title: Photophysical properties and antibacterial activity of meso-substituted cationic porphyrins.
abstract: A series of derivatives of 5,10,15,20-tetrakis-(4-N-methylpyridyl)-porphine, where one N-methyl group was replaced by a hydrocarbon chain ranging from C6 to C22, were characterized for their photophysical and photosensitizing properties. The absorption and fluorescence features of the various compounds in neutral aqueous solutions were typical of largely monomeric porphyrins, with the exception of the C22 derivative, which appeared to be extensively aggregated. This was confirmed by the very low triplet quantum yield and lifetime of the C22 derivative as compared with 0.2-0.7 quantum yields and 88-167 micros lifetimes for the other porphyrins. The photophysical properties and photosensitizing activity toward N-acetyl-L-tryptophanamide of the C22 porphyrin became comparable to those typical of the other derivatives in 2% aqueous sodium dodecyl sulfate, where the C22 compound is fully monomerized. All the porphyrin derivatives exhibited at micromolar concentrations photoinactivation activity against both Staphylococcus aureus and Escherichia coli, even though the gram-negative bacteria were markedly less photosensitive. The photosensitizing efficiency was influenced by (1) the amount of cell-bound porphyrin, which increased with increasing length of the hydrocarbon chain; and (2) the tendency to undergo partial aggregation in the cell, which seems to be especially important for the C22 derivative.
authors.affiliation: Dipartimento di Biologia, Università di Padova, Italy. reddi@civ.bio.unipd.it
authors.forename: Elena
authors.initials: E
authors.lastname: Reddi
authors.forename: Mara
authors.initials: M
authors.lastname: Ceccon
authors.forename: Giuliana
authors.initials: G
authors.lastname: Valduga
authors.forename: Giulio
authors.initials: G
authors.lastname: Jori
authors.forename: Jerry C
authors.initials: JC
authors.lastname: Bommer
authors.forename: Fausto
authors.initials: F
authors.lastname: Elisei
authors.forename: Loredana
authors.initials: L
authors.lastname: Latterini
authors.forename: Ugo
authors.initials: U
authors.lastname: Mazzucato
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry* / Q000494:pharmacology*; D013050:Spectrometry, Fluorescence
chemical_list: D000900:Anti-Bacterial Agents; D011166:Porphyrins