The role of metal ion binding in generating 8-hydroxy-2'-deoxyguanosine from the nucleoside 2'-deoxyguanosine and the nucleotide 2'-deoxyguanosine-5'-monophosphate

The metal ions Cu(II), Fe(II), and Cr(III) were allowed to react with H(2)O(2) in the presence of either the mononucleoside 2'-deoxyguanosine (dG) or the mononucleotide 2'-deoxyguanosine-5'-monophosphate (dGMP). The percentage of reacted dG or dGMP that formed the oxidative damage marker 8-hydroxy-2'-deoxyguanosine (8-OH-dG) was monitored. Oxidative damage from reactions involving Cu(II) appear dependent on an interaction between copper and N7 on the guanine base. Any interactions involving the phosphate group have little additional effect on overall oxidative damage or 8-OH-dG production. Reactions involving Fe(II) seem very dependent on an interaction that may involve both N7 on the guanine base and the phosphate group. This interaction may slow oxidation of Fe(II) to Fe(III) in solution, keeping iron in a readily available form to undergo the Fenton reaction. Chromium(III) appears to interact with the phosphate group of dGMP, resulting in significant overall oxidative damage. However, production of 8-OH-dG appears to be very dependent on the ability of Cr(III) to interact with N7 on the guanine base, an interaction that seems to be weak for both the mononucleoside and mononucleotide.     

Determination of 8-oxoguanine and 8-hydroxy-2'-deoxyguanosine in the rat cerebral cortex using microdialysis sampling and capillary electrophoresis with electrochemical detection

A rapid and sensitive method to determine 8-oxoguanine (8oxoG) and 8-hydroxydeoxyguanosine (8OHdG), biomarkers for oxidative DNA damage, in cerebral cortex microdialysate samples using capillary electrophoresis (CE) with electrochemical detection (CEEC) was developed. Samples were concentrated on-column using pH-mediated stacking for anions. On-column anodic detection was performed with a carbon fiber working electrode and laser-etched decoupler. The method is linear over the expected extracellular concentration range for 8oxoG and 8-OHdG during induced ischemia-reperfusion, with R.S.D. values 相似文献   

Assay for the determination of urinary 8-hydroxy-2′-deoxyguanosine by high-performance liquid chromatography with electrochemical detection

A high-performance liquid chromatographic procedure with electrochemical detection is described for the determination of urinary 8-hydroxy-2′-deoxyguanosine, a major oxidative DNA lesion induced by radical forming agents. A two-step solid-phase extraction procedure was followed for extracting 8-hydroxy-2′-deoxyguanosine from human urine and the analysis was performed on a RP-18 analytical column under isocratic conditions. The limit of detection of 8-hydroxy-2′-deoxyguanosine in urine was found to be 0.9 nM. The non-invasive assay provides an indirect measurement of oxidative DNA damage.     

Controlled oxidation of calf thymus DNA to produce standard samples for 8-Oxodeoxyguanosine analysis; Effects of freeze-drying,storage and hydrolysis conditions

Calf thymus DNA containing defined levels of 8-hydroxy-2′-deoxyguanosine (8-oxodG) was prepared by treatment with visible light in the presence of photosensitiser Ro 19-8022. The DNA was checked for stability; after freeze-drying, the amount of 8-oxodG did not increase during 6 weeks' storage at room temperature. However, freeze-drying itself can introduce additional oxidative damage. Two enzymic hydrolysis regimes (DNase I, phosphodiesterases I and II, and alkaline phosphatase; or P1 nuclease and alkaline phosphatase) give similar values for 8-oxodG.     

Spaciotemporal alteration of 8-hydroxy-2'-deoxyguanosine levels in cardiomyocytes after myocardial infarction in rats

