Use of nitroxide spin probes and electron paramagnetic resonance for assessing reducing power of beer. role of SH groups

Intensity of EPR spectra of stable organic free radicals, nitroxides, is decreasing with time if the radicals are dissolved in beer. The process is determined by a chemical reaction of nitroxide reduction by components naturally present in beer. Kinetics can be described as a simple irreversible first order with respect to both nitroxide and one reducing agent. Effective concentration of the reducing agent and the corresponding reaction rate constant has been determined. It is demonstrated that the nitroxide reduction is sensitive to the presence of solvent-accessible SH groups of proteins present in beer. It is proposed that quantitative analysis of reduction kinetics of small water-soluble nitroxide radicals such as TEMPO and TEMPOL can be used to assess the reducing power of beer. The effect of accelerated aging of beer achieved at elevated temperatures on nitroxide reduction kinetics is demonstrated.     

Evaluation of antioxidant and prooxidant activities of bamboo Phyllostachys nigra var. Henonis leaf extract in vitro

Solvent-extracted bamboo leaf extract (BLE) containing chlorogenic acid, caffeic acid, and luteolin 7-glucoside was evaluated in vitro for free radical scavenging and antioxidant activities using a battery of test methods. BLE exhibited a concentration-dependent scavenging activity of DPPH radical. BLE prolonged the lag phase and suppressed the rate of propagation of liposome peroxidation initiated by peroxyl radical induced by 2,2'-azobis(2-amidinopropane dihydrochloride (AAPH) at 37 degrees C. BLE also prevented human low-density lipoprotein oxidation, mediated by Cu(2+), which was monitored by the lower formation of conjugated diene and fluorescence and a reduced negative charge of apo-B protein. Finally, BLE protected supercoiled DNA strand against scission induced by AAPH-mediated peroxyl radical. Prooxidant activity of BLE was seen in a Cu(2+)-induced peroxidation of structured phosphatidylcholine liposome, indicating catalytic peroxidation due to a relatively high reducing power of BLE. It was concluded that the BLE has both antioxidant activity and prooxidant activity; the antioxidant activity was attributed to free radical scavenging activity, and the prooxidant activity, albeit minor, resulted from the reducing power of plant phenolics in the presence of transitional metal ions.     

Antioxidant activity of a combinatorial library of emulsifier-antioxidant bioconjugates

A combinatorial chemistry approach was employed for the design and systematic synthesis of antioxidant-emulsifier bioconjugates to improve antioxidant activity in the interface between oil and water. A combinatorial library of 12 bioconjugates was synthesized from the phenolic antioxidants Trolox (a water-soluble alpha-tocopherol analogue), dihydroferulic acid, dihydrocaffeic acid, and gallic acid in combination with serine ethyl ester, serine lauryl ester, and lauroyl serine by esterification of the serine side chain or amidation, respectively. The bioconjugates were characterized by NMR and mass spectrometry, and each was tested for antioxidant activity by measuring the radical scavenging rate of 2,2-diphenyl-1-picrylhydrazyl (DPPH (*)) in methanol, the radical scavenging rate of DPPH (*) in a heterogeneous solvent system, the rate of oxygen consumption in an oil-in-water emulsion with metmyoglobin initiated oxidation, and the lag phase for diene formation in unilamellar liposomes with free radical initiation in the aqueous phase; each case was compared to the antioxidant activity of the parent antioxidant. In general, the conjugates with longer chain derivatives exhibited improved antioxidative activity in heterogeneous systems, whereas no improvement was observed in homogeneous solution. The rate of oxygen consumption in oil-in-water emulsion was found to decrease with increasing octanol/water partition coefficient, which is suggested to correspond to a saturation of the water/oil interface with antioxidant bioconjugate to approach maximal protection.     

