Objective:The ultrasonic extraction process of total flavonoids from Leucas zeylanica(L.)R.Br.was optimized and its whitening activity was investigated.Methods:The extraction process of to-tal flavonoids from L.zeylanica was optimized by Box-Behnken response surface method with the yield of total flavonoids as the index.The antioxidant activity of the total flavonoid extract was evaluat-ed by the scavenging capacity of DPPH,ABTS,·OH and the total reducing capacity.Evaluation of its whitening activity by investigating its inhibitory effect on tyrosinase activity,the inhibitory mechanism and inhibition type of total flavonoids of L.zeylanica were analyzed.Results:The optimal conditions for the total flavonoids of L.zeylantca were ethanol concentration of 65%,liquid-solid ratio of 18 mL/g,extraction temperature of 75℃,ultrasonic time of 45 min,and total flavonoids yield of 107.36 mg/g.The total flavonoids of L.zeylanica had a good scavenging effect on DPPH,ABTS and·OH free radi-cals,and the total reducing capacity was good.At the same time,the inhibition of monophenolase and diphenolase was obvious.The inhibition process was an irreversible mixture of competitive and non competitive inhibition types.Conclusion:Extraction process of total flavonoids from L.zeylanica was stable and reliable,and the total flavonoids of L.zeylanica had good antioxidant capacity and tyrosi-nase inhibitory activity,which provided a theoretical basis for the development and utilization of natu-ral antioxidants and whitening products.
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