3-Hydroxykynurenine
3-Hydroxykynurenine is a metabolite of tryptophan, which filters UV light in the human lens. It is one of two pigments identified as responsible for the goldenrod crab spider's '' yellow coloration.
image:Kynurenine pathway wordless.svg|thumb|280px|left|The Kynurenine pathway, which connects quinolinic acid to tryptophan. The pathway is named for the first intermediate, kynurenine, which is a precursor to kynurenic acid and 3-hydroxykynurenine.