Increase in urocanic acid concentration in human epidermis following insolation

Epidermal Urocanic Acid and Suppression of Contact Hypersensitivity by Ultraviolet Radiation in <i>Monodelphis domestica</i>

“…The average m -urocanic acid content measured in normal epi dermis was 0.23 pg/cm2, accounting for approximately 14% of the total. UVB exposure did not markedly alter the total urocanic acid content after a single exposure; however, in the chron ically irradiated opossum, there was a 2-to 3-fold increase in total urocanic acid, due mainly to an increase in the transurocanic acid content, in agreement with the observation that UV irradiation may increase epidermal urocanic acid in man [13,14], although Norval et al [3] did not find such an increase. The /ram-urocanic acid levels (0.7-1.19 pg/cm2) observed in the UVB-exposed dorsal epidermis of these opossums, which were 26-33 months old, were in the lower range observed in normal epidermis and again may reflect a reduction in urocanic acid content in older opossums.…”

“…Urocanic acid was assayed cither by thin-layer chromatography (TLC) [13] on 40-pl samples including an internal standard o f 5 pg UV-irradiatcd urocanic acid (UV-urocanic acid) containing a mixture of Irons and cis isomers in PBS (prepared as below), or by high-pres sure liquid chromatography (HPLCs; instrumentation by ETP-Kortec, Rydalmere, N.S.W., Australia) utilising a Spherisorb ODS 25 pm co lumn, 250 mmx4.6 mm(Alltcch, Deerfield, III., USA), and an isocratic system with a mobile phase of 10 mM tetrabutylammonium phos phate (Sigma Chemical C'o., St. Louis, Mo., USA), and 10 mM sodium phosphate buffer, pH 6.8, in 15% acetonitrile (Waters/Millipore, Lane Cove, N.S.W., Australia). The elution was monitored by absorbance at 277 nm.…”

<i>Ci</i><i>s</i>-Urocanic-Acid-lnduced Suppression of Contact Hypersensitivity in <i>Monodelphis domestica</i> Is Prevented by Ultraviolet A Radiation/Photoreactivating Light

“…To produce cisurocanic acid, trails-urocanic acid dissolved in DMSO (4% w/v) was exposed as a thin film to UVB radiation for 60 min at 5 cm from the tube. This caused photo-isomerization to the photostationary state with approximately equal concentrations o f cis and irons isomers, confirmed here by thin-layer chromatography [12] to be 48% cis and 52% trans forms. The isomerized solution was diluted with PBS to 0.4% w/v and then mixed with the oil-in-water emulsion to give a final lotion containing 0.2% UV-irradiatcd urocanic acid and 5% DMSO.…”

Z/E Photoisomerization of Urocanic Acid*

“…Thus the UA level in Africans is higher than in Europeans (Zenisek et al. 1966;Kral et al, 1967) and increases upon exposure of the skin to sunlight (Baden and Pathak, 1967;Hais and Strych, 1969;Hais er a/., 1970;Hais and Strych. 1968).…”