Diketopyrrolopyrrole Derivatives as Photosensitizing Agents against Staphylococcus Aureus

AbstractDiketopyrrolopyrrole (DPP) derivatives containing sulfonamide (Sulfonamide-DPP), pyridyl (Dipyridyl-DPP) andN-methylpyridyl (MePyridyl-DPP) substituents were assessed as antibacterial photosensitizers. Non-charged DPPs showed an intense absorption band centered at about 480 nm and green fluorescence emission ( ΦF ~  0.7) in acetonitrile. The absorption ofMePyridyl-DPP was bathochromically shifted at 510 nm, with decreased fluorescence emission.Sulfonamide-DPP andDipyridyl-DPP photosensitized the formation of O2(1Δg) ( ΦΔ ~  0.15−0.17), while the production induced byMePyridyl-DPP was at least 10 times lower. Furthermore, these DPPs produced a photoreduction of NBT similar to that of the control. Photodynamic inactivation induced by DPPs was first investigated at single-bacterium level ofStaphylococcus aureus attached to a surface. After 30 min irradiation,MePyridyl-DPP produced a complete eradication of the bacteria. In bacterial cell suspensions, dicationic DPP induced more than 7 log10 decrease inS. aureus cell survival after 30 min irradiation. Potentiation with iodide anions allowed a complete elimination of bacteria after 15 min therapy. This compound was also effective to eliminateS. aureus cells on biofilms. The results show thatMePyridyl-DPP bearing two positive groups provides an amphiphilic character to the structure that improves the interaction with the cell envelop. This effect enhances the photocytotoxic activity ofMePyridyl-DPP against bacteri...
Source: Photochemistry and Photobiology - Category: Science Authors: Tags: Research Article Source Type: research