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Open AccessArticle

Simultaneous Determination of Six Isoflavones from Puerariae Lobatae Radix by CPE-HPLC and Effect of Puerarin on Tyrosinase Activity

by Limin Qu 1, Ke Song 1, Qi Zhang 1, Jie Guo 1,* and Juan Huang 2,*
1
Key Laboratory of Hunan Forest Product and Chemical Industry Engineering, Jishou University, Zhangjiajie 427000, China
2
Department of Traditional Chinese Medicine, Inner Mongolia Medical University, Inner Mongolia, Huhhot 010010, China
*
Authors to whom correspondence should be addressed.
Molecules 2020, 25(2), 344; https://doi.org/10.3390/molecules25020344
Received: 27 December 2019 / Accepted: 13 January 2020 / Published: 15 January 2020
Tyrosinase inhibitors with excellent inhibitory activities and lower side effects have promising applications in the fields of medicine, agriculture, food sciences and cosmetics. In this study, a method for simultaneous separation and determination of six target compounds (puerarin, daidzin, genistein, daidzein, genistin, and formononetin) in Puerariae Lobatae Radix was established by cloud point extraction (CPE) and concentration combined with high performance liquid chromatography (HPLC). To achieve high extraction yields, an ultrasound-assisted extraction method was developed based on a salt-modified Triton X-100 system. The optimal extraction conditions are: surfactant Triton X-100 concentration 0.07 g/mL, liquid-solid ratio 80:1 (mL/g), NaCl addition amount 0.6 g, equilibrium time 40 min, equilibrium temperature 70 °C. Under the optimal conditions, the total maximum extraction yield of the six target isoflavones reached 8.92 mg/g. Using l-tyrosine and l-dopa as substrates, the effects of puerarin on the monophenolase and diphenolase activity of tyrosinase activity were investigated by the enzyme kinetics method. The results showed that puerarin inhibited monophenolase activity with an IC50 of 0.537 mg/mL and activated diphenolase activity. The inhibition type of puerarin on monophenolase and the activation type of puerarin on diphenolase were analyzed by Lineweaver-Burk plots which show that puerarin showed mixed inhibition on monophenolase and mixed activation on diphenolase. Therefore, puerarin can be used as both a tyrosinase inhibitor and a tyrosinase activator. View Full-Text
Keywords: Puerariae Lobatae Radix; cloud point extractions; tyrosinase inhibitors; tyrosinase activator; kinetic analysis Puerariae Lobatae Radix; cloud point extractions; tyrosinase inhibitors; tyrosinase activator; kinetic analysis
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Qu, L.; Song, K.; Zhang, Q.; Guo, J.; Huang, J. Simultaneous Determination of Six Isoflavones from Puerariae Lobatae Radix by CPE-HPLC and Effect of Puerarin on Tyrosinase Activity. Molecules 2020, 25, 344.

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