Metabolism of the anti-psoriatic agent 5-methoxypsoralen in humans: comparison with rat and dog.

1. Single oral doses of 14C-5-methoxypsoralen (5-MOP) to human subjects (50 mg), rats (1 mg/kg) and dogs (1 mg/kg) were fairly well absorbed but subjected to extensive first-pass metabolism, at least in rat and human. Means of 62, 51 and 40% dose in urine and 31, 38 and 48% dose in faeces, were excreted by humans (during 5 days), rats (3 days) and dogs (1 day), respectively. In dogs, faecal 14C was probably derived, in part, from biliary excreted material. 2. Total 14C in human plasma reached peak concentrations after 2 h (mean 235 ng 5-MOP equivalent/ml) and declined relatively slowly, to about 60% of this value within 24 h. Unchanged 5-MOP was not detected in plasma using h.p.l.c. (< 5 ng/ml). 3. Tissue concentrations of 14C were generally greater in dogs than rats and reached peak levels at 1 h in dogs but at 24 h in rats. Apart from liver and bile, dog tissue 14C concentrations were lower than those in the corresponding plasma, whereas in rat they were lower only until the time of peak concentrations, after which they were generally greater. 4. 5-MOP was extensively metabolized in all three species. The major 14C-components in human and dog urine were glucuronic acid conjugates, mainly of an arylacetic acid and arylalcohols, resulting from initial oxidative metabolism of the furan ring of 5-MOP. In rat, these metabolites were excreted mainly unconjugated. An unusual metabolite was formed by reduction of the lactone moiety of 5-MOP, probably by the gut flora, giving rise to an arylpropionic acid, excreted as a glucuronic acid conjugate in the urine of all three species. 5. Unchanged drug was a very minor component of human and rat plasma, but a major component of dog plasma. In all three species, circulating 14C-metabolites were similar to those in the urine but were present mainly unconjugated. On the basis of these data, the metabolic fate of 5-MOP in humans was more similar to that in dog than to that in rat, although humans appeared to metabolize 5-MOP more rapidly than did dog.

Psoralens cleave pBR322 DNA under ultraviolet radiation.

Supercoiled (SC) pBR322 was used to probe the recent claim that 5-geranoxylpsoralen (5-GOP) did not photoreact with DNA. Contrary to expectations, 5-GOP was found to damage DNA in the presence of UV-A through two competing pathways: (a) single strand breaks, identified by the conversion of supercoiled into open circular and linear DNA, and (b) cross-linking, revealed by the fluence-dependent decrease in the extent of denaturation of the double stranded supercoiled DNA to single stranded circular DNA. In addition, a fluence-dependent modification reduced the ability of the restriction enzyme EcoR I to linearize the photosensitized DNA, and alkali-labile lesions were generated. Psoralen, 5-methoxypsoralen, and 8-methoxypsoralen, which are well-known to undergo cycloaddition to DNA, had a more pronounced effect on supercoiled DNA. Single strand breaks occurred more readily than with 5-GOP, and the surviving SC form remaining had reduced electrophoretic mobility in agarose gels. In all cases, the DNA damage was more prominent when oxygen was absent.

Establishment of hairy root cultures of Psoralea species.

Eight Psoralea species (Leguminosae) were inoculated with Agrobacterium rhizogenes, strains 8196 and 9402. Hairy roots were only induced by strain 9402. Attention was focussed on Psoralea lachnostachys. Transformed roots grew very rapidly in Gamborg B5 liquid medium with a doubling time of the culture of 38 hours. Whatever the culture conditions, the two furanocoumarins usually found in roots of Psoralea plants, psoralen and angelicin, were not detected in cultured transformed and non transformed roots even when some chitosan was added to the medium. However, 669 µg.g(-1) dry matter of psoralen and 215 µg.g(-1) dry matter of angelicin were found in roots from soil grown plants. A possible translocation of these compounds from the aerial parts to the roots is suggested.

5-Methoxypsoralen enhances plasma melatonin concentrations in the male rat: non-noradrenergic-mediated stimulation and lack of effect in pinealectomized animals.

Previous studies have shown that 8-methoxypsoralen (8-MOP) is able to enhance melatonin secretion from rat pineal glands. The effect of another psoralen, 5-methoxypsoralen (5-MOP) on plasma melatonin concentrations alone or in combination with isoproterenol (Iso, 10 mg/kg BW, i.p.) or propranolol (Prop, 20 mg/kg BW, s.c.) was studied in the rat. An increase in plasma melatonin concentrations was observed 1 h after psoralen administration and lasted 8 h. The stimulatory effect of 5-MOP on circulating melatonin concentrations was dose dependent above 5-mg/kg, BW. 5-MOP also potentiated the Iso-induced rise in plasma melatonin levels. Furthermore, Prop did not block the effect of 5-MOP, indicating that the psoralen acts independently of the noradrenergic system controlling pineal melatonin synthesis. No increase in plasma melatonin levels was observed in pinealectomized (Px) animals after injection of 5-MOP (20 mg/kg BW) or 8-MOP (20 mg/kg BW). This demonstrates that the rise in plasma melatonin concentrations observed after treatment requires the presence of the pineal gland, and that neither 5-MOP nor 8-MOP stimulates melatonin release from other structures such as the retina or Harderian gland.

Photoreactivity of 5-geranoxypsoralen and lack of photoreaction with DNA.

