HPLC-UV检测病人胃粘膜活检组织中8-羟基脱氧鸟苷

采用HPLC-UV与反相C18柱,以50 mmol/L的KH2PO4(pH 5.5)-10%的甲醇(V/V)作为洗脱液,同步快速检测了21位健康人与90位病人胃粘膜活检组织中的脱氧鸟苷(deoxyguanosine,dG)和8-羟基脱氧鸟苷(8-Hydroxydeoxyguanosine, 8-OHdG)的量.方法线性范围分别为3.0～400 μg/mL、0.2～10μg/mL,检出限可分别达到1.0、0.1 μg/mL(S/N=3).实验发现病人胃粘膜活检组织中的8-OHdG量远远高于健康人,此结果在临床早期诊断相关疾病方面具有很高的应用价值.     

分子印迹聚合物结合高效液相色谱法测定人体尿液中的8-羟基脱氧鸟苷和1-甲基鸟苷北大核心CSCD

建立了分子印迹聚合物结合高效液相色谱法测定人体尿液中的8-羟基脱氧鸟苷(8-OHdG)和1-甲基鸟苷(M1G)。选取8-OHdG为模板,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在十二烷醇-二甲基亚砜体系中制备8-羟基脱氧鸟苷分子印迹聚合物(MIPs),并将其作为分散固相萃取(DSPE)的吸附剂。在最佳萃取条件下,2种萃取目标物在对应的范围内线性关系良好(r^(2)≥0.9996),检出限为0.15~0.25 ng/mL。将方法用于实际尿样中的测定,并考察了结直肠癌患者尿液中8-OHdG和M1G的含量,平均回收率为82.6%~93.2%之间。结果表明,该方法前处理操作简单、净化效果良好,可用于人体尿液中微量8-OHdG和M1G的检测。     

8-羟基脱氧鸟苷在壳聚糖/石墨烯修饰电极上的电化学及DNA氧化损伤检测

采用循环伏安(CV)、线性扫描伏安(LSV)和示差脉冲伏安(DPV)等方法研究了8-羟基脱氧鸟苷(8-OHdG)在壳聚糖(Chi)/石墨烯(GR)修饰的玻碳电极(GCE)上的电化学行为,8-OHdG在该修饰电极上氧化峰电流与其浓度在3.5×10-7~1.4×10-4mol/L范围内呈良好的线性关系,检测限为6.4×10-8mol/L(S/N=3)。将Chi/GR/GCE用于检测DNA氧化损伤,8-OHdG在修饰电极上的氧化峰电流与损伤的DNA质量浓度在10~300 mg/L范围内呈良好的线性关系,损伤DNA检出限为0.026 mg/L(S/N=3)。     

8-羟基脱氧鸟苷在壳聚糖/石墨烯修饰电极上的电化学及DNA氧化损伤检测

采用循环伏安(CV)、线性扫描伏安(LSV)和示差脉冲伏安(DPV)等方法研究了8-羟基脱氧鸟苷(8-OHdG)在壳聚糖(Chi)/石墨烯(GR)修饰的玻碳电极(GCE)上的电化学行为,8-OHdG在该修饰电极上氧化峰电流与其浓度在3.5×10-7~1.4×10-4 mol/L范围内呈良好的线性关系,检测限为6.4×10-8 mol/L(S/N=3)。 将Chi/GR/GCE用于检测DNA氧化损伤,8-OHdG在修饰电极上的氧化峰电流与损伤的DNA质量浓度在10~300 mg/L范围内呈良好的线性关系,损伤DNA检出限为0.026 mg/L(S/N=3)。     

