摘要:

Abstract—Triplet‐state properties of 1,4,8,11,15,18,22,25‐octa‐n‐butoxy phthalocyanine and its zinc derivative were determined for the first time. The T1state of the metal‐free phthalocyanine was characterized by a short lifetime (τT= 17 µs) and low quantum yield (φT= 0.095), and quenching of the triplet by O2occurred with a bimolecular rate constant (kTσ= 1.3 times 108M‐1s‐1) that is indicative of an endogonic reaction. The zinc complex (ZnPc(OBu)8) was markedly better as a triplet photosensitizer with respect to both tT(60 µs) and φT(0.5). Quenching by O2produced singlet oxygen with nearly 100% efficiency, andkTσ(1.7 times 109M‐1s‐1) was close to the spin‐statistical diffusion‐controlled limit. Phosphorescence measurements showed the energy of the T1state of ZnPc(OBu)8to be 100 kJ/mol, which is 6 kJ/mol above thelδgstate of O2. These photoproperties, together with Q‐band absorption maxima in the mid‐700 nm range indicate that metal‐centered 1,4,8,11,15,18,22,25‐octaalkoxyphthalocyanines have excellent potential

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04160.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—Two‐dimensional imaging of photons emitted from soybean roots was achieved with an ultra‐high sensitivity photon‐counting image acquisition system. The detected images reveal that a soybean root itself emits very weak light and photon flux from the growing point of the root is more intense than that from other parts of th

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04161.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—Several antibacterial halogenated salicylanilides, including 3,3′,4′,5‐tetrachlorosalicylanilide (TCSA) and 3,4′,5‐tribromosalicylanilide (TBSA) are known to cause photoallergy. We have carried out photochemical and spin trapping studies to determine whether free radicals may be involved in the photoallergic response. Irradiation (λ>300 nm) of TCSA in buffered (pH 7.4) 50% ethanol resulted in the rapid loss of the 3‐chloro atom, followed by the much slower release of 5‐ and then the 4′‐chloro atoms to give 3′‐chlorosalicylanilide as a stable photoproduct. Under the same conditions TBSA successively lost the 3‐, 5‐ and 4′‐bromine atoms to give salicylanilide. When TCSA or TBSA were irradiated (λ= 356 nm) in buffered (pH 7.4) 50% ethanol containing 2‐methyl‐2‐nitrosopropane (MNP) only solvent‐derived free radicals were detected. However, irradiation (λ= 356 nm) of TCSA and MNP in 0.1 N NaOH generated an ESR spectrum consisting of a broad triplet (aN= 15.6 G).This spectrum was attributed to the adduct formed by the reaction of MNP with the aryl radical generated by the loss of a chlorine atom from the sterically hindered 3‐(or 4′‐)‐position. Under the same conditions TBSA initially generated a broad triplet (aN= 15.5 G) similar to that observed for TCSA. However, upon further irradiation a 21‐line spectrum (aN= 14.4 G, a2H= 2.0 G and a2H= 0.9 G) appeared. Since the same ESR spectrum was obtained by irradiating 4′‐bromosalicylanilide, the spectrum must be generated by an adduct formed by reaction of MNP with an aryl radical derived from loss of the 4′‐bromine atom of TBSA. Irradiation (λ= 356 nm) of TBSA, glutathione and the spin trap 5,5‐dirrrethyl‐l‐pyrroline‐N‐oxide (DMPO) yielded the glutathione thiyl adduct of DMPO. Irradiation of (λ= 356 nm) TCSA, MNP and glycylglycine resulted in the trapping of a carbon‐centered radical derived from hydrogen abstraction from the backbone methylene of the C‐terminal glycine residue. These studies demonstrate that photo‐irradiation of TCSA or TBSA generates highly reactive aryl radicals, which can react with peptides to form secondary radicals. Thein vivoreaction of secondary protein radicals with the primary aryl radicals from TCSA or TBSA would result in the covalent binding of t

