Extraction of bioactive compounds from Leptocarpha rivularis stems by three-stage sequential supercritical extraction in fixed bed extractor using CO2 and ethanol-modified CO2

Sequential supercritical extraction experiments were carried out in three stages each using CO2 and ethanol-modified-CO2, to improve the extraction yield of bioactive compounds from L. rivularis stems. Four experiments were carried out, each in three stages, combining different levels of temperature (40 or 60 degrees C) and pressure (20-50 MPa). The increase in pressure and use of a cosolvent increased the total yield of extract and target compounds compared to one-stage extraction. The highest extraction yields of extract (6.29 g/kg d.s.), terpenes (699.9 mg/kg d.s.), flavonoids (741.9 mg/kg d.s.), and alkaloids (6.22 mg/kg d.s.) were obtained in Experiment 4. Sequential extraction of compounds was superior to one-stage extraction using CO2, but inferior when using ethanol-modified CO2. Both sequential and one-stage cumulative extraction curves were modeled, and the effective diffusivity coefficients ranged between 1.51 and 63.3 x 10-13 m2/s, being highest in Stage 3 where the extraction yield was greatest.

Automated summary

In order to improve the extraction yield of bioactive compounds from L. rivularis stems, sequential supercritical extraction experiments were carried out in three stages using CO2 and ethanol-modified-CO2. The use of cosolvent and increased pressure resulted in higher total yield of extract and target compounds compared to one-stage extraction. Experiment 4 achieved the highest extraction yields of extract (6.29 g/kg d.s.), terpenes (699.9 mg/kg d.s.), flavonoids (741.9 mg/kg d.s.), and alkaloids (6.22 mg/kg d.s.).