5- Methoxypsoralen,

8-Methoxypsoralen and UVA (PUVA) caused photoallergic dermatitis in a psoriasis patient after 16 uneventful courses of PUVA treatment. The diagnosis of photoallergy was confirmed by reexposure to UVA and both oral and topical methoxypsoralen. UVB and UVC ( 290 nm) did not elicit the reaction and the photoallergy did not include trimethylpsoralen (Plewig et al. 1978). 

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The alkaloid reserpiae [50-55-5] which is isolated from the roots of Kauwoljia serpentina T., contains a gaUate trimethyl ether moiety. Reserpiae is used as an antihypertensive and a tranquilizer. A vinylogue of reserpiae, rescinnamine [24815-24-5] is also an antihypersensitive (75). Methoxsalen [298-81-7] (8-methoxypsoralen 7JT-9-methoxy-furo [3,2- ] [l]benzopyran-7-one) (21), a furocoumatia that occurs ia plants, eg, l eguminosae and Umbelliferae is used ia the treatment of vitiligo, as a suntanning promoter, and as a sunburn protectant. It is also available by synthesis (76). 

Methoxypsoralen (Methoxsalen) [298-81-7] plus ultraviolet A radiation (Vol. 24, Suppl. 7 1987)... 

Therapeutic Function Dermal pigmentation enhancer Chemical Name 9-methoxy-7H-furo[3,2-g] [1 ] benzopyran-7-one Common Name 8-Methoxypsoralen ammoidin xanthotoxin Structural Formula ... 

Bi Methylation of 8-Hydroxypsoralen 115 mg of 8-hydroxypsoralen was dissolved in 10 ml absolute methanol, an excess of diazomethane dissolved in ether was added and the mixture allowed to stand at room temperature with occasional stirring for 3 hours. The next day the reaction mixture was reduced in volume to 3 ml by evaporation on the steam bath and the concentrate was held in a refrigerator overnight. The next day, fine needles (80 mg) of 8-methoxypsoralen were filtered from the solution. The compound had a MP of 145° to 146°C and was obtained in a yield of 65% of theory. 

Gia O et al. (1997) Some new methyl-8-methoxypsoralens synthesis, photobinding to DNA, photobiological properties and molecular modelling. Farmaco 52(6-7) 389-397... 

The forms of phototherapy in common use include (i) the phototherapy of jaundice (neonatal hyperbilirubinemia) in the newborn, and especially in the prematurely born 5 (ii) the treatment of psoriasis using light in the UV-A range (320 100 nm) and an administered photosensitizer, such as 8-methoxypsoralen 6 (iii) the treatment of the wet form of age-related macular degeneration with a photosensitizer such as a benzoporphyrin derivative (VISUDYNE ), and a laser light source 7 and (iv) the treatment of certain cancers with a photosensitizer such as a porphyrin derivative, and red light.8... 

In the oxygen-independent Type III reactions the excited/sensi-tized psoralen donates its excitation energy directly to, or reacts with, the target compound. This occurs if the substrate and the target compound (e.g., DNA) are already in close proximity or intercalated. The reactions will proceed very rapidly via the excited singlet state, and are, typically, cyclization reactions or electron-transfer between the sensitizer and the target. In addition, the psoralen can be ionized, either directly or via the excited state, and react with the target compound in the form of a radical cation. Furocoumarins are also employed in treatment of cutaneous T-cell lymphoma and some infections connected with AIDS, by so-called photopheresis processes [71, 74-76]. In this case, peripheral blood is exposed to, e.g., photoactivated (sensitized) 8-methoxypsoralen (8-MOP) in an extracorporeal flow system. This... 

Several modifications of the basic parent compounds have also been suggested, primarily by methyl or methoxy substituents (cf. Fig. 4.13). Two of the most active and widely used psoralens are 8-methoxypsoralen (8-MOP) and trimethylpsoralen (TMP). With the exception of 3-CP, the substituents reduce the ionization energies by 5-10 kcal mol-1 compared with the unsubstituted parent compounds (Tab. 4.4). In bulk water the effects are somewhat smaller. The largest effects are observed for TMP and AMT. The IP of flavin are very similar to those of the unsubstituted psoralen. 

Viehauer S. et al., 1995. Evaluation and routine application of the novel restricted-access precolumn packing material Alkyl-Diol Silica Coupled-column high-performance liquid chromatographic analysis of the photoreactive drug 8-methoxypsoralen in plasma. J Chromatogr B 666 315. 

The ancient Egyptians used the plantAmmi majus, which contains methoxsalen (sometimes called 8-methoxypsoralen, based on a now obsolete method of naming fused heterocycles indexed in Chemical Abstracts under furo[3,2-g][l]benzopyran-7-one, 9-methoxy-, 249), in combination with sunbathing to... 

