Laser Flash Spectroscopy of Methylene Blue With Nucleic Acids

Kelly, John M.; Putten, Wilhelm J. M. van der; McConnell, David J.

doi:10.1111/j.1751-1097.1987.tb05360.x

Cited by 70 publications

(43 citation statements)

References 29 publications

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“…The emission was quenched (after quanta correction) by 68% and red shifted by 7 nm upon the addition of 0.48 mM DNA (phosphate/ dye ratio [P/D] ϭ 120). These observations are in accordance with the literature report that MB fluorescence is quenched by nucleic acids in a concentration-dependent manner (65% quenching at P/D ϭ 65) (36). BISPHEN (0.16 mM) had a smaller effect on MB fluorescence when added to a pure dye solution (4-16% quenching, curve 2) and a negligible effect when added to an MB/DNA solution (cf curves 3 vs 4 in Fig.…”

Section: Ground and Excited State Complexation Of Mb/ Bisphen/dnasupporting

confidence: 92%

Simultaneous Photoconjugation of Methylene Blue and cis-Rh(phen)2Cl2+ to DNA via a Synergistic Effect †

Morrison

2007

Photochemistry and Photobiology

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Irradiation of the red‐light absorbing dye, methylene blue (MB), in the presence of the metal complex, cis‐Rh(phen)2Cl2+ (BISPHEN), leads to irreversible photobinding of both reagents to DNA. Evidence from absorption and emission spectroscopy indicates that the dye is strongly complexed to the DNA at the concentrations used in the experiments and that this complex is unaffected by the presence of BISPHEN. The level of covalent binding is proportional to the absorbed light dose, with the quantum efficiency for covalent binding of BISPHEN to the DNA with 633 nm light equal to 3.5 × 10−4. Electrospray ionization mass spectrum of a mixture of DNA fragments created by enzymatic degradation of DNA isolated following irradiation indicates that purine adducts are formed with both BISPHEN and the dye. In addition, UV–Vis and high‐performance liquid chromatography analyses of the irradiated MB/BISPHEN/DNA mixture and isolated adducts show extensive conversion of the dye and metal complex to the corresponding N‐demethylated and aquated derivatives, respectively. Triplet quenchers for MB, for example oxygen and benzoquinone, inhibit both the photoconjugation and the photochemistry of BISPHEN. A mechanism for the synergistic interaction is proposed that involves photoconjugation of both partners to the DNA following oxidation and reduction via electron transfer between 1MB*/DNA and 3MB*/BISPHEN.

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Section: Ground and Excited State Complexation Of Mb/ Bisphen/dnasupporting

confidence: 92%

Simultaneous Photoconjugation of Methylene Blue and cis-Rh(phen)2Cl2+ to DNA via a Synergistic Effect †

Morrison

2007

Photochemistry and Photobiology

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“…Approximately 45% of MI 3 inactivation could be accounted for by the production of FSB and 25% by PLB (5). In deoxygenated conditions, possible mechanisms of the loss of MI3 infectivity may be explained by the proposal that 2'deoxyguanosine (dGuo) damage would be caused by direct singlet-state MB (IMB') reaction with dGuo at a GC-rich regions (21). Direct reaction of excited MB with DNA may take place as follows (9):…”

Section: Discussionmentioning

confidence: 99%

Potential Involvement of Both Type I and Type II Mechanisms in M13 Virus Inactivation by Methylene Blue Photosensitization

Abe¹,

Ikebuchi²,

Wagner

et al. 1997

Photochem & Photobiology

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We have investigated the mechanism of virus photoinactivation with methylene blue (MB) by conducting deuterium oxide (D2O), azide ion (N3-) and oxygen-dependent studies. Inactivation of M13 bacteriophage and singlet oxygen (1O2) generation by MB photosensitization were irradiation dose dependent. Inactivation of M13 was enhanced by D2O and inhibited by N3-, suggesting that 1O2 participates in M13 inactivation by MB photosensitization. However, N3- did not inhibit M13 inactivation completely. On the other hand, deoxygenating the reaction solution still caused 52-67% of M13 inactivation observed in the presence of oxygen. These results suggest that 1O2-mediated (Type II) and sensitizer-mediated (Type I) reactions may both play roles in M13 inactivation by MB photosensitization.

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“…The smaller effect of sodium azide also points out a minor involvement of singlet oxygen; this interpretation is further supported by the measured low quantum yields of 10 2 formation in D20:0.22 and 0.10 for dq2pyp and dq3pyp, respectively. Moreover, an even lower production of ~O2 is expected when the drug is intercalated into DNA, since molecular oxygen would have a lesser access to it [11].…”

Section: Resultsmentioning

confidence: 99%

DNA photocleavage by novel intercalating 6‐(2‐pyridinium)phenanthridinium viologens

1995

FEBS Letters

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A new type of DNA-intercalating viologen dications, derived from the N,N'-dialkyl-6-(2-pyridyl)phenanthridine structure (in which dialkyl is -CH2CH2-, -CH2CH2CH2-, or (-CH3)2, abbreviated dq2pyp, dq3pyp, and Me2pyp, respectively), are able to produce frank strand breaks in supercoiled plasmid DNA upon irradiation with visible light. The amount of photocleavage is similar for the three drugs. The observed DNA photosensitization appears to follow a single-strand cleavage model, as shown by a kinetic analysis of the reaction with dq2pyp. The photodynamic action of the drugs seems to be initiated by a light-induced electron transfer reaction from the nucleobases, given the singlet excited-state redox potentials (ca. + 2.1 V vs. SHE) and the low quantum yields of singlet molecular oxygen production of the drugs (0.1-0.2 in aerated D20). Key words. Intercalating viologen; DNA photocleavage;Photoinduced electron transfer reaction of Io 2 with guanine; (b) direct or OH'-mediated hydrogen abstraction from the deoxyribose moiety; (c) oxidation of guanine by the photoexcited drug. It is not uncommon to find the simultaneous participation of two of such processes in the sensitized photooxidation of nucleosides [4].In a recent paper [5], we have reported the intercalative interaction with DNA of a novel family of photoactive organic compounds, namely dialkylated 6-(2-pyridyl)phenanthridine (pyp) viologens (Scheme 1). The possibility of photochemistry with DNA was then suggested, based on their singlet excited state redox potentials and the efficient fluorescence quenching observed with GMP and AMP (kq = 1.2 x 10 l° and 6.8 x l09 M ~. s ], respectively). The goal of the present paper is to report the capability of dq2pyp, dq3pyp, and Me2pyp, to photosensitize DNA cleavage, as well as to obtain evidences about the possible mechanism responsible for their photodynamic activity.

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Laser Flash Spectroscopy of Methylene Blue With Nucleic Acids

Cited by 70 publications

References 29 publications

Simultaneous Photoconjugation of Methylene Blue and cis-Rh(phen)2Cl2+ to DNA via a Synergistic Effect †

Simultaneous Photoconjugation of Methylene Blue and cis-Rh(phen)2Cl2+ to DNA via a Synergistic Effect †

Potential Involvement of Both Type I and Type II Mechanisms in M13 Virus Inactivation by Methylene Blue Photosensitization

DNA photocleavage by novel intercalating 6‐(2‐pyridinium)phenanthridinium viologens

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