The chemistry behind antioxidant capacity assays

This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types: assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include the total phenols assay by Folin-Ciocalteu reagent (FCR), Trolox equivalence antioxidant capacity (TEAC), ferric ion reducing antioxidant power (FRAP), "total antioxidant potential" assay using a Cu(II) complex as an oxidant, and DPPH. In addition, other assays intended to measure a sample's scavenging capacity of biologically relevant oxidants such as singlet oxygen, superoxide anion, peroxynitrite, and hydroxyl radical are also summarized. On the basis of this analysis, it is suggested that the total phenols assay by FCR be used to quantify an antioxidant's reducing capacity and the ORAC assay to quantify peroxyl radical scavenging capacity. To comprehensively study different aspects of antioxidants, validated and specific assays are needed in addition to these two commonly accepted assays.     

β-carotene radical cation addition to green tea polyphenols. Mechanism of antioxidant antagonism in peroxidizing liposomes

Green tea polyphenols, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), all showed antioxidative effect in liposomes for lipid oxidation initiated in the lipid phase (antioxidant efficiency EC > EGCG > ECG > EGC) or in the aqueous phase (EC ? EGC > EGCG > ECG) as monitored by the formation of conjugated dienes. For initiation in the lipid phase, β-carotene, itself active as an antioxidant, showed antagonism with the polyphenols (EC > ECG > EGCG > EGC). The Trolox equivalent antioxidant capacity (TEAC EGC > EGCG > ECG > EC) correlates with the lowest phenol O-H bond dissociation enthalpy (BDE) as calculated by density functional theory (DFT). Surface-enhanced Raman spectroscopy (SERS) was used to assess the reducing power of the phenolic hydroxyls in corroboration with DFT calculations. For homogeneous (1:9 v/v methanol/chloroform) solution, the β-carotene radical cation reacted readily with each of the polyphenol monoanions (but not with the neutral polyphenols) with a rate approaching the diffusion limit for EC as studied by laser flash photolysis at 25 °C monitoring the radical cation at 950 nm. The rate constant did not correlate with polyphenol HOMO/LUMO energy gap (DFT calculations), and β-carotene was not regenerated by an electron transfer reaction (monitored at 500 nm). It is suggested that the β-carotene radical cation is rather reacting with the tea polyphenols through addition, as further evidenced by steady-state absorption spectroscopy and liquid chromatography-mass spectroscopy (LC-MS), in effect preventing regeneration of β-carotene as an active lipid phase antioxidant and leading to the observed antagonism.     

Voltammetric assay for the aging of beer

A new method for the evaluation of beer aging, based on a voltammetric analysis of beer distillates, is described. By measuring the current of both acetaldehyde and sulfite voltammetric peaks it is possible to distinguish between fresh, naturally aged, and artificially aged beers. The results obtained for the ratio of acetaldehyde and SO(2) currents correlate well with those given by an expert sensory panel. The kinetics of the combining reaction of sulfite with acetaldehyde was followed for different acetaldehyde/SO(2) molar ratios by using a programmed voltammetric procedure. The formation of an acetaldehyde-sulfite adduct is rapid, and the reaction equilibrium is reached after 30 min, which is in accordance with the results previously obtained by other methods. This voltammetric-based approach seems to be a new attractive tool for detecting chemical equilibria of the addition of sulfite to carbonyls in beer model systems.     

Kinetic model for the antiradical activity of the isolated p-catechol group in flavanone type structures using the free stable radical 2,2-diphenyl-1-picrylhydrazyl as the antiradical probe

The time evolution of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) concentration in four solvents (methanol, ethanol, propanol, and acetonitrile) during its reduction by three flavanones containing an isolated p-catechol group (taxifolin, eriodyctiol, and fustin) as well as the time evolution of the mass spectra of the reaction mixture has been determined by spectrophotometry and liquid mass spectrometry, respectively. In alcoholic solvents the reduction curves consisted of an initial short but fast kinetics step followed by a longer slow kinetics step; in contrast, in acetonitrile the reduction curves completely lacked the slow kinetics step. From the results, a kinetic model for the reaction of reduction of the DPPH* by the isolated p-catechol group in flavanone type structures is proposed. According to this model, the p-catechol group rapidly transfers two hydrogen atoms to DPPH*, through a fast rate constant k1, yielding the corresponding o-quinone. Then, the intermediate o-quinone forms an adduct with the alcoholic solvent, through a slow rate constant k2, and regenerates the p-catechol group. The regenerated p-catechol group reduces additional DPPH* through a fast rate constant k3, yielding the corresponding o-quinone, which can form a new adduct with the solvent to regenerate the p-catechol group, and so on. From the kinetics model, two explicit kinetics equations have been derived that fit very well the experimental data points acquired from all assayed compounds in all of the experiments carried out, thus allowing an accurate determination of the corresponding rate and stoichiometric constants.     

