Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “5-Methoxypsoralen”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

A reappraisal of the use of 5-methoxypsoralen in the therapy of psoriasis.

5-methoxypsoralen (5-MOP) is considered an alternative to 8-methoxypsoralen (8-MOP) for photochemotherapy of psoriasis. We have compared the clinical efficacy and tolerability of 5-MOP (1.2 mg/kg)-UVA versus 8-MOP (0.6 mg/kg)-UVA therapy in 25 patients of skin type III and IV, affected by relapsing plaque-type psoriasis of similar body involvement; indeed, the same patients were given 8-MOP during 1 year and 5-MOP during the subsequent year after relapsing. Both treatments cleared psoriatic lesions with a comparable number of exposures, but 5-MOP required significantly higher cumulative UVA doses. The difference was due to the lower phototoxicity of 5-MOP, as assessed by the determination of the minimal phototoxic dose, and to its higher tanning activity, as assessed by the weekly grading of pigmentation. Nevertheless, therapy by 5-MOP-UVA seemed particularly interesting in that it showed a higher tolerability since only 1 patient experienced nausea, whereas during therapy with 8-MOP-UVA nausea and/or vomiting occurred in 7 patients, sunburn in 6 and itching in 3. Since we have treated the same patients with the two drugs, our results were not influenced by interindividual variations of phototoxic responses, tanning ability and susceptibility to develop psoralen-induced short-term side-effects. It was concluded that, although long-term side-effects of the 5-MOP-UVA treatment have still to be determined, such treatment of psoriasis should be reappraised due to its higher tolerability in comparison to 8-MOP-UVA treatment.

5-Methoxypsoralen↗
PubMed1992

A new micronized 5-methoxypsoralen preparation. Higher bioavailability and lower UVA dose requirement.

A new tablet of micronized 5-methoxypsoralen (5-MOP) and a commonly used tablet in therapy (Psoraderm 5) were compared in 12 healthy subjects. Each subject ingested 1.2 mg/kg body weight of each formulation on different days. Bioavailability and phototoxicity of 5-MOP were compared. The results showed that serum and suction blister concentrations were significantly higher and occurred earlier after the oral intake of the micronized preparation. A series of graduated UVA doses were administered, one dose each time the concentration serum peaked, in order to determine the minimum phototoxic dose for each formulation. The micronized preparation induced greater photosensitivity than the unmicronized one. The micronized 5-MOP tablet may thus allow lower doses of UVA to achieve therapeutic results in photochemotherapy and a shortened waiting period following ingestion of drug.

5-Methoxypsoralen↗
PubMed1979

5-Methoxypsoralen (Bergapten) in photochemotherapy of psoriasis.

5-Methoxypsoralen (5-MOP, Bergapten) was evaluated as a potential photosensitizing drug in oral photochemotherapy of psoriasis. Treatment results indicate that (1) 5-MOP is as effective as, and in high doses more effective than, 8-methoxypsoralen in clearing psoriatic lesions; (2) therapeutic doses of 5-MOP do not lead to erythema; the acute side-effects of 8-MOP PUVA therapy--erythema, blistering, pruritus--are thus avoided; (3) even high doses of 5-MOP are not followed by nausea. 5-MOP PUVA therapy thus represents a real alternative to 8-MOP PUVA, its advantages over 8-MOP PUVA being greater safety and patient acceptance.

Drug Administration Schedule↗
PubMed1992

Sequence specificity of psoralen photobinding to DNA: a quantitative approach.

The effects of different DNA sequences on the photoreaction of various furocoumarin derivatives was investigated from a quantitative point of view using a number of self-complementary oligonucleotides. These contained 5'-TA and 5'-AT residues, having various flanking sequences. The furocoumarins included classical bifunctional derivatives, such as 8-methoxy- and 5-methoxypsoralen, as well as monofunctional compounds, such as angelicin and benzopsoralen. Taking into an account the thermodynamic constant for noncovalent binding of each psoralen to each DNA sequence, the rate constants for the photobinding process to each fragment were evaluated. The extent of photoreaction is greatly affected by the DNA sequence examined. While sequences of the type 5'-(GTAC)n are quite reactive towards all furocoumarins, 5'-TATA exhibited a reduced rate of photobinding using monofunctional psoralens. In addition terminal 5'-TA groups were the least reactive with 5- and 8-methoxypsoralen, but not with angelicin or benzopsoralen. Also 5'-AT-containing fragments exhibited remarkably variable responses toward monofunctional or bifunctional psoralen derivatives. As a general trend the photoreactivity rate of the former is less sequence-sensitive, the ratio between maximum and minimum being less than 2 for the examined fragments. The same ratio is about 3.4 for 8-methoxypsoralen and 6.2 for 5-methoxypsoralen. This approach, in combination with footprinting studies, appears to be quite useful for a quantitative investigation of the process of covalent binding of psoralens to specific sites in DNA.