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04162.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—An efficient method of one‐electron reduction of the anticancer agent mitoxantrone is described. The method depends on illumination of a suitable photosensitizer absorbing blue light [acriflavine, anthrapyrazole, or Ru(bpy)+] in the presence of the drug and an electron donor, such as NAD(P)H, in deaerated solutions. An EPR spectrum, assigned to a semiquinone of mitoxantrone, is generated under these conditions and identified by spectral simulation. Decay of this species, attributed to a radical‐radical reaction, gives a second order rate constant of 1.7 102M‐1s‐1in organic media [dimethylsulfoxide (DMSO)/pH 8 buffer, 1:1 vol/vol] but is more rapid (˜104M‐1s‐1) in aqueous media under comparable conditions. The considerably decreased lifetime of the mitoxantrone radical at pH 5 is attributed to an additional electron transfer, promoted by protonation of the radical, and/or to an accelerated recombination of neutral radicals, leading to an EPR‐silent species. Parallel spectrophotometric studies on the generation of the mitoxantrone reduced species by photosensitized reduction are described. The method offers convenient access to a key radical species involved in the metabolism and possible mode of action of this clinical

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04163.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (tHLR) was measured at five monochromatic excitation wavelengths in the range 450–530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XHIa impurities. The values obtained (7.2‐18 10‐4) were lower than those previously reported and showed the following wavelength dependence: 457.9<488.0<501.7<514.5 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15Eand 4E,15Zisomers also was studied. This reaction became less regioselective for the 4Z,15Eisomer with increasing wavelength. The observed wavelength dependence of tHLRand of the [4Z,15E]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formationin vivoat different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength‐dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorptio

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04164.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—The rate constants of molecular singlet oxygen quenching by saturated and unsaturated fatty‐acids and by cholesterol‐membrane critical components ‐ membrane critical components ‐ have been measured by time resolved detection of the 1270 nm phosphorescence of singlet molecular oxygen [O2(1δg)]. We have determined (i) an increment of 5.7 times 102M‐1s‐1per ‐CH2‐ in C6D6and CD3OD for saturated fatty acids between C4and C20, (ii) an increment of 3 times 104M‐1s‐1per non‐conjugated cu‐double bond for C18unsaturated fatty acids, identical in C6D6and CD3OD, (iii) a lower quenching rate constant by a factor of 2.7 for thetrans‐C16andtrans‐C18as compared to the corresponding cis‐monounsaturated fatty acids, (iv) a rate constant of O2(1δg) quenching by cholesterol of 5.7 times 104M‐ls‐lin benzene. These rate constants are compared to those obtained f

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04165.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—The fluorescence characteristics of adducts derived from the covalent binding of the highly tumorigenic (+) and the non‐tumorigenic (‐) enantiomers oftrans‐7,8‐dihydroxy‐anti‐9,10‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene (BPDE) to native calf thymus DNA are significantly different from one another both at room temperature and at 77 K. The ratioRof fluorescence intensities of the (0,0) band I (situated near 380 nm) and vibronic band V (near 400 nm) of the pyrene ring system in the BPDE‐DNA adducts and of the tetraol (BPT) hydrolysis product of BPDE is very sensitive to the polarity of the solvent, thus mimicking the well known behavior of pyrene itself (A. Nakajima, 1971,Bull. Chem. Soc. Jpn.44, 3272). The fluorescence excitation and emission spectra of the(+)‐BPDE‐DNA adducts are relatively sharp and only slightly red‐shifted (2–3 nm) with respect to those of BPT in aqueous buffer solution, andR= 1.07 when the fluorescence is excited at the maximum of the absorption spectrum; this compares withR= 1.17 for BPT in water,R= 0.75 in ether, andR= 0.84 for noncovalently intercalated BPT. These results suggest that the pyrene ring system in the covalent (+)‐BPDE‐DNA adducts is located in an environment which is relatively exposed to the aqueous environment, while physically intercalated BPT molecules are located at hydrophobic binding sites. The fluorescence characteristics of the (‐)‐BPDE‐DNA adducts are more heterogeneous and thus more complex than those of the (+)‐adducts. TheRratio depends rather strongly on the wavelength of excitation; a minor, more highly fluorescent and relatively solvent‐accessible form of adducts exhibits anRratio of 1.01. The major, less solvent accessible form is characterized by a larger red shift in the absorption spectrum (10 nm) and emission spectrum (6 nm for the (0,0) band) relative to BPT, and anRratio of 1.07. These characteristics suggest that the local environments of the pyrenyl residues in the (‐)‐BPDE‐DNA adducts are significantly different from those of BPT bound noncovalently to DNA by the intercalation mechanism. Fluorescence methods, particularly at low temperatures where the bands are better resolved and the fluorescence yields are significantly greater than at room temperature, can also be used to distinguish covalent DNA adducts derived from the binding of (+

