Reductive activation of potential antitumor bis(aziridinyl)benzoquinones by xanthine oxidase: Competition between oxygen reduction and quinone reduction

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Lusthof, K.J. and Richter, W. and Mol, N.J. de and Janssen, L.H.M. and Verboom, W. and Reinhoudt, D.N. (1990) Reductive activation of potential antitumor bis(aziridinyl)benzoquinones by xanthine oxidase: Competition between oxygen reduction and quinone reduction. Archives of Biochemistry and Biophysics, 277 (1). pp. 137-142. ISSN 0003-9861

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Abstract:The reduction of a series of 2,5-bis(1-aziridinyl)-1,4-benzoquinone (BABQ) derivatives with various 3,6 substituents by the enzyme xanthine oxidase has been studied. The reduction rate has been assayed by measuring the rate of reduction of cytochrome c, which is very efficiently reduced by reduced BABQ species. Under nitrogen, the reduction rate correlated with the quinone reduction potential and steric parameters. Comparing reduction rates under nitrogen and air demonstrates that at BABQ concentrations > 25 μm the competition for electrons from xanthine oxidase between oxygen and the BABQ derivative is dominated by the latter. This is also confirmed by the effect of superoxide dismutase (SOD): in the presence of a BABQ derivative, cytochrome c reduction can be totally inhibited by SOD, although the required amount of SOD depends on the redox potential of the quinones. This indicates that SOD causes the equilibrium between semiquinone and superoxide to shift, resulting in a decrease of the semiquinone concentration. It is concluded that reduction by xanthine oxidase is a simple and effective method for reducing aziridinylbenzoquinones.
Item Type:Article
Copyright:© 1990 Elsevier
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Science and Technology (TNW)
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Link to this item:http://purl.utwente.nl/publications/72902
Official URL:http://dx.doi.org/10.1016/0003-9861(90)90561-C
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