Notes: 3-Hydroxyhippuric acid is a polyphenol metabolite.{69477} It is an active metabolite of various polyphenols, including the flavonoid (+)-catechin (Item No. 70940), and is formed by glycine conjugation via gut microbiota. 3-Hydroxyhippuric acid inhibits kynureninase (Ki = 60 µM).{69478}