Photodimerization of urocanic acid in vitro and in vivo

Abstract

• 1.

  1. Irradition of urocanic acid or urocanate frozen in aqueous solution with 280–320-mμ light produced a photodimer which was isolated by gradient elution from an anion-exchange resin.

• 2.

  2. A similar substance was shown to be present in dilute acid extracts of guinea-pig epidermis after irradiation with 280–320-mμ light.

• 3.

  3. The photodimer formed with 280–320-mμ light when irradiated in solution with 254-mμ light was converted to urocanic acid and smaller amounts of several other products.

• 4.

  4. Irradiation of crystalline urocanic acid or its solutions does not produce an accumulation of the photodimer.