Base Sequence↗
PubMed1976

Photochemotherapy (PUVA) and psoriasis: comparison of 8-MOP and 8-MOP/5-MOP.

Twenty-eight psoriatic patients received PUVA treatment (psoralen and long ultraviolet irradiations. Two preparations were used; 8-methoxypsoralen and a mixture of 5-methoxypsoralen and 8-methoxypsoralen. Both gave considerable improvement, but in 6 cases the lesions reappeared after 2 to 8 weeks, in spite of maintenance treatment. In this report, photochemotherapy of psoriasis was compared, using a UVA emitting lamp, 8-MOP, and a mixture of 8-MOP and 5-methoxypsoralen (5-MOP).

Coumarins↗
PubMed1992

Liquid formulations of 8-methoxypsoralen (8-MOP) and 5-MOP: a prospective double-blind crossover assessment of acute non-phototoxic adverse effects.

Thirty-nine patients with psoriasis undergoing PUVA participated in a prospective double-blind study of acute non-phototoxic adverse effects comparing the liquid formulations of 8-methoxypsoralen (0.6 mg/kg) and 5-methoxypsoralen (1.2 mg/kg). A much higher number of patients experienced nausea (8-MOP = 51.3%, 5-MOP = 7.7%) and pruritus (8-MOP = 71.8%, 5-MOP = 43.6%) than has been reported for crystalline tablets. No attempt was made to compare therapeutic efficacy between liquid and crystalline tablet formulations or between 8-MOP and 5-MOP, which both appeared to be effective. The high incidence of adverse effects suggests that current dosage recommendations be reviewed.

5-Methoxypsoralen↗
PubMed1992

The evolution of photochemotherapy with psoralens and UVA (PUVA): 2000 BC to 1992 AD.

The therapeutic uses of naturally occurring psoralens in modern-day medicine (8-methoxypsoralen (8-MOP), 5-methoxypsoralen (5-MOP), 4,5',8-trimethylpsoralen, and a few other synthetic psoralens) have evolved through five stages of development. (1) In the historical period (2000 BC to 1930 AD), the pigment-stimulating properties of naturally occurring plants containing psoralens were described anecdotally. (2) The second period (1930-1960) dealing with the chemistry of psoralens involved extraction, identification of their structure, synthesis, and the relationship between chemical structure and their photoreactivity and pigment-stimulating properties. The treatment of vitiligo with oral and topical 8-MOP became popular. (3) In the third period (1960-1974), we witnessed a new beginning and the growth of basic science studies and clinical investigations into various biological properties of psoralens including action spectrum studies, mutagenesis and carcinogenesis studies, in vitro and in vivo photoreactivity studies of various psoralens with DNA, RNA, proteins, and pharmacological and toxicological studies in vitiligo patients undergoing long-term therapy for repigmentation. (4) The fourth period (1974-1988) is recognized as the period of photochemotherapy and the development of the science of photomedicine which established the therapeutic effectiveness of psoralens in combination with newly developed UV irradiation systems that emitted high-intensity UVA radiation in the treatment of severe psoriasis, mycosis fungoides, and over 16 other skin diseases. The effectiveness of PUVA (psoralen + UVA) was confirmed by well controlled clinical trials in thousands of patients, both in the USA and in European countries. Combination therapy with oral retinoids and PUVA contributed to greater effectiveness and long-term safety of psoralen photochemotherapy. (5) In the fifth period (1989 and beyond), psoralens are now emerging as photochemoprotective agents against non-melanoma skin cancers and as immunologic modifiers in the management of certain patients with disorders of circulating T-cells using new techniques of photopheresis. In the final analysis, perhaps the application of pharmacological and therapeutic concepts and principles of using psoralens in combination with UVA has contributed to the development of a new science of photomedicine in which the interaction between basic scientists, photobiologists, and physicians has produced both basic and new clinical knowledge for the care and control of human suffering.

Furocoumarins↗
PubMed1992

Expression of cytochrome P450 in yeast after different chemical treatments.

