title: Evaluation of antibacterial properties of novel phthalocyanines against Escherichia coli--comparison of analytical methods.
abstract: We analyzed antibacterial effects of several novel phthalocyanines against Escherichia coli and evaluated the suitability of flow cytometry for the detection of antibacterial effects of phthalocyanines in comparison with routinely used cultivation. After 3h of exposure under cool white light eight cationic phthalocyanines showed very high antibacterial activity in the concentration of 2.00 mg L(-1) and four of them were even efficient in the concentration of 0.20 mg L(-1). Antibacterial activity of neutral and anionic compounds was considerably lower or even negligible. No antibacterial effect was detected when bacteria were exposed without illumination. Binding affinity to bacterial cells was found to represent an important parameter influencing phthalocyanine antibacterial activity that can be modified by total charge of peripheral substituents and by the presence of suitable functional groups inside them. Agglomeration of cells observed in suspensions treated with a higher concentration of certain cationic phthalocyanines (the strongest binders to bacterial membrane) affected cytometric measurements of total cell counts, thus without appropriate pretreatment of the sample before analysis this parameter seems not to be fully valid in the evaluation of phthalocyanine antibacterial activity. Cytometric measurement of cell membrane integrity appears to be a suitable and even more sensitive parameter than cultivation.
authors.affiliation: Institute of Botany of the ASCR, Department of Experimental Phycology and Ecotoxicology, Lidicka 25/27, 602 00 Brno, Czech Republic. Electronic address: premysl.mikula@centrum.cz.
authors.forename: Premysl
authors.initials: P
authors.lastname: Mikula
authors.affiliation: Mendel University in Brno, Faculty of Agronomy, Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition, Zemedelska 1, 613 00 Brno, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Kalhotka
authors.affiliation: Institute of Botany of the ASCR, Department of Experimental Phycology and Ecotoxicology, Lidicka 25/27, 602 00 Brno, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jancula
authors.affiliation: Institute of Botany of the ASCR, Department of Experimental Phycology and Ecotoxicology, Lidicka 25/27, 602 00 Brno, Czech Republic.
authors.forename: Stepan
authors.initials: S
authors.lastname: Zezulka
authors.affiliation: Centre for Organic Chemistry, Rybitvi 296, 533 54 Rybitvi, Czech Republic.
authors.forename: Radka
authors.initials: R
authors.lastname: Korinkova
authors.affiliation: Centre for Organic Chemistry, Rybitvi 296, 533 54 Rybitvi, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Cerny
authors.affiliation: Institute of Botany of the ASCR, Department of Experimental Phycology and Ecotoxicology, Lidicka 25/27, 602 00 Brno, Czech Republic.
authors.forename: Blahoslav
authors.initials: B
authors.lastname: Marsalek
authors.affiliation: Institute of Macromolecular Chemistry of the ASCR, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Toman
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D005434:Flow Cytometry; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology*; D054833:Isoindoles; D008027:Light; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D026082:Singlet Oxygen / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D007211:Indoles; D054833:Isoindoles; D017319:Photosensitizing Agents; D026082:Singlet Oxygen; C013647:phthalocyanine
keywords: Antibacterial effect; Binding affinity; Cell membrane integrity; Cultivation techniques; Flow cytometry; Photosensitizers; Phthalocyanines; Singlet oxygen