Reduction Of Oxidative DNA Damage Research Articles

Hypoxia-induced stabilization of HIF2A promotes cardiomyocyte proliferation by attenuating DNA damage.

Gradual exposure to a chronic hypoxic environment leads to cardiomyocyte proliferation and improved cardiac function in mouse models through a reduction in oxidative DNA damage. However, the upstream transcriptional events that link chronic hypoxia to DNA damage have remained obscure. We sought to determine whether hypoxia signaling mediated by the hypoxia-inducible factor 1 or 2 (HIF1A or HIF2A) underlies the proliferation phenotype that is induced by chronic hypoxia. We used genetic loss-of-function models using cardiomyocyte-specific HIF1A and HIF2A gene deletions in chronic hypoxia. We additionally characterized a cardiomyocyte-specific HIF2A overexpression mouse model in normoxia during aging and upon injury. We performed transcriptional profiling with RNA-sequencing on cardiac tissue, from which we verified candidates at the protein level. We find that HIF2A - rather than HIF1A - mediates hypoxia-induced cardiomyocyte proliferation. Ectopic, oxygen-insensitive HIF2A expression in cardiomyocytes reveals the cell-autonomous role of HIF2A in cardiomyocyte proliferation. HIF2A overexpression in cardiomyocytes elicits cardiac regeneration and improvement in systolic function after myocardial infarction in adult mice. RNA-sequencing reveals that ectopic HIF2A expression attenuates DNA damage pathways, which was confirmed with immunoblot and immunofluorescence. Our study provides mechanistic insights about a new approach to induce cardiomyocyte renewal and mitigate cardiac injury in the adult mammalian heart. In light of evidence that DNA damage accrues in cardiomyocytes with aging, these findings may help to usher in a new therapeutic approach to overcome such age-related changes and achieve regeneration.

Mechanism of Curcuma longa and Its Neuroactive Components for the Management of Epileptic Seizures: A Systematic Review.

Curcuma longa (Turmeric) is a tropical herbaceous perennial plant of the family Zingiberaceae and contains curcuminoids, sesquiterpenoids and monoterpenoids as its major components. Given the broad range of activities that Curcuma longa possesses and also its use as a traditional epilepsy remedy, this review attempts to systematically review the experimentally proven activities of Curcuma longa and its bioactive components, which are related to the management of epileptic seizures. Using the PRISMA model, five databases (Google Scholar, PubMed, ScienceDirect, SCOPUS and SpringerLink) were searched using the keywords [“Curcuma longa” AND “Epilepsy”] and [“Curcuma longa” AND “Seizures”], leaving 34 articles that met the inclusion criteria. The present systematic review elaborated on the experimentally proven potential of Curcuma longa components, such as an aqueous extract of Curcuma longa itself, Curcuma longa oil and active constituents like curcuminoids and bisabolene sesquiterpenoids found in Curcuma longa with anti-seizure potential. Using human equivalent dose calculations, human treatment parameters were suggested for each component by analysing the various studies in this review. This review also determined that the principal components possibly exert their anti-seizure effect via the reduction of corticosterone, modulation of neurotransmitters signalling, modulation of sodium ion channels, reduction of oxidative DNA damage, reduction of lipid peroxidation, upgregulation of brain-derived neurotrophic factor (BDNF) and γ-aminobutyric acid (GABA) mediated inhibition. It is anticipated that this review will help pave the way for future research into the development of Curcuma longa and its neuroactive constituents as potential drug candidates for the management of epilepsy.

