Furocoumarins linear

New synthetic routes (Scheme 9) to photosensitive linear and angular furocoumarins, furoquinolones, furoquino-lines, and their analogs were the subject of a review <2004MOL50>. It focuses on the Fries rearrangement of acyloxyheteroarenes, like 70 — 71, the condensation of acylhydroxyheteroarenes with a-carbonyl compounds, like 72 73, and the transformations of dihydrofuroheteroarenes, like 74 75. 

A series of 3-alkyl- and 3-aryl-7/7-furo[3,2- ]-l-benzopyran-7-ones 78 (linear furocoumarins) was synthesized and evaluated for their photochemical and nonphotochemical crosslink formation with DNA as well as for their spectro-photometric and fluorescent properties, lipophilicity, and ability to photobleach A, A -dimethyl-/)-nitrosoaniline (RNO) after irradiation with UVA light <2002AP187>. The synthesis of the linear furocoumarins (Scheme 10) was a modification of a previously published method in which 7-hydroxy-2//-l-benzopyran-2-ones 76 were converted into / -ketoethers 77 by alkylation with haloketones under phase-transfer catalysis conditions. Base-catalyzed intramolecular condensation and subsequent acidification gave the corresponding 78. A molecular complex between each one of these fluorescent furocoumarins and DNA was observed, but only compounds with a 3-Me or 3-Ph group showed UVA irradiation-induced crosslink formation. 

Methoxypsoralen 188 is a naturally occurring linear furocoumarin found in citrus fruit rind and celery and parsley leaves. The use of oral or topical 5-methoxypsoralen plus UVA irradiation in the management of the skin disorders psoriasis and vitiligo was the subject of a medically oriented review <1998MI667>. 

Only one class of benzofuran derivative, natural or synthetic, shows this property—the furocoumarins-, these are important for plant biosynthesis, since they take part in the elaboration of chlorophyll.308 13 Among linear furocoumarins, psoralene (27a) is particularly active. Angelicin (28), another fundamental furocoumarin heterocycle with an angular structure, has only about 12% of the photosensitizing activity of 27a.74-75 On the other hand, it has antibiotic activity. Furochromones have no photosensitizing properties. 

Beier, R.C., Ivie, C.W., Oertli, E.H. and Holt, D.L. (1 983) HPLC analysis of linear furocoumarins (psoralens) in healthy celery (Apium graveoiens). Food and Chemical Toxicology 21, 1 63-1 65. 

Triplet states of xanthone depend upon the composition of the solvent the presence of water enhances the yield of 2 un state Dual phosphorescence from 2-(2 -hydroxyphenyl) benzoxazole is due to keto-enol tautomerism and the kinetics multi-exponential decay is due to differences of environment . Triplet state properties and triplet state-oxygen interactions of the biologically interesting linear and angular furocoumarins are useful in view of possible clinical application . 

In the final chapter, Gambari et aL summarize the structure and biological effects of furocoumarins. The authors mainly focus on linear and angular psoralens. Borrowing from their laboratory experiences, they describe the interesting biological effects of such compounds on cell cycle, apoptosis and differentiation as well as their use for the treatment of j6-thalassemia. 

The crosslinking process depends on the structure of the psoralen derivative. Linear furocoumarins form crosslinks efficiently with a yield up to 50% of the overall adducts formed. 

Furocoumarins. The angular furocoumarin oroselone (3) has been obtained by reaction of the iodophenol 2 with 1 in pyridine. The linear isomer can be obtained by the same method. ... 

The effects of furan substituents on the coumarin nucleus have been estimated in some angular (117) and linear (118) furocoumarins <84P697>. The effect of the furan ring on H methoxyl signals is similar to its effect on protons in the same position but an additional downfield shift is observed. 

The differences in the methoxyl chemical shifts thus provide a simple method for distinguishing between an angular and a linear furocoiunarin. Spectral H and C data for some 3,4-fused furocoumarins have also been reported recently <91MRC631). 

F. BACCICCHETTI, F. CARLASSARE. 1980. Comparative mutagenicity of linear and angular furocoumarins in Escherichia coli strains deficient in known repair functions. Chem.-Biol. Interact. 30 203-207. 

G. RODIGHIERO. 1982. Photoinactivation of enzymes by linear and angular furocoumarins. Photochem. Photobiol. 36 25-30. 

Because of low solvent consumption and short development time of OPLC, this technique is very useful for preliminary experiments for eluent-selection to HPLC. This is possible because of the linear correlation between OPLC relative retention values and logarithms of the capacity ratios obtained by HPLC (47,70). The correlation can be seen in case of furocoumarin-isomers in Fig. 18. 

Coumarins X Spectral Studies on Some Linear Furocoumarins. J. Pharm. Sci. 

Oertli EH, Beier RC, Ivie GW, Rowe LD 1984 Linear furocoumarins and other constituents from Thamnosma texana. Phytochemistry 23 439-441... 

The CAN-promoted oxidative cycloaddition processes of 4-hydroxycoumarins were extended to terminal alkynes, the reactions leading in this case to mixtures of angular and linear furocoumarins (Scheme 17) [87,88]. 

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