Comparative photobiology of psoralens.

The comparative photobiological effects of several furocoumarins [i.e., angelicin, psoralen, 8-methoxypsoralen (8-MOP), and 5-methoxypsoralen (5-MOP)] have been evaluated in a number of biological systems. The photosensitized induced lethality and genetic damage have been assessed in bacterial, animal, and human cells, and the rank order of effectiveness established psoralen as the most active compound followed by 8-MOP, 5-MOP, and angelicin, 5-MOP and 8-MOP are, however, essentially equally active in the production of chromosome damage in human cells in vitro.

Lack of genetic damage in mammalian cells after cryopreservation at -196 degrees C.

Mammalian tissue culture cells when cryopreserved according to standard procedures do not show gross chromosomal changes as evidenced by the formation of micronuclei. Cryoprotective agents used in this study included dimethyl sulfoxide (DMSO), glycerol and polyvinylpyrollidone (PVP) in combination with serum and using freezing and thawing rates normally employed in cryopreservation studies. In preliminary experiments, point mutations as evidenced by oubain resistance were not observed. These results are discussed in relation to previous studies indicating genetic stability after freezing and thawing.

Concerted contractions of tumour fragments derived from a pure mucoid carcinoma of the breast in vitro.

Organized tissue fragments obtained by dissociation of a pure mucoid carcinoma of the breast were cultured in vitro. The cellular organization of the fragments appears similar to that observed in vivo, and consist of mucous-filled spherules surrounded by a single layer of tumour cells. Time-lapse video recordings revealed that the cells surrounding these fragments undergo a concerted contraction and relaxation over the time span of several hours. The presence of cytokeratin and oestrogen receptors in the cells suggests an epithelial derivation. Movement of tumour fragments of the type described here could potentially influence the metastatic process of some breast cancers.

Photobiological properties of a novel, naturally occurring furoisocoumarin, coriandrin.

The photobiological properties of a novel, naturally occurring furoisocoumarin isolated from coriander and named coriandrin are described. Photosensitized lethal and mutagenic effects in bacteria indicate that it is more active than psoralen. It is a weak frameshift mutagen in the dark. Mammalian cells in tissue culture are photosensitized more actively with coriandrin than with psoralen even though preliminary evidence from interrupted radiation experiments and DNA analysis suggest that coriandrin does not form DNA interstrand crosslinks. Sister chromatid exchanges were induced with a unit dose of 1.1 x 10(-2) with coriandrin; the value for psoralen is 3 x 10(-3). Coriandrin appears to be metabolized more rapidly than furocoumarins by liver mixed function oxidases. Skin photosensitizing activity is very weak compared with psoralen, a surprising observation considering its potency in biological test systems.

The photobiological activity of 5-geranoxypsoralen and its photoproducts.

5-geranoxypsoralen (Bergamottin) does not photosensitize bacteria or a bacterial virus. It does, however, photosensitize mammalian cells in tissue culture. Irradiation with either black light (300-400 nm) or fluorescent ceiling lights produced at least four photobiologically active degradation products, the chemical nature of which still remains to be elucidated. Prolonged exposure to black light resulted in the formation of inactive molecule(s).

The unusual UVA-dependent antiviral properties of the furoisocoumarin, coriandrin.

The novel furoisocoumarin, coriandrin, which was found recently to possess an interesting combination of photobiological properties, was investigated for antiviral activity in the presence and absence of UVA (long-wavelength ultraviolet radiation). In contrast to results obtained with other antiviral furocoumarins, such as 8-MOP (8-methoxypsoralen), coriandrin was much more phototoxic to the RNA-virus Sindbis virus than to the DNA-virus murine cytomegalovirus, although both viruses were substantially more sensitive to this compound than they were to 8-MOP. Human immunodeficiency virus, HIV-1, was also susceptible to coriandrin + UVA. Another unexpected finding was that viruses without membranes were completely resistant to coriandrin. This suggests that a membrane component was a target for the compound. The antiviral activity of coriadrin was profoundly inhibited by serum components in the reaction mixtures, which suggests that the compound may have a strong affinity for certain protein or lipid materials, although maximal interference was only obtained when all components of the reaction mixture, virus, coriandrin and serum, were irradiated simultaneously. Thus it appears that coriandrin has unusual antiviral properties that would not be predicted from its chemical similarity to furocoumarins.

Frameshift mutations in bacteria produced in the dark by several furocoumarins; absence of activity of 4,5',8-trimethylpsoralen.

4 furocoumarins, namely psoralen (P), 8-methoxypsoralen (8-MOP), 4,5',8-trimethylpsoralen (TMP) and angelicin (A) were tested for dark mutagenesis in E. coli lac-. Three compounds; P, 8-MOP and A were shown to be weak frame-shift mutagens. TMP, surprisingly in view of its very active photosensitizing action, was found to be non-mutagenic. These results are discussed in relation to the photosensitizing action of the furocoumarins.

Lack of mutagenicity and putative carcinogenicity of several novel benzopyrene derivatives.

Several novel benzopyrene derivatives with the same gross structure and the same electronic periphery as benzo(a)pyrene, but with some alteration in the complete electronic structure, when tested in the Ame's Salmonella/microsome test (TA 1537, TA 100 and TA 98], were found to lack mutagenicity and, therefore, putative carcinogenicity.

Mutagenic activity of swimming-pool water.