5-Geranoxypsoralen, commonly called bergamottin, a major furocoumarin contained in bergamot oil, is reported in vitro as a highly photoreactive psoralen. In ethanol, it exhibits quite a high triplet state quantum yield (approximately 0.37). The triplet state is involved in subsequent photochemistry which depends on the initial concentration and on the presence of oxygen. In contrast to most psoralens, absorption and fluorescence data suggest that 5-geranoxypsoralen does not interact with DNA in the dark. No UVA-induced interstrand cross-links in DNA were shown.

The effects of bergapten and sunlight on cutaneous pigmentation.

The effects of bergapten-containing preparations in sunlight-induced skin pigmentation were evaluated. Oil and lotion vehicles with bergapten/UV-B sunscreen or sunscreen alone were applied to the backs of subjects twice weekly for 4 weeks and the subjects were exposed to gradually increasing doses of midday sunlight. The degree of skin darkening was assessed by clinical examination, reflectometry, and light microscopy of skin biopsy specimens. At 5 weeks, 1 week after the last sunlight exposure, the sites treated with either the bergapten/UV-B sunscreen lotion or the lotion vehicle were significantly darker than the sites treated with the sunscreen lotions without bergapten. Oil preparations produced less clearcut results, possibly because of a less potent sunscreen or because the bergapten did not leave the vehicle and absorb into the epidermis. In type I skin, the bergapten/sunscreen and the oil vehicle alone produced the same amount of tanning; both yielded more tanning than the sunscreen in oil by clinical examination. The findings were not confirmed by reflectometry or by light microscopy. Thus, we conclude that bergapten added to a UV-B sunscreen lotion preparation can increase skin pigmentation over the sunscreen alone when one is exposed to sunlight. The bergapten/UV-B sunscreen combination is a potentially useful product since one can develop a psoralen and UV-A-induced tan while being protected from UV-B-induced sunburn by the UV-B sunscreen incorporated into the formulation.

Photoprotective effect of vitamins A and E on polyamine and oxygenated free radical metabolism in hairless mouse epidermis.

The purpose of this study was to confirm the photoprotective effect on skin of vitamins A and E, due to inhibition of polyamine synthesis and production of free radicals. These variables were measured in the lumbar epidermis of the female hairless mouse subjected to UVA + B irradiation. Polyamines were assayed in epidermal homogenate by HPLC, and production of oxygenated free radicals was determined by spectrofluorometric assay of malonyl dialdehyde. It was determined that butyl-hydroxy-toluene and vitamin E inhibited production of free radicals (56% and 60%, respectively) and caused a significant reduction in polyamine biosynthesis (P less than 0.01), whereas the inhibitory effect of malonyl dialdehyde induced by vitamin A (30%) had no associated effect on polyamine metabolism.

[Evaluation of the results of lumbar sympathectomy with functional vascular tests. Statistical study (author's transl)]. / Evaluation des résultats de la sympathectomie lombaire par des épreuves fonctionnelles vasculaires. Etudes statistiques

A series of 100 unselected patients operated on for lumbar sympathectomy were studied by digit plethysmography, thest of hyperemia, rheography, measurement of segmental pressure and dynamic tests, treadmill and Strandness test. Statistical analysis of data showed that isolated lesions of atheroma yield the best result. Increase in walking perimeter and in blood flow (rheographic quotient) were the only parameters showing statistical change. Forecasting of the effect of lumbar sympathectomy by the hyperemia test of Hillestad was confirmed. Other forms of disease : diffuse lesions, lesions of arteries in the legs or due to diabetes were followed by very numerous failures. Lumbar sympathectomy is justified as an isolate procedure for femoral lesions, and associated to reconstructive aorto-iliac surgery whenever the distal runoff consists only of a deep femoral artery.

[Objective results of lumbar sympathectomy. Statistical study, based on vascular function tests]. / Résultats objectifs de la sympathectomie lombaire. Etude statistique fondée sur les épreuves fonctionnelles vasculaires

A series of 100 unselected patients who had undergone low lumbar sympathectomy were studied using vascular function tests (digital plethysmography, hyperaemia test, rheography, measurement of segmental pressures and dynamic tests, walking tolerance on a conveyor belt, Strandness test). Statistical study of the results obtained showed that, above all, isolated lesions of atherosclerotic origin gave excellent results. Increase in walking tolerance and circulatory flow (rheographic quotient) were the only statistically valid parameters. Prediction of the effects of lumbar sympathectomy by Hillestad's hyperaemia test was confirmed. There were many failures amongst the other cases (diffuse lesions, leg artery involvement, diabetic type lesions). Lumbar sympathectomy is hence justified only in the presence of femoral lesions and in association with reconstructive aorto-iliac surgery in all cases when the distal bed consists of the deep femoral only.

[Ultrastructural study of bacterial plaques from caries-free human subjects (author's transl)]. / Etude ultrastructurale de plaques microbiennes dentaires chez des sujets indemnes de carie

Bacterial plaques from the teeth of individuals without caries were prepared for examination under the electron microscope (Ryter and Kellenberger's fixation). Microbial polymorphism within bacterial plaques has previously been usually studied in relation to the age of the plaque. Actually, the presence of polymorphous micro-organisms and variations in microbial density observed in 48 hours old plaques, must be related to other factors. Micro-organisms of the same type, as well as bacteria of different types which adhere together, reveal symbiosis and a competition process within the bacterial plaque, thus leading to changes in metabolism and lysis of many of the bacteria. Disturbances in bacterial cell walls; septal vesicular formation and intracellular structures are observed. Bacteriophages found in the plaques may be the cause of lysis of bacteria. Disturbances in bacterial metabolism could explain the lack of carcinogenicity of micro-organisms, and bacterial antigenic complexes which induce probably useful immunological reactions in the host are revealed by the lack of dental caries.