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B M Hoey

Publications and source records attributed to B M Hoey.

23 records · Page 2Linked to original sources
PubMed1987

Are reduced quinones necessarily involved in the antitumour activity of quinone drugs?

Several studies have shown that the antitumour quinones, adriamycin, mitomycin C, mitozantrone and 3,6-diaziridinyl-2,5-bis (carboethoxyamino)-1,4-benzoquinone (AZQ) can form semiquinone radicals in vitro. The biophysical chemistry data for these reactions and the properties of the radical quinones are presented together with the proposed mechanisms for cytotoxicity. An attempt has been made to correlate the available in vitro data for the quinones with each other and with the available in vivo data. As a consequence of these correlations a number of conclusions have been proposed regarding the techniques of investigation and the evidence for the role of reduced quinones in antitumour activity.

Antineoplastic Agents↗
PubMed1986

The apparent inhibition of superoxide dismutase activity by quinones.

It has been demonstrated that several quinones can modify the activity of bovine copper superoxide dismutase by undergoing equilibrium reactions with superoxide radicals. The extent of this apparent inhibition correlates with the one electron reduction potentials of the quinones and the equilibrium constants of the semiquinone radical/superoxide radical reactions. Various rate constants have been estimated including those for the reactions of semiquinone radicals with cytochrome c and with superoxide dismutase. Semiquinone radicals cannot be dismutated by superoxide dismutase.

Animals↗
PubMed1985

The radiation chemistry of some platinum-containing radiosensitizers and related compounds.

Oxidation and reduction of cis- and trans-dichlorodiammine platinum II (cis- and trans-PDD), cis-dichlorobis(1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole-N3)-p latinum II (cis-Flap), and cis-dichlorobis(isopropylamine)-trans-dihydroxyplatinum IV (Chip) have been studied using pulse radiolysis. Spectra corresponding to platinum in various oxidation states have been observed and several rate constants have been obtained. Reduction of all the compounds, except cis-Flap, produces species of a lower oxidation state of platinum which subsequently have both chloride ligands replaced. Ultimately, these products disproportionate. In the case of cis-Flap, reduction occurred on the nitroimidazole ligand. This was verified by the absence of platinum metal after disproportionation. Oxidation of all four compounds consists of production of a higher oxidation state of platinum followed by replacement of chloride ligands and finally disproportionation of the products. Only cis-Flap and Chip could be reduced by oxidized DNA bases. The one-electron reduction potential of cis-Flap was found to be -370 +/- 10 mV. trans-Flap had almost the same value. It was not possible to measure the potentials of the other compounds since their ligands were replaced rapidly but it is estimated that the one-electron reduction potentials decrease in the order cis- or trans-Flap greater than Chip greater than cis-PDD greater than trans-PDD.

Antineoplastic Agents↗
PubMed1984

The repair of oxidized amino acids by antioxidants.

Natural and synthetic antioxidants have been shown to repair tryptophan radicals produced from the one-electron oxidation of the free tryptophan amino acid. It has also been observed that both tryptophan and tyrosine radicals in lysozyme can be repaired by these antioxidants to varying degrees of efficiency. Although SDS-solubilized alpha-tocopherol efficiently repairs free tryptophan radicals, it is very inefficient in repairing the amino acids in lysozyme. The rigidity and immobility of solubilized alpha-tocopherol can explain this lack of efficiency.

Antioxidants↗