Figure 2.

Quercetin serves as prodrug to generate bioactive derivatives. Quercetin undergoes in vivo modification and transforms into isorhamnetin and chloronaphthoquinone quercetin (CNC) that similarly exert anti-IBD effect. Intriguingly, gut microbiota is involved in the degrading process of quercetin, and the resulting products like 3,4-dihydroxy phenylacetic acid (3,4-DHPAA) and protocatechuic acid (PCA) are also potent therapeutic agents for IBD.