Coumarin distribution

FigureBl.5.16 Rotational relaxation of Coumarin 314 molecules at the air/water interface. The change in the SFI signal is recorded as a fimction of the time delay between the pump and probe pulses. Anisotropy in the orientational distribution is created by linearly polarized pump radiation in two orthogonal directions in the surface. (After [90].)...

It is notable that flavone and its derivatives are substituted predominantly in the phenyl group at positions 3 and 4 whereas reaction with Fenton s reagent gives mainly the S-hydroxy isomer." " Similarly, comparison of the distribution of products from coumarin obtained with Udenfriend s system with that given by Fenton s reagent re-... 

The distributions of phenolic isomers in hydroxylations in the animal body arc often similar to those obtained by Fenton s reagent. For example, the hydroxylation of coumarin by the rabbit gives the six hydroxycoumarins in amounts decreasing in the order 3- >7->6- >8- >4- /—5-, whereas Fenton s reagent gives mainly the 3-, 5-, and 7-derivatives with traces of the 6- and 8-derivatives. It may, however, be misleading to draw conclusions about the nature of... 

The fluorescent labels reported for investigation of intracellular uptake and distribution by CLSM comprise Nile red [13], Texas Red, and 6-coumarin [14]. Not only for fluorescence microscopy but also for transmission electron microscopy (TEM), the loading of markers proved to be useful. Osmium tetroxid as an electron dense marker and bovine serum albumin (BSA) as a model protein were entrapped in PLGA-nanoparticles to elucidate their uptake and intracellular distribution in human vascular smooth muscle cells [15]. 

Competition between drugs for plasma binding sites occurs and is responsible for some of the clinically most important changes in drug distribution. Phenylbutazone and oxyphenbutazone, for example, potentiate the action of warfarin by displacement (A2) and trichloroacetic acid, a major metabolite of chloral hydrate has a similar effect (S12) and is the cause of hemorrhagic complications during coumarin therapy (A2). 

Plouvier, V. Occurrence and distribution of syringoside, calycanthoside and similar coumarinic glycosides in several botanical groups. C R Acad Sci Ser II 1985 301(4) 117-120. 

Coumarin is widely distributed in the plant kingdom, but for commercial use has been mostly produced synthetically for many years. In addition to its use in the perfumery, cosmetic and related industries, coumarin has several other industrial applications. Formerly, large quantities of coumarin were used in the food industry, mostly associated with vanillin, for flavouring chocolates, baked goods, and in cream soda-flavoured beverages (Perone, 1972), but since 1954 its use as a direct food additive has been suspended in the United States (Boisde Meuly, 1993 Lake, 1999). 

The absorption, distribution, metabolism and excretion of coumarin in humans have been reviewed (Cohen, 1979 Fentem Fry, 1993 Pelkonen et al., 1997 Lake, 1999). 

The major pathway of coumarin metabolism in most human subjects is 7-hydroxyl-ation to form 7-hydroxy coumarin, which is excreted in the urine as both glucuronic acid and sulfate conjugates. Coumarin 7-hydroxylation activity exhibits a Gaussian distribution in Caucasian populations (Cholerton et al, 1992 Rautio et al, 1992), but some individuals are deficient in this activity. 

Following oral administration, coumarin is rapidly absorbed from the gastrointestinal tract and is distributed throughout the body (Cohen, 1979 Fentem Fry, 1993 Pelkonen et al., 1997 Lake, 1999). The compound is extensively metabolized in all species, with little excretion of unchanged coumarin. No significant tissue accumulation of coumarin and/or coumarin metabolites occurred after oral administration to rats and rabbits (Kaighen Williams, 1961) or intraperitoneal administration to rats (van Sumere Teuchy, 1971). 

Figure 2. Experimental and simulated fluorescence Stokes shift function 5(f) for coumarin 343 in water. The curve marked Aq is a classical molecular dynamics simulation result using a charge distribution difference, calculated by semiempirical quantum chemical methods, between ground and excited states. Also shown is a simulation for a neutral atomic solute with the Lennard-Jones parameters of the water oxygen atom (S°). (From Ref. 4.)...

Figure 12. Reconstructed fluorescence spectra of 7-(dimethylamino)-coumarin-4-acetate ion 0.1 and 1 ps after excitation. The solid line represents the best fit of the log normal distribution function to the data. From Ref. 33 with permission, from J. Phys. Chem. 93, 7040 (1988). Copyright 1988, American Chemical Society.

The quantity 17(f) is the time-dependent friction kernel. It characterizes the dissipation effects of the solvent motion along the reaction coordinate. The dynamic solute-solvent interactions in the case of charge transfer are analogous to the transient solvation effects manifested in C(t) (see Section II). We assume that the underlying dynamics of the dielectric function for BA and other molecules are similar to the dynamics for the coumarins. Thus we quantify t](t) from the experimental C(t) values using the relationship discussed elsewhere [139], The solution to the GLE is in the form of p(z, t), the probability distribution function. 

Coumarins are widely distributed in plants, and are commonly found in families such as the Umbelliferae/Apiaceae and Rutaceae, both in the free form and as glycosides. Coumarin itself is... 

Scopoletin is purported as the most widely distributed coumarin in higher plants, and scopoletin, umbelliferone, and esculetin are the ones most frequently linked to allelopathy. Given their phenylpropane origin, it is not surprising that these simple coumarins have many actions in common with the cinnamic acids. One variance is that coumarin and scopoletin have been reported to decrease mitosis,2 whereas at least at concentrations that correlate with growth inhibition, the phenolic acids do not appear to affect cell division. 

Extensive studies in reverse micelles revealed a similar water distribution [127-130], which is consistent with the distinct water model proposed by Finer [150]. For example, when the molar ratio (wo) of water to the surfactant is 6.8 in lecithin reverse micelles with a corresponding diameter of 37 A, three solvation time scales of 0.57 (13%), 14 (25%), and 320 ps (62%) were observed using coumarin 343 as the molecular probe. At w0 = 4.8 with a 30-A water core diameter, only a single solvation dynamic was observed at 217 ps, which indicates that all water molecules are well ordered inside the aqueous pool. The lecithin in these reverse micelles have charged headgroups, which have much stronger interactions with water than the neutral headgroups of monoolein in the... 

Further comparison between PCM and MPE was reported in the paper by Rinaldi et al. [26] using several multipole moment distribution types. Again, an excellent agreement was obtained. The authors reported examples for which the computational time with the MPE method represents only 30% of the time required for the equivalent computation with PCM (for details on code versions, see that paper). MPE and PCM results are also found comparable for IR properties [91] as well as for UV spectra [91,92] of substituted coumarins and chromones at the TD-DFT level. 

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