In vitro antioxidant activity and antigenotoxicity of 5-n-alkylresorcinols

Incubation with 5-n-alkylresorcinols (chain lengths C15:0, C17:0, C19:0, C21:0, and C23:0) increased the self-protection capacity of HT29 human colon cancer cells against DNA damage induced by hydrogen peroxide and genotoxic fecal water samples using comet assay (single-cell gel electrophoresis assay). The alkylresorcinols did not exert potent antioxidant activity in the FRAP (ferric reduction ability of plasma) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical assays. However they were able to significantly inhibit copper-mediated oxidation of human LDL (low-density lipoprotein) in vitro, and pentadecylresorcinol at 25 micromol/L increased lag time by 65 min. The results show that alkylresorcinols have antigenotoxic and antioxidant activity under in vitro conditions.     

Antioxidant effects of water extracts from barley (Hordeum vulgare L.) prepared under different roasting temperatures

The antioxidant effects of water extracts of roasted barley (WERB) were investigated under different roasting temperatures and compared with those of the water extracts of unroasted barley (WEUB). It was found that the Maillard reaction products increased upon increasing the roasting temperatures. Both WERB and WEUB exhibited significant antioxidant activities in linoleic acid and liposome model systems. Although WERB and WEUB afforded considerable protection against the damage of deoxyribose and proteins, the antioxidant efficiency of roasted samples was weaker than that of unroasted samples because of the reduction of antioxidant components (catechin, tocopherol, and lutein) with increasing roasting temperature. Unroasted samples were more effective in reducing power, quenching free radical, hydroxyl radical, and chelating iron than the roasted samples. The different antioxidant activity among roasted and unroasted barley samples may be partly attributed to the changes in catechin, tocopherol, and lutein contents.     

High-throughput quantitation of peroxyl radical scavenging capacity in bulk oils

Autoxidation of methyl linoleate (8:2 mixture with decane, 37 degrees C) was induced by 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN, 17.7 mM) and the kinetics of oxygen consumption monitored using a 96-well microplate coated with an oxygen-sensitive fluorescence probe, a ruthenium dye, embedded in a silicone matrix at the bottom of the microplate. The probe does not participate in the reaction; instead, its fluorescence intensity is inversely proportional to the solution oxygen concentration as it changes during oxidation. In the absence of antioxidants, the oxidation rate has a linear relationship with the square root of the initiator concentrations. This is in agreement with theoretical autoxidation kinetics equations. In the presence of tocopherol-type antioxidants, a sharp lag phase appears. The quantitation of the antioxidant capacity is achieved using the area under the curve (AUC) approach. The assay has a 2 h running time, a linearity range from 1.56 to 18.7 microM (Trolox), and a limit of quantitation at 2.7 microM Trolox equivalency. The peroxyl radical scavenging capacities of several cold-pressed and organically grown plant seed oils were quantified along with the tocopherol concentrations of the oils. Tocopherols contribute only a fraction of the peroxyl radical scavenging capacity of the oils, and there is poor correlation between total tocopherol concentrations and radical scavenging capacity, suggesting that the antioxidant capacity of oils is due not only to tocopherols but also to other lipid-soluble antioxidants.     

