Free radicals-mediated induction of oxidized DNA bases and DNA−protein cross-links by nickel chloride

2002 ◽  
Vol 514 (1-2) ◽  
pp. 233-243 ◽  
Author(s):  
Katarzyna Woźniak ◽  
Janusz Błasiak
Keyword(s):  
Free Radicals ◽  
Nickel Chloride ◽  
Dna Bases ◽  
Cross Links

scholarly journals UJI AKTIVITAS ANTIOKSIDAN SPONS Stylissa sp. DENGAN MENGGUNAKAN METODE DPPH (1,1-difenil-2-pikrilhidrazil)

PHARMACON ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 419
Author(s):  
Samuel I.M. Sibarani ◽  
Adithya Yudistira ◽  
Deby A. Mpila
Keyword(s):  
Antioxidant Activity ◽  
Cell Wall ◽  
Free Radicals ◽  
Ethanol Extract ◽  
Dna Bases ◽  
Oxidation Reactions ◽  
Terrestrial Plants ◽  
Dpph Method ◽  
High Antioxidant Activity ◽  
Ethanol Extracts

ABSTRACTHabitat of sponge Stylissa sp., were under the sea and these sponges contain active compounds, which are more active than the compounds produced by terrestrial plants. Antioxidants are inhibitors of oxidation reactions due to the free radicals, which can cause weak damage to unsaturated cells, cell wall membranes, blood vessels, DNA bases, and lipid tissue, that causing disease. The study was conducted to determine the antioxidant activity of ethanol extracts  of sponge Stylissa sp., which is located on the Bangka Island, Likupang District, North Minahasa Regency. Sponge Stylissa sp., was extracted by maceration with using ethanol. Testing of antioxidant activity was carried out by the DPPH method measured by a UV-Vis spectrophotometer. The results of the study showed that ethanol extracts of sponge Stylissa sp., has antioxidant activity in each concentration and the highest at a concentration of 100 mg / L. The conclusion is a ethanol extract of sponge Stylissa sp. have high antioxidant activity with a concentration of 25 mg/L (77,40%), concentration of 50 mg/L (85,63%), concentration of 75 mg/L (88,66%), and concentration 100 mg/L (88,96%). Key words: Stylissa sp. Sponge, Antioxidant, DPPH (1,1-diphenyl-2-picrylhydrazyl) ABSTRAKHabitat dari spons Stylissa sp. terdapat di bawah laut dan spons ini mengandung senyawa aktif yang persentase keaktifannya lebih besar dibandingkan dengan senyawa-senyawa yang dihasilkan oleh tumbuhan darat. Antioksidan adalah zat penghambat reaksi oksidasi akibat radikal bebas yang dapat menyebabkan kerusakan lemah tak jenuh, membran dinding sel, pembuluh darah, basa DNA, dan jaringan lipid sehingga menimbulkan penyakit. Penelitian dilakukan untuk mengetahui aktivitas antioksidan ekstrak etanol biota laut spons Stylissa sp. yang terdapat di pulau Bangka, Kecamatan Likupang, Kabupaten Minahasa Utara. Spons Stylissa sp. ini diekstrak dengan metode maserasi menggunakan etanol. Pengujian aktivitas antioksidan ini dilakukan dengan metode DPPH yang diukur dengan alat spektrofotometer UV-Vis. Hasil dari penelitian menunjukan bahwa ekstrak etanol spons Stylissa sp. memiliki aktivitas antioksidan disetiap konsentrasi dan yang tertinggi pada konsentrasi 100 mg/L. Kesimpulan yang didapat bahwa ekstrak etanol spons Stylissa sp. memiliki aktivitas antioksidan yang tinggi dengan konsentrasi 25 mg/L (77,40%), konsentrasi 50 mg/L (85,63%), konsentrasi 75 mg/L (88,66%), dan konsentrasi 100 mg/L (88,96%). Kata Kunci : Spons Stylissa sp., Antioksidan, DPPH (1,1-difenil-2-pikrilhidrazil)

