryudai gold (RD) and Okinawa ukon], C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria. The antioxidant activity was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, oxygen radical absorbance capacity (ORAC), reducing power and 2-deoxyribose (2-DR) oxidation assay. Our results suggested that RD contained significantly higher concentrations of total phenolic (157.4 mg gallic acid equivalent/g extract) and flavonoids (1089.5 mg rutin equivalent/g extract). RD also showed significantly higher DPPH radical-scavenging activity (IC50: 26.4 μg/mL), ORAC (14,090 μmol Trolox equivalent/g extract), reducing power absorbance (0.33) and hydroxyl radical scavenging activity (IC50: 7.4 μg/mL). Therefore, RD was chosen for the isolation of antioxidant compounds using silica gel column, Toyopearl HW-40F column, and high-performance liquid chromatography. Structural identification of the compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. The purified antioxidant compounds were bisabolone-9-one (1), 4-methyllene-5-hydroxybisabola-2,10-diene-9-one (2), turmeronol B (3), 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1-hepten-3-one (4), 3-hydroxy-1,7-bis(4-hydroxyphenyl)-6-hepten-1,5-dione (5), cyclobisdemethoxycurcumin (6), bisdemethoxycurcumin (7), demethoxycurcumin (8) and curcumin (9). The IC50 for DPPH radical-scavenging activity were 474, 621, 234, 29, 39, 257, 198, 47 and 18 μM and hydroxyl radical-scavenging activity were 25.1, 24.4, 20.2, 2.1, 5.1, 17.2, 7.2, 3.3 and 1.5 μM for compound 1, 2, 3, 4, 5, 6, 7, 8 and 9, respectively. Our findings suggested that the RD variety of C. longa, developed by the University of the Ryukyus, Okinawa, Japan, is a promising source of natural antioxidants.

Spectroscopic investigation and computational studies on the interaction of Acriflavine with various estrogens

The fluorescence quenching of Acriflavine (AFN) by certain estrogens was examined in aqueous media by employing steady state and time-resolved fluorescence measurements. The absorption spectra of AFN change with significant bathochromic shift in presence of quencher molecules. The quenching behavior was examined by correlating the bimolecular quenching rate constant (kq) with the free energy change (ΔG). The decrease in quenching rate constant depends on the increase in oxidation potential of quencher molecules. The fluorescence quenching experiments were carried out in different solvents of varying polarities and reveals the possibility of charge transfer quenching mechanism. Lifetime measurements indicate static quenching. The quenching behavior is addressed from bond dissociation enthalpy (BDE) calculations. The antioxidant activity of estrogen compounds were evaluated by deoxyribose oxidation assay.

Вплив цистеїл-гістидил-тирозил-гістидил-ізолейцину на вміст продуктів пероксидного окиснення ліпідів та активних форм Оксигену в щурів різного віку за дії важких металів і гліфосату

Introduction. Oxidative stress plays a critical role in the pathophysiology of several diseases: liver cirrhosis, atherosclerosis, diabetes mellitus, ischemic heart disease, carcinogenesis, etc. The main mechanism of oxidative stress induced is the disturbance oxidation and reduction processes by various factors such as toxic substances, radiation, temperature, drugs. Ions of heavy metals (transition metals) lead to the production of reactive oxygen species (ROS), causing a lipid peroxidation and other main biomolecules (proteins, nucleic acids).The aim of the study – to learn the influence of peptid: cisteil-histidil-tyrosil-histidil-isoleucine on generation of active forms of oxygen the content of products of free lipid peroxidation.Research Methods. The experiment was carried out on lab nonlinear white rats – males three age periods: puberty, mature and old aging animals. The rats received the lead acetate, copper sulfate, glyphosate (in herbicide Roundup) in combined and peptide as correction agent. Subhronic lesions in rats was modelled by intragastric administration of water solution of Lead Acetate at a dose of 11 mg/kg, Copper Sulfate at a dose of 13 mg / kg, Glyphosate at a dose of 250 mg / kg. Dehlorinated drinking tap water to intact animals was added. The correction effect was research by the during 10 days intragastric administration of water solution of peptide cisteil-histidil-tyrosil- histidil-isoleucine in a dose of 9 mg / kg at 21th day of the experiment after 6 hours after toxins. The degree of lipid peroxidation was assayed by estimating the thiobarbituric acid reactive substances (TBARS) and diene conjugates (DK) in blood serum and liver homogenates by spectrophotometric method. The superoxide anion-radical content was determined by test with Nitrobluetetrazolium, hydroxyl radical content was determined by the product of oxidation of 2-deoxyribose.Results and Discussion. It was established that the production of reactive oxygen species and lipid peroxidation increase by the combined effect of glyphosate (in Roundup form herbicide), lead acetate, copper sulfate in different age rats. There was a significant increase in concentration of TBARS, diene conjugates, superoxide anionradical and hydroxyl radical. One of the most probable mechanisms of peptide: cisteil-histidil-tyrosil-histidil-isoleucine corrective activity is based on its ability to antioxidantion activity that decrease concentration of a production of reactive oxygen species and a lipid peroxidation.Conclusion. The protective effect of peptide: tsysteil-histidil-tyrosil-histidil-isoleucine on liver damages rats induced by toxicity is administration induced loss to the production of reactive oxygen species, causing a lipid peroxidation