羟基自由基引起的脱氧核糖核酸损伤研究

以鲱鱼精脱氧核糖核酸(Herring sperm DNA)为研究对象,利用紫外光(UV,200～275 nm,66.4 Lx)激发纳米TiO2发生光催化作用介导产生羟基自由基(Hydroxyl radical,.OH),探讨.OH引发DNA氧化损伤特性。采用凝胶电泳和高效液相色谱(HPLC)分析法跟踪DNA损伤历程;应用电子自旋共振(Electron spinresonance,ESR)及分光光度法跟踪损伤过程氧化物种及H2O2相对浓度的变化;运用生物标准样8-羟基脱氧鸟苷(8-Hydroxy-2’-deoxyguanosine,8-OHdG)为内标物,通过HPLC分析DNA损伤产物,研究DNA损伤机理。结果表明,较单纯UV辐照或暗光(Dark)催化条件,DNA浓度10 mg/L,TiO2浓度1.5 g/L、pH 7～8,紫外光激发纳米TiO2介导产生.OH引发DNA损伤程度最大;DNA损伤为.OH氧化历程,并伴随有深度氧化过程;DNA结构中鸟嘌呤最易氧化损伤,8-OHdG为DNA氧化损伤中间产物及鸟嘌呤氧化损伤的特异产物。     

中草药对DNA氧化损伤水平的微分脉冲伏安法测定

采用微分脉冲伏安法(DPV)研究了中草药对脱氧核糖核酸分子(DNA)的损伤效应。在pH 5.0的磷酸盐缓冲液中,采用DPV法研究了8-羟基脱氧鸟苷(8-OHdG)在玻碳电极上的伏安行为,发现8-OHdG在+0.5 V电位处产生一灵敏的微分脉冲阳极氧化峰。该氧化峰的峰电流与8-OHdG的浓度在1.0×10-6～7.1×10-4mol/L范围内呈良好的线性关系,r=0.999 8,检出限(S/N=3)为3.5×10-7mol/L。将该方法应用于暴露于浓度均为40 g生药/L的甘草、金樱子、杜仲、半夏、马钱子提取液2 h的小牛胸腺DNA(ctDNA)中8-OHdG的分析,以及连续灌服低剂量和高剂量马钱子提取液30 d的昆明小鼠血中8-OHdG的分析。结果发现甘草、金樱子、杜仲、半夏提取液对ctDNA无氧化损伤作用,马钱子提取液能引起ctDNA氧化损伤形成8-OHdG,平均水平为(3.2±0.2)μmol/L。长期服用低剂量和高剂量马钱子提取液的小鼠,其血液中8-OHdG的平均水平分别为(2.0±0.1)、(5.3±0.3)μmol/L,表明马钱子具有潜在的遗传毒性。     

DNA氧化损伤评价模型的构建及其中药保护剂的筛选

香烟烟气含有上千种化合物,其中60多种证明具有致癌作用.另外香烟烟气含有高水平活性氧基团,例如超氧自由基、羟基自由基等,能够对细胞DNA造成氧化损伤~([1,2]).近年来研究表明:8-羟基脱氧鸟苷(8-OHdG)已成为检测DNA损伤的一种重要标志物.本研究以8-羟基脱氧鸟苷(8-OHdG)为DNA氧化损伤的标志物,构建了Fenton试剂(Fe~(2+)+H_2O_2)及吸烟产生的活性自由基对DNA的氧化损伤评价体系,并利用该体系筛选对DNA具有保护作用的中药单体.     

基于纳米金在线扫集-毛细管电泳法测定尿样中8-羟基-2′脱氧鸟嘌呤核苷

提出了纳米金在线富集-毛细管电泳法测定尿样中8-羟基-2′脱氧鸟嘌呤核苷(8-OHdG)的方法。试验选择了以下的分析条件:①运行电压-20kV;②背景电解质为pH 8.2的20mmol.L-1硼砂(含粒径10nm纳米金溶液200μL和0.1mmol.L-1 CTMAB);③检测波长254nm。试验证明背景电解质中的纳米金粒子与CTMAB形成胶束,提高了对8-OHdG的扫集能力,8-OHdG与dG在10min内可实现基线分离。8-OHdG浓度在0.50～50.0μmol.L-1范围内呈线性,检出限(3S/N)为39nmol.L-1。方法用于尿样中8-OHdG含量的测定,所得加标回收率在90.0%～104.6%之间。     