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04166.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—The relation between the lifetimes of the triplet states of various porphyrins and their photosensitizing effects on the photodynamic therapy (PDT) of tumor has been examined. Diethylene‐triamine pentaacetic acid ester of 4‐[1‐(2‐hydroxy‐ethyloxy)ethyl]‐2‐vinyl deuteroporphyrin‐IX gallium (III) complex (Ga‐DP), zinc (II) complex (Zn‐DP), and manganese (III) complex (Mn‐DP) and Photofrin II (PII) are used as the photosensitizer. The triplet lifetimes have been measured for the samples adsorbed on filter paper (FP) and found to be 57 ms (Ga‐DP), 26 ms (Zn‐DP), 610 |xs (Mn‐DP) and 9 ms (PII). The phosphorescence of Ga‐DP in tumor‐bearing golden hamsters are measured both in tumor tissue and in liver. They show bi‐exponential decay with the lifetimes of about 5 and 20 ms. From the values, the generation rate, kct[3O2], of singlet molecular oxygen in living animal tissue may be estimated to be an order of 102s‐1. The PDT effects have been quantitatively investigated forin vitroexperiments; upon irradiation the growth inhibitions of mouse p388 leukemia cells are obtained as a function of concentration of Ga‐DP, Zn‐DP, Mn‐DP and PII. The experimental results indicate that the PDT effects depend essentially on th

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04167.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—Fluorescence emission spectra indicate that oligomers containing both hematoporphyrin and its dehydration products (vinyl porphyrins) comprise the tumor‐localizing fraction of HPD. In the relatively polar solvent methanol, the vinyl porphyrins exhibit reduced fluorescence yields while the hematoporphyrin residues are relatively resistant to fluorescence quenching by Fe+3. In the less polar solvent tetrahydrofuran, fluorescence from oligomeric vinyl porphyrins was enhanced, and Fe+3‐induced quenching of oligomeric hematoporphyrin promoted. These, together with other studies in biological systems, suggest a substantial degree of interaction among the porphyrin units contained in these oligomers, as a function of the polarity of the enviro

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04168.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—Rubella virus is very sensitive to photodynamic action. When tested with 1.2 times10‐5Mtoluidine blue and 8 W fluorescent lamp at a fluence of 11 W/m2, inactivation kinetics showed a linear single hit curve with akvalue of 1.48 min‐1. Photodynamic inactivation of rubella virus greatly enhanced recombination with a latent virus (R‐virus) of baby hamster kidney BHK21 cells. In contrast, no hybrids were detected in lysates of the cells infected with either UV‐treated or untreated rubella virus. Therefore, hybrid viruses were readily detected only in lysates of BHK21 cells infected with photodynamically treated rubella virus. Photodynamic damage of rubella virus genomes generated a new hybrid type (hybrid type 3) in addition to a previously described type 2 hybrid (formerly designated as HPV‐RV variant). Although both of these hybrid types carry the CF antigens of rubella virus, plaque forming ability of type 3 hybrid is neutralized neither by anti‐rubella serum nor by anti‐latent virus serum while type 2 hybrid is neutralized by anti‐l

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1989.tb04169.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY