Effect of doxycycline on the generation of reactive oxygen species: A possible mechanism of action of acne therapy with doxycycline

On the basis of a recent report that minocycline is effective in the treatment of acne inflammation by acting directly as an antioxidant on infiltrating neutrophils, we investigated whether doxycycline might also be capable of reducing the generation of reactive oxygen species, using human neutrophils and a cell-free, xanthine-xanthine oxidase system. The species investigated are superoxide radical anion (O₂^-), hydrogen peroxide (H₂O₂) and hydroxyl radical (OH·). Doxycycline significantly reduced the levels of O₂^-, H₂O₂ and OH· generated by both systems. Our results seem to suggest that the clinical effectiveness of doxycycline in the treatment of acne inflammation is due partly to its antioxidant effect on neutrophils.