title: Oligolysine-conjugated zinc(II) phthalocyanines as efficient photosensitizers for antimicrobial photodynamic therapy.
abstract: A series of zinc(II) phthalocyanines conjugated with an oligolysine chain (n=2, 4, and 8) were synthesized and characterized by using various spectroscopic methods. As shown by using UV/Vis and fluorescence spectroscopic methods, these compounds were nonaggregated in N,N-dimethylformamide, and gave a weak fluorescence emission and high singlet oxygen quantum yield (Φ(Δ) =0.86-0.89) as a result of their di-α-substitution. They became slightly aggregated in water with 0.05 % Cremophor EL, but they could still generate singlet oxygen effectively. The antimicrobial photodynamic activities of these compounds were then examined against various bacterial strains, including the Gram-positive methicillin-sensitive Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus ATCC BAA-43, and the Gram-negative Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853. Generally, the dyes were much more potent toward the Gram-positive bacteria. Only 15 to 90 nM of these photosensitizers was required to induce a 4 log reduction in the cell viability of the strains. For Escherichia coli, the photocytotoxicity increased with the length of the oligolysine chain. The octalysine derivative showed the highest potency with a 4 log reduction concentration of 0.8 μM. Pseudomonas aeruginosa was most resistant to the photodynamic treatment. The potency of the tetralysine derivative toward a series of clinical strains of Staphylococcus aureus was also examined and found to be comparable with that toward the nonclinical counterparts. Moreover, the efficacy of these compounds in photodynamic inactivation of viruses was also examined. They were highly photocytotoxic against the enveloped viruses influenza A virus (H1N1) and herpes simplex virus type 1 (HSV1), but exhibited no significant cytotoxicity against the nonenveloped viruses adenovirus type 3 (Ad3) or coxsackievirus (Cox B1). The octalysine derivative also showed the highest potency with an IC(50) value of 0.05 nM for the two enveloped viruses.
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong (China), Fax: (+852) 2603-5057.
authors.forename: Mei-Rong
authors.initials: MR
authors.lastname: Ke
authors.forename: Jennifer Mary
authors.initials: JM
authors.lastname: Eastel
authors.forename: Karry L K
authors.initials: KL
authors.lastname: Ngai
authors.forename: Yuk-Yam
authors.initials: YY
authors.lastname: Cheung
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Chan
authors.forename: Mamie
authors.initials: M
authors.lastname: Hui
authors.forename: Dennis K P
authors.initials: DK
authors.lastname: Ng
authors.forename: Pui-Chi
authors.initials: PC
authors.lastname: Lo
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line / Q000821:virology; D060326:Chemistry Techniques, Synthetic; D004285:Dogs; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects; D054833:Isoindoles; D061985:Madin Darby Canine Kidney Cells; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009942:Organometallic Compounds / Q000737:chemistry*; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D011107:Polylysine / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship; D017967:Zinc Compounds
chemical_list: D000890:Anti-Infective Agents; D000998:Antiviral Agents; D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D017967:Zinc Compounds; C052159:Zn(II)-phthalocyanine; D011107:Polylysine
keywords: antimicrobials; bacteria; photodynamic therapy; photosensitizers; phthalocyanines; viruses