Physicochemical characterisation and antimicrobial phototoxicity of an anionic porphyrin in natural deep eutectic solvents.
Natural deep eutectic solvents (NADES) are a newly discovered group of eutectics which has shown promise as a solvent in antimicrobial photodynamic therapy (aPDT). The purpose of this study was to investigate preparations of an anionic porphyrin, meso-tetra-(4-carboxyphenyl)-porphine (TCPP), solubilised in NADES, with regard to their physicochemical and antibacterial properties. The NADES CS (pH∼0), ChX (pH∼4) and MFG (pH∼1) solubilised TCPP with absorption maximum ∼443nm and emission maximum ∼678nm, indicating formation of the TCPP dication. Dilution of TCPP-NADES>1:1 (water) reduced the physical stability of the preparations. The photostability half-lives of TCPP in methanol, MFG, and CS were ∼9h, 6.9h and 3.2h, respectively. Nanomolar concentrations of TCPP solubilised in diluted MFG combined with ⩽27J/cm(2) blue light increased Gram-positive and Gram-negative bacterial phototoxicity, >99.98% and 96% bacterial reduction, respectively, compared to TCPP in PBS/ethanol under equivalent treatment conditions. TCPP solubilised in diluted CS was toxic to bacteria both in the absence (36-72% reduction) and presence of light. TCPP in CS, and in the CS component citric acid, induced a TCPP-concentration dependent increase in Gram-negative phototoxicity relative to controls, which was most pronounced for TCPP-CS. The mechanism behind the increased toxicity is unknown.
Department of Pharmacy, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway. Electronic address: k.o.wikene@farmasi.uio.no.
Kristine Opsvik
KO
Wikene
Nordic Institute of Dental Materials, Sognsveien 70A, 0855 Oslo, Norway. Electronic address: h.v.rukke@niom.no.
Håkon Valen
HV
Rukke
Nordic Institute of Dental Materials, Sognsveien 70A, 0855 Oslo, Norway. Electronic address: ellen.bruzell@niom.no.
Ellen
E
Bruzell
Department of Pharmacy, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway. Electronic address: h.h.tonnesen@farmasi.uio.no.
Hanne Hjorth
HH
Tønnesen
D000838:Anions; D000890:Anti-Infective Agents / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000528:radiation effects; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D008826:Microbial Sensitivity Tests; D011166:Porphyrins / Q000737:chemistry* / Q000494:pharmacology*; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013211:Staphylococcus aureus / Q000187:drug effects / Q000528:radiation effects
D000838:Anions; D000890:Anti-Infective Agents; D011166:Porphyrins; D012997:Solvents
Antimicrobial photodynamic therapy (aPDT); Choline chloride (PubChem CID: 6209); Citric acid (PubChem CID: 311); Enterococcus faecalis; Escherichia coli; Fructose (PubChem CID: 5984); Glucose (PubChem CID: 107526); Malic acid (PubChem CID: 525); Natural deep eutectic solvents (NADES); Porphyrin; Solubility; Stability; Staphylococcus aureus; Sucrose (PubChem CID: 5988); TCPP (PubChem CID: 5479495); Xylitol (PubChem CID: 6912)