Methylation of DNA bases by methyl free radicals: mechanism of formation of C8-methylguanine

2018 ◽  
Vol 29 (5) ◽  
pp. 1333-1340 ◽  
Author(s):  
Swarnadeep Biswas ◽  
Pramod Kumar Shah ◽  
P. K. Shukla
Keyword(s):  
Free Radicals ◽  
Dna Bases ◽  
Mechanism Of Formation ◽  
Methylation Of Dna

Electron transfer in biologically important systems: Polycyclic aromatic hydrocarbons, DNA bases and free radicals

2018 ◽  
Vol 17 (01) ◽  
pp. 1850008
Author(s):  
M. K. Tiwari ◽  
P. C. Mishra
Keyword(s):  
Electron Transfer ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Free Radicals ◽  
Aromatic Hydrocarbons ◽  
Polarizable Continuum Model ◽  
Dna Bases ◽  
Free Energies ◽  
Species Barrier ◽  
Polycyclic Aromatic ◽  
Polarizable Continuum

Occurrence of electron transfer was studied for different combinations of polycyclic aromatic hydrocarbons (PAHs) and DNA bases as electron donors or acceptors and free radicals only as electron acceptors. Geometries of all the molecules and radicals were optimized in aqueous medium employing the polarizable continuum model. Single electron transfer (SET) and sequential proton loss electron transfer mechanisms were investigated employing Gibbs free energies of the appropriate neutral, anionic and cationic species. Barrier energies involved in these phenomena were calculated using the Marcus theory. The SET barrier energies were found to be linearly correlated with [Formula: see text] (Electron affinities of acceptors – Ionization potentials of donors). SET barrier energies from the DNA bases to the PAHs follow the order Cy [Formula: see text] Th [Formula: see text] Ad [Formula: see text] Gu, whereas SET barrier energies from the PAHs to the DNA bases follow the order Gu [Formula: see text] Ad [Formula: see text] Th [Formula: see text] Cy. Thus, guanine, among the DNA bases, is the best electron donor to the PAHs and worst electron acceptor from the same.

Modification of DNA bases in mammalian chromatin by radiation-generated free radicals

Biochemistry ◽  
1990 ◽  
Vol 29 (34) ◽  
pp. 7876-7882 ◽  
Author(s):  
Ewa Gajewski ◽  
Govind Rao ◽  
Zeena Nackerdien ◽  
Miral Dizdaroglu
Keyword(s):  
Free Radicals ◽  
Dna Bases

Reactions between Organic Nitroxyl Free Radicals and Radiation-induced Transients in the DNA Bases

1972 ◽  
Vol 22 (2) ◽  
pp. 115-129 ◽  
Author(s):  
T. Brustad ◽  
H. Bugge ◽  
W. B. G. Jones ◽  
E. Wold
Keyword(s):  
Free Radicals ◽  
Dna Bases ◽  
Radiation Induced

scholarly journals Histone H1- and other protein- and amino acid-hydroperoxides can give rise to free radicals which oxidize DNA

1999 ◽  
Vol 344 (1) ◽  
pp. 125-134 ◽  
Author(s):  
Catherine LUXFORD ◽  
Benedicte MORIN ◽  
Roger T. DEAN ◽  
Michael J. DAVIES
Keyword(s):  
Amino Acid ◽  
Transition Metal ◽  
Metal Ions ◽  
Transition Metal Ions ◽  
Histone H1 ◽  
Dna Bases ◽  
Nuclear Proteins ◽  
Dependent Manner ◽  
Product Analysis ◽  
Cross Links

