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At least 937 records · Page 52Linked to original sources
PubMed1978

Some properties of vicinal diol-epoxides derived from benzo(a)anthracene and benzo(a)pyrene.

The alkylating properties of pairs of syn- and anti-isomers of 2 diol-epoxides derived from benzo(a)pyrene (BP) and of 1 derived from benz(a)anthracene (BA) have been investigated. Of the anti-diol-epoxides, anti-BP 7,8-diol-9,10-oxide was the most reactive compound towards DNA, towards sodium p-nitrothiophenolate in a non-aqueous solvent system, and towards 4-(p-nitrobenzyl)pyridine in aqueous solution; anti-BP 9,10,-diol-7,8-oxide was of intermediate reactivity and anti-BA 8,9-diol-10,11-oxide was least reactive. The syn-diol-epoxides gave unsatisfactory results with DNA and 4-(p-nitrobenzyl)pyridine because of their rapid solvolysis in aqueous solution, but with sodium p-nitrothiophenolate showed the order of reactivity syn-BP 7,8-diol-9,10-oxide greater than syn-BA 8,9-diol-10,11-oxide greater than syn-BP 9,10-diol-7,8-oxide. The products of the reaction between diol-epoxides and nucleic acids were examined by Sephadex LH-20 chromatography followed by high-pressure liquid chromatography (HPLC) and the diol-epoxides were shown to react principally with the guanosine and adenosine moieties of RNA.

Alkylating Agents↗
PubMed1978

Effects of benzo(a)pyrene adducts of DNA synthesis in vitro.

Two diol epoxides of benzo(a)pyrene (BP), and benzo(a)pyrene 4,5-oxide, have been used to make adducts in the homopolymers polyribocytidylic acid, (rC); polyriboadenylic acid (rA), polydeoxycytidylic acid (dC) and polydeoxyadenylic acid (dA). With appropriate oligomers as primers these modified and unmodified polynucleotides were used as templates for DNA synthesis with avian myeloblastosis virus DNA polymerase (AMV) or E. coli Pol I DNA polymerase. We have found that: (1) the size of the DNA product is not markedly decreased by the presence of these these polycyclic aromatic hydrocarbon adducts in the templates; (2) the presence of adducts does not lead to increased incorporation of erroneous bases. These results, supported by kinetic data, suggest that these polymerases can bypass a site containing an adduct on the template without leaving a gap or causing misincorporation of a base and they imply that mutagenesis by BP may not be attributable to either of these mechanisms.

Avian Myeloblastosis Virus↗
PubMed1979

Reactions of the carcinogen N-acetoxy-4-acetamidostilbene with polynucleotides in vitro.

N-Acetoxy-4-acetamidostilbene (N-AcO-AAS) has been shown to react with mononucleosides to give numerous alkylation products [1]. In this work, homopolynucleotides, RNA and DNA were treated with N-[beta-14 C]-AcO-AAS, washed, degraded with S1 nuclease and acid phosphatase, and chromatographed on Sephadex LH-20. RNA prepared in vitro with 14C on cytosine, adenine or guanine was treated with non-radioactive N-AcO-AAS, then digested and chromatographed similarly. By this means, many of the adducts rising from nucleoside reactions were shown to result from treatment of nucleic acids with the same carcinogen, as well as a number of products which have not been matched to products of monomer alkylation. Labeled 1-(4-acetamidophenyl)-2-phenyl-1, 2-ethanediol was detected in the digest of RNA treated with radioactive N-AcO-AAS, suggesting that phosphate alkylation had taken place.

Chemical Phenomena↗
PubMed1981

Arachidonic acid-dependent metabolism of (+/-)-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene to polyguanylic acid-binding derivatives.

Microsomal and solubilized enzyme preparations from ram seminal vesicles catalyze the oxidation of (+/-)-7,8-dihydroxy-7,8-dihydrobenzo[alpha]-pyrene (BP-7,8-diol) to derivatives which covalently bind to polyguanylic acid (poly(G)). Oxidation requires prostaglandin endoperoxide synthetase and its substrate arachidonic acid and is inhibited by indomethacin. High performance liquid chromatographic (HPLC) analysis of the nucleoside adducts obtained following chemical and enzymatic digestion reveals an adduct pattern which is identical to that obtained by the reaction of poly(G) with (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene (diol-epoxide 2). The ratios of the diastereomeric pairs of cis- and trans-diolepoxide 2-guanosine adducts indicate that both enantiomers of (+/-)-BP-7,8-diol are metabolized to an equal extent.

Animals↗
PubMed1985

The in vitro interaction of naphthyridinomycin with deoxyribonucleic acids.

The binding of naphthyridinomycin (NAP) to deoxyribonucleic acid was investigated using radioisotope labeled antibiotic. Dithiothreitol (DTT) enhances complex formation in a concentration dependent fashion but was found to be slightly inhibitory at concentrations above 10 mM. [C3H3]-NAP-DNA complexes, formed in the presence or absence of reducing reagents, were stable to Sephadex G-25 chromatography and precipitation with ethanol, indicating a strong bond formed between the drug and DNA. Time course studies showed that the difference between the binding of activated and non-activated antibiotic was a DTT-dependent burst. This was followed by a second phase of binding which was similar in both the activated and non-activated antibiotics. The activation of the antibiotic by DTT was a reversible reaction at pH 7.9. The activated form at pH 5.0 was extremely stable and did not revert to the unactivated form even after an 8-h incubation period. Antibiotic-DNA complex formation was pH independent between pH 5.0 and 7.0 for activated NAP. The non-activated antibiotic bound to DNA much better at pH 5.0 than at physiological pH values. Release of antibiotic from complexes (as followed by long term dialysis) formed in the presence of DTT and at pH 5.0 was biphasic, suggesting that the drug can bind to DNA in more than one way. A constant rate of antibiotic release was observed at pH 7.9 with or without DTT. At pH 2.0 and pH 12.0, greater than 95% of the antibiotic is released from the complexes. Most of the acid released antibiotic is NAP while most of the base released antibiotic had decomposed to a more polar compound. NAP binds well to calf thymus DNA, poly(dG) . poly(dC), and T4 DNA but shows significantly less affinity for poly(dA) . poly(dT), poly(dA . dT) . poly(dA . dT), poly(dG), poly(dC), poly(dI) . poly(dC) or poly(dG . dC) . poly(dG . dC). This specificity of NAP for DNA is similar to that observed for the pyrrolo(1,4)benzodiazepine antibiotics and saframycin A and S; all of which bind to double stranded DNA through their carbinolamine or masked carbinolamine functionalities. Two mechanisms which can explain the need for activation of NAP are also proposed.

Animals↗