Effects of in vivo treatment of mice with sulforaphane on repair of DNA pyridyloxylbutylation

The phytochemical sulforaphane (SF) has gained interest for its apparent association with reduced cancer risk and other cytoprotective properties, at least some of which are attributed to activation of the transcription factor Nrf2. Repair of bulky DNA adducts is important for mitigating carcinogenesis from exogenous DNA damaging agents, but it is unknown whether in vivo treatment with SF affects adduct repair. At 12 h following a single oral dose of 100 mg/kg SF, an almost doubling in activity for repair of pyridyloxobutylated DNA was observed in CD-1 mouse liver nuclear extracts, but not in lung extracts. This change at 12 h in repair activity was preceded by the induction of Nrf2-regulated genes but not accompanied by changes in levels of the specific nucleotide excision repair (NER) proteins XPC, XPA, XPB and p53 or in binding of hepatic XPC, XPA and XPB to damaged DNA. SF also did not significantly alter histone deacetylase activity as measured by acetylated histone H3 levels, or stimulate formation of γ-H2A.X, a marker of DNA damage. A significant reduction in oxidative DNA damage, as measured by 8-OHdG (a biomarker of oxidative DNA damage), was observed only in DNA from the lungs of SF-treated mice 3 h post-dosing. These results suggest that the ability of SF to increase bulky adduct repair activity is organ-selective and is consistent with activation of the Nrf2 signaling pathway.

Risk of knee osteoarthritis in patients using N-acetylcysteine (NAC): A nationwide population-based cohort study

Knee osteoarthritis (OA) is known as a progressive degenerative disorder, but recent evidence suggests that inflammatory mediators contribute to cartilage degradation. N-acetylcysteine (NAC) is an antioxidant that can directly scavenge reactive oxygen species. According to basic studies, NAC had an apparent effect on reducing the synthesis of proinflammatory and structural mediators by synovial cells. In contrast, chondrocyte in osteoarthritic cartilage was found significantly lower intracellular p53 expression. NAC was also reported to decrease p53 expression through reduction of oxidative DNA damage. Due to lacking clinical trials, we conducted this study to determine the relationship between NAC use and risk of knee OA. We designed a retrospective cohort study using the Taiwan's Longitudinal Health Insurance Database from 2000 to 2013. Patients receiving oral form N-acetylcysteine over 28 days within one year after first prescription were defined as case group, whereas those without N-acetylcysteine use were considered as candidates of control group. We adopted a 1:10 propensity score matching by age, sex, index year and comorbidities to consist the control group. Patients with previous history of knee operation (total knee replacement and anterior cruciate ligament reconstruction), bed-ridden status, and less than 20 years old were excluded. The primary outcome was a new diagnosis of knee OA during follow-up period. Our study samples consist of 7726 using NAC subject and 77260 non-used NAC subject. People with NAC use have significantly higher incidence of osteoarthritis (adjusted HR: 1.39, P < 0.0001) ( Fig. 1 ). In addition, analyses stratified by age group and sex, all subgroups showed significantly higher incidence of osteoarthritis ( P < 0.0001) in NAC users ( Table 1 ). Patients who take oral N-acetylcysteine more than 28 days per year have higher risk of developing knee osteoarthritis.

Effects of a bilberry preparation on selected cell lines of the digestive system

Bilberry is a valuable wild forest fruit harvested in many countries in Europe. The biological activities of bilberry include antioxidant, anticancer, antiviral, antibacterial, and anticholinesterase activities. This study examines the protective effects of a bilberry (BB) preparation on IEC-6, Caco-2, and HepG2 cell lines. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to study the cytotoxicity of BB. The genotoxicity was determined using single-cell microgel electrophoresis. The Ames test was employed to assay bilberry mutagenicity. No significant effects of BB (12.5–100 µg dry mass/ml) were observed on the viability of IEC-6, Caco-2, and HepG2 cells. There were no differences in the percentage of DNA in the comet tail between the cells treated with BB (100 µg dry mass/ml) and the control cells. However, a significant reduction of oxidative DNA damage in the HepG2 cells was found. BB exhibited neither mutagenic nor promutagenic effects. Our results suggest that bilberry can be a potential tool in the prevention of chronic diseases, without any undesired effects on the cells of the gastrointestinal tract.