Temporary or persistent heart failure is one of the major complications after myocardial infarction (MI). In order to elucidate the pathogenesis of MI, we studied the spaciotemporal alteration of 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in cardiomyocytes in a rat model of ligation of the left anterior descending branch of the coronary artery. The lethality in this model was 18%. Hearts were dissected at 0, 3, 6, 12, 24, 48 h, and 1, 2, 4, 6 weeks after the operation. The cardiac level of 8-OHdG was evaluated biochemically as well as by immunohistochemistry with monoclonal antibody N45.1. Three to 6 h after ligation, the 8-OHdG levels were increased in the cardiomyocytes of MI (six-fold) and peri-MI (four-fold) areas. After 24 h, the myocardium in the MI area was necrotized, and thereafter the 8-OHdG level decreased. 8-OHdG levels in the myocardium of peri-MI areas returned once to a normal level, but were significantly increased at 2-4 weeks along with the appearance of apoptotic cardiomyocytes in this area. The heart after MI has been generally considered as clinically stable after four weeks. However, cardiomyocytes near the infarcted area were oxidatively stressed even after four weeks when the affected lesion was extensive. The present data support the use of supplementary antioxidant therapies to save functional myocardium after MI. (213 words)     

Neopterin, a marker of immune response, and 8-hydroxy-2'-deoxyguanosine, a marker of oxidative stress, correlate at high age as determined by automated simultaneous high-performance liquid chromatography analysis of human urine

Using an established high-performance liquid chromatography (HPLC) method based on anion exchange chromatography, fraction collection, and electrochemical detection, the oxidative DNA damage marker 8-hydroxy-2′-deoxyguanosine (8-OH-dG) can be analyzed rapidly and precisely in human urine samples. In addition, by ultraviolet (UV) detection, it was shown recently that it is possible to simultaneously analyze creatinine and 7-methylguanine (m⁷Gua), an RNA degradation product, in urine. By adding a fluorescence detector to the HPLC system, we now report that it is also possible to detect pteridins such as neopterin and biopterin. The fluorescence detection was evaluated in detail for neopterin, an immune response and tumor marker. The urinary content of neopterin, assessed by using the HPLC method, was verified with a commercial neopterin enzyme-linked immunosorbent assay (ELISA) kit as indicated by the high correlation between the two methods (r = 0.98). In urinary samples from 58 young healthy individuals (male and female nonsmokers, ages 19-39 years), it was found that there was no significant correlation (r = −0.04) between the levels of 8-OH-dG and neopterin (as normalized to urinary creatinine levels). In contrast, in urinary samples from 60 old healthy individuals (male and female nonsmokers, ages 60-86 years), there was a significant correlation (r = 0.47) found between the levels of 8-OH-dG and neopterin (as normalized to urinary creatinine levels). These findings strongly indicate that the higher level of immune response that was correlating with old age contributes significantly to the higher level of oxidative damage as assessed in the form of 8-OH-dG. Using this type of HPLC system, it is possible to evaluate oxidative DNA damage and immune response simultaneously using the respective urinary markers. These data may contribute to understanding of the pathophysiology of diseases such as infections and tumor progression where both oxidative stress and immune response occur simultaneously.     

Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a reliable oxidative stress marker in hypertension

The potential use of oxidative stress products as disease markers and progression is an important aspect of biomedical research. In the present study, the quantification of urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) concentration has been used to express the oxidation status of hypertensive subjects.

8-oxo-dG has been simultaneously isolated and assayed in nuclear (nDNA) and mitochondrial DNA (mtDNA). In addition, oxidative stress of mononuclear cells has been estimated by means of GSH and GSSG levels and GSSG/GSH ratio in hypertensive subjects before and after antihypertensive treatment. It is shown that oxidative stress decreases significantly in hypertensive patients after treatment the effect being accompanied by reduction of their blood pressure.

A significant correlation is observed comparing the yield of urine 8-oxo-dG and that isolated from mitochondria DNA. Moreover, urinary excretion of 8-oxo-dG also correlates with the GSSG/GSH ratio of cells. Conclusion: urine 8-oxo-dG assay is a good marker for monitoring oxidative stress changes in hypertensives.     

Markers of macromolecular oxidative damage in maternal serum and risk of neural tube defects in offspring

Neural tube defects (NTDs) are among the most common and severe congenital malformations. To examine the association between markers of macromolecular oxidative damage and risk of NTDs, we measured levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), protein carbonyl (PC), and 8-iso-prostaglandin F2α (8-iso-PGF2α) in maternal serum samples of 117 women with NTD-affected pregnancies and 121 women with healthy term newborns. We found higher levels of 8-OHdG and PC in the NTD group than in the control group; however, we did not observe a statistically significant difference in 8-iso-PGF2α levels between the NTD and the control groups. NTD risk increased with increasing quartiles of 8-OHdG [odds ratio (OR)=1.17; 95% confidence interval (CI) 0.39–3.51; OR=2.19; 95% CI, 0.68–7.01; OR=3.70; 95% CI, 1.30–10.51, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.009], and with increasing quartiles of PC (OR=2.26; 95% CI, 0.66–7.69; OR=3.86; 95% CI, 1.17–12.80; OR=5.98; 95% CI, 1.82–19.66, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.002]. Serum levels of 8-OHdG were higher in women who did not take folic acid supplements during the periconceptional period. These results suggest that oxidative stress is present in women carrying pregnancies affected by NTDs.     

