Extraction of indole alkaloids from Tabernaemontana catharinensis using supercritical CO2+ethanol: an evaluation of the process variables and the raw material origin

Indole alkaloids from Tabernaemontana catharinensis, collected from different places, were extracted using a mixture of supercritical CO2 plus ethanol. The effects of the process variables: temperature, pressure, solvent flow rate, and percentage of cosolvent on the total yield, chemical composition of the extract, and extraction kinetics were determined. The extracts were solvent-partitioned and their composition analyzed by TLC, GC-MS and 1H and 13C NMR. Voacangine and coronaridine were identified as the major compounds in the extracts; the individual alkaloids were quantified by GC-FID using external standard. At 250 bar and 45 °C the largest yield (1.29%) and the faster extraction rate were obtained; increasing the percentage of cosolvent improved the extraction rate as well as the yield. Employing an intermittent process consisting in six pressurization–depressurization steps appreciably reduced the total extraction time.