In Saccharomyces cerevisiae a number of chemical agents induce synthesis of cytochrome P450. A cytochrome P450 gene has been well characterized in this yeast: CYP51, which codes for a constitutive enzyme involved in the 14 alpha-demethylation of lanosterol, a key step in the biosynthesis of ergosterol. In this work, we have analysed the level of transcription of the CYP51 gene in correlation with cytochrome P450 enzymatic activity after treatment with several chemical agents known to interact with cytochrome P450. Using as a probe a DNA fragment whose identity to the CYP51 gene was established by sequence analysis and mapping on chromosome VIII, a unique RNA species was observed in all treatment samples. The increased level found for this transcript in cells treated with ethanol, 20% glucose, phenobarbital or 5-methoxypsoralen correlates with the levels of induction in cytochrome P450 enzymatic activity measured in cells grown under the same conditions, indicating that induction of cytochrome P450 by these treatments is regulated at the transcriptional level.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1979

Reversible binding of 5- and 8-methoxypsoralen to human serum proteins (albumin) and to epidermis in vitro.

Binding of the two photosensitizers, 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP), to serum proteins and to epidermis was measured. 8-MOP binds to serum proteins with an apparent dissociation constant (Kd) of 4 x 10(-5) M. Under conditions of oral therapy, serum concentrations of the photosensitizer 2 h after administration are usually in the range of 100-1000 ng per ml serum. In this concentration range, 75-80% of the drug was found to be reversibly bound to serum proteins. 5-MOP shows a higher binding affinity to serum proteins and 98-99% of the drug is protein bound. The binding of both psoralen derivatives appears to take place mainly to serum albumin. 5-MOP and 8-MOP bind to different and non-interacting sites on serum proteins and the binding of the one has no effect on the binding of the other methoxypsoralen. Both photosensitizers bind reversibly to human epidermis. 8-MOP concentration in the epidermis is increased by ten to twenty fold compared with the equilibrium buffer. 5-MOP shows a higher binding affinity, resulting in a higher tissue concentration of the photosensitizer. As in serum, the two drugs appear to be bound in the epidermis to independent and non-interacting sites. No binding competition was found between the two methoxypsoralens and hydrocortisone, fluocinonide and acetyl salicylic acid, either in serum or in epidermis, using up to 1000 fold higher concentrations as compared with those of 5-MOP and 8-MOP.

Binding, Competitive↗
PubMed1977

Psoralen photoallergy caused by plant contact.

A case of acquired photocontact allergy to furocumarins in plants is reported. Photopatch testing was performed with four psoralens [8-methoxypsoralen (8-MOP), 5-methoxypsoralens (5-MOP), trimethylpsoralen (TMP) and imperatorin (IMP)[. The use of serial dilutions of the test compounds made it possible to differentiate between photoallergic and phototoxic reactions. 8-MOP gave a positive eczematous test reaction down to a concentration of 0.0001%. The reactions to 5-MOP and imp also were positive, while that to TMP awas negative. Histopathological examination of a biopsy specimen from a positive test site showed changes consistent with photoallergic contact dermatitis. The multiple reactions could be explained on the basis of multiple sensitization but cross reactions cannot be ruled out.

Coumarins↗
PubMed1977

A study of oil of bergamot and its importance as a phototoxic agent. II. Factors which affect the phototoxic reaction induced by bergamot oil and psoralen derivatives.

Using a standardized open photopatch test technique, the phototoxic reactions produced by bergamot oil bergapten (5-methoxypsoralen) the active component of the oil, and xanthotoxin (8-methoxypsoralen) were studied. The reaction was affected by a range of factors such as the vehicle (PMF or ethanol), the concentration of ethanol in the vehicle, the skin site, the interval between application of the psoralen and irradiation, the hydration of the skin, and the degree of natural or sun-induced pigmentation. Repeated photopatch testing at the same skin site produced an increase in sensitivity. Eye colour, natural susceptibility to suntanning, age, and sex, had no effect on the phototoxic response to psoralens.

Adolescent↗
PubMed1978

Phototoxicity of Dictamnus alba.

Phytophotodermatitis from Dictamnus alba was observed in three patients. Thin-layer chromatography and spectrophotometry disclosed the occurrence of 5-methoxypsoralen and 8-methoxypsoralen in the plant extracts which was also demonstrated by their phototoxic activity in vitro.

Dermatitis, Contact↗
PubMed1992

Is postmenopausal osteoporosis related to pineal gland functions?

