Solvent composition effects on efficiency of pressurized liquid extraction of bioactive isoflavonoids from Belamcanda chinensis rhizomes

A pressurized liquid extraction (PLE) technique was developed for the extraction of bioactive isoflavonoids including tectoridin (1), iridin (2), tectorigenin (3), iristectorigenin A (4), irisflorentine (5), and irigenin (6) from Belamcanda chinensis using aqueous ethanol as the extraction solvent. The effects of various key factors of PLE, including solvent composition (0-100% ethanol in water), temperature (80-180�� C) and extraction time (5-20min), were evaluated with respect to the extraction efficiency. Only solvent compositions altered the extraction yields of isoflavonoids with 60% ethanol providing the best extraction efficiency. When compared with conventional extraction methods, such as reflux or sonication extraction, PLE resulted in higher extraction efficiency with shorter extraction time and lower solvent consumption. We also tested the thermal stability of tectoridin, isoflavonoid glycoside, at various temperatures (80-180�� C) in 60% ethanol for a 20min extraction time to mimic conditions that could be encountered during PLE. Tectoridin was degraded to tectorigenin (aglycone) at temperatures over 150�� C, therefore, care should be taken in the choice of temperature used for PLE. Copyright �� 2011 Taylor & Francis Group, LLC.This work was supported by grant no. RTI05-01-02 from the Regional Technology Innovation Program of the Ministry of Knowledge Economy, Republic of Korea