PHWE has been previously undertaken on a custom built system for analysis of shikimic acid content on samples of up to 0.5 g of dry plant material Although high extraction efficiency was reported natural product was not isolated and the method was not repeated on a semipreparative scale we sought to specifically utilize relatively cheap unsophisticated and commercially available equipment to achieve the extraction of multigram quantities of star anise Consequently given that the pump in an espresso machine enables the continuous flow of water at temperatures up to 96 and at pressures of typically 9 bar we believed that such a system would be suitable for our purposes
In our approach ground star anise (20 g) was packed in the portafilter of an espresso machine and extracted with a 30 % ethanol water solution (200 ml) this was achieved very quickly (2 min per 20 g sample) and repeated with another 20g sample of star anise. The extracts were combined silica gel (20g) was added and the suspension was evaporated to dryness The ensuing solid was wased with dichloromethane and ethyl acetate before extraction with a 10% acetic acid/ethyl acetate solution. The solvent was evaporated and the residue was washed with dichloromethane then dried to provide shikimic acid as an off-white solid(2.21g 5.5% w/w) that was sufficiently pure as judged by 1H and C13 NMR