Anti-inflammatory effects of 8-hydroxy-2'-deoxyguanosine on lipopolysaccharide-induced inflammation via Rac suppression in Balb/c mice

Recently, we observed that 8-hydroxyguanosine triphosphate and 8-hydroxy-2′-deoxyguanosine (oh⁸dG) inactivate Rac and consequently down-regulate the Rac-linked NADPH oxidase, iNOS, and Cox2. Based on these observations, we tested whether oh⁸dG has anti-inflammatory activity in vivo in lipopolysaccharide (LPS)-treated mice. LPS (1 mg/kg, ip)-treated mice exhibit marked inflammatory responses, including increases in proinflammatory cytokines (TNF-, IL-6, IL-18, and IL-12p70) in serum and infiltration of neutrophils, increased translocation of NF-κB p50 from the cytosol to the nucleus, and phosphorylation of c-Jun in lung tissues. Mice were pretreated with oh⁸dG (up to 60 mg/kg, ip) 4 h before LPS injection, and this pretreatment dose-dependently inhibited the inflammatory responses; the inhibitions observed with 60 mg/kg oh⁸dG were statistically significant. At the same time, oh⁸dG pretreatment inactivated Rac in lung tissues. Oh⁸dG pretreatment (50 mg/kg, ip) also significantly protected against LPS-induced septic death. Furthermore, oh⁸dG was more effective than acetyl salicylic acid in inhibiting these inflammatory responses. 8-Hydroxyguanosine also had some effect but was much weaker than oh⁸dG. The effects of normal nucleosides (dG, G, and A) were negligible or not significant. These results support an anti-inflammatory activity for oh⁸dG, which could be ascribed to its Rac-inactivating action.     

Comparison of different methods of measuring 8-oxoguanine as a marker of oxidative DNA damage

We are attempting to resolve some of the problems encountered in measuring 8-hydroxy-2′-deoxyguanosine (8-oxodG) in human cellular DNA as a marker of oxidative stress. Samples of authentic 8-oxodG were distributed, and participating laboratories undertook to analyse this material within a specified period. Most HPLC procedures gave values for 8-oxodG within ±40% of the target, as did two of four GC-MS procedures, and both LC-MS-MS methods. Calf thymus DNA samples containing increasing amounts of 8-oxodG were also distributed for analysis. Fewer than half the procedures tested were able to detect the dose response; those that were successful tended to be procedures with low coefficients of variation. For the analysis of 8-oxodG in human cells, where it is likely to be present at much lower concentrations than in the calf thymus DNA, it is crucial to reduce analytical variation to a minimum; a coefficient of variation of less than 10% should be the aim, to give reasonable precision. HPLC with amperometric electrochemical detection is not recommended, as it is less sensitive than coulometric detection. Immunological detection, ³²P-postlabelling and LC-MS-MS are alternative approaches to measurement of 8-oxodG in DNA that, on the grounds of precision and detection of dose response, cannot at present be recommended.     

Evaluation of enzyme-linked immunosorbent assay and liquid chromatography-tandem mass spectrometry methodology for the analysis of 8-oxo-7,8-dihydro-2'-deoxyguanosine in saliva and urine