自制混合型小柱净化-高效液相色谱-串联质谱法同时测定尿液中有机磷酸酯代谢物和8-羟基-2'-脱氧鸟苷

建立了基于自制混合型小柱的样品净化-高效液相色谱-串联质谱同时测定7种有机磷酸酯（OPEs）主要代谢产物及生物标志物8-羟基-2'-脱氧鸟苷（8-OHdG）的分析方法。样品经乙腈提取后用自制小柱富集净化,以乙腈-0.2%（v/v）氨水溶液作为流动相进行梯度洗脱,在多反应监测模式下进行定性和定量分析。结果显示,8种目标物在0.1~200 μg/L范围内呈良好的线性关系,7种OPEs代谢物的回收率为52.36%~114.56%,8-OHdG回收率为88.63%~97.72%。将该方法应用于人体尿液实际样品中,7种OPEs代谢物和8-OHdG的检出范围分别为6.24~46.07 μg/L和5.90~16.71 μg/L,8-OHdG与7种OPEs代谢物总含量之间存在显著相关性。该方法操作简单、灵敏度高、准确性好、重现性强,可为更全面地评价人体内OPEs暴露水平及机体损伤提供可靠的技术支持。     

高效液相色谱-电化学检测法测定脱氧核糖核酸分子氧化损伤标志物8-羟基脱氧鸟苷

采用螯合剂-Fe^2 -H2O2作为Fenton型反应的氧化源,与小牛胸腺脱氧核糖核酸反应生成8-羟基脱氧鸟苷（8-OhdG),建立脱氧核糖核酸（DNA）分子氧化损伤的体外反应模型,用高效液相色谱-电化学检测方法对8-OhdG进行定量。建立的方法灵敏度高,最低检出限30fmol,线性范围宽,从0.32pmol到3.2nmol,相关系数达0.9996,方法能够适用于生物体与细胞脱氧核酸分子低水平氧化损伤的检测。     

A label-free ultrasensitive assay of 8-hydroxy-2′-deoxyguanosine in human serum and urine samples via polyaniline deposition and tetrahedral DNA nanostructure

Oxidative damage is an important factor in causing various human disease and injury. As an oxidative DNA damage product, 8-hydroxy-2′-deoxyguanosine (8-OHdG) is a key marker, which is widely used to study oxidative damage mechanism in diseases. Most reported electrochemical methods were based on oxidation current of 8-OHdG. In this work, a simple electrochemical biosensor for ultrasensitive detection of 8-OHdG was proposed based on it triggered polyaniline (PANI) deposition on tetrahedral DNA nanostructure (TDN). TDN was immobilized onto a gold electrode surface based on self-assembly between three thiolated nucleotide sequences. 8-OHdG-aptamer on the top of TDN formed a hemin/G-quadruplex structure in the presence of 8-OHdG and hemin, which have high catalytic activity to trigger PANI deposition. Numerous negative charges on the duplex DNAs contained in hemin/G-quadruplex and TDN supplied exquisite environment for PANI deposition, which improved the detection sensitivity greatly by increasing the DPV current to10-fold (∼3 μA) compared to our previously reported method without TDN. The response signals correlated linearly with the concentration of 8-OHdG ranging from 10 pM to 2 nM, with a detection limit of 1 pM (S/N = 3). The sensitivity was improved to almost 300-fold when compared with most of previously reported electrochemical methods. The method was also simple and reliable, avoiding complex, expensive label procedures and nanomaterial synthesized procedures. The method had been successfully applied to quantify 8-OHdG in urine and human serum samples with satisfactory results.     

