Psoralen, 5-methoxy

The synthesis of the psoralen containing a methyl rather than methoxy group on the aromatic ring starts with construction... 

Psoralen, or derivatives of 9-methoxy-7H-furo[3,2-g]chromen-7-one tricyclic ring structures, are used as photoreactive groups in crosslinkers, biotinylation compounds, and nucleic acid probes. Psoralens have been used for many years as photochemotherapy agents for treatment of psoriasis and vitiligo (Smith and Barker, 2006). Psoralens react when exposed to UV light... 

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. 

The positive control material will be a lotion containing 1% 8-methoxy-psoralen. 

Umbelliferone (7-hydroxycoumarin) readily dimerizes in sunlight,236 and certain naturally occurring furocoumarins have been photochemically dimerized in the laboratory. These include psoralen (249), bergapten (5-methoxy psoralen), angelicin237 (250), and peucedanin.238 The corresponding dimer of xanthotoxin (8-methoxy-psoralen) could not be obtained under identical conditions, but on... 

Total bergapten (5-methoxy psoralene) level in the fragrance compound. 

Methoxy psoralen and xanthotoxin were reported by Ceska et al. (1987). Zobel et al. (1991) isolated psoralen, bergapten, scoparon, scopoletin and seslin from the leaves of aniseed and Zobel and Brown (1991) isolated psoralen and bergapten from the fruit. 

The substitution pattern of TfOH-mediated electrophilic aminomethylation of psoralens (furo-coumarins) by V-(hydroxymethyl)phthalimide has been elucidated <85JHC73>. Multiple phthal-imidoylated adducts were obtained when a B-ring hydroxy or methoxy activating group was present, and these resisted simple cleavage with NH2NH2. However, this two-step procedure to aminomethyl group introduction worked well when the psoralens contained only methyl substituents. 

SYNS AMMOIDIN 6-HYDROXY-7-METHOXY-5-BENZOFURANACRYLIC ACID A-LACTONE MELADI-NIN MELADININE MELOXINE METHOXA-DOME METHOXSALEN 8-METHOXY-(FUR, NO-3, 2 il3.7-COUMARIN) 9-METHOXY-7H-FURO(3,2-g)BENZOPYRAN-7-ONE 8-METHOXY-2, 3, 6,7-FURO-COUMARIN 8-METHOXY-4, 5, 6,7-FUROCOUiMARIN 8-METHOXYPSOR. LEN 9-METHOXYPSORALEN 8-MOP 8-MP NCI-C55903 OXSORALEN OXY-PSORALEN PRORALONE-MOP... 

Other Arsenic trioxide Phenacetin Chloramphenicol 5-Methoxy psoralen... 

Stephens RB, Cooper A. Hepatitis from 5-methoxy-psoralen occurring in a patient with previous flucloxaciUin hepatitis. Australas J Dermatol 1999 40(4) 217-19. 

XANTHOTOXIN Xanthotoxin (8-methoxy— psoralen, 8-MOP) is found in the fruits of Ammi majus, (L.), family Apiaceae, which grows in the Nile delta, but is now also cultivated in India and Argentina. Xanthotoxin has two dermatological uses psoriasis and vitiligo. The mode of action is in both cases an inhibition by ultraviolet light of DNA synthesis in the epidermis. 

Cat s claw bark extracts are not mutagenic in the Ames test, and in fact show a protective effect against mutation caused by the photosensitizer 8 -methoxy-psoralen (8-MOP) and UVA radiation. In addition to testing the extracts and fractions directly, the investigators also tested urine from two volunteers (a smoker and a nonsmoker) who had ingested 6.5 g/d of cat s claw for 15 d. The decoction was prepared by boiling the dried bark in water for 3 h until the initial volume was reduced by one third. 

Beaumont, P.C., Parsons, B.J., Phillips, G.O., and Allen, J.C. (1979) A laser flash photolysis study of the triplet states of 8-methoxy psoralen and 4,5, 8-trimethoxypsoralen with nucleic acids in solution, Biochim. Biophys. Acta, 562, 214-221. 

Methoxy SCS on the benzenoic carbon atoms in benzene, coumarin (A-l) and psoralen (F-l). 

The mechanism of psoralen phototoxicity has been studied extensively, and 5-methoxy psoralen, which is only 0.33% of Bergamot oil, is believed to be the principal phototoxic component of the oil [190]. 5-Methoxy psoralen absorbs ultraviolet light above 310 millimicrons and is elevated to an excited state (free radical). The psoralen radicals link to pyrimidine bases... 

Pirila V, Kilpio O, Olkkonen A, Pirila L, Siltanen E (1969) On the chemical nature of the eczematogens in oil of turpentine. Dermatologica 139 183-194 Plewig G, Hofmann C, Braun-Falco O (1978) Photoallergic dermatitis from 8-methoxy psoralen. Arch Dermatol Res 261 201-211... 

Results complementary to those shown in Table 1 were obtained when the time course of the appearance of newly synthesized repair patches in isolated 8-methoxy-psoralen-accessible chromatin domains (MOPS-DNA [8]) was studied. Table 2 shows an example of such an experiment. When newly synthesized repair patches were pulse labeled followed by a chase period as repair proceeded for up to 120 min, an increasing proportion of the radioactivity was found contained in MOPS-DNA. The rate of this increase was significantly different in MOPS-DNA compared to random DNA. Inhibition of chromatin associated ADP-ribosylation greatly modified this process... 

Fig. 1. Amount of 8-methoxy-psoralen (8-MOP) reacting with hepatocellular DNA at different times after UV irradiation (UV 254 nm, 45 J/m2) relative to an unirradiated control (= 100% value, dashed line). Experimental protocols were as described in [8]...

A number of chemicals have been tested as inhibitors of P450 2A6 in human hver micro-somes [463]. Of these, the most selective and potent inhibitors appear to be 8-methojgrpsoralen, tranylcypromine, and tryptamine, with values 1 pM [463-465]. The inhibition by the natural product 8-methoxypsoralen (present in many foods) is mechanism based [466]. 8-Methoxy-psoralen (methoxysalen) inhibits P450 2A6 in vivo [462] and has also been reported to decrease... 

Yoshikawa, K., Mori, N., Sakakibara, S.D., Mizuno, N., and Song, P.S., Photoconjugation of 8-methoxy-psoralen with proteins, Photochem. PhotobioL, 29, 1127,1979. 

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