Protective activity of probiotic bacteria against 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ) and 2-amino-1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridine (PhIP) – an in vitro study

Heterocyclic aromatic amines (HAAs) are carcinogenic compounds present in a typical Western diet rich in thermally processed meat. These nutritional factors can modulate the cytotoxicity of faecal water (FW) and induce tumours in the human gastrointestinal tract. Supplementation with probiotics is promising in terms of reducing the harmful effects of HAAs in the human body. The aim of the study was in vitro assessment of the protective activity of the probiotic strains Lb. rhamnosus 0900, Lb. rhamnosus 0908, Lb. casei 0919 and Lb. casei DN 114001 against IQ (2-amino-3-methyl-3H-imidazo[4,5-f]quinoline) and PhIP (2-amino-1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridine) after incubation with faeces from 15 persons aged 4 months to 82 years (children, adults and the elderly). The highest mean cytotoxicity of FW was observed for the elderly (63.2% ± 3.7%) and the lowest for children (28.0% ± 9.5%), as estimated by a neutral red uptake assay. The probiotics lowered the average cytotoxicity of FW exposed to IQ or PhIP. The concentration of IQ and PhIP in FW was most effectively reduced by Lb. rhamnosus 0900 (47.5%) and Lb. casei 0919 (45.8%), respectively, as determined by high -performance liquid chromatography. All the tested strains bound PhIP to a higher extent than IQ. In an alkaline comet assay, Lb. casei 0919 and Lb. rhamnosus 0908 displayed the strongest protective effect against IQ and PhIP (up to 80% reduction of DNA damage). Also in a comet assay, Lb. rhamnosus 0908 exhibited antioxidative activity toward H2O2 and PhIP (up to 63% and 69.5% reduction of oxidative DNA damage, respectively). The protective activity of the probiotic strains was specific to a given person’s FW, which implies the involvement of intestinal microbiota in the process.

Antioxidant effects of gastrointestinal digested purple carrot extract on the human cells of colonic mucosa

Purple carrot (PC) is a potential dietary constituent, which represents a valuable source of antioxidants and can modulate the reactive oxygen species (ROS) level in the gastrointestinal tract. Antioxidant capacity of a PC extract subjected to digestion process simulated in the artificial alimentary tract, including the stomach, small intestine and colon, was analyzed in normal human cells of colon mucosa. Results indicated that the extract obtained upon passage through the gastrointestinal tract, which could come into contact with the colonic cells in situ, was less potent than the extract, which was not subjected to digestion process. Digested PC extract exhibited intracellular ROS-inhibitory capacity, with 1mg/mL showing the ROS clearance of 18.4%. A 20.7% reduction in oxidative DNA damage due to colon mucosa cells’ treatment with digested PC extract was observed. These findings indicate that PC extract is capable of colonic cells’ protection against the adverse effects of oxidative stress.

Diallyl Disulfide Prevents Cyclophosphamide-Induced Hemorrhagic Cystitis in Rats through the Inhibition of Oxidative Damage, MAPKs, and NF-κB Pathways.

This study investigated the possible effects and molecular mechanisms of diallyl disulfide (DADS) against cyclophosphamide (CP)-induced hemorrhagic cystitis (HC) in rats. Inflammation response was assessed by histopathology and serum cytokines levels. We determined the protein expressions of nuclear transcription factor kappa-B (NF-κB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and tumor necrosis factor-α (TNF-α), oxidative stress, urinary nitrite-nitrate, malondialdehyde (MDA), and 8-hydroxy-2’-deoxyguanosine (8-OHdG). Finally, we studied the involvement of mitogen-activated protein kinases (MAPKs) signaling in the protective effects of DADS against CP-induced HC. CP treatment caused a HC which was evidenced by an increase in histopathological changes, proinflammatory cytokines levels, urinary nitrite-nitrate level, and the protein expression of NF-κB, COX-2, iNOS, TNF-α, p-c-Jun N-terminal kinase (JNK), and p-extracellular signal regulated kinase (ERK). The significant decreases in glutathione content and glutathione-S-transferase and glutathione reductase activities, and the significant increase in MDA content and urinary MDA and 8-OHdG levels indicated that CP-induced bladder injury was mediated through oxidative DNA damage. In contrast, DADS pretreatment attenuated CP-induced HC, including histopathological lesion, serum cytokines levels, oxidative damage, and urinary oxidative DNA damage. DADS also caused significantly decreased the protein expressions of NF-κB, COX-2, iNOS, TNF-α, p-JNK, and p-ERK. These results indicate that DADS prevents CP-induced HC and that the protective effects of DADS may be due to its ability to regulate proinflammatory cytokines production by inhibition of NF-κB and MAPKs expressions, and its potent anti-oxidative capability through reduction of oxidative DNA damage in the bladder.

