Xanthurenic acid is an endogenous substrate for the silkworm cytosolic sulfotransferase, bmST1

► Xanthurenic acid is a specific and good substrate for silkworm sulfotransferase. ► The major expression of this SULT is in Malpighian tubule at 4th molting stage. ► High dose of xanthurenic acid induces toxicity to cuticle formation.