Author(s): Molnr J, Schneider B, Mndi Y, Farkas S, Holland IB
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Abstract Methylene blue enhanced the plasmid curing efficiency of chlorpromazine, imipramine and amitriptyline with strains of Escherichia coli K12 carrying F-prime lac or the resistance factor R-144. In contrast, methylene blue inhibited the elimination of plasmids by acridine orange and ethydium bromide at all concentrations tested. Two metabolic derivatives of chlorpromazine, chlorpromazine sulphoxide and 7.8-dioxochlorpromazine had no plasmid curing effect even in the presence of methylene blue. Amitriptyline, 7,8-dioxochlorpromazine and acridine orange were effective inhibitors of the conjugal transfer of the resistance plasmid, R-144, whilst methylene blue, chlorpromazine sulphoxide, and imipramine had only slight effects. We were therefore unable to demonstrate a simple correlation between curing ability and inhibition of plasmid transfer amongst the psychoactive drugs tested. A mechanism of plasmid curing by surface action of the drugs is suggested as an alternative to direct intercalation of the drugs into plasmid DNA.
This article was published in Acta Microbiol Acad Sci Hung
and referenced in Biochemistry & Pharmacology: Open Access