OBJECTIVETo investigate DNA repair in CHL cells and HeLa cells after DNA damage induced by different oxidative agents.

METHODSCHL cells and HeLa cells were exposed to various damaging agents, CHL cells: H(2)O(2) for 25 min, K(2)Cr(2)O(7) for 105 min, doxorubicin (Dox) for 75 min HeLa cells: H(2)O(2) for 25 min, K(2)Cr(2)O(7) for 105 min; then cells were continuously cultured for 0-3 h after washing. Alkaline single cell gel electrophoresis (ASCGE) assay was used to detect DNA strand breaks.

RESULT(1) DNA strand breaks were induced in CHL cells after exposure to H(2)O(2) K(2)Cr(2)O(7) or Dox, which were repaired evidently after continuous culture for 1 h(P<0.01). The damages induced by H(2)O(2) or K(2)Cr(2)O(7) were repaired completely after culture for 2-3 h. However, the demage induced by Dox was repaired incompletely. (2) DNA strand breaks were induced also in HeLa cells after exposure to H(2)O(2) or K(2)Cr(2)O(7), which were repaired evidently after continuous culture for 0.5 h(P<0.01),and completely after culture for 1 h. (3) The regression coefficient related to the rate of comet cells and repair time was statistically different (P<0.05) between CHL cells and HeLa cells.

CONCLUSIONDNA damage induced by Dox is repaired more difficult than that induced by H(2)O(2) or K(2)Cr(2)O(7). The repair initiates immediately after DNA damage in both of cells, but more rapidly in HeLa cells than in CHL cells.

DNA ; metabolism ; DNA Damage ; DNA Repair ; HeLa Cells ; Humans ; Hydrogen Peroxide ; toxicity ; Oxidation-Reduction ; Regression Analysis

Five undescribed sesquiterpenoids (1-5), and nine known sesquiterpenoids (6-14) were obtained from the fruits of Litsea lancilimba Merr. by LC-MS/MS molecular networking strategies. Litsemene A (1) possessed a unique 8-member ring through unexpected cyclization of the methyl group on C-10 of guaiane. Their structures were elucidated by spectroscopic techniques including IR, UV, NMR, HR-ESI-MS, and their absolute configurations were assigned by ECD calculations. All isolated sesquiterpenoids were analyzed by bioinformatics and evaluated for their neuroprotective effects against H₂O₂-induced injury in human neuroblastoma SH-SY5Y cells.
Chromatography, Liquid ; Humans ; Hydrogen Peroxide/toxicity* ; Litsea ; Molecular Structure ; Neuroblastoma/drug therapy* ; Neuroprotective Agents/pharmacology* ; Sesquiterpenes/chemistry* ; Tandem Mass Spectrometry

OBJECTIVEWe evaluate the effects of Thymus algeriensis (TEO) against hydrogen peroxide (H2O2) toxicity on body and testis weight, testis sperm count, testis lipid peroxidation, and antioxidant enzyme activities in rats.

METHODSRats were treated with low (LD) and high dose (HD) of H2O2 (0.1 and 1 mmol/L) in the presence or absence of TEO (150 mg/kg).

RESULTSThe results exhibited a significant decrease in body weight and testis weight, in total sperm number decrease (P<0.05), sperm motility and percentage of sperm viability, leading to complete arrest, in sperm flagellar beat frequency by the gavage of 1 mmol/L H2O2 compared to controls. The administration of H2O2 resulted in a significant reduction in testis GSH, GPx, CAT, SOD, and GST activity and significant increase (P<0.05) in MDA concentration compared with the untreated control animals. TEO pre-treatment protected testis from the H2O2 generated oxidative stress. These results were confirmed by histological architecture examinations.

CONCLUSIONH2O2 has the ability to alter the sperm function, characteristics and development of testis. However, TEO is an efficient natural agent, which can prevent the testis from H2O2-induced oxidative damage in rats.

Animals ; Hydrogen Peroxide ; toxicity ; Male ; Oxidative Stress ; Plant Extracts ; pharmacology ; Rats ; Rats, Wistar ; Testis ; drug effects ; Thymus Plant ; chemistry

OBJECTIVETo study the potential association of DNA oxidation and DNA methylation, in vitro cultured cells were exposed to different doses of H2O2, 8-oxo-dG formation, cell DNA 5-mC contents were analyzed to explore the time- dose-response relationship of DNA oxidation and DNA methylation.

METHODSA549 cells were exposed to different doses of H2O2, 8-oxo-dG formation and cell genomic DNA 5-mC contents were analyzed by a high-performance liquid chromatography system and high performance capillary electrophoresis (HPCE), respectively.

RESULTSH2O2 induced the formation of 8-oxo-dG and 5-mC in different characteristics, it need at least 10 days for significant changes in the level of DNA methylation, whereas under the same conditions, changes in the level of DNA oxidation cast only 12 hours. H2O2 induced decreased levels of DNA methylation in A549 cells in a dose-dependent manner. In a certain range of time and dose, it showed a negative correlation between DNA oxidation and DNA methylation.

