(p-Salicylic Acid-d4) 4-Glucuronide Potassium Salt is deuterium labeled p-Salicylic Acid 4-Glucuronide (S088140), an anthocyanin-derived phenolic acid degraded to form 4' glucuronide of 4-hydroxybenzoic acid during simulated gastrointestinal digestion and in human liver microsome.