A Comparison Study on Microwave-Assisted Extraction of Catalpol from <i>Rehmannia glutinosa Libosch</i> with Conventional Methods

Abstract

Catalpol, an iridoid glycoside, has been verified to be of neuroprotection and may be a potential agent for the treatment of neurodegenerative disease. The extraction technology of catalpol has been tested in this paper. We used different extraction methods including extraction at room temperature (ERT), heat reflux extraction, Soxhlet extraction, ultrasonic extraction and microwave-assisted extraction (MAE) to evaluat the percentage extraction of catapol fromRehmannia glutinosa Libosch.The extracts were analyzed by high performance liquid chromatography (HPLC). Methanol (100%, v/v) extracted high percentage extraction of catapol compared to ethanol (60%, v/v) which achieved the highest percentage extraction of catapol in different concentration of ethanol. The results showed that the percentage extraction of catalpol fromRehmannia glutinosa Liboschby MAE was more efficient in short time followed by ultrasonic extraction, Soxhlet extraction, heat reflux extraction and ERT methods. MAE has need of 4 min, whereas ultrasonic extraction, Soxhlet extraction, heat reflux extraction and ERT techniques require 70, 140, 180 min and 60 h respectively, to leach higher percentage extraction of catalpol. The time taken by MAE was nearly 18 times less than the ultrasonic extraction, 35 times less than Soxhlet extraction, 45 times less than heat reflux extraction and 900 times less than ERT for the highest percentage extraction of catalpol. The present results showed that the high extraction efficiency and considerable saving of time by MAE were more competent than the conventional extraction techniques.