The aim of this study was to extract and purify anthocyanins from Lycium ruthenicum Murr. and evaluate their tyrosinase inhibitory activity. Response surface methodology was devoted to optimize enzyme-assisted extraction of anthocyanins from L. ruthenicum dried fruits. Extraction at 38 °C for 37 min using water-containing pectinase (52.04 mg/100 g dried fruit) rendered an anthocyanin extraction yield of 19.51 ± 0.21 mg/g. The purified anthocyanins were separated from the extract by macroporous resin XDA-6. Antioxidant tests in vitro suggested that the extract and the purified anthocyanins exhibited a potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging capacity, hydroxyl radical scavenging capacity, superoxide radical scavenging capacity, and total reducing power. Thirteen anthocyanins from L. ruthenicum dried fruits were analyzed by HPLC-MS. Moreover, the purified anthocyanins had inhibitory effect on tyrosinase monophenolase (IC50 = 1.483 ± 0.058 mg/mL), and the type of inhibition was competitive inhibition (Ki = 39.83 ± 1.4 mg/mL). The maximum inhibitory activity of the purified anthocyanins (3.00 mg/mL) on tyrosinase diphenolase was 42.16 ± 0.77%, and the type of inhibition was anticompetitive inhibition (Kis = 2.387 ± 0.10 mg/mL). PRACTICAL APPLICATION: The anthocyanins from L. ruthenicum dried fruits can be used as tyrosinase inhibitors in medicine, cosmetics, and food preservation industries.
Keywords: RSM; antioxidant activity; extract; natural pigment; tyrosinase inhibition.
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