Electrochemistry on Mars.
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Biosensing Techniques↗
Biomedical subjects
J Herdan
Publications and source records attributed to J Herdan.
In vitro inhibition of DNA adduct formation by hindered hydroquinols and quinones.
A series of thirty-one chemicals (substituted phenols, hydroquinols, quinones and quinoneimines) were investigated as in vitro inhibitors of DNA-benzo[a]pyrene adducts formation. In order to establish the mechanisms by which such compounds may elicit a protective effect at DNA level, the influence of these compounds upon benzo[a]pyrene (BaP) activation by 3-methyl-cholanthrene-stimulated microsomes was also studied. The data obtained suggest that the tested compounds act mainly (but not only) by BaP metabolism inhibition. Several substituted hydroquinols (e.g. 2-methyl-6-tert-butyl-hydroquinol, 2,6-di-isopropyl-hydroquinol, 2,3-dimethyl-hydroquinol) and quinones (e.g. 2-methyl-6-tert-butyl-1,4-benzoquinone, 2,6-di-isopropyl-1,4-benzoquinone, 2,3-di-methyl-1,4-benzoquinone) were found to be powerful inhibitors of both BaP metabolism and of BaP-DNA adduct formation (> 95%) at a BaP:inhibitor ratio of 1:10. This effect is significantly stronger than that exerted by the 'classical' BHA or other phenolic antioxidants in similar experimental conditions. Generally, quinones were more active than their corresponding hydroquinols, suggesting that the effectiveness of hydroquinols to prevent DNA adduct formation may be due to their oxidation to quinonic forms.
Benzo(a)pyrene↗
A new class of potential carcinogenesis inhibitors: hindered p-benzoquinones.
The investigation of the mechanisms of action by which phenolic antioxidants (i.e. BHA, BHT, etc.) protect DNA against interaction with activated BaP, led us to the finding that oxidated aminophenols are much more potent in this respect, being also powerful inhibitors of cytochrome P-450 dependent monooxygenases. However, the quinoneimine structures probably involved in this effect are chemically unstable reactive species and therefore difficult to handle. Based on these observations, we extended this study on several types of benzoquinones. We demonstrated that 2,6-di-t-butylbenzoquinone exerted a very good protective effect at DNA level (in standard conditions) as compared to the "classical" BHA (i. e. 91.3% and 34.4%, respectively). This hindered quinone is nontoxic (DL50 = 3085 mg/kg b. w.) and also did not exhibit inhibitory activity against GST. In contrast, the nonsubstituted p-benzoquinone is a powerful inhibitor of this last enzyme. Recently, 2,6-di-t-butylbenzoquinone was isolated from mutagenic depressing food and was considered one of the factors responsible for this effect.
Animals↗