Urocanic acid is a cinnamic acid-like compound formed by the decarboxylation of histidine by the enzyme, histidase. Urocanic acid is produced by a number of Bacillus, Streptomyces and other bacteria, but is also broadly found in microbial fermentations. Urocanic acid has weak activity in a diverse range of bioassays and is a useful standard for analytical and bioassay dereplication of crude microbial extracts.