Anchoring 20(R)-Ginsenoside Rg3 onto Cellulose Nanocrystals To Increase the Hydroxyl Radical Scavenging Activity

Cellulose nanocrystals (CNCs) exhibit attractive properties as carriers for bioactive molecules, including their large surface area, charge characteristics, and abundant surface hydroxyl groups, among others. In this study, we used CNCs as carriers for a hydrophobic drug, 20(R)-ginsenoside Rg3 (here abbreviated as 20(R)-Rg3), to improve its bioavailability, dispersity, and antioxidation activity in an aqueous system. The CNC/20(R)-Rg3 nanocomposites were fabricated and then characterized by transmission electron microscopy, Fourier transform IR spectroscopy, and X-ray diffraction. The particle size of 20(R)-Rg3 was in the range of 8–22 nm. In vitro hydroxyl radical scavenging by the 2-deoxyribose oxidation method and the salicylic acid hydroxylation method showed that the CNC/20(R)-Rg3 nanocomposites had much higher antioxidation activity (33.58% and 48.62%) than CNC-free 20(R)-Rg3, water-dispersed 20(R)-Rg3, and CNCs.

Effect of Selected Plant Phenolics on Fe2+-EDTA-H₂O₂ System Mediated Deoxyribose Oxidation: Molecular Structure-Derived Relationships of Anti- and Pro-Oxidant Actions.

In the presence of transition metal ions and peroxides, polyphenols, well-known dietary antioxidants, can act as pro-oxidants. We investigated the effect of 13 polyphenols and their metabolites on oxidative degradation of deoxyribose by an •OH generating Fenton system (Fe2+-ethylenediaminetetraacetic acid (EDTA)-H2O2). The relationship between phenolics pro-oxidant/anti-oxidant effects and their molecular structure was analyzed using multivariate analysis with multiple linear regression and a backward stepwise technique. Four phenolics revealed a significant inhibitory effect on OH-induced deoxyribose degradation, ranging from 54.4% ± 28.6% (3,4-dihydroxycinnamic acid) to 38.5% ± 10.4% (catechin) (n = 6), correlating with the number of –OH substitutions (r = 0.58). Seven phenolics augmented the oxidative degradation of deoxyribose with the highest enhancement at 95.0% ± 21.3% (quercetin) and 60.6% ± 12.2% (phloridzin). The pro-oxidant effect correlated (p < 0.05) with the number of –OH groups (r = 0.59), and aliphatic substitutes (r = −0.22) and weakly correlated with the occurrence of a catechol structure within the compound molecule (r = 0.17). Selective dietary supplementation with phenolics exhibiting pro-oxidant activity may increase the possibility of systemic oxidative stress in patients treated with medications containing chelating properties or those with high plasma concentrations of H2O2 and non-transferrin bound iron.

