Comparison of microwave-assisted extraction and conventional extraction techniques for the extraction of tanshinones from Salvia miltiorrhiza bunge

Extraction techniques using microwave-assisted extraction (MAE), extraction at room temperature (ERT), heat reflux extraction, ultrasonic extraction and Soxhlet extraction were evaluated for the extraction of tanshinones (Cryptotanshi none, Tanshinone I and Tanshinone IIA) from Salvia miltiorrhiza bunge. The extracts were analyzed by high performance liquid chromatography (HPLC) without any treatment. The results showed that the percentage extraction of Cryptotanshinone, Tanshinone I and Tanshinone IIA from S. miltiorrhiza bunge by MAE was equivalent with and in fact higher than that of conventional extraction methods. MAE only needs 2 min, whereas ERT, heat reflux extraction, ultrasonic extraction and Soxhlet extraction need 24 h, 45, 75 and 90 min, respectively. Due to the considerable saving of time and high extraction efficiency, MAE was more effective than the conventional methods. (C) 2002 Elsevier Science B.V. All rights reserved.