Antioxidant capacity of broccoli sprouts subjected to gastrointestinal digestion.

Broccoli is a common vegetable recognized as a rich source of antioxidants. To date, research on the antioxidant properties of broccoli, predominantly conducted on extracts, has not considered the lesions of composition and this activity after gastrointestinal digestion. Here the stability of antioxidants during gastrointestinal digestion was evaluated in conjunction with the protective effects of broccoli sprouts (BS) against oxidative stress in human colon cells. The obtained data suggest that, among the biocompounds identified in BS, glucosinolates were mainly degraded under gastrointestinal digestion, while phenolics, particularly hydroxycinnamic acid derivatives, were the most resistant constituents. The antioxidant capacity of BS extract subjected to gastrointestinal digestion was similar to or higher than that determined for non-digested BS. Gastrointestinal digested BS extract exhibited reactive oxygen species (ROS)-inhibitory capacity in NCM460 human colon cells, with 1 mg mL(-1) showing an ROS clearance of 76.59%. A 57.33% reduction in oxidative DNA damage in NCM460 cells due to treatment with digested BS extract was observed. The results lend support to the possible application of BS as a rich source of antioxidants to improve the defensive system against oxidative stress in the human colon mucosa.

Potential anti-aging agents suppress the level of constitutive mTOR- and DNA damage- signaling

Two different mechanisms are considered to be the primary cause of aging. Cumulative DNA damage caused by reactive oxygen species (ROS), the by-products of oxidative phosphorylation, is one of these mechanisms (ROS concept). Constitutive stimulation of mitogen- and nutrient-sensing mTOR/S6 signaling is the second mechanism (TOR concept). The flow- and laser scanning- cytometric methods were developed to measure the level of the constitutive DNA damage/ROS- as well as of mTOR/S6- signaling in individual cells. Specifically, persistent activation of ATM and expression of γH2AX in untreated cells appears to report constitutive DNA damage induced by endogenous ROS. The level of phosphorylation of Ser235/236-ribosomal protein (RP), of Ser2448-mTOR and of Ser65-4EBP1, informs on constitutive signaling along the mTOR/S6 pathway. Potential gero-suppressive agents rapamycin, metformin, 2-deoxyglucose, berberine, resveratrol, vitamin D3 and aspirin, all decreased the level of constitutive DNA damage signaling as seen by the reduced expression of γH2AX in proliferating A549, TK6, WI-38 cells and in mitogenically stimulated human lymphocytes. They all also decreased the level of intracellular ROS and mitochondrial trans-membrane potential ΔΨm, the marker of mitochondrial energizing as well as reduced phosphorylation of mTOR, RP-S6 and 4EBP1. The most effective was rapamycin. Although the primary target of each on these agents may be different the data are consistent with the downstream mechanism in which the decline in mTOR/S6K signaling and translation rate is coupled with a decrease in oxidative phosphorylation, (revealed by ΔΨm) that leads to reduction of ROS and oxidative DNA damage. The decreased rate of translation induced by these agents may slow down cells hypertrophy and alleviate other features of cell aging/senescence. Reduction of oxidative DNA damage may lower predisposition to neoplastic transformation which otherwise may result from errors in repair of DNA sites coding for oncogenes or tumor suppressor genes. The data suggest that combined assessment of constitutive γH2AX expression, mitochondrial activity (ROS, ΔΨm) and mTOR signaling provides an adequate gamut of cell responses to evaluate effectiveness of gero-suppressive agents.