Latt, S.A. and Loveday, K.S. (1978). Characterization of sister chromatid exchange induction by 8-methoxypsoralen plus UV light. Cytogenet. Cell Genet. 21 184-200. 

Quinolone (antibacterial) Oral Xanthotoxin (8-methoxypsoralen) Oral, ip, im... 

Treatment There can be up to four sites per animal, each measuring 1.5 x 1.5 cm (2.25 cm2). In general, one side should be for a vehicle control, and another for a positive control [8-methoxypsoralen (8-MOP),... 

Several compounds are inhibitors of CYP2A6-mediated nicotme metabolism m vitro, mcludmg methoxsalen (8-methoxypsoralen), tranylcypromine, tryptamine and coumarin (Le Gal et al. 2003 MacDougall et al. 2003 Nakajima et al. 1996 Zhang et al. 2001). Raloxifene is a potent inhibitor of aldehyde oxidase and it has been shown to inhibit the formation of cotinine from nicotme-A -iminium ion in human liver cytosol (Obach 2004). 

Some secondary plant compounds have proven carcinogenic in laboratory rodents. These include D-limonene in orange juice 5-8-methoxypsoralen in parsley and parsnips and caffeic acid in coffee, but also in smaller amounts in apples, apricots, broccoli, Brussels sprouts, cabbage, cherries, kale, peaches, pears, and plums (Ames and Gold, 1990 Ames etal., 1990). How dangerous these compounds can be to human health, is still being debated. 

The levels of antifeedants can be raised safely only in plants such as forest trees or fiber crops, not in food plants for humans or livestock. Such problems have arisen inadvertently. For instance, a new insect-resistant potato cultivarhad to be withdrawn from the market because it contained high levels of the carcinogens solanine and chaconine (Renwick etal, 1984). In another example, an insect-resistant celery had 10 times the usual concentration of the carcinogen 8-methoxypsoralen (and related psoralens), which caused dermatitis in produce handlers (Seligman etal, 1987). 

Our initial studies (25,26) determined the comparative fate of a radiocarbon-labeled preparation of the commonly occurring linear furanocoumarln, xanthotoxln (8-methoxypsoralen) in black swallowtail caterpillars and in fall armyworm (Spodoptera frugiperda J. E. Smith) larvae. Black swallowtail caterpillars are known not to be adversely affected by linear furanocoumarlns (22), while Spodoptera spp. avoid such plants as food sources... 

Figure 2. Major metabolites of xanthotoxin (8-methoxypsoralen) in last-stage larvae of the black swallowtail butterfly (Papilio polyxenes) and the fall armyworm (Spodoptera frugiperda).

I. 8-Methoxypsoralen, chlorpromazine and sunscreen compounds in bacterial and yeast assays. Mutation Research,... 

Orally administered psoralens are rapidly absorbed (maximum photosensitivity for the most common preparation, 8-methoxypsoralen [Oxsoralen Ultra], is 1-1.5 hours). Although the elimination half-life is 2.2 hours, the skin remains photosensitive for 8 to 12 hours. Most excretion is renal, and the drug does not accumulate. It can be absorbed if applied topically, and after application to the entire body, therapeutic plasma levels can be detected. 

A set of N1-unsubstituted furo[2,3- ]quinolin-2(l/f)-ones including 81a-c, 83, and 84a and 84b were prepared by the route shown in Scheme 11, and their photobiological activities were compared with those of the photoche-motherapeutic drugs 4,6,8,9-tetramethylfuro[2,3-, ]quinolin-2(l//)-one (HFQ) and 8-methoxypsoralen 8-MOP <2002BMC2835>. The anti-proliferative activity of these furoquinolinones was tested upon UVA irradiation in mammalian cells, and almost all were found more active than 8-MOP, and free of any mutagenic activity and skin phototoxicity. 

Compound (XIV) was the most activity against Pseudomonas fluorescens, an organism that Is not affected by the potent photosensitizer 8-methoxypsoralen (27). The three compounds were active against Saccharomyces cerevlslae and Candida albicans. 

Methoxypsoralen see also 8-Methoxypsoralen plus ultraviolet radiation)... 

Methoxypsoralen plus ultraviolet radiation Methyl acrylate... 

Furans can also undergo covalent binding to macromolecules [20]. Furans, such as 8-methoxypsoralen, are epoxidized by Cyt P450 to yield a highly electrophilic species, which is so reactive that it covalently modifies an amino acid residue of CYP itself and thus inactivates the enzyme irreversibly (hence it is also in the class of suicide inhibitors) [21]. 

Methoxypsoralen [298-81-7] M 216.2, m 148 . Crystd from EtOH/ether or benzene/pet ether. 

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