High-throughput and cost-effective global DNA methylation assay by liquid chromatography-mass spectrometry

An affordable and fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the accurate and precise determination of global DNA methylation levels in peripheral blood. Global DNA methylation extent was expressed as the ratio of methylated 2′-deoxycytidine (5MedC) to 2′-deoxyguanosine (dG), which were obtained after DNA extraction and hydrolysis and determined by positive electrospray LC–ESI-MS/MS. The cost-effective internal standards ¹⁵N₃-dC and ¹⁵N₅-dG were incorporated for the accurate quantification of 5MedC and dG, respectively. The desired nucleoside analytes were separated and eluted by LC within 2.5 min on a reverse phase column with a limit of detection of 1.4 femtomole on column for 5MedC. Sample preparation in 96-well format has significantly increased the assay throughput and filtration was found to be a necessary step to assure precision. Precision was performed with repeated analysis of four DNA QC sample over 12 days, with mean intra- and inter-day CVs of 6% and 11%, respectively. Accuracy was evaluated by comparison with a previously reported method showing a mean CV of 4% for 5 subjects analyzed. Furthermore, application of the assay using a benchtop orbitrap LCMS in exact mass full scan mode showed comparable sensitivity to tandem LCMS using multiple reaction monitoring.     

Quantitation of 8-hydroxydeoxyguanosine in DNA by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

A methodology has been developed and validated for quantifying 8-hydroxydeoxyguanosine (8-OHdG) in both commercial DNA and DNA isolated from livers of male Sprague-Dawley rats by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry. The analytical method conditions, including conditions for stabilizing 8-OHdG during complex nuclease P1 enzymatic digestion, were also evaluated. The limit of detection for 8-OHdG was 1.0 ng/mL (17.6 fmol on-column), and the linearity of the calibration curve was greater than 0.998 from 1.0 to 500 ng/mL. The intraday assay precision relative standard deviation (RSD) value for quality control (QC) samples was < or =5.59% with accuracies ranging from 91.84 to 117.61%. The interday assay precision (RSD) value was < or =1.76% with accuracies ranging from 91.84 to 116.67%. This method, combined with the LC/UV analysis of deoxyguanosine (dG), was used for determination of the levels of 8-OHdG/10(6) dG in DNA nuclease P1 enzymatic hydrolysates from both commercial DNA and rat liver DNA.     

Optimization of fluorescence property of the 8-oxodGclamp derivative for better selectivity for 8-oxo-2′-deoxyguanosine

2′-Deoxyguanosine (dG) suffers from oxidation by reactive oxygen species (ROS) to form 8-oxo-2′-deoxyguanosine (8-oxo-dG), which is regarded as a marker of oxidative stress in the cells. In our continuous study for the recognition molecule of 8-oxo-dG, 8-oxoGclamp and its derivatives have been identified as the selective fluorescent probe. However, it is an obstacle for further application that dG also forms a complex with 8-oxoGclamp, resulting in fluorescence quenching in less polar solvents. Quenching of the fluorescence of 8-oxoGclamp is thought to involve photo-induced electron transfer in the complex. It was hypothesized that the energy level of the excited state of 8-oxoGclamp and the HOMO energy of dG are the preliminary determinant of the quenching efficiency. Thus, fluorescence properties of the substituted derivatives at the 7-position of the 1,3-diazaphenoxazine part of 8-oxoGclamp were investigated. Among the new derivatives, fluorescence of the 7-phenyl substituted 8-oxoGclamp was not quenched by dG even in the stable complex, exhibiting the highest selectivity for 8-oxo-dG.     

Molecularly imprinted monolith in-tube solid-phase microextraction coupled with HPLC/UV detection for determination of 8-hydroxy-2′-deoxyguanosine in urine

Urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) has been widely used as a biomarker of oxidative DNA damage. Measurements of 8-OHdG in urinary samples are challenging owing to the low level of 8-OHdG and the complex matrix. In this study, a novel molecularly imprinted polymer (MIP) monolithic column was synthesized with guanosine as a dummy template which was used as the medium for in-tube solid-phase microextraction (SPME). In-tube SPME coupled with HPLC/UV detection for extraction and determination of urinary 8-OHdG was developed. The synthesized MIP monolithic column exhibited high extraction efficiency owing to its greater phase ratio with convective mass transfer and inherent selectivity. The enrichment factor for 8-OHdG was found to be 76 and the limits of detection and quantification of the method for urinary samples were 3.2 nmol/L (signal-to-noise ratio 3) and 11 nmol/L (signal-to-noise ratio 10), respectively. The MIP^’s selectivity also made the sample preparation procedure and chromatographic separation much easier. The linear range of the proposed method was from 0.010 to 5.30 μmol/L (r = 0.9997), with a relative standard deviation of 1.1–6.8%, and the recovery for spiked urine samples was 84 ± 3%. The newly developed method was successfully applied to determine urinary samples of healthy volunteers, coking plant workers, and cancer patients. The 8-OHdG level in cancer patients was significantly higher than that in healthy people.     