Differential expression of HIF-1α in CD44+CD24-/low breast ductal carcinomas

BackgroundCancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self-renewing CSC population that is also capable of differentiating into non-self-renewing cell populations that constitute the bulk of tumor. Stem cells renewal and differentiation can be directly influenced by the oxygen levels of determined tissues, probably by the reduction of oxidative DNA damage in hypoxic regions, thus leading to a friendlier microenvironment, regarding to clonal expansion and for resistance to chemotherapeutic regimens. Furthermore, there have been strong data indicating a pivotal role of hypoxic niche in cancer stem cells development. There are evidence that hypoxia could drive the maintenance of CSC, via HIF-1α expression, but it still to be determined whether hypoxia markers are expressed in breast tumors presenting CD44+CD24-/low immunophenotype.MethodsImmunohistochemical analysis of CD44+CD24-/low expression and its relationship with hypoxia markers and clinical outcome were evaluated in 253 samples of breast ductal carcinomas. Double-immunolabeling was performed using EnVision Doublestain System (Dako, Carpinteria, CA, USA). Slides were then scanned into high-resolution images using Aperio ScanScope XT and then, visualized in the software Image Scope (Aperio, Vista, CA, USA).ResultsIn univariate analysis, CD44+CD24-/low expression showed association with death due to breast cancer (p = 0.035). Breast tumors expressing CD44+CD24-/low immunophenotype showed relationship with HIF-1α (p = 0.039) and negativity for HER-2 (p = 0.013).ConclusionConsidering that there are strong evidences that the fraction of a tumour considered to be cancer stem cells is plastic depending upon microenvironmental signals, our findings provide further evidence that hypoxia might be related to the worse prognosis found in CD44+CD24-/low positive breast tumors.

786 INTRA-HEPATIC NK CELLS FROM CHRONICALLY HCV-INFECTED PATIENTS ARE AS RESPONSIVE AS THOSE FROM NON-INFECTED LIVER

OHdG – HPLC-EC)], telomere length [T/S – RT-PCR], apoptosis [M30 – ELISA test] and liver fibrosis [Pro-Collagen III (PIIINP – ELISA)]. At t0 the patients were categorized into two groups, in relation to their routine coffee intake (0–2 and 3–5 cups/day). Results: At t0, AST, GGT and ALP levels were significantly lower while HCV-RNA levels significantly higher in patients with higher coffee consumption (p =0.05). During the month of coffee intake, 8-OHdG and PIIINP levels significantly dropped, to regrow during the abstinence period (p =0.05/p = 0.04, respectively), while T/S became significantly shorter (p = 0.006). A significant negative correlation was found between T/S and 8-OHdG levels (p = 0.03). HCV-RNA and M30 (apoptosis) levels were significantly higher during coffee intake (p =0.002 and p=0.04). Conclusions: During coffee intake, despite an increase in viral load, that however is not considered a strong prognostic factor for HCC development, we observed: – a lower level of collagen deposition in the liver, that probably mediates the protection exerted by coffee with respect to progression to cirrhosis; – a reduction in oxidative DNA damage, correlated with increased telomere length (with consequent increased genomic stability) and an increased apoptosis, that both potentially mediate the reduced risk of HCC development. Supported by ISIC Scientific Committee.

마전자 추출물의 항산화 및 Alpha-Glucosidase 저해 활성

본 연구는 마전자(Strychnos nux-vomica) 추출물의 항산화 활성 및 α-glucosidase 저해활성을 측정하였다. 먼저, 마전자를 각각의 용매로 추출하여 페놀 함량을 알아본 결과 100 g당 SNM에서 71.43 ㎎을 함유하고 있으며, SNE에서는 24.51 ㎎, SNA에서는 11.17 ㎎을 함유하고 있었다. DPPH 라디칼 소거능은 SNM, SNE가 1 ㎎/㎖의 농도에서 50% 정도의 활성을 나타내 항산화 효과가 있다는 것을 확인할 수 있었다. 또한 200 μM H₂O₂에 의한 DNA 손상에 대해 마전자 추출물의 보호 효과를 확인할 수 있었다. SNM의 α-glucosidase 저해활성 측정 시 SNM 1 ㎎/㎖의 농도에서 12.8%의 억제 활성을 나타내었고, SNM 처리시간을 증가시킬 경우 그 활성도가 유의적으로 증가하는 것을 보였다. 이상의 결과로 마전자 추출물의 항산화 활성 및 SNM의 α-glucosidase 억제 활성을 확인할 수 있었다.

