Formation of 8-nitroguanine in blood of patients with inflammatory gouty arthritis

Hepatocellular carcinoma antibodies preferably identify nitro-oxidative-DNA lesions induced by 4-Chloro-orthophenylenediamine and DEANO

The widespread use of oxidative hair colouring cosmetics threatens public health. Phenylenediamine derivatives serve as the main pigment in permanent hair colours. They interact with biological macromolecules, altering their functional and structural physiology. The study aimed to investigate the effect of a typical synthetic hair dye pigment, 4-Chloro-orthophenylenediamine (4-Cl-OPD), under a nitrating environment of DEANO on the calf thymus DNA molecule. The results showed single-stranded regions, base/sugar-phosphate backbone alterations, molecular changes, and nitro-oxidative lesions. These modifications are referred to as neo-epitopes on the DNA molecule. IgGs from cancer patients with a history of permanent hair dye use were screened for the recognition of neo-epitopes on DNA molecules. Hepatocellular carcinoma IgG showed the highest binding with 56% inhibition in the competition ELISA. The immune complex formation was observed through electrophoretic mobility shift assay. In conclusion, synthetic hair dye users are likely to present with heightened immunological triggers under elevated nitric oxide levels. The study reports chronic hair dye exposure as one of the factors responsible for altering the intricacies of the DNA's microarchitectural structure and inducing neo-epitopes on the molecule. The physiological status of NO may define the susceptibility towards 4-Cl-OPD and humoral response in hair dye users. Persistent nitro-oxidative stress due to 4-Cl-OPD and NO may induce a heightened immune response against neoepitopes in the nitro-oxidatively modified DNA. Therefore, chronic hair dye exposure may be identified as a risk to human health. These findings may contribute to a better understanding and reinforcement of hair dye as one of the modifiable risk factors responsible for the pro-inflammatory carcinogenic environment.

High serum uric acid is associated with oxidation of nucleosides in patients with type 2 diabetes

Uric acid presents different roles in an organism, since it can act as an antioxidant or a pro-oxidant molecule. High serum uric acid levels may cause damage to several structures, including nucleic acids and its components. Therefore, in this study the association between increased serum uric acid concentrations and oxidation of nucleosides was investigated by assessment of urinary 8-hydroxydeoxyguanosine (8-OHdG) in patients with type 2 diabetes (T2D) and in healthy individuals. Urinary 8-OHdG and biochemical parameters were assessed in 61 patients who were initially grouped into 2 groups based on the median serum uric acid levels (<5.3 mg/dL and ≥5.3 mg/dL). Urinary 8-OHdG was higher in patients with T2D and serum uric acid levels ≥5.3 mg/dL, when compared with the patients with serum uric acid levels <5.3 mg/dL; however, co-occurrence of high serum uric acid with high urinary 8-OHdG was not observed in healthy individuals. A significant positive correlation between 8-OHdG and uric acid (r = 0.40, P < 0.01) was observed in patients with T2D. High serum uric acid levels were associated with high urinary 8-OHdG levels in patients with T2D, and this association was independent of gender, hypertension, body mass index, and serum creatinine.

Sensitive Detection of 8-Nitroguanine in DNA by Chemical Derivatization Coupled with Online Solid-Phase Extraction LC-MS/MS

8-Nitroguanine (8-nitroG) is a major mutagenic nucleobase lesion generated by peroxynitrite during inflammation and has been used as a potential biomarker to evaluate inflammation-related carcinogenesis. Here, we present an online solid-phase extraction (SPE) LC-MS/MS method with 6-methoxy-2-naphthyl glyoxal hydrate (MTNG) derivatization for a sensitive and precise measurement of 8-nitroG in DNA. Derivatization optimization revealed that an excess of MTNG is required to achieve complete derivatization in DNA hydrolysates (MTNG: 8-nitroG molar ratio of 3740:1). The use of online SPE effectively avoided ion-source contamination from derivatization reagent by washing away all unreacted MTNG before column chromatography and the ionization process in mass spectrometry. With the use of isotope-labeled internal standard, the detection limit was as low as 0.015 nM. Inter- and intraday imprecision was <5.0%. This method was compared to a previous direct LC-MS/MS method without derivatization. The comparison showed an excellent fit and consistency, suggesting that the present method has satisfactory effectiveness and reliability for 8-nitroG analysis. This method was further applied to determine the 8-nitroG in human urine. 8-NitroG was not detectable using LC-MS/MS with derivatization, whereas a significant false-positive signal was detected without derivatization. It highlights the use of MTNG derivatization in 8-nitroG analysis for increasing the method specificity.