While ELISA is a frequently used means of assessing 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) in biological fluids, differences in baseline urinary 8-oxodG levels, compared to chromatographic techniques, have raised questions regarding the specificity of immunoassays. Recently, ELISA of salivary 8-oxodG has been used to report on periodontal disease. We compared salivary 8-oxodG levels, determined by two commercial ELISA kits, to liquid chromatography-tandem mass spectrometry (LC-MS/MS) with prior purification using solid-phase extraction. While values were obtained with both ELISA kits, salivary 8-oxodG values were below or around the limit of detection of our LC-MS/MS assay. As the limit of detection for the LC-MS/MS procedure is much lower than ELISA, we concluded that the assessment of salivary 8-oxodG by ELISA is not accurate. In contrast to previous studies, ELISA levels of urinary 8-oxodG (1.67 ± 0.53 pmol/μmol creatinine) were within the range reported previously only for chromatographic assays, although still significantly different than LC-MS/MS (0.41 ± 0.39 pmol/μmol creatinine; p = 0.002). Furthermore, no correlation with LC-MS/MS was seen. These results question the ability of ELISA approaches, at present, to specifically determine absolute levels of 8-oxodG in saliva and urine. Ongoing investigation in our laboratories aims to identify the basis of the discrepancy between ELISA and LC-MS/MS.     

Fast quantification of the urinary marker of oxidative stress 8-hydroxy-2′-deoxyguanosine using solid-phase extraction and high-performance liquid chromatography with triple-stage quadrupole mass detection

Exogenous and endogenous oxidants constantly cause oxidative damage to DNA. Since the reactive oxidants itself are not suitable for analysis, oxidized bases like 8-hydroxy-2′-deoxyguanosine (8OHdG) are used as biomarkers for oxidative stress, either in cellular DNA or as elimination product in urine. A simple, fast and robust analytical procedure is described for urinary 8OHdG as an indicator of oxidative damage in humans. The adduct was purified from human urine by applying a single solid-phase extraction step on LiChrolut EN^®. After evaporation of the eluate, the residue was resolved and an aliquote was injected into a HPLC system with a triple quadrupole mass spectrometer. The limit of detection was 0.2 ng ml⁻¹ (7 fmol absolute) when using one product ion as quantifier and two further product ions as qualifier. The coefficient of variation was 10.1% (n=5 at 2.8 ng ml⁻¹ urine). The sample throughput was about 50 samples a day. Thus, this method is more sensitive and much faster than the common method using HPLC with electrochemical detection. The results of a study with nine volunteers investigated at six time-points each over 5 days are presented. The mean excretion of 8OHdG was 2.1 ng mg⁻¹ creatinine (range 0.17–5.9 ng mg⁻¹ creatinine; 4 of 53 samples were below the LOD). A relatively large intra- (relative SD 66%) and inter-individual (relative SD 71%) variation in urinary 8OHdG excretion rates was found.     

Simultaneous determination of 8-hydroxy-2′-deoxyguanosine and 5-methyl-2′-deoxycytidine in DNA sample by high performance liquid chromatography/positive electrospray ionization tandem mass spectrometry

8-Hydroxy-2′-deoxyguanosine (8-OHdG) and 5-methyl-2′-deoxycytidine (5-mdC) are utilized as useful biomarkers not only for early diagnosis but also for the detection and assessment of high-risk individuals. In the present study, a sensitive and specific method was developed for simultaneous determination of 8-OHdG and 5-mdC in DNA by high performance liquid chromatography/positive electrospray ionization tandem mass spectrometry. The limits of quantification for 8-OHdG and 5-mdC were 80 and 40 pg/ml, respectively. The calibration curves of 8-OHdG and 5-mdC were linear over the concentration range of 0.02–100 ng/ml and the correlation coefficients were higher than 0.9990. The intra-day and inter-day relative standard derivative values were in the range of 0.70–7.47% for 8-OHdG and 1.07–7.06% for 5-mdC, respectively. The recoveries were 93.4–108.5% for 8-OHdG and 87.4–104.9% for 5-mdC, respectively. This method was validated by determination of the background levels of 8-OHdG and 5-mdC in calf thymus DNA, and satisfactory results were obtained.     

Solution structure of a DNA duplex containing 8-hydroxy-2'-deoxyguanosine opposite deoxyguanosine