Effects of ethanol extracts from stalked sea squirt (Styela clava) on antioxidant potential, oxidative DNA damage and DNA repair

The aim of this study was to assess the total radical trapping antioxidant potential and antigenotoxic effects by comet assay of ethanol extracts of stalked sea squirt, Styela clava, (tunic, substrate, and whole). All extracts of stalked sea squirt effectively scavenged ABTS· + in a dose dependent manner. Pretreatment with each extract of stalked sea squirt produced significant reductions in oxidative DNA damage at concentrations of 1–50 μg/mL, with whole extract of stalked sea squirt showing higher inhibition (16.1 μg/mL) of H2O2 induced DNA damage than substrate or tunic extracts based on ED50 values. The addition of 50 μg/mL of stalked sea squirt extracts to human leukocytes after oxidative stimulus (200 μM H2O2) for 5 min positively influences the kinetics of DNA repair during 24 hr of incubation. These results indicate that the ethanol extracts of tunic, substrate, and whole stalked sea squirt have significant antioxidant activities that protect against oxidative DNA damage and improve DNA repair capacity.

Selenium Supplementation Reduced Oxidative DNA Damage in Adnexectomized BRCA1 Mutations Carriers

Some experimental evidence suggests that BRCA1 plays a role in repair of oxidative DNA damage. Selenium has anticancer properties that are linked with protection against oxidative stress. To assess whether supplementation of BRCA1 mutation carriers with selenium have a beneficial effect concerning oxidative stress/DNA damage in the present double-blinded placebo control study, we determined 8-oxodG level in cellular DNA and urinary excretion of 8-oxodG and 8-oxoGua in the mutation carriers. We found that 8-oxodG level in leukocytes DNA is significantly higher in BRCA1 mutation carriers. In the distinct subpopulation of BRCA1 mutation carriers without symptoms of cancer who underwent adnexectomy and were supplemented with selenium, the level of 8-oxodG in DNA decreased significantly in comparison with the subgroup without supplementation. Simultaneously in the same group, an increase of urinary 8-oxoGua, the product of base excision repair (hOGG1 glycosylase), was observed. Therefore, it is likely that the selenium supplementation of the patients is responsible for the increase of BER enzymes activities, which in turn may result in reduction of oxidative DNA damage. Importantly, in a double-blinded placebo control prospective study, it was shown that in the same patient groups, reduction in cancer incidents was observed. Altogether, these results suggest that BRCA1 deficiency contributes to 8-oxodG accumulation in cellular DNA, which in turn may be a factor responsible for cancer development in women with mutations, and that the risk to developed breast cancer in BRCA1 mutation carriers may be reduced in selenium-supplemented patients who underwent adnexectomy.

Polypodium leucotomos Extract Decreases UV-Induced Cox-2 Expression and Inflammation, Enhances DNA Repair, and Decreases Mutagenesis in Hairless Mice

