[Enzymatic synthesis of acylated quercetin 3-O-glycosides: a review]

Quercetin 3-O-glycosides (Q3Gs) are important members of quercetin glycosides with excellent pharmacological activities such as anti-oxidation, anti-inflammation, anti-cancer and anti-virus. Two representatives of Q3Gs, rutin and troxerutin, have been developed into clinical drugs, demonstrating Q3Gs have become one of the important sources of innovative drugs. However, the applications of Q3Gs in food and pharmaceutical industries are hampered by its poor bioavailability. Of the known means, selective acylation modification of Q3Gs through enzymatic catalysis to obtain Q3G esters is one of the effective ways to improve its bioavailability. Herein, the enzyme-mediated acylation of Q3Gs were reviewed in details, focusing on the four tool enzymes (acyltransferases, lipases, proteases and esterases) and the whole-cell mediated biotransformation, as well as the effect of acylations on the biological activities of Q3Gs. Furthermore, the highly efficient synthesis and diversification of acylated site for Q3G esters were also discussed. Taken together, this review provides a new perspective for further structural modifications of Q3Gs towards drug development.