cis-Urocanic acid is a 5-HT2A receptor agonist. cis-Urocanic acid binds to 5-HT receptor with relatively high affinity (Kd=4.6 nM). cis-Urocanic acid is an immune modulator that induces immunosuppression by binding to the 5-HT2A receptor[1].
Treatment with 100 μg/mL cis-Urocanic acid (cis-UCA) completely suppresses IL-6 and IL-8 secretion, decreases caspase-3 activity, and improves cell viability against UV-B irradiation. No significant effects on IL-6 or IL-8 secretion, caspase-3 activity, or viability of the non-irradiated cells are observed with 100 μg/mL cis-Urocanic acid in both cell types. The 5000 μg/mL concentration is toxic[1]. Cell Viability Assay[1] Cell Line: Human corneal epithelial cells (HCE-2) and human conjunctival epithelial cells (HCECs)
[1]. Walterscheid JP, et al. Cis-urocanic acid, a sunlight-induced immunosuppressive factor, activates immune suppression via the 5-HT2A receptor. Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17420-5. [2]. Viiri J, et al. Cis-urocanic acid suppresses UV-B-induced interleukin-6 and -8 secretion and cytotoxicity in human corneal and conjunctival epithelial cells in vitro. Mol Vis. 2009 Sep 8;15:1799-805.