Mutagenesis vol.7 no.5 pp.395-396, 1992

Letter to the Editor

In a paper published in the July issue of Mutagenesis, Phillips et al. (1992) demonstrated that there was no covalent binding of omeprazole to DNA following administration of [14C]omeprazole to male rats. They, however, reported that radioactivity was 'associated' with DNA purified from gastrointestinal tissues. The authors failed to define what the nature of this 'association' was, although they postulated the possible existence of labile DNA adducts. The authors suggested that a non-covalent interaction of omeprazole with DNA was an alternative explanation for their results, and speculated that this non-covalent interaction could still induce genotoxicity. We have a number of concerns about the authors' work, including the lack of positive and negative controls and especially the possibility of contamination of DNA by protein or other cellular material. We believe the 'association' described by the authors is radiolabel bound to proteins that copurify with DNA. This belief is based upon the following: (i) omeprazole did not produce detectable DNA adducts by P-postlabeling procedures (Phillips etal., unpublished observations, as mentioned in the 1992 reference), and in the [l4C]omeprazole experiments, the radioactivity was clearly separated from the DNA fraction by

To investigate our theory that protein co-purified with DNA, we needed to know how much protein was present in 'pure' DNA (A26(/A280 ~ 1-93) and 'less pure' DNA (A260/A2g0

Comments on the report of 'association' of omeprazole with DNA by Phillips et al.

Mutagenesis vol.7 no.5 pp.395-396, 1992 Letter to the Editor In a paper published in the July issue of Mutagenesis, Phillips et al. (1992) demonstra...
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