Swimming pool water, being chlorinated and exposed to trace organics from use was investigated as a possible source of mutagens using the Salmonella/mammalian-microsome test. Procedures previously described for the extraction of trace organics from water using XAD-2 macroreticular resin were modified to allow quantitative extraction of mutagens. These procedures were superior to freeze-drying and solvent-extraction. Using a base-pair histidine mutant, strain TA100, of Salmonella typhimurium significantly mutagenic responses were observed using concentrates from 3 variations of the extraction procedure. Acidified pool-water extracts eluted with ether or acetone were mutagenic, the former enhanced in the presence of the induced microsomal fraction from rat livers. Non-acidified pool-water extracts eluted with acetone were mutagenic without microsomal activation. These results indicate the presence of more than one mutagen in what is likely a complex mixture of organic molecules in swimming-pool water.

Mutagenicity and purative carcinogenicity tests of several polycyclic aromatic compounds associated with impurities of the insecticide methoxychlor.

Several polycyclic hydrocarbons, 3,6-dimethoxy-9,10-bis(p-methoxyphenyl)-phenathrene, tetrakis(p-methoxyphenylyethylene and 3,6,11,14-tetramethoxydibenzo(g,p)chrysene, which are associated as impurities in commerical samples of the insecticide methoxychlor, have been tested in the Ames mutagenicity test with strains of Salmonella thyphimurium, TA 1535, TA 1537, TA 1538, and TA 98. Activation by liver microsomes induced with either phenobarbitol or Aroclor was examined. The only active compound was 3,6,11,14-tetramethoxydibenzo(g,p)chrysene, mutagenic (0.39 revertants/nmol) tostrain TA 98.

Chromosome damage in Chinese hamster cells sensitized to near-ultraviolet light by psoralen and angelicin.

The clastogenic effect of furocoumarins psoralen and angelicin in the presence of near-UV (320-380 nm) differs greatly, as do their modes of interaction with DNA. Psoralen, which requires only one-fifth as much light energy to produce the same lethal effect as angelicin at equimolar concentrations, is able to cross-link DNA whereas angelicin cannot. The frequency of micronuclei which arise from chromosomal fragments shows the same differential effect as lethality. Indeed aberrations account for much or all of the lethality observed. Metaphase analysis at comparable aberration frequencies revealed that angelicin and psoralen both induce chromatid deletions and a wide spectrum of chromatid exchanges. These data show that both cross-links and monoadducts to the DNA can result in chromosomal aberrations. The relative contributions of cross-links and monoadducts to chromosomal aberrations still remain to be determined. It is noteworthy that extensive chromosomal damage is induced in mammalian cells by the combination of psoralen and near-UV, a treatment which is currently widely used in the therapy of psoriasis.

Photobiological studies with dictamnine, a furoquinoline alkaloid.

Dictamnine, a naturally occurring furoquinoline, produces bacterial frameshift mutations in the dark. It does not form DNA interstrand crosslinks in bacterial cells in the presence of near-ultraviolet light (300-380 nm). It is more active than angelicin but slightly less active than 8-MOP as a phototoxic agent with E. coli. It is however a more active mutagen than 8-MOP at equivalent concentration. Dictamnine is slightly more potent than the same concentration of angelicin in producing photosensitized lethality in Chinese hamster cells. It does, however, produce almost twice as many sister-chromatid exchanges per lethal event than angelicin. The concept of 'unit dose' relating the observable photoinduced damage by the photosensitizer and the total irradiation appears to apply reasonably well to the actions of dictamnine in killing bacterial and mammalian cells, in the formation of sister-chromatid exchanges, but not to the induction of bacterial mutations.

Chromosomal damage induced by furocoumarins and UVA in hamster and human cells including cells from patients with ataxia telangiectasia and xeroderma pigmentosum.

The comparative photosensitizing effects to near-UV irradiation (UVA) of several naturally occurring furocoumarins, 5-methoxypsoralen (5MOP), psoralen, 8-methoxypsoralen (8MOP) and angelicin in producing chromosome damage in vitro in cells derived from hamster, normal human, ataxia telangiectasia (AT) and xeroderma pigmentosum (XP) patients were studied. In Chinese hamster cells, lethality was greatest with psoralen and least with angelicin; 8MOP and 5MOP were intermediate. 8MOP and 5MOP produced sister-chromatid exchanges with almost equal efficiency and to a larger extent by far than angelicin. In all human cell lines studied, 8MOP and 5MOP were similarly effective in the production of sister-chromatid exchanges and chromosomal aberrations. AT and XP cells responded with higher frequencies of sister-chromatid exchanges as well as chromosomal aberrations than normal human cells to 5MOP, 8MOP and angelicin. Evidence is presented which suggests that cell death in Chinese hamster cells following angelicin photosensitization is not clearly related to the production of sister-chromatid exchanges. AT cells were unexpectedly more sensitive to angelicin than normal cells. The presence of 5MOP in some sun-tan preparations is not acceptable in view of the present evidence of its biological activity.

Environmental survey of RCMP detachment building in Powell River, B.C., implicated in a cancer cluster.

The rationale and approach are presented that were used to investigate the Powell River RCMP detachment building, perceived to have a higher than normal cancer incidence and whose occupants demanded to know whether the building was safe to work in. On the basis of the history of the building and the cancers observed, a set of carcinogens were looked for in areas where the worst conditions were expected. A positive result would initiate a second more in-depth survey. This was done for Fyrol-PCF, which was shown to be a contaminant of the charcoal adsorption tubes used. The results of the survey indicated a safe work environment. The chemical analyses, complemented by the bioassay and comparison with a recognizable control site, were found to be most effective in the acceptance of the results by the public. The conclusions from this survey were confirmed by the findings of an epidemiological survey.