Detail of "3465-72-3"

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Cis-Urocanic acid down-regulates the induction of adenosine 3',5'-cyclic monophosphate by either trans-urocanic acid or histamine in human dermal fibroblasts in vitro

Cis-Urocanic acid down-regulates the induction of adenosine 3',5'-cyclic monophosphate by either trans-urocanic acid or histamine in human dermal fibroblasts in vitro. Palaszynski, Edmund W.; Noonan, Frances P.; De Fabo, Edward C. (Sch. Med., George Washington Univ., Washington, DC 20037, USA). Photochem. Photobiol., 55(2), 165-71 (English) 1992. CODEN: PHCBAP. ISSN: 0031-8655. DOCUMENT TYPE: Journal CA Section: 8 (Radiation Biochemistry) Section cross-reference(s): 14 It has been demonstrated that UVB radiation (290-320 nm) suppresses mammalian cell-mediated immunity by effecting the trans-to-cis isomerization of urocanic acid (UCA) in the stratum corneum, the uppermost layer of the skin. Trans-urocanic acid has been shown to be the photoreceptor for UVB-induced immune suppression and the cis-isomer has been demonstrated to be immunosuppressive. Little is known, however, about how the isomerization of UCA may affect the proximal or distal cells of the skin or the immune system. It is reported here that trans-UCA is biol. active in vitro in human dermal fibroblasts, inducing adenyl cyclase as measured by cAMP (adenosine 3',5'-cyclic monophosphate) formation in dose-dependent manner similar to the action of histamine.Several substances with their cas registry numbers 3465-72-3 and 51-45-6 may be metioned in this study. Trans-UCA and histamine stimulate 50% of max. activity at concns. of 3.3 mM and 13.8 mM, resp. Cis-UCA does not increase cAMP in these human fibroblasts but actively down regulates the increase of cAMP induced by either histamine or trans-UCA. Cis-UCA down regulated the histamine response by 75% and the trans-UCA response by 60% at a concn. range of 1 mM to 1 nM. The trans-UCA induction of cAMP can also be downregulated with an H2 histamine receptor antagonist cimetidine. These results the hypothesis that a cellular target for cis-UCA is the dermal fibroblast and the effects reported here may represent the initial biochem. and cellular event for UVB-induced immune suppression, i.e., the immediate step following the isomerization of trans to cis-UCA is the down regulation to cAMP by cis-UCA. Regulation of such an important second messenger such as cAMP could then allow cascading signals to occur, leading to immune suppression. .

A Spectroscopic Study of the Epidermal Ultraviolet Chromophore trans-Urocanic Acid

A Spectroscopic Study of the Epidermal Ultraviolet Chromophore trans-Urocanic Acid. Hanson, Kerry M.; Li, Bulang; Simon, John D. (Department of Chemistry and Biochemistry, University of California, La Jolla, CA 93093-0341, USA). Journal of the American Chemical Society, 119(11), 2715-2721 (English) 1997 American Chemical Society. CODEN: JACSAT. ISSN: 0002-7863. DOCUMENT TYPE: Journal CA Section: 8 (Radiation Biochemistry) Photoacoustic calorimetry and steady-state spectroscopic techniques are used to investigate the wavelength-dependent photoreactivity of trans-urocanic acid under representative physiol. conditions in vitro. The maxima of the emission and excitation spectra and the value of DrH, the reaction enthalpy as detd. from photoacoustic measurements, varied as a function of the excitation wavelength. From these data, we are able to confirm that the photolysis of trans-UA at 266 nm (the peak of the absorption spectrum where isomerization is inefficient) generates a long-lived electronically excited triplet state that lies approx. 230 kJ/mol above the ground state. Isomerization does not occur from this triplet electronic state, but bimol. energy transfer to O2, generating 1Dg (O2), does occur. Excitation of trans-UA at 308 nm (in the tail of the absorption spectrum) does not lead to triplet state formation. Instead, excitation at this wavelength leads to isomerization. Using measured isomerization quantum yields at this photolysis wavelength (F = 0. 3465-72-3 which is the cas registry number of some chemical is mentioned.49), we are able to det. that the ground state of cis-UA lies about 40 kj/mol above that of the trans isomer. Photoacoustic data recorded following the photolysis of cis-UA at 266 and 308 nm show the same trends, supporting the conclusion that the wavelength-dependent chem. is not due to the presence of multiple ground-state rotamers. The data indicate that the broad structureless absorption spectrum of trans-UA is comprised of overlapping transitions due to at least two distinct electronic states. The different reactivities of these two states result in the wavelength-dependent isomerization yields that have been measured for trans-UA in the UV-B (280-320 nm) range. .