Polylysine-porphycene conjugates as efficient photosensitizers for the inactivation of microbial pathogens

Porphycenes are electronic isomers of porphyrins which, when neutral, displ ay no appreciable photosensitizing action towards Gram-negative bacteria. T he covalent binding of oligomeric polylysine moieties, which are cationic a t physiological pH values, endows porphycenes with a significant phototoxic activity against Gram-negative bacteria while retaining their photoefficie ncy against a variety of microbial pathogens, including Gram-positive bacte ria, fungi and mycoplasmas. The effect of the polylysine moiety is dependen t on both the polylysine concentration and the degree of oligomerization. A suitable interplay among the various parameters opens the possibility to o btain either a broad spectrum of antimicrobial activity or a selective acti on toward a specific pathogen while minimizing the damage to human fibrobla sts. (C) 2000 Elsevier Science B.V. All rights reserved.