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Stable Synthetic Bacteriochlorins for Photodynamic Therapy: Role of Dicyano Peripheral Groups, Central Metal Substitution (2H, Zn, Pd), and Cremophor EL Delivery
Author(s) -
Huang YingYing,
Balasubramanian Thiagarajan,
Yang Eunkyung,
Luo Dianzhong,
Diers James R.,
Bocian David F.,
Lindsey Jonathan S.,
Holten Dewey,
Hamblin Michael R.
Publication year - 2012
Publication title -
chemmedchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.817
H-Index - 100
eISSN - 1860-7187
pISSN - 1860-7179
DOI - 10.1002/cmdc.201200351
Subject(s) - chemistry , photodynamic therapy , hela , chelation , photosensitizer , palladium , fluorescence , cytotoxicity , zinc , solvent , nuclear chemistry , in vitro , photochemistry , organic chemistry , biochemistry , catalysis , physics , quantum mechanics
A series of four stable synthetic bacteriochlorins was tested in vitro in HeLa cells for their potential in photodynamic therapy (PDT). The parent bacteriochlorin (BC), dicyano derivative (NC) 2 BC and corresponding zinc chelate (NC) 2 BC–Zn and palladium chelate (NC) 2 BC–Pd were studied. Direct dilution of a solution of bacteriochlorin in an organic solvent ( N , N ‐dimethylacetamide) into serum‐containing medium was compared with the dilution of bacteriochlorin in Cremophor EL (CrEL; polyoxyethylene glycerol triricinoleate) micelles into the same medium. CrEL generally reduced aggregation (as indicated by absorption and fluorescence) and increased activity up to tenfold (depending on bacteriochlorin), although it decreased cellular uptake. The order of PDT activity against HeLa human cancer cells after 24 h incubation and illumination with 10 J cm −2 of near‐infrared (NIR) light is (NC) 2 BC–Pd (LD 50 =25 n M ) > (NC) 2 BC > (NC) 2 BC–Zn ≈ BC. Subcellular localization was determined to be in the endoplasmic reticulum, mitochondria and lysosomes, depending on the bacteriochlorin. (NC) 2 BC–Pd showed PDT‐mediated damage to mitochondria and lysosomes, and the greatest production of hydroxyl radicals as determined using a hydroxyphenylfluorescein probe. The incorporation of cyano substituents provides an excellent motif for the enhancement of the photoactivity and photostability of bacteriochlorins as PDT photosensitizers.