Ultrasound-assisted extraction of oxymatrine from Sophora flavescens

Oxymatrine is one of main active compounds found in Sophora flavescens, which have been extensively used in China for the treatment of several diseases on viral hepatitis, cancer, cardiac and skin. The optimization of ultrasound-assisted extraction of oxymatrine from S. flavescens was investigated, and the extracts were analyzed by high-performance liquid chromatography (HPLC). Effects of several experimental parameters, such as concentration of extracting solvent, the ratio of liquid to material, extraction temperature, and extraction time on extraction efficiencies of oxymatrine from S. flavescens using ultrasound-assisted extraction were evaluated. The optimal extraction conditions were 1 g ground plant sample with 65% (v/v) ethanol solution in water, the ratio of liquid to material at 30:1 (ml/g) and extraction for 10 min at 50°C under ultrasonic irradiation. The extraction rate of oxymatrine using ultrasound-assisted extraction was higher than those obtained using other methods, such as conventional solvent extraction, decocting method, Soxhlet extraction and microwave-assisted extraction. The results indicated that ultrasound-assisted extraction is a very useful method, and helpful for the full utilization of S. flavescens.   Key words: Ultrasound, extraction, oxymatrine and Sophora flavescens.