Tyrosinase inhibitory mechanism and the anti-browning properties of piceid and its ester

Different mechanisms for inhibiting tyrosinase can be exploited to avoid quality losses caused by the enzymatic browning of fruits and vegetables. Piceid (PI) and piceid 6 ''-O- azelaic acid ester (PIA) are oxidized by tyrosinase; however, their oxidation products may have inhibitory effects on tyrosinase. This notion is because L-DOPA oxidation was inhibited after the pre-incubation of PI/PIA with tyrosinase, however, L-DOPA oxidation was not affected if this pre-incubation was not performed. Circular dichroism analysis indicated a conformational change in the secondary structure of tyrosinase after pre-incubation. Further, molecular docking and enzyme reaction kinetics assays were employed to reveal the mechanism underlying the effects of PI/PIA on tyrosinase in the absence of pre-incubation with tyrosinase. PI/PIA had anti-browning effects in the potato models. The increased rate of A420 in PI/PIA groups at 24 h were 281% and 279%, which were approximately 2.4- and 2.5-fold lower than that of control (668%).