Antiplasmid activity of tricyclic compounds.

Three representative groups of tricyclic psychopharmacons were shown to have antiplasmid activity. The first group, e.g., comprises promazine, chlorpromazine, promethazine, levo- and dextromepromazine, thioridazine, diethazine, thiethylperazine. There are two heteroatoms (S and N) in the ring system of these compounds. In the second group, which includes desipramine, imipramine, however, there is only one heteroatom N, or S in chlorprothixene, chlorpenthixols and in the third group amitriptyline, maprotiline contain no heteroatoms. The medical significance of plasmid elimination by tricyclic psychopharmacons and related compounds in vitro is that this opens up a new perspective in the struggle against bacterial resistance to antibiotics. This approach utilizes the beneficial side-effect of the plasmid curing ability of these psychopharmacons, and may serve as a guideline for drug design in the future, to develop related substances which are potent in eliminating the drug resistance-carrying plasmids of bacteria, but which have no other pharmacological effects. Here we propose a new mechanism for plasmid curing by tricyclic drugs.