English

The antioxidant potential of the crude ethanolic (CCE), hexane (HF), chloroform (CLF), ethyl acetate (EAF) and remaining extracts (RF), from the leaves of Ocotea pulchella, was verified using seven antioxidant assays: DPPH (2.2-diphenyl-1-picrylhydrazyl), phosphomolybdenum complex, reducing power (prussian blue), lipid peroxidation (TBARs- thiobarbituric acid reactive substances), deoxyribose oxidation and H2O2 scavenging. The obtained results showed that the EAF was more active in the DPPH, phospho-molybdenum, lipid peroxidation, deoxyribose oxidation and H2O2 scavenging methods; and the CLF showed to be more active in the reduction potential method. The hierarchical cluster analysis (HCA) and principal component analysis (PCA) analysis demonstrated that DPPH is the method which requires less extract and fractions concentrations to show antioxidant potential and that deoxyribose oxidation and H2O2 scavenging showed a relative antioxidant activity when compared to other methods. The reduction potential and phosphomolybdenum complex showed less antioxidant potential. The cluster analysis also shows that the EAF possesses an antioxidant activity similar to the tested standards. These results indicate that the EAF may contain promising antioxidant agents that can also be useful for the treatment of diseases caused by free radicals. Key words: free radicals, antioxidant assays, PCA, HCA.

Evaluation of the antioxidant activity and the healing action of the ethanol extract of Calotropis procera bark against surgical wounds.

The objective of the present study was to evaluate the antioxidant potential and the wound healing effect of the ethanolic extract of the bark of Calotropis procera. The antioxidant study was evaluated in vitro, using 2,2-diphenylpicrylhydrazyl (DPPH) and deoxyribose degradation assays. Wound healing was studied using excision and incision wound on normal and dexamethasone-suppressed wound healing rodent models. Alkaloids, flavonoids, proteins and phenols were screened in the extract used whereas saponins and true tannins were absent. The extract contains only 12.5 gallic acid equivalent and 399.54 rutin equivalent. It was found to inhibit DPPH and deoxyribose oxidation (IC50 = 24.24 and 5.40 respectively). In vivo study demonstrated a significant reduction in the epithelialization time (P < 0.001) to 17-18 days in normal and dexamethasone treated rats following the ethanolic extract of the bark of C. procera application. The same extract also significantly increased the breaking strength in dexamethasone treated rats. Histological examination of incision wounds of treated group showed matured extracellular matrix, numerous fibroblasts. This study illustrated an excellent potential of the bark of C. procera therapy on dermal wound healing, with a tentative mechanism of action related to improved collagen deposition and reduced inflammatory reaction.

The protonation state of trans axial water molecule switches: the reactivity of high-valent manganese-oxo porphyrin

The cationic manganese porphyrin (Mn-TMPyP) was activated by an oxygen atom donor KHSO5 (oxone) to form a high-valent manganese-oxo species (MnVO) in aqueous buffer. The high-valent MnVO mediated oxidative damage of short double-stranded DNA models. The nature of the oxidation products (guanine oxidation DGh, 2Ih, imidazolone, and 2-deoxyribose oxidation, 2-deoxyribonolactone) and the mechanism of their formation varied with the pH of the reaction. Oxidation proceeded mainly through the electron transfer mechanism at pH 6 while oxygen atom transfer proved to be favored at pH 8. This was evidenced by different ratios of products arising from different mechanisms of oxidation as a function of pH but also by different mechanisms leading to the same oxidation product (DGh) as a function of pH. The reactivity shift of the active manganese-oxo species was attributed to the protonation state of the proximal water molecule as an axial ligand (trans to the oxo). A high-valent manganese-oxo in the oxo-hydroxo form (HO–MnVO) at higher pH undergoes oxygen atom transfer reactions while in the oxo-aqua form (H2O–MnVO) at lower pH it performs oxidation reactions by electron transfer. These data are an illustration of the influence of the “push” effect of the proximal ligand on the changing reactivity of high-valent metal-oxo species. They also give access to the pKa of the axially bound water molecule of manganese-oxo porphyrin.

Inhibition of iNOS and DNA Oxidation by Methanol Extract of &lt;em&gt;Schizonepeta tenuifolia&lt;/em&gt;

Purpose: To investigate the antioxidant properties of the methanol extract of S. tenuifolia as well as its effect on inducible nitric oxide synthase (iNOS) and cycleooxygenase-2 (COX-2) expression in lipopolysaccharides (LPS)-induced cell damage in macrophage cells. Methods: The antioxidant activities of the plant extract were explored by measuring free radical scavenging activity, viz, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO), and deoxyribose oxidation levels. The mechanism of antioxidant action of the extract was determined by Western blot analysis for iNOS and COX-2 expression in LPS-stimulated RAW 264.7 cells. Results: The extract contained antioxidant components, including phenolics, flavonoids and anthocyanin and exerted significant radical scavenging activity in a dose-dependent manner. It also produced deoxyribose oxidation and dramatic reducing power. Production of iNOS induced by LPS was significantly inhibited by the extract, suggesting that the extract inhibits nitric oxide (NO) production by suppressing iNOS expression. However, COX-2 induced by LPS was not significantly affected by the extract. Conclusion: These results suggest that the methanol extract of S. tenuifolia exerts significant antioxidant activity via inhibition of free radicals, iNOS and DNA oxidation.