Exposure of amino acids, peptides and proteins to radicals, in the presence of oxygen, gives high yields of hydroperoxides. These materials are readily decomposed by transition metal ions to give further radicals. We hypothesized that hydroperoxide formation on nuclear proteins, and subsequent decomposition of these hydroperoxides to radicals, might result in oxidative damage to associated DNA. We demonstrate here that exposure of histone H1 and model compounds to γ-radiation in the presence of oxygen gives hydroperoxides in a dose-dependent manner. These hydroperoxides decompose to oxygen- and carbon-centred radicals (detected by electron paramagnetic resonance spectroscopy) on exposure to Cu+ and other transition metal ions. These hydroperoxide-derived radicals react readily with pyrimidine DNA bases and nucleosides to give adduct species (i.e. protein-DNA base cross-links). Product analysis has demonstrated that radicals from histone H1-hydroperoxides, and other protein and amino acid hydroperoxides, can also oxidize both free 2′-deoxyguanosine and intact calf thymus DNA to give the mutagenic oxidized base 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-hydroxy-2′-deoxyguanosine, 8-oxodG). The yield of 7,8-dihydro-8-oxo-2′-deoxyguanosine is proportional to the initial protein-hydroperoxide concentration, and corresponds (for histone H1-hydroperoxide, 280 μM) to approx. 1.4% conversion for free 2′-deoxyguanosine (200 μM), and 0.14% for 2′-deoxyguanosine in DNA (70 μg/ml). Evidence has also been obtained with DNA for reaction at cytosine and thymine, but not adenine; the lack of damage to the latter may result from damage transfer to 2′-deoxyguanosine residues. These studies demonstrate that initial radical-induced damage to nuclear proteins can give rise to subsequent DNA damage; the latter includes both DNA-protein cross-links and formation of oxidized DNA bases.

Study of eukaryotic flagellar components by cryo-electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 98-101
Author(s):  
John M. Murray ◽  
Rob Ward
Keyword(s):  
Electron Microscopy ◽  
Primary Motion ◽  
Cryo Electron Microscopy ◽  
Cross Links ◽  
Cilia And Flagella

The eukaryotic flagellum is constructed from 11 parallel tubular elements arranged as 9 peripheral fibers (doublet microtubules) and 2 central fibers (singlet microtubules). The primary motion generating component has been found to be arranged as axially periodic “arms” bridging the adjacent doublets. The dynein, comprising the arms, has been isolated and characterized from several different cilia and flagella. Various radial and azimuthal cross-links stabilize the axially aligned microtubules, and probably play some role in controlling the form of the flagella beat cycle.

Electron microscopic study of the membrane glycoproteins in the rat kidney after cisplatin treatment

1989 ◽  
Vol 47 ◽  
pp. 912-913
Author(s):  
S.K. Aggarwal
Keyword(s):  
Alkaline Phosphatase ◽  
Rat Kidney ◽  
Light And Electron Microscopy ◽  
Kidney Tissue ◽  
Membrane Glycoproteins ◽  
Electron Microscopic ◽  
Before And After ◽  
Interstrand Cross Links ◽  
Cross Links

The proposed primary mechanism of action of the anticancer drug cisplatin (Cis-DDP) is through its interaction with DNA, mostly through DNA intrastrand cross-links or DNA interstrand cross-links. DNA repair mechanisms can circumvent this arrest thus permitting replication and transcription to proceed. Various membrane transport enzymes have also been demonstrated to be effected by cisplatin. Glycoprotein alkaline phosphatase was looked at in the proximal tubule cells before and after cisplatin both in vivo and in vitro for its inactivation or its removal from the membrane using light and electron microscopy.Outbred male Swiss Webster (Crl: (WI) BR) rats weighing 150-250g were given ip injections of cisplatin (7mg/kg). Animals were killed on day 3 and day 5. Thick slices (20-50.um) of kidney tissue from treated and untreated animals were fixed in 1% buffered glutaraldehyde and 1% formaldehyde (0.05 M cacodylate buffer, pH 7.3) for 30 min at 4°C. Alkaline phosphatase activity and carbohydrates were demonstrated according to methods described earlier.

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