Extraction of rotundifuran and casticin from chaste tree fruits by near critical liquid carbon dioxide

In this study we investigated the use of near critical liquid CO2 for the extraction of chaste tree ripe fruits (Vitex agnus-castus L.). Two procedures utilizing near critical liquid CO2 were tested: (1) the extraction of plant material via continuous solvent recycling and (2) the extraction by a Soxhlet-type process via periodic solvent recycling. The results were compared with data obtained from the traditional Soxhlet extraction process using three different solvents, namely n-hexane, dichloromethane, and methanol. Extractions with liquid CO2, recycled in continuous mode, of chaste tree fruits in three sizes: (1) <0.3 mm, (2) 0.3–0.8 mm, and (3) 3–3.2 mm resulted in maximum yields of 4.9%, 4.1% and 2.8%, respectively. Extraction times of 0.17–25 h were used. Extraction by continuous recycling of liquid CO2 is more efficient than Soxhlet-type periodic recycling of liquid CO2, resulting in up to three times higher yield for the same solvent-to-feed ratio. Comparison of HPLC data for extracts obtained by liquid CO2, n-hexane, dichloromethane and methanol showed that the diterpene rotundifuran is best extracted by liquid CO2 (3.010 g/kg drug), and the flavonoid casticin is best extracted by n-hexane (1.067 g/kg drug).