Comprehensive analysis of the formation and stability of peroxynitrite-derived 8-nitroguanine by LC-MS/MS: Strategy for the quantitative analysis of cellular 8-nitroguanine

Peroxynitrite is a major oxidizing and nitrating biological agent formed at sites of inflammation. Peroxynitrite can cause DNA damage and is thought to contribute to inflammation-related carcinogenesis. This study describes a sensitive and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct determination of peroxynitrite-derived 8-nitroguanine (8-nitroGua) in DNA hydrolysates. This method exhibited a sensitive detection limit of 3 fmol and inter- and intraday imprecision of <10% and was applied to systemically examine the formation and stability of peroxynitrite-derived 8-nitroGua in different DNA substrates under various conditions. The 8-nitroGua formation was maximal at pH 8. The formation rate of 8-nitroGua in different DNA substrates decreased in the order of monodeoxynucleoside>single-stranded DNA>double-stranded DNA. A stability test revealed that the half-life for the depurination of 8-nitroGua from DNA was short and affected by both the temperature and DNA structure. When present in monodeoxynucleoside, the half-life of 8-nitroGua was estimated to be ~6min at 25°C and 2.3h at ~0°C. In single-stranded DNA, the half-life varied from 1.6h at 37°C to 533h at -20°C, whereas the half-life increased from 2.4h at 37°C to 1115h at -20°C in double-stranded DNA. We demonstrated that the measurement of 8-nitroGua in isolated DNA is not practicable because 8-nitroGua is unstable and lost during DNA extraction from cell. Therefore, we suggest that directly detecting cellular 8-nitroGua following nuclear membrane lysis is an alternative measure of the nitrative damage of nucleic acids, accounting for both DNA and RNA lesions within cells.

Activation of AQP4, p66Shc and endoplasmic reticulum stress is involved in inflammation by carrageenan and is suppressed by argirein, a derivative of rhein

Objectives

We investigated the effect of argirein on acute inflammation edema and examined that aquaporin 4 (AQP4), p66Shc and activating transcription factor (ATF-6) might be involved in carrageenan-induced rat paw inflammation and be reversed by argirein, rhein and indometacin, but not l-arginine.

Methods

Inflammation was produced by carrageenan injected into rat paw and treated orally with argirein (100 mg/kg), rhein (100 mg/kg), l-arginine (100 mg/kg) or indometacin (5 mg/kg). Inflammatory oedema and biomarkers were examined.

Key findings

Swelling was reduced by argirein, rhein and indometacin; argirein was more effective than rhein at 1 h following medication. Activation of AQP4, p66Shc, ATF-6, NADPH oxidase subunits p22phox, gp91phox and matrix metalloproteinase 2 (P &lt; 0.01) was significant and was suppressed by arginine, rhein and indometacin but not by l-arginine.

Conclusions

Activated AQP4, endoplasmic reticulum stress and p66Shc were actively implicated in the inflammation and these were suppressed by argirein, and its activity is favorable due to synergism in combination with l-arginine.

Capillary electrophoretic determination of DNA damage markers: content of 8-hydroxy-2'-deoxyguanosine and 8-nitroguanine in urine

A sensitive and low-cost analytical method has been developed to determine 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-nitroguanine (8-NO(2)Gua) based on capillary electrophoresis with amperometric detection (CE-AD) after solid phase extraction (SPE). Under optimized condition, these two markers were well separated from other components coexisting in urine, exhibiting a linear calibration over the concentration range of 0.1-50.0 μg/mL with the detection limits ranging from 0.02 to 0.06 μg/mL. The relative standard deviations (RSDs) were in the range of 0.1-2.1% for peak area, 0.1-1.5% for migration time, respectively. The average recovery and RSD were within the range of 100.0-108.0% and 0.1-1.7%, respectively. It was found that the urinary contents of 8-OHdG and 8-NO(2)Gua in cancer patients were significantly higher than those in healthy ones.