Furocoumarines

Synthesis and antiproliferative activity of furocoumarin isosters (pyrrolo-, thieno-, oxazolo-, and triazolocoumarins, 8- and 4- azapsoralenes) 95F479. 

A detailed description of the versatility of multiple development techniques in one dimension has been given by Szabady and Nyiredy (18). These authors compared conventional TLC with unidimensional (UMD) and incremental (IMD) multiple development methods by chromatographing furocoumarin isomers on silica using chloroform as the monocomponent mobile phase. The development distance for all three methods was 70 mm, while the number of development steps for both of the "D techniques was five. Comparison of the effects of UMD and IMD on zone-centre separation and on chromatographic zone width reveals that UMD increases zone-centre separation more effectively in the lower Rf range, while IMD results in narrower spots (Figure 8.8). 

Gambari R, Lampronti I, Bianchi N, Zuccato C, Viola G, Vedaldi D, Dall Acqua F (2007) Structure and Biological Activity of Furocoumarins. 9 265-276 Garg R, Bhhatarai B (2006) QSAR and Molecular Modeling Studies of HIV Protease Inhibitors. 3 181-272... 

Zobel, A.M. and Brown, S.A. (1988). Determinations of furocoumarins on the leaf surface of Ruta graveolens with an improved extraction technique. Journal of Natural Products 51 941-946. 

Wawrzynowicz T and Waksmundzka Hajnos M. 1990. The application of systems with different selectivity for the separation and isolation of some furocoumarins. J Liq Chromatogr 13(20) 3925— 3940. 

The sulfide derivative of furocoumarin based natural products can be synthesized by treatment of a thiadiazole 107 with KO-f-Bu and an organohalide in an one-pot operation. This process presumably involves the generation of a phenolate 108 and is followed by an intramolecular proton shift and a rearrangement to give an alkynethiolate 109, which undergoes a sequence of intramolecular proton shift, cyclization and alkylation to lead to the furocoumarin product. The thiadiazole, in turn, can be prepared by reaction of the corresponding acetyl precursor with carbethoxyhydrazine, followed by treatment with thionyl chloride . 

Psoralens, or furocoumarins, are a class of heterocyclic aromatic compounds used in photochemotherapy treatment of a variety of skin diseases such as psoriasis, vitiligo, mycosis fungoides, polymorphous light eruption, and more [68-71]. The compounds are present in numerous plants throughout the world. In photoche-... 

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... 

Here we will present some basic theoretical photochemistry of a set of furocoumarin compounds, starting from the basic building blocks furan and pyrone, as shown in Fig. 4.13. Comparison is also made with the photochemistry of flavin, the active component of vitamin B2. 

Fig. 4.13 Furocoumarins and related compounds investigated in this work.

Tab. 4.4 Vertical and adiabatic ionization energies (kcal mol-1) for a set of furocoumarins and related compounds, in vacuum and in bulk water solvent. 1 eV=23.06 kcal mol-1.

Tab. 4.6 Singlet excitation energies of substituted furocoumarins and related compounds. Experimental data in aqueous solution given in parentheses [99]. Experimental absorption coefficients are denoted w=weak (<8000), i = intermediate (8000-15 000), and s = strong (>15000). 

Interestingly, the flavin molecule is significantly easier to excite than the other heterocycles investigated. The first singlet excitation energy is only 3.0 eV (413 nm), and the probability of transition is intermediate. The second band with possible singlet excitation lies at 3.8 eV. Hence, if one intends to construct systems that are more readily excited, substituted flavins seem to be a more appropriate route than the furocoumarins, whereas the latter are easier to ionize. 

Alarmingly, the ozone hole has turned mammalian food into food for thought. The ozone hole permits an increase of ultraviolet radiation in the range 290 to 320 nm, the same wavelengths that induce furocoumarin (also known as... 

A well-investigated group of potent phototoxic compounds are the/wra-nocoumarins (psoralens) (Fig. 11.16), compounds that are also used as fish poisons. Furocoumarins absorb ultraviolet at around 330 nm and are converted to triplet stages these, in turn, produce singlet oxygen that damages amino acids (Fig. 11.17). 

Hypericin (a quinone) or furocoumarin production and extrusion in plants... 

Ashkenazy, D., Kashman, Y., Nyska, A., and Friedman, J. (1985). Furocoumarins in shoots of Pituranthos triradiatus (Umbelliferae) as protectants against grazing by hyrax [Pro-cavia capensis syriaca). Journal ofChemical Ecology 11,231-239. 

Some naturally occurring and synthetic food components, furocoumarins and ultraviolet radiation, pp 161-206. Lyon, International Agency for Research on Cancer, 1986 6. Tanaka T, Oishi S, Takahashi O Three generation toxicity study of butylated hydroxy-toluene administered to mice. Toxicol Lett 66(3) 295-304, 1993... 

Natarajan, A.T., Verdegaal-lmmerzeel, E.A.M., Ashwood-Smifh, M.J. and Poulton, G.A. (1981) Chromosomal damage induced hy furocoumarins and UVA in hamster and human cells including cells from patients with ataxia telangiectasia and xeroderma pigmentosum. Mutation Research, 84, 113-124. 

Furan-3-one, tetrahydro, 2-methyl LP Furocoumarin, angular, 4-hydroxy-2 -methoxy LP ... 

DC082 Ceska, O., S. K. Chaudhary, P. ]. Warrington, and M. ]. Ashwood-Smith. Phytoactive furocoumarins in fruit of some Umbelifers. Phytochemistry 1987 26(1) 165-169. 

Warrington, and M. ]. Ashwood-Smith. DC133 Furocoumarins in the cultivated carrot,... 

Avoid furocoumarin-containingfoods (e.g., limes, figs, parsley, parsnips, mustard,... 

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