CONCLUSIONThe study suggests that oxidative DNA could lead to reduced levels of DNA methylation, DNA oxidation may affect the regulation of cellular methylation mechanisms, in the course of chemical mutagenesis, DNA oxidation may be an earlier important molecule event than DNA methylation.

Cell Line ; DNA ; chemistry ; DNA Damage ; DNA Methylation ; Deoxyguanosine ; analogs & derivatives ; chemistry ; Humans ; Hydrogen Peroxide ; toxicity ; Oxidative Stress

OBJECTIVETo investigate the main factors that influence the results of sperm alkaline single-cell gel electrophoresis (SCGE), optimize the conditions, and standardize its procedures.

METHODSUsing alkaline SCGE, we detected the DNA fragments of sperm treated with different concentrations of H2O2 and determined the influences of the number of agarose gel layers, pH during DNA unwinding and electrophoresis, the time of DNA unwinding and electrophoresis, and cumulative sperm number on the results of sperm alkaline SCGE. Then we optimized the procedures, analyzed the repeatability of the optimized method, and examined 40 semen samples using the method.

RESULTSThree agarose gel layers could reduce the background. The optimal pH during DNA unwinding and electrophoresis was 10, and the best times for DNA unwinding and electrophoresis were 40 min and 30 min, respectively. Fifty sperm were adequate to ensure the reliability of the results. Based on the percentage of tail DNA, the intra- and inter-assay repeatabilities of the optimized sperm alkaline SCGE were 3.12% and 7.13%, and by the DNA damage score, they were 2.38% and 6.09%, respectively. Sperm DNA fragments were significantly increased in the infertile patients with oligoasthenoteratozoospermia as compared with healthy fertile males (P <0.05).

CONCLUSIONThe optimized sperm alkaline SCGE, highly repeatable and easy to be standardized, can be applied to the clinical detection of sperm DNA fragmentation in infertile men.

Asthenozoospermia ; genetics ; Comet Assay ; standards ; DNA Damage ; DNA Fragmentation ; Humans ; Hydrogen Peroxide ; toxicity ; Male ; Oligospermia ; genetics ; Oxidants ; toxicity ; Reproducibility of Results ; Sperm Count ; Spermatozoa ; drug effects ; enzymology ; Time Factors

OBJECTIVEIn vitro model of hydrogen peroxide induced apoptosis of SW-480 cells was used to investigate the role of NF-kappaB in the pathogenesis of reactive oxygen species induced apoptosis of intestinal epithelial cells.

METHODSUltra-structural changes were observed. Apoptosis of SW-480 cell line was determined by Annexin-V and PI double-stained flow cytometry. Nuclear translocation of NF-kappaB was determined by anti-NF-kappaB polyclonal antibody and EB double-staining. NF-kappaB activity was studied by electrophoretic mobility shift assays. RT-PCR was performed to study expression of NF-kappaB mRNA.

RESULTSHydrogen peroxide led to apoptosis of SW-480 cells, condensed or semilunar chromatin even apoptotic bodies could be observed. Nuclear translocation of NF-kappaB, increase of NF-kappaB activity and expression of NF-kappaB mRNA were found simultaneously.

CONCLUSIONSEarly activation of NF-kappaB may be one of the mechanisms of apoptosis in intestinal epithelial cells by reactive oxygen species.

Apoptosis ; Humans ; Hydrogen Peroxide ; toxicity ; Intestinal Mucosa ; metabolism ; Microscopy, Confocal ; NF-kappa B ; metabolism ; Reactive Oxygen Species ; toxicity ; Tumor Cells, Cultured

OBJECTIVETo investigate the antioxidant and cytotoxic properties of five diarylheptanoids (1-5) isolated from the rhizomes of Zingiber officinale.

METHODVarious models such as scavenging superoxide anions and 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals, inhibiting lipid peroxidation, as well as protecting of rat pheochromocytoma (PC12) cells induced by hydrogen peroxide (H2O2) were employed to assay the antioxidative effects of the diarylheptanoids. The cytotoxicities of compounds 1-5 were measured with MTT assays.

RESULTThe test compounds (1-5) showed promising DPPH inhibitory activities, and compound 5 exhibited the strongest DPPH scavenging activity with an IC50 value of (22.6+/-2.4) micromol x L(-1). Compounds 1, 3 and 4 showed potential anti-peroxidative effects with inhibitory rates of (66.3+/-15.4)%, (68.7+/-15.8)% and (72.2+/-10.6)%, respectively, at 100 microg x mL(-1). It could be observed that compounds 1, 3 and 4 demonstrated significant neuroprotective activities in a dose-dependent manner. Moreover, compound 3 exhibited certain cytotoxicities against human chronic myelogenous leukemia cells (K562) and its adriamycin-resistant cells (K562/ADR) with IC50 values of (34.9+/-0.6), (50.6+/-23.5) micromol x L(-1), respectively.

