Photophysical, photochemical and antibacterial photosensitizing properties of a novel octacationic Zn(II)-phthalocyanine.
A novel Zn(II)-phthalocyanine (1). peripherally substituted with four bis(N,N,N-trimethyl)amino-2-propyloxy groups prepared by chemical synthesis is shown to be an efficient photodynamic sensitizer with a quantum yield of 0.6 for singlet oxygen generation in neat water, which is reduced to about 0.3 in phosphate-buffered saline. The physicochemical properties of 1 in both the ground and the electronically excited states strongly depend on the nature of the medium; in particular, aggregation of 1 was favoured by polar media of high ionic strength. Compound 1 exhibited an appreciable affinity for a typical Gram-positive bacterium (Staphylococcus aureus) and a typical Gram-negative bacterium (Escherichia coli). Both bacterial strains were extensively inactivated upon 5 min-irradiation with 675 nm light in the presence of 1 microM photosensitizer, even though the binding of 1 to the two bacterial cells appears to occur according to different pathways. In particular, E. coli cells underwent initial photodamage at the level of specific proteins in the outer wall, thus promoting the penetration of the photosensitizer to the cytoplasmic membrane where some enzymes critical for cell survival were inactivated.
Segalla
Anna
A
Department of Biology, University of Padova, I-35131 Padova, Italy.
Borsarelli
Claudio D
CD
Braslavsky
Silvia E
SE
Spikes
John D
JD
Roncucci
Gabrio
G
Dei
Donata
D
Chiti
Giacomo
G
Jori
Giulio
G
Reddi
Elena
E
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D007211:Indoles / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects; D054833:Isoindoles; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D009245:NADH Dehydrogenase / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology; D013385:Succinate Dehydrogenase / Q000378:metabolism; D017967:Zinc Compounds
D000900:Anti-Bacterial Agents; D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D017967:Zinc Compounds; C052159:Zn(II)-phthalocyanine; D007770:L-Lactate Dehydrogenase; D013385:Succinate Dehydrogenase; D009245:NADH Dehydrogenase