Oxidative degradation of lipids during mashing

Although hardly any polyunsaturated fatty acids (PUFAs) are present in the endproduct, the ingredients used for the production of beer contain a high concentration of PUFAs, such as linolic and linolenic acid. These compounds are readily oxidized, resulting in the formation of lipid-derived products that reduce the taste and quality of beer enormously. During mashing relatively high amounts of PUFAs are exposed to atmospheric oxygen at a relatively high temperature. This makes mashing a critical step in the brewing process with regard to the formation of lipid-derived off-taste products. F1 phytoprostane (PPF1) changes in antioxidant capacity and monohydroxy fatty acids (OH-FAs) were used as markers for the detection of oxidative damage to fatty acids during mashing. The pattern of OH-FA formation indicates that enzymatic oxidation of PUFAs is more important than nonenzymatic oxidation during the mashing process. Nevertheless, substantial nonenzymatic radical formation is evident from the increase of specific OH-FAs and PPF1s. It was found that a low oxygen tension reduces oxidative damage and gives a high antioxidant capacity of the mashing mixture. This indicates that mashing should be done under low oxygen pressure.     

茶叶添加方式对酿造啤酒理化特性及感官品质的影响

在啤酒酿造工艺的煮沸和主发酵阶段分别添加乌龙茶,探讨茶叶不同添加方式对啤酒理化特性、抗氧化能力、啤酒贮存稳定性以及感官特性的影响。结果显示,与未添加茶叶的啤酒产品（对照组CG）相比,在煮沸阶段（煮沸添加组BG）和主发酵阶段（主发酵添加组MG）分别添加0.3 g/L的茶叶均提高了酵母发酵速率;添加茶叶的两个茶啤酒产品（煮沸添加组和主发酵添加组）的DPPH自由基清除能力分别提升至82.74%和89.21%、ABTS+自由基清除能力分别提升至41.53%和51.49%、铁离子还原能力分别提升至36.49和43.83 mg/L,且成品茶啤酒贮藏期间的抗老化能力提高;茶啤酒中总酚以及儿茶素（EGC、C、EGCG、EC、GCG、ECG）和咖啡碱（CAF）含量升高,其中,主发酵添加组茶啤酒样品总酚和EGCG含量显著高于对照组和煮沸添加组啤酒（P<0.05）,分别达到734.40和8.43 mg/L。进一步的感官品评结果显示添加茶叶提高了啤酒产品的茶香气和茶滋味,其中主发酵添加组啤酒的茶香气、茶滋味及酒体协调性最好。由此可知,在啤酒酿造工艺中添加茶叶提高了酵母发酵速率,增强了啤酒中酚类物质含量及其抗氧化和抗老化性能,同时也为啤酒增添了新的茶风味产品。     

Antioxidative activity of protein hydrolysates prepared from alkaline-aided channel catfish protein isolates

Antioxidative activity of hydrolyzed protein prepared from alkali-solubilized catfish protein isolates was studied. The isolates were hydrolyzed to 5, 15, and 30% degree of hydrolysis using the protease enzyme, Protamex. Hydrolyzed protein was separated into hydrolysates and soluble supernatants, and both of these fractions were studied for their metal chelating ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and their ability to inhibit the formation of thiobarbituric acid reactive substances (TBARS) in washed tilapia muscle containing tilapia hemolysate. Both hydrolysates and supernatants were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results showed that DPPH radical scavenging ability and reducing power of catfish protein hydrolysates decreased, whereas the ORAC value, metal chelating ability, and ability to inhibit TBARS increased, with an increase in the degree of hydrolysis. Hydrolysate samples showed higher DPPH radical scavenging ability and Fe(3+) reducing ability, and supernatant samples had higher metal chelating ability. In general, low molecular weight (MW) peptides had high ORAC values and high metal chelating ability, and high MW peptides had a higher reducing power (FRAP) and were more effective in scavenging DPPH radicals. In a washed muscle model system, the ability of catfish protein hydrolysates and their corresponding supernatants to inhibit the formation of TBARS increased with an increase in the degree of hydrolysis.     