UV-irradiated skin and UV-induced tumors overexpress the inducible isoform of cyclooxygenase-2 (Cox-2), and Cox-2 inhibition reduces photocarcinogenesis. To evaluate photoprotective effects of Polypodium leucotomos extract (PL), hairless Xpc(+/-) mice were fed for 10 days with PL (300 mg/kg) or vehicle then UV-irradiated, once. By 24 hours, UV-induced Cox-2 levels were increased in vehicle-fed and PL-fed mice, whereas by 48 and 72 hours, Cox-2 levels were four- to fivefold lower in PL-fed mice (P < 0.05). p53 expression/activity was increased in PL-fed versus vehicle-fed then UV-irradiated mice. UV-induced inflammation was decreased in PL-fed mice, as shown by approximately 60% decrease (P < 0.001) in neutrophil infiltration at 24 hours, and macrophages by approximately 50% (<0.02) at 24 and 48 hours. By 72 hours, 54 +/- 5% cyclobutane pyrimidine dimers remained in vehicle-fed versus 31 +/- 5% in PL-fed skin (P < 0.003). The number of 8-hydroxy-2'-deoxyguanosine-positive cells were decreased before UV irradiation by approximately 36% (P < 0.01), suggesting that PL reduces constitutive oxidative DNA damage. By 6 and 24 hours, the number of 8-hydroxy-2'-deoxyguanosine-positive cells were approximately 59% (P < 0.01) and approximately 79% (P < 0.03) lower in PL-fed versus vehicle-fed mice. Finally, UV-induced mutations in PL-fed-mice were decreased by approximately 25% when assessed 2 weeks after the single UV exposure. These data demonstrate that PL extract supplementation affords the following photoprotective effects: p53 activation and reduction of acute inflammation via Cox-2 enzyme inhibition, increased cyclobutane pyrimidine dimer removal, and reduction of oxidative DNA damage.

해양세균 Pseudoa/teromonas psicida TA20의 색소 추출물의 물리화학적 안정성과 생리활성

해양세균 Pseudoalteromonas psicida TA20의 ethanol 색소 추출물에 대한 안정성과 기능성을 검토한 결과, 본 해양세균 색소는 pH 4.0에서 pH 8.0의 조건과 <TEX>$40^{\circ}C$</TEX> 이하에서 매우 안정하였으며, <TEX>$25^{\circ}C$</TEX> 14일간 90% 이상의 잔존율을 나타내어 빛에 대한 안정성이 매우 우수한 것으로 나타났다. 금속이온의 경우 <TEX>$Al^{3+}$</TEX>과 <TEX>$Cu^{2+}$</TEX>를 제외한 실험된 모든 금속이온에 대하여 매우 안정하였으며 특히, 다른 색소추출물들에 비해 <TEX>$Fe^{2+}$</TEX>에 대한 안정성이 높은 것으로 나타났다. 해양세균 색소추출물에 대한 생리활성 실험 결과, free radical 소거 활성 (3495 <TEX>${\mu}g/ml$</TEX>)이 나타났으며, 색소농도 10 <TEX>${\mu}g/ml$</TEX>일 때 44%의 인체세포 DNA 손상 회복능이 있음을 보여 항산화능이 우수함을 알 수 있었다. 또한 주요 식품유해세균에 대하여 항균활성을 나타내었다. 따라서 본 해양세균 색소는 항산화능과 항균활성을 갖는 식품 색소로의 적용을 검토할 수 있을 것으로 기대된다. We investigated the physicochemical stabilities and biological activities of ethanol- extracted pigment from marine bacterium Pseudoalteromonas psicida TA20. This bacterial pigment was very stable at a pH range of between 4.0 and 8.0 at a temperature below <TEX>$40^{\circ}C$</TEX>. In the presence of light, the pigment was also very stable, showing more than 90 percent remaining absorbance during 14 days at <TEX>$25^{\circ}C$</TEX>. The stability of the pigment, when metal ions were present, showed higher stability in all examined metal ions except for <TEX>$Al^{3+}$</TEX> and <TEX>$Cu^{2+}$</TEX>, especially in the presence of <TEX>$Fe^{2+}$</TEX>. This pigment showed higher stability than other pigment extracts reported. The pigment has free-radical scavenging (3,495 <TEX>${\mu}g/ml$</TEX>) activity and 44% antioxidant protective effect against DNA damage of human lymphocyte cells at a concentration of 10 <TEX>${\mu}g/ml$</TEX>. The results indicate that the bacterial pigment produced a significant reduction in oxidative DNA damage. The pigment also showed antimicrobial activity against major food poisoning bacteria. Therefore, these results suggest that this bacterial pigment could be used as a natural colorant in the food industry, having the advantages of antioxidant and antimicrobial activities.