超高效液相色谱-串联质谱法鉴定与分析乙醛诱导脱氧核糖核苷酸加合物

采用超高效液相色谱-串联质谱法对两种非对映异构体（6S,8S）1,N²-丙基-2'-脱氧鸟苷（ProdG）和（6R,8R）ProdG加合物进行鉴定与分析。通过色谱保留时间及质谱碎裂方式分析,证明乙醛与2'-脱氧鸟苷（dG）反应可形成ProdG加合物。体外实验表明,乙醛能够诱导脱氧核糖核苷酸（DNA）形成ProdG加合物,并且（6R,8R）ProdG的生成量大于（6S,8S）ProdG的生成量。细胞实验结果显示,乙醛暴露能显著提高人肺胚成纤维细胞（MRC5）基因组DNA中ProdG加合物的水平,且ProdG加合物的水平与乙醛的暴露浓度呈正相关。此外,100 μ mol/L的乙醛暴露使（6R,8R）ProdG的含量从（6.4±0.3） 个/10⁸个碱基增加到（127.2±2.7） 个/10⁸个碱基,上调程度大于（6S,8S）ProdG（从（6.5±0.3） 个/10⁸个碱基增加到（115.3±2.5） 个/10⁸个碱基）。该工作为乙醛暴露所引起的DNA加合物水平上升提供了实验依据。     

Singlet oxygen oxidation of 2′-deoxyguanosine. Formation and mechanistic insights

Emphasis was placed in this work on the delineation of mechanistic aspects of the singlet oxygen-mediated oxidation reactions of 2′-deoxyguanosine 1 used as a DNA model compound in aerated aqueous solution. For this purpose a thermolabile naphthalene endoperoxide derivative was used allowing the generation of [¹⁸O]-labeled singlet oxygen for dedicated mechanistic studies. The analysis and characterization of the oxidized nucleosides of the ¹O₂ reactions were achieved on the basis of accurate HPLC-tandem mass spectrometry measurements. Thus it was found that primary oxidation products include, in addition to the previously identified 8-oxo-7,8-dihydro-2′-deoxyguanosine 5 and the two diastereomers of spiroiminodihydantoin 8, two relatively minor nucleosides, namely the two diastereomers of 4-hydroxy-8-oxo-4,8-dihydro-2′-deoxyguanosine 9.     

高效液相色谱-电喷雾离子阱质谱联用测定尿中的8-羟基脱氧鸟嘌呤

建立了尿样中8-羟基脱氧鸟嘌呤的HPLC-MS测定方法.尿样中的8-羟基脱氧鸟嘌呤采用WCX固相萃取小柱预富集后,以0.5%甲酸-甲醇洗脱,吹干后用0.5 mL流动相溶解剩余物上机测定.采用分子的二级碎片,方法在5.0～500.0 μg/L范围内呈良好线性关系,相关系数r=0.999 4,检出限(S/N=3)为0.50...     

LET dependence of the formation of oxidative damage 8-hydroxy-2′-deoxyguanosine (8-OHdG) in 2′-deoxyguanosine aqueous solution irradiated with heavy ions

To evaluate the contribution of indirect action mediated by OH radicals in biological effects of high LET radiations, we examined the production of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in 2′-deoxyguanosine aqueous solution using various ion species with an LET range from 20 to 300 keV/μm. The 8-OHdG yield decreased with increasing LET. In the hypoxic irradiation condition, the yield showed constant or rather increasing tendency above about 100 keV/μm, which is consistent with an oxygen-in-the-track hypothesis to explain the diminishment of oxygen effect.