摘要:

Abstract—Photooxidation of 16‐O‐acetylvindoline in methanol using chlorpromazine‐HCl as a photosensitizing agent produces nearly quantitative yields of an iminium derivative. The 16‐O‐acetylvindol‐ine‐iminium product was characterized spectrally by proton NMR and mass spectrometry; and by chemical reduction with sodium borodeuteride. Proton NMR and mass spectral analyses of the reduced product revealed that deuterium was stereospecifically incorporated into the 3‐a‐position. The iminium product formed by photochemical oxidation is identical to that produced by copper oxidases and peroxidase. Photochemical oxidation provides direct evidence for the involvement of free radicals inAspidospermaalkal

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02819.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The o‐, m‐, and p‐isomers of 5, 10, 15, 20‐ tetra(hydroxyphenyl)‐porphyrin have been of recent interest as potential second‐generation sensitisers in tumour phototherapy. Fluorescence spectroscopy, nanosecond laser flash photolysis and pulse radiolysis have been used to characterise the singlet and triplet excited states of tetraphenylporphyrin and the o, m‐, and p‐isomers of tetra(hydroxyphenyl)porphyrin. This has included evaluation of fluorescence yields and lifetimes, triplet spectra, lifetimes, oxygen quenching rate constants, extinction coefficients, and yields and singlet oxygen yields. Whilst the fluorescence quantum yields were low, the triplet yields were all 0.7 ± 10% and the singlet oxygen yields 0.6 ± 10%: all these parameters are in the ranges shown by other efficient porphyrin photosensitisers. The similar photophysical properties found for these compounds suggest that their differing tumour sensitising efficiencies are likely to be d

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02820.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The rate constantk5/>for physical quenching of singlet oxygen O2(δ1;) by the sensitizer in dye‐sensitized photooxygenations is determined in the case of chlorophyllsaandb(7.3 times 108, 4.2 times 108M‐1s‐1respectively), pheophytinsaandb(7.4 times 107, 3.0 times 107M‐1s_1respectively), tetraphenylporphyrin (4.4 times 107M‐1s_1), magnesium tetraphenylporphyrin (5.0 times 108M‐1s_1), zinc tetraphenylporphyrin (1.5 times 108M‐1s_l) and protoporphyrin IX‐dimethylester (9.1 times 107M‐1s_1) in benzene. These sensitizers show a linear correlation between logksO, and their half‐wave oxidation potentials and the value of the slope is similar to that observed for various compounds such as phenols. It is concluded that (i) the interaction between chlorophylls and related compounds with singlet oxygen may involve an exciplex as for phenols, and (ii) physical quenching may be envisaged as a spin‐orbit‐induced intersystem cr

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02821.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The light‐induced capacitance changes and also both photovoltage and photocurrent under continuous illumination have been investigated in pigmented liquid crystal bilayer membranes (PBLM)‡ containing TCNQ as photosensitizer with Na2SO3electron donor on one side and methylene blue electron acceptor on the other side. The results have shown that TCNQ in cyanobiphenyl membrane produces a unique photoactive BLM system in which all three main parameters (conductivity, capacity and voltage across the membrane) are in a wide range altered by the light. It is shown that a TCNQ‐cyanobiphenyl charge transfer complex is responsible for the observed photochanges. The possible mechanism of photoinduced electrical effects in this type of PBLM is di

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02822.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—We have studied the antiviral properties of three different groups of photo‐sensitizers,viz.(i) various furyl compounds; (ii) β‐carboline alkaloids; (iii) thiophenes and their acetylene derivatives. In general the antiviral potency of the furyl compounds correlated with their ability to produce DNA photoadducts.Among the naturally occurring β‐carboline alkaloids, harmine was considerably more potent (in the presence of long wavelength UV radiation, UVA) than several other harmane‐related compounds. Slight alterations in chemical structure had profound effects on their antiviral activities. Harmine was shown to inactivate the DNA‐virus murine cytomegalovirus (MCMV) by inhibiting viral gene expression, although other targets may also exist. Several eudistomins, carboline derivatives isolated from a tunicate, were also photoactive against viruses.Various plant thiophenes and polyacetylenes were studied in detail. These compounds also required UVA for antiviral activity, and some of them were extremely potent against viruses with membranes, e.g. α‐terthienyl, which showed significant activity at only 10‐5μg/ml. When MCMV had been treated with α‐terthienyl plus UVA, the virus retained its integrity and penetrated cells normally; but the virus did not replicate. More than 30 additional thiophenes have recently been evaluated, including many synthetic ones, and some of these are even more potent than a‐terthienyl. We believe that certain thiophenes possess potential therapeutic value and should be tested against model vir