Antioxidant activity of oregano, parsley, and olive mill wastewaters in bulk oils and oil-in-water emulsions enriched in fish oil

The antioxidant activity of oregano, parsley, olive mill wastewaters (OMWW), Trolox, and ethylenediaminetetraacetic acid (EDTA) was evaluated in bulk oils and oil-in-water (o/w) emulsions enriched with 5% tuna oil by monitoring the formation of hydroperoxides, hexanal, and t-t-2,4-heptadienal in samples stored at 37 degrees C for 14 days. In bulk oil, the order of antioxidant activity was, in decreasing order (p < 0.05), OMWW > oregano > parsley > EDTA > Trolox. The antioxidant activity in o/w emulsion followed the same order except that EDTA was as efficient an antioxidant as OMWW. In addition, the total phenolic content, the radical scavenging properties, the reducing capacity, and the iron chelating activity of OMWW, parsley, and oregano extracts were determined by the Folin-Ciocalteau, oxygen radical absorbance capacity, ferric reducing antioxidant power, and iron(II) chelating activity assays, respectively. The antioxidant activity of OMWW, parsley, and oregano in food systems was related to their total phenolic content and radical scavenging capacity but not to their ability to chelate iron in vitro. OMWW was identified as a promising source of antioxidants to retard lipid oxidation in fish oil-enriched food products.     

Kinetic model for studying the effect of quercetin on cholesterol oxidation during heating

Inhibition of the heat-induced cholesterol oxidation at 150 degrees C by incorporation of quercetin was kinetically studied. Results showed that without quercetin, the cholesterol oxidation products (COPs) concentration increased with increasing heating time. A low amount (0.002%, w/w) of quercetin was effective in inhibiting the formation of COPs during the initial heating period (< or =30 min) at 150 degrees C. However, after prolonged heating (30-120 min), a low antioxidant activity was observed because of the degradation of quercetin. When using nonlinear regression models for kinetic study of cholesterol oxidation in the absence of quercetin, the epoxidation showed the highest rate constant (h(-1) = 683.1), followed by free radical chain reaction (h(-1) = 453.5), reduction (h(-1) = 290.3), dehydration (h(-1) = 155.5), triol dehydrogenation (h(-1) = 5.35), dehydrogenation (h(-1) = 0.68), thermal degradation (h(-1) = 0.66), and triol formation (h(-1) = 0.38). However, in the presence of quercetin, the reaction rate constants (h(-1)) for epoxidation (551.4), free radical chain reaction (111.7), and thermal degradation (0.28) were reduced greatly. The kinetic model developed in this study can be used to predict the inhibition of COPs by quercetin during the heating of cholesterol.     

Effects of processing steps on the phenolic content and antioxidant activity of beer

A new analytical method (liquid chromatography-antioxidant, LC-AOx) was used that is intended to separate beer polyphenols and to determine the potential antioxidant activity of these constituents after they were allowed to react online with a buffered solution of the radical cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(?+)). Using the LC-AOx method, it was possible to demonstrate that the extent of the antioxidant activity was very much dependent on the phenolic compound considered. The method was also applied to the analysis of beer extracts and allowed the evaluation of their antioxidant activity at different steps of beer processing: brewing, boiling, and fermentation. This study showed that the total antioxidant activity remained unchanged throughout beer processing, as opposed to the polyphenolic content, which showed a 3-fold increase. Hopping and fermentation steps were the main causes of this increase. However, the increase measured after fermentation was attributed to a better extraction of polyphenols due to the presence of ethanol, rather than to a real increase in their content. Moreover, this method allowed the detection of three unknown antioxidant compounds, which accounted for 64 ± 4% of the total antioxidant activity of beer and were individually more efficient than caffeic acid and epicatechin.     

广东石豆兰不同溶剂提取物抗氧化及与总黄酮、总酚含量的关系

为明确广东石豆兰的抗氧化能力及抗氧化成分,以鳞茎为材料,以甲醇、乙醇、丙酮和乙酸乙酯为提取剂得到4种提取物,测定了4种提取物中总黄酮、总酚含量及其抗氧化活性,并分析了两者之间的关系。结果表明,石豆兰总酚含量高于总黄酮,乙醇为总酚和总黄酮2种物质的最佳提取溶剂;甲醇提取物对羟基自由基清除力和对Fe²⁺的螯合力最强,对DPPH自由基清除效果最差;丙酮提取物具有最强的总还原力和清除超氧阴离子的能力,而清除羟基自由基能力最弱;乙酸乙酯提取物清除DPPH自由基的能力最强,但总还原力、清除超氧阴离子的能力、Fe²⁺的螯合力最弱。此外,除了DPPH自由基外,其他4个抗氧化指标与总黄酮或总酚含量呈正相关(0.185相似文献   

