Reduction In DNA Strand Breaks Research Articles

Protective Effects of Natural Products and Their Derivatives on Genetic Material: A Critical Review

Although treatment with natural products and the substances derived from them has gained much attention, it is important to know the genomic safety of these substances prior to their use in humans. The present review aims to present the current knowledge on the genoprotective effects and possible mechanism of actions of natural compounds. Therefore, an up-to-date search was conducted using known databases such as PubMed, ScienceDirect, and Clinicaltrials.gov. For the investigation of genotoxic/genoprotective activity of these substances, comet or micronucleus assay were frequently used models applied through eukaryotic test systems, bacterial strains, cultured animal cells or tissues (e.g., mice, rats) but also human by using oxidizing or carcinogenic agent-induced DNA damage capacity. Findings suggest that several extracts, including those from medicinal plants, marine algae or their preparations, antioxidants such as quercetin, retinoids, resveratrol, hyaluronic acid, carnosol, rosmarinic acid, and naringin have shown genoprotective effects in various test systems. Antioxidant, anti-inflammatory, mitogenic, reduction of DNA strand breaks and DNA lesions, formation of micronucleus, and chromosomal aberrations were the observed mechanisms of action of genoprotective substances. In conclusion, this review highlights the importance of natural products, especially dietary antioxidants, which can be safely used for the treatment of various diseases.

The effects of urbanization on Lepomis macrochirus using the comet assay

Urbanization has been linked to increased concentrations of polycyclic aromatic hydrocarbons in natural waterways. This study was designed to examine the impact of urbanization and a wastewater treatment plant by investigating the impact on field-collected bluegill (Lepomis macrochirus). Results show a significant increase in DNA strand breaks in blood cells (comet assay) linked to urbanization and a reduction in DNA strand breaks downstream of the WWTP, likely the result of dilution. A laboratory study exposing L. macrochirus to the known mutagen, methyl methanesulfonate, was performed to validate the comet assay endpoints in this species. Results of the laboratory study showed that the comet assay endpoints of tail length and tail extent moment responded in a dose- and time-dependent manner. Habitat quality assessments, along with chemical concentrations of polycyclic hydrocarbons in sediments showed that habitat quality between all sites were similar and that hydrocarbons likely contributed to the DNA strand breaks observed.

Modulation of cellular defense processes in human lymphocytes in vitro by a 1,4-dihydropyridine derivative

The aim of this pilot study was to assess whether a compound of the β-carbonyl-1,4-dihydropyridine series (AV-153 or sodium 3,5-bis-ethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine-4-carboxylate), which has high efficiency in stimulating DNA repair, can simultaneously modulate apoptosis in human cells. Peripheral blood lymphocytes of healthy donors were used in this study. DNA strand-break rejoining was assessed with the alkaline comet assay after a 3-h incubation of lymphocytes in the presence of a wide range of concentrations of AV-153 (10 −10–10 −5 M). Apoptotic and micronucleated (MN) cells were scored in phytohaemagglutinin-stimulated lymphocytes after a 72-h incubation with AV-153, using the standard cytokinesis -blocked micronucleus test. The study revealed dual effects of AV-153 on cellular defense systems against endogenously generated DNA damage: the compound per se simultaneously reduces DNA strand breaks and stimulates apoptosis, with a maximal efficiency of 76% and 42%, respectively; in contrast, after genotoxic stress (2 Gy of gamma-radiation) AV-153 reduces DNA strand breaks, the number of MN cells and apoptotic cells in a similar dose-dependent manner. A maximal efficiency of 67% was found for reduction of DNA strand breaks, while for MN cells and apoptotic cells the efficiencies were, respectively, 47% and 44%. While limited in number, these preliminary studies show the direct correlation between the efficiency of AV-153 in reduction of radiation-induced DNA breaks and MN cells on one side, and in reduction of apoptosis on the other. It suggests that the major target of the compound's action on genotoxic stress is DNA repair, followed by reduction of the number of damaged cells entering apoptosis.

Myricetin, quercetin, (+)-catechin and (−)-epicatechin protect against N-nitrosamines-induced DNA damage in human hepatoma cells

The aim of this study was to investigate the protective effect of myricetin, quercetin, (+)-catechin and (−)-epicatechin, against N-nitrosodibutylamine (NDBA) and N-nitrosopiperidine (NPIP)-induced DNA damage in human hepatoma cells (HepG2). DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or Comet assay. (+)-Catechin at the lowest concentration (10 μM) showed the maximum reduction of DNA strand breaks (23%), the formation of endonuclease III (Endo III, 19–21%) and formamidopyrimidine-DNA glycosylase (Fpg, 28–40%) sensitive sites induced by NDBA or NPIP. (−)-Epicatechin also decreased DNA strand breaks (10 μM, 20%) and the oxidized pyrimidines/purines (33–39%) induced by NDBA or NPIP, respectively. DNA strand breaks induced by NDBA or NPIP were weakly reduced by myricetin at the lowest concentration (0.1 μM, 10–19%, respectively). Myricetin also reduced the oxidized purines (0.1 μM, 17%) and pyrimidines (0.1 μM, 15%) induced by NDBA, but not the oxidized pyrimidines induced by NPIP. Quercetin did not protect against NDBA-induced DNA damage, but it reduced the formation of Endo III and Fpg sensitive sites induced by NPIP (0.1 μM, 17–20%, respectively). In conclusion, our results indicate that (+)-catechin and (−)-epicatechin at the concentrations tested protect human derived cells against oxidative DNA damage effects of NDBA and NPIP. However, myricetin at the concentrations tested only protects human cells against oxidative DNA damage induced by NDBA and quercetin against oxidative DNA damage induced by NPIP.

