Metronidazole induces DNA strand-breaks in cultures of human lymphocytes and phytohemagglutinin-stimulated human lymphocytes.

Metronidazole (CAS 443-48-1) induces DNA single strand-breaks in resting human cells (non-stimulated lymphocytes) and in proliferating human cells (phytohemagglutinin-(PHA-)stimulated lymphocytes). The DNA damage depends on metronidazole concentration and time of culture or stimulation. In proliferating lymphocytes the number of DNA single strand-breaks is higher than in resting lymphocytes. In non-stimulated lymphocytes the 3H-thymidine incorporation increases after incubation with metronidazole, possibly due to DNA repair processes. In PHA-stimulated lymphocytes 3H-thymidine incorporation is inhibited by metronidazole. This could be due to the inhibitory effect of DNA damage on cell proliferation. Vitality is not reduced by metronidazole, indeed it may be, as a consequence of DNA repair processes, higher than in controls. DNA repair processes can be also demonstrated after washing out metronidazole from the culture medium.