Global yield isotherms and kinetic of artemisinin extraction from Artemisia annua L leaves using supercritical carbon dioxide

Artemisinin is an effective drug used in the malaria treatment. This drug, present in the Artemisia annua L leaves, was extracted using pressurized CO2 as solvent. The artemisinin global yields isotherms were determined at 30 and 50 degrees C with pressures in the range of 75-400 bars. The influences of temperature, pressure, and solvent flow rate on the extraction kinetics were also investigated, using a complete factorial design 2(3) (pressures of 200 and 400 bars, temperature of 30 and 50 degrees C and CO2 mass flow rate of 5.5 x 10(-5) and 11.1 x 10(-5) kg CO2/s). Extracts of A. annua L. leaves were also prepared by hydrodistillation and hexane Soxhlet. The mass transfer coefficients for constant extraction rate period were obtained from the experimental data. The extracts were analyzed by GC-FID and the artemisinin content was determined by the indirect method. The maximum artemisinin global yields were obtained at 30 degrees C and 150 bar (0.62% dry basis - d.b.) and 50 degrees C and 300 bar (0.70% d.b.). The extract obtained by hydrodistillation presented no artemisinin and the main compounds presented were camphor, P-caryophyllene, borneol e 1,8-cineol. The hexane Soxhlet artemisinin yield was 0.77% in dry basis. The experimental extraction curves were well fitted by the mathematical models of Sovova and Martinez et al., and by the empirical model. (c) 2005 Elsevier B.V. All rights reserved.