Study of factors influencing pressurised solvent extraction of polar steroids from plant material : application to the recovery of withanolides

Pressurised solvent extraction was applied to the extraction of three withanolides from the leaves of lochroma gesnerioides. A study was carried out of the influence of various parameters on the extraction efficiency and kinetic parameters; these included the nature of the extracting solvent, its flow rate, the pressure and temperature, as well as the particle size of the plant material. The pressurised solvent extraction method compared to a conventional Soxhlet extraction showed similar recoveries and extraction selectivity but the total handling time and solvent volume were dramatically reduced