Deoxyguanosine residues are hydroxylated by reactive oxygen species at the C-8 position to form 8-hydroxy-2'-deoxyguanosine (8-OG), one of the most important mutagenic lesions in DNA. Though the spontaneous G:C to C:G transversions are rare events, the pathways leading to this mutation are not established. An 8-OG:G mispair, if not corrected by DNA repair enzymes, could lead to G:C to C:G transversions. NMR spectroscopy and restrained molecular dynamics calculations are used to refine the solution structure of the base mismatch formed by the 8-OG:G pair on a self complementary DNA dodecamer duplex d(CGCGAATT(8-O)GGCG)(2). The results reveal that the 8-OG base is inserted into the helix and forms Hoogsteen base-pairing with the G on the opposite strand. The 8-OG:G base-pairs are seen to be stabilized by two hydrogen bonding interactions, one between the H7 of the 8-OG and the O6 of the G, and a three-center hydrogen bonding between the O8 of the 8-OG and the imino and amino protons of the G. The 8-OG:G base-pairs are very well stacked between the Watson-Crick base-paired flanking bases. Both strands of the DNA duplex adopt right-handed conformations. All of the unmodified bases, including the G at the lesion site, adopt anti glycosidic torsion angles and form Watson-Crick base-pairs. At the lesion site, the 8-OG residues adopt syn conformations. The structural studies demonstrate that 8-OG(syn):G(anti) forms a stable pair in the interior of the duplex, providing a basis for the in vivo incorporation of G opposite 8-OG. Calculated helical parameters and backbone torsional angles, and the observed 31P chemical shifts, indicate that the structure of the duplex is perturbed near lesion sites, with the local unwinding of the double helix. The melting temperature of the 8-OG:G containing duplex is only 2.6 deg. C less than the t(m) of the unmodified duplex.     

Urinary 8-Hydroxydeoxyguanosine in Infants and Children

Several diseases of prematurity are thought to be related to oxidative injury and many of the available markers are unsatisfactory. An assay was developed using HPLC with electrochemical detection for the quantitation of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) as a proposed indicator for oxygen-derived free radical injury to DNA in preterm infants.

A median value of 3.79 pmol/mol creatinine was obtained for normal children (2–15 years old, n = 14). Urinary 8-OHdG excretion in neonates ranged from 0–99μmol/mol creatinine. There were no gestation or birthweight related differences in urinary 8-OHdG, and no correlation with urinary malondialdehyde. Mean 8-OHdG excretion increased with postnatal age (r= 0.80, p < 0.0001, n = 15), mirroring the growth velocity curve. These changes could also be due to changes in the activity of the enzyme responsible for 8-OHdG excision.

Urinary 8-OHdG levels are unlikely to accurately reflect oxygen derived free radical activity given the strength of the relationship with growth.     

Oxidative DNA damage in tissues of English sole (Parophrys vetulus) exposed to nitrofurantoin

Juvenile English sole were exposed intramuscularly to nitrofurantoin (NF) and the levels of 8-hydroxy-2′deoxyguanosine (8-OH-dG) in liver, kidney and blood were determined using reversed-phase HPLC with electrochemical detection. Identification and quantitation of the 8-OH-dG in the samples was accomplished by comparison with standard 8-OH-dG, which was characterized by UV spectroscopy and fast-atom bombardment mass spectrometry. The levels of hepatic 8-OH-dG increased (r² = 0.59, P = 0.015) with the dose of NF (0.10 – 10 mg NF/kg fish). In kidney and blood, however, the levels of 8-OH-dG were significantly higher than controls only at the highest dose tested. The level of binding in liver ranged from 0.37 to 0.76 fmol 8-OH-dG/μg DNA. The levels of hepatic 8-OH-dG reached a maximum (approx. 1 fmol 8-OH-dG/μg DNA) between 1 and 3 days after exposure, followed by a decrease to control levels (approx. 0.25 fmol 8-OH-dG/μg DNA) at 5 days post-exposure. These data demonstrate the first direct evidence for the formation of oxidized DNA bases resulting from the metabolism of a nitroaromatic compound by fish.     

Age-related increases of 8-hydroxy-2′-deoxyguanosine and DNA–protein crosslinks in mouse organs