Biochemical characterization of radical scavenging polyphenols from Nyctanthes arbortristis

Context:Antioxidants are quenchers of free radical that are responsible for inducing oxidative stress generated via reactive oxygen species-induced degenerative diseases such as cancer, diabetes, and cardiovascular diseases etc. Plant and plant products are recognized as safe and potential health promoting and nutritive sources.Aims:To investigate the antioxidant potency of polyphenol extract (PE) of Nyctanthes arbortristis leaves and identification of the active constituent by HPLC.Materials and Methods:PE of N. arbortristis leaves was investigated for antioxidant activity employing various established in vitro systems, such as lipid peroxidation in liposome, DPPH and hydroxyl radical scavenging, reducing power assay, and iron ion chelation. Identification of active constituent in PE of N. arbortristis responsible for antioxidant activity by HPLC. Statistical analysis used: All experiments were carried out in triplicates. Data were shown as mean ± standard deviation (SD). SPSS 10.0.5 version for windows (SPSS software Inc., USA) computer program was used for statistical analysis.Results:Identification of active constituent in PE revealed gallic acid 75.8 ± 0.21, protocatechuic acid 14.6 ± 0.5, chlorogenic acid 6.79 ± 0.43, and caffeic acid 5.34 ± 0.2 μg/ml. PE showed strong inhibitory activity of 73% at 200 μg/ml toward lipid peroxidation in egg lecithin, concentration-dependent inhibition of deoxyribose oxidation at 200 μg/ml was 85% inhibition, and considerable antioxidant activity in DPPH radical assay system at 200 μg/ml was 79% inhibition. BHA and gallic acid showed significant observations.Conclusion:The antioxidant potency significantly correlated with the phenolic content of PE. Considering that medicinal herbs contain potent phytochemicals, which is effectively utilized for various degenerative disease, these in vitro results showed that N. arbortristis leaves could be effectively employed in functional food, to alleviate oxidative stress.

Antioxidant effects of crude extracts from Baccharis species: inhibition of myeloperoxidase activity, protection against lipid peroxidation, and action as oxidative species scavenger

The objective of this study was to show a comparison of the antioxidant properties of aqueous and ethanolic extracts obtained from Baccharis articulata (Lam.) Pers., Baccharis trimera (Less.) DC., Baccharis spicata (Lam.) Baill. and Baccharis usterii Heering, Asteraceae, by several techniques covering a range of oxidant species and of biotargets. We have investigated the ability of the plant extracts to scavenge DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical, action against lipid peroxidation of membranes including rat liver microsomes and soy bean phosphatidylcholine liposomes by ascorbyl radical and peroxynitrite. Hydroxyl radical scavenger activity was measured monitoring the deoxyribose oxidation. The hypochlorous acid scavenger activity was also evaluated by the prevention of protein carbonylation and finally the myeloperoxidase (MPO) activity inhibition. The results obtained suggest that the Baccharis extracts studied present a significant antioxidant activity scavenging free radicals and protecting biomolecules from the oxidation. We can suggest that the supposed therapeutic efficacy of this plant could be due, in part, to these properties.

Antioxidant capacity of juice from different papaya (Carica papaya L.) cultivars grown under greenhouse conditions in Turkey

The fruits of Carica papaya L. (Caricaceae) are valuable as food and are also used in traditional medicine. The present study was designed to assess the antioxidant potential of the juices of 3 papaya cultivars (PCJ): Sunrise Solo, Red Lady, and Tainung. The antioxidant capacity of PCJ obtained from fully ripened fruit was determined by the following methods: scavenging of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), reducing power assay, scavenging of superoxide radicals, 2-deoxyribose oxidation assay, and thiocyanate assay. Total phenolic content (TPC) of PCJ was determined by the Folin-Ciocalteu method. In the DPPH assay (IC_{50} values), the effect of Sunrise Solo (52.1 ± 1.5 mL PCJ/g DPPH) was better than that of the Red Lady (63.4 ± 2.9 mL PCJ/g DPPH) and Tainung juices (71.8 ± 1.8 mL PCJ/g DPPH). PCJ showed a linoleic acid peroxide scavenging activity that was 5 times higher (during 72 h) than in the negative control but close to that of vitamin E, which served as the positive control. These PCJ antioxidant activities were significantly different from each other (P < 0.05). The tested reducing power activity, superoxide anion scavenging activity, and hydroxyl radical scavenging activity were found to follow the order of Sunrise Solo > Red Lady > Tainung, depending on their concentrations. This study demonstrated that different papaya cultivars have different antioxidant capacities and TPC amounts. Significant correlations were found between antioxidant capacity and TPC, indicating that phenols contribute to antioxidant capacity.

