Microwave-assisted extraction of homoharringtonine from <Emphasis Type="Italic">Cephalotaxus koreana</Emphasis>

An efficient method using microwave energy was developed to extract homoharringtonine (HHT), an alkaloid component effective in the treatment of leukemia, from Cephalotaxus koreana. The effects of major process parameters on extraction efficiency were also investigated. Using a fixed biomass-to-methanol ratio of 1:8 (w/v), an extraction temperature of 30°C, an extraction time of 20 min, and a stirrer velocity of 250 rpm, a 25% higher yield of HHT was achieved using microwave-assisted extraction (MAE) than using conventional solvent extraction. It was possible to recover more than 95% of the HHT by extracting twice using MAE. In addition, the HHT yield increased as the extraction temperature increased, but the content of plant-derived tar and waxy compounds increased as well. Removal of these impurities and of the pigments from extracts was most effectively accomplished at a mixing ratio of biomass-to-sylopute of 1:1.5 (w/w). The effects of using different organic solvents (acetone, chloroform, ethanol, or methanol) for MAE were also assessed; the highest extraction efficiency was obtained using methanol. When the agitation speed was altered, most of the HHT (> 99%) was recovered at 250 rpm. A mixing ratio of biomass-to-methanol of 1:6 (w/v) at an extraction temperature of 40°C and an extraction time of 10 min proved to be the most effective for reducing processing time and organic solvent usage while enabling nearly all of the HHT (> 99%) to be recovered.