Effects Of Ultrasound On Glycyrrhiza-water Leaching Equilibrium And Mathematical Model

Glycyrrhiza is the most popular herb used in traditional Chinese medicine. The mainactive ingredient is glycyrrhizic acid (GA), which has been proved to have varioustherapeutic activities, including diminish inflammation, antiviral, anti-cancer, fight ulcer,antibiosis, immunoregulation and so on. So, there is considerable interest in the extractionof GA from glycyrrhiza.This paper reported that ultrasound enhanced the extraction of GA from glycyrrhiza andthe GA was analyzed by UV-VIS spectrophotometry. First, the chemical structure of GAstandard before ultrasound treatment and after that was characterized by fourier transforminfrared (FT-IR) spectroscopy and proton nuclear magnetic resonances (1H NMR). Theresult showed that the chemical structure of GA standard had no changes, soultrasound-assisted extraction (UAE) of GA from glycyrrhiza was feasible. Secondly, theinfluences of extraction temperature, ultrasonic power, ultrasonic frequency, liquid-solidratio and solvent type to leaching equilibrium of GA were considered. By othogonalexperiment, the optimum leaching condition was obtained: extraction temperature was60℃, ultrasonic power was125W, ultrasonic frequency was20kHz, liquid-solid ratio was400:4mL/g, solvent was50%ethanol, and the concentration of GA in leaching solution was1.536mg/mL. And the effect of the factors to leaching equilibrium was liquid-solid ratio>solvent type> extraction temperature> ultrasonic frequency> ultrasonic power.The crude GA was prepared by acid precipitation and recrystallized by ethanol. Thecrude GA was recrystallized by50%ethanol for twice, and the purity of GA reached91.24%.The GA molecule adsorbing to glycyrrhiza did the forced vibration with damp underthe ultrasonic field, while the GA molecule in leaching solution was one of ultrasonicpropagation medium. According to vibration theory, the energy of GA molecule in twodifferent states was confirmed. Based on the difference of the energy of GA molecule intwo states, the modle of leaching equilibrium under the ultrasonic field was established bythe theory of statistical thermodynamics. The parameter of modle could be obtained byusing numerical simulation of Matlab, the data calculated by the modle gave a goodmatching with the experimental data, maximum relative deviation was6.67%.