Reactivity of beer bitter acids toward the 1-hydroxyethyl radical as probed by spin-trapping electron paramagnetic resonance (EPR) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS)

The iso-α-acids or isohumulones are the major contributors to the bitter taste of beer, and it is well-recognized that they are degraded during beer aging. In particular, the trans-isohumulones seem to be less stable than the cis-isohumulones. The major radical identified in beer is the 1-hydroxyethyl radical; however, the reactivity between this radical and the isohumulones has not been reported until now. Therefore, we studied the reactivity of isohumulones toward the 1-hydroxyethyl radical through a competitive kinetic approach. It was observed that both cis- and trans-isohumulones and dihydroisohumulones are decomposed in the presence of 1-hydroxyethyl radicals, while the reactivities are comparable. On the other hand, the tetrahydroisohumulones did not react with 1-hydroxyethyl radicals. The apparent second-order rate constants for the reactions between the 1-hydroxyethyl radical and these compounds were determined by electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization-tandem mass spectrometry [ESI(+)-MS/MS]. It follows that degradation of beer bitter acids is highly influenced by the presence of 1-hydroxyethyl radicals. The reaction products were detected by liquid chromatography-electrospray ionization-ion trap-tandem mass spectrometry (LC-ESI-IT-MS/MS), and the formation of oxidized derivatives of the isohumulones was confirmed. These data help to understand the mechanism of beer degradation upon aging.     

Studies on the antioxidant activity of Echinacea root extract

Methanol extracts of freeze-dried Echinacea (E. angustifolia, E. pallida, and E. purpurea) roots were examined for free radical scavenging capacities and antioxidant activities. Root extracts of E. angustifolia, E. pallida, and E. purpurea were capable of scavenging hydroxyl radical. Similar scavenging activities for each variety were found for both 1,1-diphenyl-2-picrylhydrazyl radical and ABTS radical. Meanwhile, antioxidant activities of all three varieties of Echinacea were found to delay the formation of conjugated diene hydroperoxide induced by the thermal decomposition of 2, 2'-azobis(2-amidinopropane) dihydrochloride and extend the lag phase of peroxidation of soybean liposomes. Echinacea root extracts suppressed the oxidation of human low-density lipoprotein, as evaluated by reduced agarose electrophoretic mobility following oxidative modification by Cu(2+). The mechanisms of antioxidant activity of extracts derived from Echinacea roots included free radical scavenging and transition metal chelating.     

Inhibition of induced DNA oxidative damage by beers: correlation with the content of polyphenols and melanoidins

Beers are a source of dietary flavonoids; however, there exist differences in composition, alcohol concentration, and beneficial activities. To characterize these differences, three kinds of lager beer of habitual consumption in Spain, dark, blond, and alcohol-free, were assayed for total phenolic content, antioxidant activity, superoxide and hydroxyl radical scavenging activities, and in vitro inhibitory effect on DNA oxidative damage. Furthermore, their melanoidin content and correlation with antioxidant activity were evaluated. Dark beer contained the highest total phenolic (489 +/- 52 mg/L) and melanoidin (1.49 +/- 0.02 g/L) contents with a 2-fold difference observed when compared to the alcohol-free beer. For the three kinds of beer, the antioxidant activity measured as N,N-dimethyl-p-phenylenediamine dihydrochloride concentration was strongly correlated with the total polyphenol content (R(2) = 0.91102, p < 0.005) and with the melanoidin content (R(2) = 0.7999, p < 0.05). The results support a positive effect of beers on the protection of DNA oxidative damage, by decreasing the deoxyribose degradation, DNA scission (measured by electrophoresis), and inhibition of 8-hydroxydeoxyguanosine (8-OH-dG) formation. Furthermore, a correlation between the total melanoidin content (R(2) = 0.7309, p < 0.01) and inhibition of 8-OH-dG was observed.