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02823.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—Chloroaluminum phthalocyanine (CAPC) is an efficient photosensitizer for the inactivation of Chinese hamster V79 cells. In order to investigate possible molecular mechanisms in the photo‐dynamic action of CAPC and visible light, the induction and repair rate of two classes of DNA lesions have been determined, i.e. DNA single‐strand breaks and DNA‐protein cross‐links. In cells pretreated with 1 μ.M CAPC, a fluence of 12 kJ/m2of red light (>600 nm) kills approximately 50% of the cells and induces 3 to 3.5 Gy‐equivalents of single‐strand breaks. The repair of these breaks was slower than the repair of single‐strand breaks induced bym̀‐irradiation. The photodynamic action of CAPC also induces a large number of DNA‐protein cross‐links which, in contrast tom̀‐radiation‐induced DNA‐protein cross‐links, do not appear to be repaired during 4 h of post‐treatment incubation in fresh medium. These studies suggest that DNA may be an important target for th

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02824.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The accumulation of (J‐carotene in the ph/ph+y diploid strain of the smut fungusUstilago violaceawas associated with reduced killing and lower levels of induced mitotic recombination compared to the β‐carotene lackingph/ph+wstrain in response to both incandescent photosensitization and treatment with H202. Theph/ph+ystrain was only slightly more resistant to killing by exogenous toluidine blue (TB) photosensitization. Theph/ph+ystrain exhibited significantly greater levels of survival when exposed to incandescent radiation and 1.5μ.MTB for 15 min, as well as 3.0. 0.3, 0.03, 0.003% H202in the dark. Theph/ph+ystrain also exhibited lower levels of mitotic recombination after endogenous TB photosensitization and the latter two H202treatments. Similar survival results were obtained for the carotene accumulating haploid strain l.C2y and the carotene lacking haploid strain l.C2iv in response to H202e

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02825.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—In this study, human tumor cell lines of different origin (colon carcinoma HT29, breast carcinoma MCF7 and malignant melanoma M14) were incubated for 24 h at 37*deg;C with Rhodamine 123 (Rh123) at concentrations ranging up to 4 μg/ml;. Immediately after drug removal, light irradiation was delivered at 500 W/m2for 5 min using an argon laser. After irradiation, viable cells were counted and assayed for colony formation. When only Rh123 was administered, a 50% survival was obtained at about 2.77 μg/ml and 1.48 μg/ml; for HT29 and MCF7, respectively. After light irradiation, 50% survival doses decreased to 0.47 μg/ml and 0.18 μg/ml for the two carcinoma cell lines, respectively. In the case of malignant melanoma, the decrease in survival was relatively lower than those obtained with carcinoma cells: 50% survival dose was 3.54 μg/ml with Rh123 alone and 1.32 μ/ml after irradiation. The lower sensitivity of M14 melanoma cells seems to be related to different uptake and release of drug by these cells with respect to carcino

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02826.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—DNA damage induced by 8‐methoxypsoralen (8‐MOP) plus near UV light (UVA) was analyzed in diploid yeast using the alkaline step elution technique. The presence of 8‐MOP and UVA induced DNA interstrand cross‐links was revealed by the increase of DNA retained on elution filters as compared to untreated controls. The fraction of DNA retained on filters increased linearly with UVA dose. The amount of cross‐links was estimated from the fraction of DNA retained on filters using a dose ofm̀‐radiation leading to a number of DNA strand breaks at least equivalent to the number of 8‐MOP induced photoadducts.When 8‐MOP treated cells were exposed to monochromatic light, 365 nm light induced monoadducts and cross‐links whereas 405 nm light induced only monoadducts. When submitting 8‐MOP plus 405 nm light treated cells to 365 nm irradiation, after removal of unbound 8‐MOP by washing, a portion of 8‐MOP plus 405 nm light induced monoadducts was converted into cross‐links. The amount of monoadducts transformed into cross‐links was dependent on the dose of 365 nm irradiation up to a maximum likely to correspond to the number of suitably positioned furan‐side monoadducts that could be converted into biadducts. When 8‐MOP plus 365 nm light treated cells were reirradiated with 365 nm light, following the same protocol, the maximum level of cross‐linking obtainable in yeast was lower than that obtained with 8‐MOP in a 405 nm plus 365 nm reirradiation protocol.In the presence of 8‐MOP single exposures to 405 nm light were found to be only slightly genotoxic. However, when followed by second exposures to 365 nm light, a dose‐dependent increase in genetic effects, i.e. mutation and gene conversion, was observed in parallel to the induction of DNA crosslinks. These results stress again the prominent role of DN

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02827.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The direct photomodification of DNA by ultraviolet light or the photo‐induced addition of exogenous compounds to DNA components results in alterations of DNA structure ranging from subtle to profound. There are two consequences of these conformational changes. First, cells in which the DNA has been damaged are capable of executing repair steps. Second, the DNA which is usually of very low immunogenicity now becomes highly antigenic. This latter property has allowed the production of a series of monoclonal antibodies that recognize photo‐induced DNA damage. Monoclonal antibodies have been generated that recognize the 4′,5′‐monoadduct and the crosslink of 8‐methoxypsoralen in DNA. In addition, another antibody has been prepared which recognizes the furan‐side monoadduct of 6,4,4′‐trimethylangelicin in DNA. These monoclonal antibodies have been characterized as to sensitivity and specificity using non‐competitive and competitive enzyme‐linked‐imm

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02828.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY