| The demands for licorice in the world are growing with the further research on pharmacological effects of licorice. Thus, it is necessary to exploit rationally resources of licorice due to its sharp decline. The phytochemical components of licorice are so complex. However, only the terpenoids such as glycyrrhizic acid were investigated in-depth previously. It is not reasonable to assess the quality of licorice in general only by referring to content of glycyrrhizic acid. In recent years, the in-depth study of pharmacological effects of licorice indicated that flavonoids from licorice were effective active ingredients, possessing a variety of pharmacological effects, and have become research hotspots in herbs. In this study, the isolation, identification and pharmacodynamics of total flavonoids of licorice (TFL), licochalcone A and glabridin were investigated. Meanwhile, the HPLC fingerprint of flavonoids of Glycyrrhiza inflata was established for the effective and reasonable exploitation and evaluation of flavonoids of licorice.The method for the determination of TFL was established. The concents of TFL in Glycyrrhiza inflata Bat., Glycyrrhiza glabra L. and Glycyrrhiza uralensis Fisch were 4.476 %, 2.478 % and 1.372 %, respectively..The extraction techniques for TFL were investigated by contrast. The results showed that ultrasonic-assisted extraction was better than other extractions. The extracting parameters of TFL through ultrasonic-assisted extraction were determined using Response Surface Methododlogy. The extraction of TFL was 80.56 % under the obtained better process conditions. The optimum purification conditions of TFL with macroporous resin AB-8 was obtained. With macroporous resin to adsorb and purify, the yield of TFL was higher than 80 % and the content was higher than 60 %.Based on numerator docking, a new method was established for evaluating the anti-acetylcholinesterase activity of flavonoids from licorice. The results showed that the docking and binding energy of glabridin were lower than those of others components, and were considerable with those of acetylcholinesterase inhibitors (galanthamine, huperzine and metrifonate). The formed compounds are steady. Based on molecular docking analysis, 5'-fluglabridin was obtained with equivalent energy with glabridin when replacing H atom or hydroxy in the A-ring or B-ring of glabridin with F atom.According to molecular docking evaluation, glabridin was isolated from Glycyrrhiza glabra and its structure was identified. The method for the determination of glabridin was established. The content of glabridin in Glycyrrhiza glabra L. was 0.199 %, but it could not be detected in Glycyrrhiza inflata Bat. or Glycyrrhiza uralensis Fisch.The effects of glabridin on scopolamine-induced learning and memory impairment were studied in mice. In Y-electronic maze test and step-down test, glabridin (2, 4 mg kg-1, p.o.) could significantly enhance the learning and memory ability of mice compared with the model group in mice. The effect exhibited by glabridin at higher dose (4 mg/kg) was considerable with that of piracetam (400 mg kg-1, i.p.), a clinically used nootropic agent. Furthermore, both glabridin (2, 4 mg kg-1) and metrifonate (50 mg kg-1, i.p.), used as a standard drug, can reduced the brain cholinesterase activity to 14.4 %, 19.0 % and 21.3 %, respectively, compared with control group.Licochalcone A was isolated from the roots of Glycyrrhiza inflata and identified with LC-MS and NMR. The method for determination of licochalcone A was established. The contents of licochalcone A in Glycyrrhiza inflata Bat. and Glycyrrhiza glabra L. were 0.411 % and 0.054 %, respectively, but it could not be detected in Glycyrrhiza uralensis Fisch.Furthermore, the anti-inflammatory activity of licochalcone A was evaluated in xylene-induced mice ear edema and carrageenan-induced paw edema tests. At the concentrations of 5 and 10 mg/ear, licochalcone A showed remarkable effect against acute inflammation induced by xylene, and at the doses of 2.5, 5, 10 mg/kg (p.o.), licochalcone A reduced significantly paw edema induced by carrageenan compared with the control group. Both COX-2 activity and expression were significantly inhibited by licochalcone A at all tested doses. The inhibitory effect of glabridin on COX-2 expression exhibited by glabridin at higher dose (1μg/mL) was higher than that of indomethacin (0.5μg mL-1).The flavonoids from 10 samples of Glycyrrhiza inflata were analysized with HPLC using a step gradient of acetonitrile-0.1 % acetic acid. The HPLC fingerprint chromatogram of flavonoids from Glycyrrhiza inflata was established using computer software to evaluate the data of chromatographic peaks. It is effective to evaluate the quality of licorice in virtue of the characteristic peaks of HPLC fingerprint chromatogram...
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