Experimental data suggest a possible role of DNA damage in aging, mainly related to oxidative lesions. With the objective of evaluating DNA lesions as molecular biomarkers of aging, we measured 8-hydroxy-2′-deoxyguanosine (8-OH-dG) and DNA–protein crosslinks (DPXL) levels in different organs of mice aged 12 and 24 months. 8-OH-dG was detected by ³²P postlabelling after removing unmodified dG by trifluoracetic acid, which prevented the artificial formation of 8-OH-dG during ³²P labelling procedures. Appreciable 8-OH-dG amounts were detected in 12-month-old mice in liver (1.8±0.7 8-OH-dG/10⁵ normal nucleotides), brain (1.6±0.5) and heart (2.3±0.5). In 24-month-old mice these values were higher in all examined organs (liver, 2.7±0.4; brain, 3.6±1.1; heart, 6.8±2.2 8-OH-dG/10⁵ normal nucleotides). This accounted for a 1.5-fold increase in liver (not significant), 2.3-fold increase in brain (P<0.01), and 3.0-fold increase in heart (P<0.001). A similar trend was observed for DPXL levels, which were the 1.8±0.3%, 1.2±0.2%, and 2.2±0.3% of total DNA in liver, brain, and heart of 12-month-old mice and 1.9±0.4%, 2.0±0.4%, and 3.4±0.5% in 24-month-old mice, with ratios of 1.0, 1.7 (P<0.01), and 1.5 (P<0.001), respectively. Highly significant correlations between 8-OH-dG and DPXL levels were recorded in brain (r=0.619, P<0.001) and heart (r=0.800, P<0.0001), but not in liver (r=0.201, not significant). These data suggest that brain and heart are more severely affected by the monitored age-related DNA lesions than liver, which can be ascribed to certain characteristics of these postmitotic organs, including the low detoxifying capacities, the high oxygen consumption, and the impossibility to replace damaged cells by mitosis. The strong correlation between 8-OH-dG and DPXL supports a possible contribution of oxidative mechanisms to formation of DPXL in those organs, such as brain and heart, which play a primary role in the aging of the whole organism.     

Up-regulation of base excision repair activity for 8-hydroxy-2'-deoxyguanosine in the mouse brain after forebrain ischemia-reperfusion

The repair enzyme 8-oxoguanine glycosylase/ apyrimidinic/apurinic lyase (OGG) removes 8-hydroxy-2'deoxyguanosine (oh8dG) in human cells. Our goal was to examine oh8dG-removing activity in the cell nuclei of male C57BL/6 mouse brains treated with either forebrain ischemia-reperfusion (FblR) or sham operations. We found that the OGG activity in nuclear extracts, under the condition in which other nucleases did not destroy the oligodeoxynucleotide duplex, excised oh8dG with the greatest efficiency on the oligodeoxynucleotide duplex containing oh8dG/dC and with less efficiency on the heteroduplex containing oh8dG/dT, oh8dG/dG, or oh8dG/dA. This specificity was the same as for the recombinant type 1 OGG (OGG1) of humans. We observed that the OGG1 peptide and its activity in the mouse brain were significantly increased after 90 min of ischemia and 20-30 min of reperfusion. The increase in the protein level and in the activity of brain OGG1 correlated positively with the elevation of FblR-induced DNA lesions in an indicator gene (the c-fos gene) of the brain. The data suggest a possibility that the OGG1 protein may excise oh8dG in the mouse brain and that the activity of OGG1 may have a functional role in reducing oxidative gene damage in the brain after FblR.     

Suppression of 8-oxo-2'-deoxyguanosine formation and carcinogenesis induced by N-nitrosobis (2-oxopropyl)amine in hamsters by esculetin and esculin

Effects of esculetin (6,7-dihydroxycoumarin) and its glycoside, esculin, on 8-oxo-2'-deoxyguanosine (8-oxodG) formation and carcinogenesis induced by a chemical carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP), were examined in the pancreas of female Syrian golden hamsters. Animals were administered esculetin by gastric intubation into the stomach 30 min before BOP administration or ingestion of a diet containing esculin for 7 days before BOP administration, and killed 1 or 4 h after BOP treatment, and the contents of thiobarbituric acid-reacting substrates (TBARS) and 8-oxodG in the pancreas were determined. Both compounds suppressed significantly the BOP-induced increases in 8-oxodG and TBARS contents in hamster pancreas. We further investigated the effect of esculin on pancreatic carcinogenesis by the rapid production model induced by augmentation pressure with a choline-deficient diet, ethionine, methionine and BOP. Esculin was given ad libitum as a 0.05% aqueous solution in either the initiation or promotion phases. The incidence of invasive tumors in animals given esculin during the initiation phase was significantly smaller than in the control group, while esculin given during the promotion phase showed no apparent effects. These results suggest that the intake of esculin has an inhibitory effect on BOP-induced oxidative DNA damage and carcinogenesis in hamster pancreas.