Brazilian Bidens pilosa Linné yields fraction containing quercetin-derived flavonoid with free radical scavenger activity and hepatoprotective effects

Bidens pilosa is a plant used by Amazonian and Asian folks for some hepatopathies. The hydroethanol crude extract and three fractions were assessed for antioxidant and hepatoprotective effects. Higher levels of scavenger activity on the 1,1-diphenyl-2-picrylhydrazyl radical, inhibition of deoxyribose oxidation and lipid peroxidation in vitro were detected for the ethyl acetate fraction (IC50∼4.3–32.3 µg/ml) followed by the crude extract (IC50∼14.2–98.0 µg/ml). The ethyl acetate fraction, again followed by the crude extract, showed high contents of total soluble polyphenols (3.6±0.2 and 2.1±0.2 GAE/mg, respectively) and presence of a quercetin-derived flavonoid identified as quercetin 3,3′-dimethyl ether 7-O-β-d-glycopyranoside. Both products were assayed for hepatoprotector effects against CCl4-induced liver injury in mice. Markers of oxidative stress and hepatic injury were evaluated. The results showed that the 10-day pretreatments (15 mg/kg, p.o.) protected the livers against injury by blocking CCl4-induced lipid peroxidation and protein carbonylation and the DNA fragmentation was decreased (∼60%). The pretreatments avoided the loss of the plasma ferric reducing/antioxidant power and the elevation of serum transaminases and lactate dehydrogenase activities. The results suggest that the main constituents responsible for the hepatoprotective effects with free radical scavenger power associated are well extracted by performing fractionation with ethyl acetate. The findings support the Brazilian traditional use of this plant and justify further evaluations for the therapeutic efficacy and safety of the constituents of the ethyl acetate fraction to treat some liver diseases.

Antioxidant effects of herbal extracts and their food application

Herbal extracts are considered as a good sources of antioxidant compounds. This work describes antioxidant effect of 15 kinds of herbs. Three different antioxidant assays were used, Trolox equivalent antiradical activity (TEAC), test based on deoxyribose oxidation and DPPH method. The TEAC values ranged from 0.38mM to 0.77 mM. Deoxyribose assay showed antioxidant activity of selected extracts expressed as the inhibition of formation of oxidative products of deoxyribose from 2.68 to 50.05 %. The DPPH method values ranged from 6.47 to 73.80 %. Extracts of Prunus spinosa L., Euphrasia rostkoviana Hayne were the best antioxidants confirmed by all methods. Scrophularia nodosa L. extract showed the weak antioxidant effect determined by all selected methods. Phenolic content was in relation to the antioxidant effect of herbs, very high significancy between DPPH and polyphenols content was found. To improve selected properties of apple juice (taste, smell, functional properties) by addition of medicinal herbs was achieved in this work. Antioxidant effect of apple juice variants with herbs additions determined by DPPH method was high and ranged from 73 to 78.49 %. Herbal extracts can be utilised in selected combinations to improve sensory and functional properties of some kinds of beverages.

What Fraction of DNA Double-Strand Breaks Produced by the Direct Effect is Accounted for by Radical Pairs?

