Singlet Oxygen and Superoxide: Experimental Differentiation and Analysis

Maurette, Marie-Thérèse; Oliveros, Esther; Infelta, Pierre P.; Ramsteiner, Klaus; Braun, André M.

doi:10.1002/hlca.19830660236

Cited by 76 publications

(42 citation statements)

References 41 publications

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“…It is also a singlet oxygen quencher, although its efficiency is relatively low (Koka and Song, 1978). However,p-benzoquinone is an effective quencher of radical species such as superoxide anion (Maurette et al, 1983). In this connection, it should be noted that carotenoids too have also been suggested to be a free radical quencher (Parker et al, 1981;Krinsky and Deneke, 1982: for a recent review, see Krinsky, 1983).…”

Section: Discussionmentioning

confidence: 99%

PHOTODYNAMIC ACTION IN Stentor coeruleus SENSITIZED BY ENDOGENOUS PIGMENT STENTORIN

Yang

Prusti

Walker

et al. 1986

Photochem & Photobiology

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Abstract— Stentorin acts as the photoreceptor for the step‐up photophobic and negative phototactic responses in Stentor coeruleus. The chromophore of stentorin appears to be hypericin which is linked to apoprotein. In addition to the photomovement responses of the organism, S. coeruleus was found to be photodynamically sensitive to light absorbed by the hypericin chromophore, as the apparent action spectrum for the photodynamic killing matches the absorption spectrum of stentorin. The protective effect of β‐carotene and crocetin on the photodynamic killing of S. coeruleus suggests that singlet oxygen generated by the stentorin‐sensitization plays an important role, according to the so‐called Type II mechanism of photosensitization. The generation of singlet oxygen via hypericin triplet was confirmed by in vitro photooxidation of tryptophan as a substrate. The photodynamic killing was more effective in deuterium oxide than in H2O in both the photosensitization by stentorin (endogenous) and added hypericin (exogenous). These results are consistent with the involvement of singlet oxygen in the photodynamic killing of S. coeruleus.

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Section: Discussionmentioning

confidence: 99%

PHOTODYNAMIC ACTION IN Stentor coeruleus SENSITIZED BY ENDOGENOUS PIGMENT STENTORIN

Yang

Prusti

Walker

et al. 1986

Photochem & Photobiology

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“…Furfuryl alcohol was chosen because it reacts chemically with singlet oxygen with good efficiency (rate constant 1.2 x 1081 M -1). In addition, it does not react with hydrogen peroxide or superoxide and most likely does not undergo radical initiated autooxidation [28,29]. Reaction mixtures were illuminated with a 500 W slide projector provided with a 407 nm interference filter (bandwidth 10 ± 2 nm at 50% peak transmittance;…”

Section: Preparation Of Copolymer Bound Drugsmentioning

confidence: 99%

A polymeric drug delivery system for the simultaneous delivery of drugs activatable by enzymes and/or light