There is currently considerable interest in the pathogenesis of postmenopausal osteoporosis, which is the most common metabolic bone disease. Osteoporosis affects approximately 20 million persons in the United States, 90% of whom are postmenopausal women. Although there is evidence that estrogen deficiency is an important contributory factor, the pathogenesis of osteoporosis is multifactorial and presently poorly understood. There is evidence that pineal melatonin is an anti-aging hormone and that the menopause is associated with a substantial decline in melatonin secretion and an increased rate of pineal calcification. Animal data indicate that pineal melatonin is involved in the regulation of calcium and phosphorus metabolism by stimulating the activity of the parathyroid glands and by inhibiting calcitonin release and inhibiting prostaglandin synthesis. Hence, the pineal gland may function as a "fine tuner" of calcium homeostasis. In the following communication, we propose that the fall of melatonin plasma levels during the early stage of menopause may be an important contributory factor in the development of postmenopausal osteoporosis. Consequently, plasma melatonin levels taken in the early menopause could be used as an indicator or perhaps as a marker for susceptibility to postmenopausal osteoporosis. Moreover, light therapy, administration of oral melatonin (2.5 mg at night) or agents which induce a sustained release of melatonin secretion such as 5-methoxypsoralen, could be useful agents in the prophylaxis and treatment of postmenopausal osteoporosis. Finally, since application of external artificial magnetic fields has been shown to synchronize melatonin secretion in experimental animals and humans, we propose that treatment with artificial magnetic fields may be beneficial for postmenopausal osteoporosis.

Aged↗
PubMed1976

Determination of bergapten in fragrance preparations by thin layer chromatography and spectrophotofluorometry.

A method has been developed for the determination of bergapten (5-methoxypsoralen), a known phototoxin, in perfumes,colognes, and toilet waters. The bergapten and other lactonic compounds were first isolated from the sample by a series of extractions. The extract containing the bergapten was diluted to a known volume and a aliquot was spotted on a thin layer chromatographic (TLC) plate coated with silica gel G. After 2-dimensional development with hexane - carbon tetrachloride - tert - butylamine (180+12+9) and hexane-toluene-ethyl acetate-acetic acid (100+10+15+0.5), the TLC plate was dried and the emitted fluorescence of bergapten was measured, using a spectrophotofluorometer equipped with a TLC accessory and coupled to an automatic digital integrator. The amount of bergapten was determined by comparing its peak area to those of bergapten standards. The average recovery for levels of 0.001, 0.005, and 0.01% bergapten was 88%.

Chromatography, Thin Layer↗
PubMed1992

Transformation and degradation of leukotriene B4, 12-hydroxyeicosatetraenoic acid and 5-hydroxyeicosatetraenoic acid induced by ultraviolet radiation.

To reveal the underlying mechanisms in the therapeutic effectiveness of ultraviolet (UBV)- and psoralen plus UVA phototherapy, the photostability of leukotriene B4 (LTB4), 12-hydroxyeicosatetraenoic acid (12-HETE) and 5-HETE was investigated in the presence and absence of photosensitizers (8-methoxypsoralen and 5-methoxypsoralen). Arachidonic lipoxygenase products were irradiated with doses of narrow-band UVB (311 nm) ranging from 0.5-3.2 J/cm2, UVB and UVA (305-400 nm) ranging from 0.6-6.3 J/cm2 and UVA ranging from 5.0-60.0 J/cm2, respectively. High-performance liquid chromatography demonstrated a dose-dependent decrease of LTB4, 12-HETE, and 5-HETE. The photostability of 12-HETE was much higher than that of LTB4 and 5-HETE. Two products of transformation of LTB4 were identified as 5(S), 12(R)-dihydroxy-(6E, 8E, 10E, 14Z)-eicosatetraenoic acid [6-trans-LTB4] and 5(S), 12(R)-dihydroxy-(6E, 8Z, 10E, 14Z)-eicosatetraenoic acid [5(S), 12(R)-DiHETE]. There was no significant increase in photodegradation after addition of photosensitizing psoralens.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1979

Drug-protein interaction: plasma protein binding of furocoumarins.

The binding of six furocoumarins (angelicin, psoralen, 8-methoxypsoralen, 5-methoxypsoralen, 8-methylpsoralen, 4,5'8-trimethylpsoralen) to human serum and human serum albumin was studied by equilibrium dialysis using tritium labelled compounds. The results indicated that in serum all furocoumarins are bound mostly by albumin, the extent of binding being related to the structure of the furocoumarins; at any rate, high values of the bound drug, ranging from 84 to 97% were observed. The percentage of binding is strictly related to the water solubility of the compounds. A limited number of binding sites, n = 1-2.4, were detected in the albumin molecule, indicating a high specificity in the binding process. The association constants of the furocoumarins to albumin. Ka, ranged from 1.2 X 10(4) M-1 (8-methoxypsoralen) to 1.9 X 10(5) M-1 (4,5'8-trimethylpsoralen).

Biological Availability↗
PubMed1992

8-MOP vs 5-MOP.

Explore the source record for details and available documents.

5-Methoxypsoralen↗