CONCLUSIONIn vitro results demonstrated that five diarylheptanoids (1-5) isolated from the roots of Z. officinale were capable of scavenging radicals, inhibiting lipid peroxidation and protecting PC12 cells against the insult by H2O2. Additionally, compound 3 could inhibit the growth of K562 and K562/ADR cells.

Animals ; Antioxidants ; toxicity ; Cell Proliferation ; drug effects ; Cytotoxins ; toxicity ; Diarylheptanoids ; isolation & purification ; metabolism ; toxicity ; Free Radicals ; metabolism ; Ginger ; chemistry ; Humans ; Hydrogen Peroxide ; metabolism ; K562 Cells ; Oils, Volatile ; pharmacology ; PC12 Cells ; Rats ; Rats, Sprague-Dawley

Butylated hydroxyanisole (BHA) is a synthetic phenolic compound consisting of a mixture of two isomeric organic compounds: 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. We examined the effect of BHA against hydrogen peroxide (H2O2)-induced apoptosis in primary cultured mouse hepatocytes. Cell viability was significantly decreased by H2O2 in a dose-dependent manner. Additionally, H2O2 treatment increased Bax, decreased Bcl-2, and promoted PARP-1 cleavage in a dose-dependent manner. Pretreatment with BHA before exposure to H2O2 significantly attenuated the H2O2-induced decrease of cell viability. H2O2 exposure resulted in an increase of intracellular reactive oxygen species (ROS) generation that was significantly inhibited by pretreatment with BHA or N-acetyl-cysteine (NAC, an ROS scavenger). H2O2-induced decrease of cell viability was also attenuated by pretreatment with BHA and NAC. Furthermore, H2O2-induced increase of Bax, decrease of Bcl-2, and PARP-1 cleavage was also inhibited by BHA. Taken together, results of this investigation demonstrated that BHA protects primary cultured mouse hepatocytes against H2O2-induced apoptosis by inhibiting ROS generation.
Animals ; Apoptosis/*drug effects ; Butylated Hydroxyanisole/chemistry/*pharmacology ; Cell Survival/drug effects ; Cells, Cultured ; Hepatocytes/*drug effects ; Hydrogen Peroxide/*toxicity ; Male ; Mice ; Mice, Inbred ICR ; Molecular Structure

OBJECTIVE: To study the mechanisms of cultured neurons injury mediated by nitric oxide and free oxygen radical during hypoxia and oxidative stress. METHODS: The cultured newborn rat neurons were treated with hypoxia, H2O2 and pretreated superoxide dismutase (SOD) respectively. We examined the content of NO, malonaldehyde (MDA), lactate dehydrogenase (LDH) and SOD in cultured supernatant. RESULTS: Comparing with that of control group, the content of NO, LDH, MDA increased and the content of SOD decreased in hypoxia group and H2O2 group. The content between NO and SOD showed the negative correlation. Administration of 200 U/ml SOD before oxidative stress could efficiently decrease the release of NO, LDH and MDA in neurons. The content of NO, LDH and MDA manifested in positive correlation in each group. CONCLUSION Hypoxia and oxidative stress increased NO production which strengthen neurons injury induced by free radical. SOD played an important role in elimination of free oxygen radicals and protecting neurons from injury by NO.
Animals ; Animals, Newborn ; Cell Hypoxia ; Cells, Cultured ; Hydrogen Peroxide/toxicity* ; Neurons/pathology* ; Nitric Oxide/physiology* ; Oxidative Stress ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase/pharmacology*

AIMTo observe the relationship between amyloid beta-protein (Abeta) and oxidative stress and the protective role of pituitary adenylate cyclase activating polypeptide (PACAP, PACAP-27) against damage induced by oxidative stress (H2O2) in neurem-2a cells.

METHODSWith cultured neuro-2a cells the cell survival and apoptosis were measured by MTT assay, Hoechest33258 staining, DNA ladder and the percentage of small DNA fragment.

RESULTSConcentration-dependent toxicity was induced with H2O2 treatment for 24 h. The neurotoxicity of H2O2 was increased by about 10 times with cotreatment neurons with amyloid beta-protein fragment 25-35 (Abeta(25-35)). While decrease the percentage of small DNA fragmentation the cell survival was increased with co-treatment with PACAP-27(which were added to the culture everyday). The effect of PACAP was not reversed with antagonist of PACAP receptor, PACAP(6-27).

CONCLUSIONAbeta and H2O2 can promote each other's neurotoxicity. Cultured neurons were protected by PACAP27 from the neurotoxicity of H2O2 but not through the activation of PACAP-27 receptor.

Amyloid beta-Peptides ; toxicity ; Apoptosis ; Cell Survival ; Cells, Cultured ; Humans ; Hydrogen Peroxide ; pharmacology ; Neurons ; cytology ; drug effects ; Oxidative Stress ; Pituitary Adenylate Cyclase-Activating Polypeptide ; pharmacology