The purpose of this investigation was to determine what fraction of double strand breaks (dsb's), generated by the direct effect of ionizing radiation on DNA, can be accounted for by radical pairs. A radical pair is defined as two radicals trapped within a separation distance of <3 nm. Q-band EPR was used to measure the yield of radical pairs in calf thymus DNA films X-irradiated at 4 K. The EPR spectrum of DNA showed no evidence of radical pairs. To determine the relative sensitivity for radical pair detection via Q-band EPR, we measured the yield of radical pairs in single crystals of thymine, G(rp-Thy). Under the same conditions employed for DNA, G(rp-Thy) was approximately 8 nmol/J. The value of G(rp-Thy), in conjunction with the measured signal-to-noise, was used to calculate an upper limit for the yield of radical pairs in DNA, G(max)(rp-DNA) < 0.7-1.4 nmol/J. The upper limit, G(max)(rp-DNA), was compared with the yield of dsb's, G(total)(dsb) = 10 nmol/J, previously measured in pUC18 DNA films by Purkayastha, S.; Milligan, J. R.; Bernhard, W. A. Radiat. Res. 2007, 168, 357. We found that G(total)(dsb) > 2 x G(max)(rp-DNA), implying that a significant fraction of dsb's were not derived from a pair of trappable radicals. At least one of the two precursors needed to form a dsb was a diamagnetic (molecular) product. The hypothesis is that EPR silent lesions are formed through a molecular pathway. For example, a two-electron oxidation of deoxyribose would result in a deoxyribose carbocation intermediate that ultimately leads to a strand break.

Quantification of the 2-Deoxyribonolactone and Nucleoside 5′-Aldehyde Products of 2-Deoxyribose Oxidation in DNA and Cells by Isotope-Dilution Gas Chromatography Mass Spectrometry: Differential Effects of γ-Radiation and Fe2+−EDTA

The oxidation of 2-deoxyribose in DNA has emerged as a critical determinant of the cellular toxicity of oxidative damage to DNA, with oxidation of each carbon producing a unique spectrum of electrophilic products. We have developed and validated an isotope-dilution gas chromatography-coupled mass spectrometry (GC-MS) method for the rigorous quantification of two major 2-deoxyribose oxidation products: the 2-deoxyribonolactone abasic site of 1'-oxidation and the nucleoside 5'-aldehyde of 5'-oxidation chemistry. The method entails elimination of these products as 5-methylene-2(5H)-furanone (5MF) and furfural, respectively, followed by derivatization with pentafluorophenylhydrazine (PFPH), addition of isotopically labeled PFPH derivatives as internal standards, extraction of the derivatives, and quantification by GC-MS analysis. The precision and accuracy of the method were validated with oligodeoxynucleotides containing the 2-deoxyribonolactone and nucleoside 5'-aldehyde lesions. Further, the well-defined 2-deoxyribose oxidation chemistry of the enediyne antibiotics, neocarzinostatin and calicheamicin gamma(1)(I), was exploited in control studies, with neocarzinostatin producing 10 2-deoxyribonolactone and 300 nucleoside 5'-aldehyde per 10(6) nt per microM in accord with its established minor 1'- and major 5'-oxidation chemistry. Calicheamicin unexpectedly caused 1'-oxidation at a low level of 10 2-deoxyribonolactone per 10(6) nt per microM in addition to the expected predominance of 5'-oxidation at 560 nucleoside 5'-aldehyde per 10(6) nt per microM. The two hydroxyl radical-mediated DNA oxidants, gamma-radiation and Fe(2+)-EDTA, produced nucleoside 5'-aldehyde at a frequency of 57 per 10(6) nt per Gy (G-value 74 nmol/J) and 3.5 per 10(6) nt per microM, respectively, which amounted to 40% and 35%, respectively, of total 2-deoxyribose oxidation as measured by a plasmid nicking assay. However, gamma-radiation and Fe(2+)-EDTA produced different proportions of 2-deoxyribonolactone at 7% and 24% of total 2-deoxyribose oxidation, respectively, with frequencies of 10 lesions per 10(6) nt per Gy (G-value, 13 nmol/J) and 2.4 lesions per 10(6) nt per microM. Studies in TK6 human lymphoblastoid cells, in which the analytical data were corrected for losses sustained during DNA isolation, revealed background levels of 2-deoxyribonolactone and nucleoside 5'-aldehyde of 9.7 and 73 lesions per 10(6) nt, respectively. Gamma-irradiation of the cells caused increases of 0.045 and 0.22 lesions per 10(6) nt per Gy, respectively, which represents a approximately 250-fold quenching effect of the cellular environment similar to that observed in previous studies. The proportions of the various 2-deoxyribose oxidation products generated by gamma-radiation are similar for purified DNA and cells. These results are consistent with solvent exposure as a major determinant of hydroxyl radical reactivity with 2-deoxyribose in DNA, but the large differences between gamma-radiation and Fe(2+)-EDTA suggest that factors other than hydroxyl radical reactivity govern DNA oxidation chemistry.