Antioxidative and Antigenotoxic Activity of Extracts from Cosmos (Cosmos bipinnatus) Flowers

The Cosmos bipinnatus has been used in a traditional herbal remedy for various diseases such as jaundice, intermittent fever, and splenomegaly. The present study describes the preliminary evaluation of antioxidant activities and antigenotoxic effect of Cosmos bipinnatus flowers according to four different colors (white, pink, orange, and violet). The antioxidants properties were evaluated by determining TPC, DPPH RSA, ABTS RSA, and RP. The highest TPC of methanolic CFE (at concentration of 1 mg/ml) showed in violet colored CF (1,013 microM), and IC(50) of DPPH RSA, ABTS RSA, and RP were also the lowest in violet colored CFE with values of 0.61, 1.48, and 0.82 mg/ml, respectively. The antigenotoxic effect of the CFE on DNA damage induced by H(2)O(2) in human leukocytes was evaluated by Comet assay. Pretreatments with CFE produced significant reductions in oxidative DNA damage at the concentration of 500 microg/ml, except for violet colored CFE. The ED(50) value of white colored CFE has shown the highest inhibition (0.40 mg/ml) on H(2)O(2) induced DNA damage, followed by orange > pink > violet color. These results suggested that Cosmos bipinnatus has significant antioxidant activity and protective effect against oxidative DNA damage.

Tempol Protects against Oxidative Damage and Delays Epithelial Tumor Onset in Fanconi Anemia Mice

Fanconi anemia (FA) is a genetic disorder characterized by congenital abnormalities, bone marrow failure, and marked cancer susceptibility. FA patients have an elevated risk of developing hematologic malignancies and solid tumors. Using Fancd2(-/-) knockout mice as a model of FA, we examined the potential of tempol, a nitroxide antioxidant and a superoxide dismutase mimetic, as a tumor-delaying agent for solid tumors. Dietary tempol increased the mean tumor-free survival time of Fancd2(-/-) Trp53(+/-) mice by 27% (P < 0.01), from 308 to 390 days, without changing the overall tumor spectrum. More strikingly, tempol delayed the onset of epithelial tumors and increased the mean epithelial tumor-free survival time by 38% (P < 0.0001), from 312 to 432 days, in Fancd2(-/-) Trp53(+/-) mice. These results show that tempol can significantly delay tumor formation in Fancd2(-/-) Trp53(+/-) mice. Furthermore, tempol treatment did not adversely affect the repopulating ability of FA hematopoietic stem cells. The reduction in oxidative DNA damage in tempol-treated FA fibroblasts and mice suggests that its tumor-delaying function may be attributed to its antioxidant activity.

2-Deoxy-D-glucose Reduces the Level of Constitutive Activation of ATM and Phosphorylation of Histone H2AX

Histone H2AX phosphorylated on Ser-139, defined as γH2AX, is a reporter of DNA double-strand breaks (DSBs). While H2AX undergoes phosphorylation after induction of DNA damage by genotoxic agents or during physiological events that involve DNA recombination, it also is phosphorylated in untreated normal and tumor cells. We recently reported that this constitutive H2AX phosphorylation (CHP) is markedly reduced by the antioxidant N-acetyl-L-cysteine (NAC), and postulated that it reflects the oxidative DNA damage (“endogenous DSBs”) induced by reactive oxygen species (ROS) generated by metabolic activity during progression through the cell cycle. In the present study, we provide evidence that growth of cells from three human lymphoblastoid cell lines TK6, NH32 and WTK1 in the presence of the glucose antimetabolite 2-deoxy-D-glucose (2-DG) led to a distinct reduction in the level of CHP. The reduction of CHP was more pronounced in S and G2M than in G1 phase cells. Constitutive activation of ATM was also reduced. The data suggest that a decrease in a cell’s metabolic activity as a result of inhibition of glycolysis by 2-DG reduces generation of ROS which leads to the reduction of oxidative DNA damage. The data also point out that ATM may play a role in CHP induced by oxidative DNA damage. Therefore, the assay of CHP by multiparameter cytometry provides the means to measure effects of antioxidants and metabolic inhibitors on endogenous oxidative DNA damage in relation to cell cycle phase.