Aminoguanidine delays the replicative senescence of human diploid fibroblasts

The accumulation of free radicals and advanced glycation end products (AGEs) in cell plays a very important role in replicative senescence. Aminoguanidine (AG) has potential antioxidant effects and decreases AGE levels. This study aimed to investigate its effect on replicative senescence in vitro. The effects of aminoguanidine on morphology, replicative lifespan, cell growth and proliferation, AGEs, DNA damage, DNA repair ability and telomere length were observed in human fetal lung diploid fibroblasts (2BS). Aminoguanidine maintained the non-senescent phenotype of 2BS cells even at late population doubling (PD) and increased cumulative population doublings by at least 17 - 21 PDs. Aminoguanidine also improved the potentials of growth and proliferation of 2BS cells as detected by the MTT assay. The AGE levels of late PD cells grown from early PD in DMEM containing aminiguanidine decreased significantly compared with those of late PD control cells and were similar to those of young control cells. In addition, the cells pretreated with aminoguanidine had a significant reduction in DNA strand breaks when they were exposed to 200 micromol/L H(2)O(2) for 5 minutes which indicated that the compound had a strong potential to protect genomic DNA against oxidative stress. And most of the cells exposed to 100 micromol/L H(2)O(2) had much shorter comet tails and smaller tail areas after incubation with aminoguanidine-supplemented DMEM, which indicated that the compound strongly improved the DNA repair abilities of 2BS cells. Moreover, PD55 cells grown from PD28 in 2 mmol/L or 4 mmol/L aminoguanidine retain telomere lengths of 7.94 kb or 8.12 kb, which was 0.83 kb or 1.11 kb longer than that of the control cells. Aminoguanidine delays replicative senescence of 2BS cells and the senescence-delaying effect of aminoguanidine appear to be due to its many biological properties including its potential for proliferation improvement, its inhibitory effect of AGE formation, antioxidant effect, improvement of DNA repair ability and the slowdown of telomere shortening.

Immunity and antioxidant capacity in humans is enhanced by consumption of a dried, encapsulated fruit and vegetable juice concentrate.

The daily consumption of fruits and vegetables is a common dietary recommendation to support good health. We hypothesized that a commercially available encapsulated fruit and vegetable juice powder concentrate (FVJC) could support functional indices of health due to increased intake of various phytonutrients. This was a double-blind, randomized, placebo-controlled investigation of 59 healthy law students who consumed either FVJC or placebo capsules for 77 d. Blood was collected on d 1, 35, and 77 to examine the number of circulating alphabeta- and gammadelta-T cells, cytokine production, lymphocyte DNA damage, antioxidant status, and levels of carotenoids and vitamin C. A log of illnesses and symptoms was also kept. The FVJC group tended to have fewer total symptoms than the placebo group (P < 0.076). By d 77 there was a 30% increase in circulating gammadelta-T cells and a 40% reduction in DNA damage in lymphocytes in the FVJC group relative to the placebo group. Plasma levels of vitamin C and of beta-carotene, lycopene, and lutein increased significantly from baseline in the FVJC group as did plasma oxygen radical absorptive capacity (50%). Interferon-gamma produced by phorbol-stimulated lymphocytes was reduced 70% in the FVJC group, whereas other cytokines (IL-4, IL-6, transforming growth factor beta) were unchanged relative to treatment or time. FVJC consumption during this study period resulted in increased plasma nutrients and antioxidant capacity, reduction in DNA strand breaks, and an increase in circulating gammadelta-T cells.

Rosemary-stimulated reduction of DNA strand breaks and FPG-sensitive sites in mammalian cells treated with H 2O 2 or visible light-excited Methylene Blue

In this study possible protective effects of rosemary against oxidative DNA damage induced by H 2O 2- and visible light-excited Methylene Blue in colon cancer cells CaCo-2 and hamster lung cells V79 were investigated. The level of DNA damage (DNA strand breaks) was measured using the classical and modified single cell gel electrophoresis, so-called comet assay. Our findings showed that an ethanol extract from rosemary reduced the genotoxic activity of both agents after a long-term (24 h; 0.3 μg/ml) or short-term (2 h; 30 μg/ml) pre-incubation of cells. We suggest that the extract of rosemary exhibits a protective effect against oxidative damage to DNA as a consequence of scavenging of both OH radicals and singlet oxygen ( 1O 2).