Krinick¹,

Sun²,

Joyner³

et al. 1994

Journal of Biomaterials Science, Polymer Edition

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Three water soluble copolymers based on N-(2-hydroxypropyl)methacrylamide were prepared. Copolymer I contains adriamycin, a chemotherapeutic agent, attached via enzymatically degradable oligopeptide (glycylphenylalanylleucylglycine; G-F-L-G) side chains. The other two copolymers contained the photosensitizer, meso-chlorin e6 monoethylene diamine disodium salt (Mce6). In Copolymer II, the chlorin is attached via the degradable G-F-L-G sequence, and it was bound by the nondegradable glycyl spacer in Copolymer III. Initially, the copolymers were characterized separately in vitro and in vivo. Combinations of the copolymer bound chemotherapeutic agent and each of the copolymer bound photosensitizers were then assessed for antitumor effect in vivo. Localization/retention studies (A/J mice; Neuro 2A neuroblastoma solid tumor) were performed with the two copolymers containing Mce6 as well as the free drug. Results of these experiments demonstrated a very different tumor uptake profile for the two copolymers. While the free drug was rapidly cleared from tumor tissue, the copolymer containing Mce6 attached via the non-degradable bond was retained for an extended period; drug concentrations in the tumor were high even after 5 days. On the other hand, a high concentration of the copolymer containing Mce6 bound via the degradable sequence was taken up by the tumor, yet its concentration in the tumor was substantially diminished at 48 h after administration. This shows indirect evidence of in vivo cleavage of Mce6 from the copolymer in the lysosomal compartment which is supported by direct evidence of cleavage by cathepsin B (a lysosomal enzyme) in vitro. Antitumor effects were assessed on Neuro 2A neuroblastoma induced in A/J mice for all three copolymers. Photodynamic therapy (PDT) proved the copolymer with Mce6 bound via the degradable oligopeptide sequence to be a more effective photosensitizer in vivo than the other chlorin containing copolymer. The difference in activity was consistent with the results obtained by photophysical analyses in which the free drug had a higher quantum yield of singlet oxygen generation than the polymer bound drug in buffer. The quantum yield of singlet oxygen generation increased with the enzymatic cleavage of the chlorin from the copolymer. Conditions were subsequently determined for which chemotherapy or PDT would show some antitumor effect, yet be incapable of curing tumors. Finally, combination therapy experiments were performed in which the copolymer bound adriamycin was mixed with either of the copolymer bound chlorin compounds and injected intravenously (i.v.) into the tail veins of mice.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…B) (14), product C (7-hydroxy-3H-phenothiazine-3-one) may have a similar gene sis, and 7-(10-phenothiazinyl)-3H-phenothiazine-3-one (D) represents one of the many possible recombination products starting from PT*. D Dye sensitized photooxidation of phenothiazine should reveal whether in addition to reaction 9 any competitive singlet oxygen re action (Equation 5) or electron transfer process (Equation 7) is oc cur ing.…”

Section: β Cmentioning

confidence: 98%

Electron and Energy Transfer from Phenothiazine Triplets

Braun¹,

Gilson²,

Krieg³

et al. 1985

ACS Symposium Series

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Phenothiazine derivatives have found many applications in todays chemical industry; they have been and are used primarily as dye--stuffs, antioxidants and in pharmaceutical preparations. This application is due to the discovery of their neuroleptic activity (1) (e.g. Chlorpromazine), but allergic skin reactions and ocular opacity are known to occur during therapy.Assuming that these side effects might be primarily initiated by light induced electron or energy transfers, investigations on the conditions where such transfers take place with high efficiency and with some specificity are of fundamental interest. Phenothiazine and its N-alkylated derivatives have also been of interest as electron donating substrates in early investigations of photochemically induced charge separation (2-5), necessary for a successfull photochemical energy conversion. Besides phototoxicity, which might involve oxygen, and energy conversion, just two examples of model investigations, phenothiazine derivatives are convenient probes in micelles and mixed aggregates, model systems themselves for preparative applications (6) as well as biomimetic environments (7). PhenothiazinePhenothiazine is readily oxidized when irradiated in solution with chlorinated hydrocarbones 08). The reaction has been shown to be an electron transfer generating the phenothiazine (PTH) radical cation (ΡΤΗ + ') and the halogen anion as shown in equation 1. hv , PTH + RC1• PTH + R* + Cl (1) Photooxidation may lead to a similar electron transfer yielding PTH + * and superoxide, hv . PTH + 0 2 • PTH + ' + 0"' (2) 7

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Singlet Oxygen and Superoxide: Experimental Differentiation and Analysis

Cited by 76 publications

References 41 publications

PHOTODYNAMIC ACTION IN Stentor coeruleus SENSITIZED BY ENDOGENOUS PIGMENT STENTORIN

PHOTODYNAMIC ACTION IN Stentor coeruleus SENSITIZED BY ENDOGENOUS PIGMENT STENTORIN

A polymeric drug delivery system for the simultaneous delivery of drugs activatable by enzymes and/or light

Electron and Energy Transfer from Phenothiazine Triplets

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