In Vitro Photodynamic Activity of a Series of Methylene Blue Analogues¶

Abstract

We have synthesized a series of symmetrical phenothiazines in which the methyl groups of methylene blue have been substituted by longer alkyl chains. Intrinsic photosensitizing ability was not altered by increasing the chain length. However, in vitro phototoxicity after 2 h incubation of RIF‐1 murine fibrosarcoma cells followed the order n‐propyl > n‐pentyl > n‐butyl > n‐hexyl > ethyl > methyl, with ethyl and n‐propyl analogues being 14‐ and 130‐fold more phototoxic than methylene blue, respectively. All analogues also had an improved ratio of phototoxicity : dark toxicity (4:1 to 27:1) compared with methylene blue (3:1). Phototoxicity did not correlate with cellular phenothiazine levels, suggesting that the site of subcellular localization may be more important. After 2 h incubation of RIF‐1 cells with the phototoxicity LD50 concentration, methylene blue and all analogues were observed to be localized in the lysosomes by fluorescence microscopy. On exposure to light, methylene blue relocalized to the nucleus, the ethyl analogue did not relocalize, whereas the more phototoxic n‐propyl –n‐hexyl analogues relocalized to the mitochondria. Relocalization to the mitochondria was associated with an octanol : buffer partition coefficient ≥ 1. Therefore, the longer‐chain analogues of methylene blue show significantly improved phototoxicity in vitro and, in addition, are expected to avoid the problems of mutagenicity associated with the nuclear localization of methylene blue.

Thionine Dye Confined in Zeolite L: Synthesis Location and Optical Properties

“…24,29 The family of phenothiazine derivatives (thionine = Th hereafter, methylene blue = MB hereafter, azure A and azure B) attracted considerable attention over the years due to their appropriate biological, chemical, photochemical, and photophysical properties 30 which led them to be used as a model for phototherapeutic agents in photodynamic therapy (PDT) as well as for dye-sensitized solar energy converter. 31,32 Calzaferri et al 33 performed first kinetics experiments on the incorporation of Th, MB, and ethylene blue into ZL. They demonstrated the successful incorporation of Th into the zeolite channels, estimating that the dye can exchange at most 7.5% of the K + cations sited in the channel.…”

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

“…and was optimized to allow functionalization with both protected and deprotected carbohydrates in high yields. A sequential "double-click" process was used to obtain a new class of bismodified 5,10-diglycoporphyrins (263) In continuation of this initial work, a significantly large library of mono-, di-and trideprotected glycoporphyrins (316)(317)(318)(319)(320)(321)(322)(323)(324)(325)(326)(327)(328)(329)(330)(331)261) were synthesized with monosaccharides and for the first time, synthetic disaccharides and trisaccharide [33] . These studies also provide the first examples of bismodified glycosylated porphyrins and a significant highlight was the ligation of the synthetic trisaccharide Lewis X , a histo-blood group antigen.…”

“…Again TPP was functionalized with an azido moiety and subsequently reacted with synthetic mono-, di-and tri-saccharide via optimized Huisgen 'click' cycloaddition reaction in very high yields. With a sequential "double-click" process used again to obtain bis-modified 5,10-diglycoporphyrins (331). This study was the first example of synthetic carbohydrates including N-Ac-lactosamine and Lewis X conjugated to the porphyrin scaffold [33] .…”

“…The localization of each individual PS is different. mTHPC has been identified to localize in the nuclear envelope [330] while δ-aminolevulinic acid (ALA) localizes in the mitochondria and methylene blue in lysosomes [331] . The mechanism of uptake of PSs has not been clarified.…”

Papel das proteínas XPD e DNA polimerase eta nas respostas de células humanas a danos no genoma

“…Pela sua característica hidrofílica, o MB é facilmente incorporado pelas células (Blazquez-Castro et al, 2009), onde ele pode ser encontrado em diferentes compartimentos celulares dependendo da concentração utilizada no tratamento, sendo que a quantidade de MB detectada no núcleo , onde ele se liga ao DNA de diversas formas (Rohs et al, 2000), aumenta depois da fotoativação (Mellish et al, 2002). Após absorção no comprimento de onda do vermelho (665 nm), a fotoativação do MB, que nas concentrações utilizadas neste trabalho (4 e 8 M)…”