1,721,065 research outputs found
Tetrahydrobenzo-4,6-dimethylangelicin: a new angular furocoumarin forming interstrand photo-cross-links.
No full textIsomerization of 4-Aminobenzofurans to 4-Hydroxyindoles.
No full text4-Amino-2-methylbenzofurans are quantitatively converted to 4-hydroxy-2-methylindoles in acidic medium. The rearrangement mechanism involves the ring opening of the furan ring to produce an intermediate carbocation, which undergoes ring closure to the indole system. Isomerization takes place only in the presence of a methyl substituent in 2 position
Synthesis of various angular methylfurocoumarins
No full textA number of new methylfurocoumarins, in wich the furan, benzene and pyrone rings are annulate angularly with various arrangements, were synthesized. The synthesis were performed starting from the appropriate hydroxycoumarins on which the furan ring was built. According to this scheme, methyl groups could be introduced into positions which look most promising for enhancement of photoreactivity in the respect to the corresponding unmethylated compounds
2,6-Dimethyl-9-methoxy-4H-pyrrolo[3,2,1-ij]quinolin-4-one, a new compound with unusual photosensitizing properties. -
No full textSome photobiological properties of 2,6-dimethyl-9-methoxy-4H-pyrrolo[3,2,1-ij]quinolin-4-one (PQ) have been studied in comparison with 8-methoxypsoralen (8-MOP). In Ehrlich cells, PQ induced a moderate inhibition in DNA and RNA syntheses in the dark, which appeared to be more pronounced upon UVA irradiation. In contrast to 8-MOP, in the presence of UVA, PQ also affected protein synthesis. Likewise marked antiproliferative effects were also observed in the study of the clonal growth of CHO cells cultivated in vitro. Using alkaline elution and CHO cells, a moderate formation of single-strand breaks (SSBs) and of DNA-protein cross-links (DPCs) was observed by incubation in the dark; upon UVA irradiation the amount of both lesions increased greatly, whereas no inter-strand cross-links (ISCs) were formed. As expected, 8-MOP did not damage DNA in the dark, but induced SSBs, ISCs and DPCs in the presence of WA. The induction of SSBs by both compounds seems to be directly related to a photochemical event rather than to incisions during DNA repair. As the induction of ISCs, and also the formation of DPCs by 8-MOP and UVA, appears to be based on a two-step reaction involving photo-bound 8-MOP-DNA moieties. In contrast, the formation of DPCs by PQ and UVA seems to involve photosensitization by free PQ molecules connected with SSB and DPC formation rather than with a DNA photo-binding activity. The PQ activity observed in the dark could probably be ascribed to a moderate inhibition of topoisomerases
Disposition of 4, 6, 4'-trimethylangelicin in mice maintained in the dark and after uva irradiation.
No full textimpact factor 0.79
The disposition of the furocoumarin 4,6,4'-trimethylangelicin (4,6,4'-TMA) was studied in mice. After oral administration of (3)H 4,6,4'-TMA, radioactivity measured in serum shows fast absorption and slow elimination. Serum protein binding is higher as compared to 8-methoxypsoralen (8-MOP), currently used in photochemotherapy (PUVA) and linearly declines from 30 min to 6 h after administration. Distribution in the various organs was similar to that of 8-MOP and was relatively uninfluenced by UVA radiation, required for the biological effects of 4,6,4'-TMA. Mice eliminate (3)H 4,6,4'-TMA mostly through the urine, but also through the faeces. Two metabolites were identified in the urine and serum of the treated mice, one of which proved to be a derivative of 4,6,4'-TMA, formed by hydrogenation of the double 4',5' bond of the furocoumarin nucleus
Collisional spectroscopy potentialities in structural characterization of variously annulated furanocoumarins
No full textPyrrolocoumarin derivatives as potential photoreagents toward DNA.
No full textA number of new methyl derivatives of linear and angular pyrrolocoumarins were synthesized by direct Fischer’s indole synthesis. In the same way some linear and angular pyranocarbazolones. The synthesis were performed starting from the appropriate methyl-7-aminocoumarins and methyl groups were introduced into positions which look most promising for the photoreactivity toward DNA
13C-NMR Spectra and carbon-proton coupling constants of various annulated furocoumarins
No full textThe 13C NMR spectra of variously annulated methylfurocoumarins are reported. The assignments of chemical shifts for all the C resonances have been achieved by using carbon-proton coupling costants, relaxation efficiency considerations and shift effects caused by the introduction of methyl groups at various position of the furocoumarin nucleus. Substituent effects on chemical shifts and C-H coupling constants are discussed
DNA Damage and Citotoxicity Induced in Mammalian Cells by a Tetramethylfuroquinolinone Derivative
Full text link1,4,6,8-Tetramethyl-2H-furo[2,3-h]quinolin-2-one (FQ) is an angelicin isoster characterized by a strong photosensitizing activity. FQ shows a significant antiproliferative activity also in the dark, i.e., without UVA activation. The cytotoxic activity of FQ in the dark was detected in Hero cells and in normal human lymphocytes; FQ showed notable antiproliferative effects, barely lower in comparison with ellipticine, used as a reference. Similar results were obtained studying the FQ's capacity for forming chromosome aberrations. For both FQ and ellipticine, the chromosomal damage correlated closely with cell killing; when compared with ellipticine at the same levels of survival, FQ appeared to be much less genotoxic. Using alkaline elution we have investigated the ability of FQ to damage DNA. The formation of equivalent amounts of single-strand breaks (SSB) and DNA-protein cross-links (DPC) was observed; in addition, these lesions appeared to be located at the some sites in DNA. Experiments carried out with neutral elution demonstrated the formation of double-strand breaks (DSB). All these data are consistent with an inhibition of topoisomerase II; this hypothesis was confirmed performing an enzymatic test in vitro using topoisomerase II from Drosophila melanogaster embryos. (C) 1997 Wiley-Liss, Inc
METHYLTRIAZOLOCOUMARINS - NEW FUROCOUMARIN ISOSTERS AS POTENTIAL PHOTOCHEMOTHERAPEUTIC AGENTS
No full textA number of new methyltriazolocoumarins were synthesized. The synthesis was performed starting from the appropriate methylated 7-aminocoumarins which were nitrated, reduced and diazotized with concomitant cyclization to form the triazole ring
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