The powdered plant material (1467 g) was extracted exhaustively in a Soxhlet-apparatus in portions of approximately 240 g with 1.5 L dichloromethane (DCM) for 36 h until the supernatant was colorless. After rotary evaporation under reduced pressure at 40 °C, a total of 112 g of crude extract (GBUS) was obtained.
An acid–base extraction was carried out to enrich the alkaloids from 103 g of the crude extract. For each extraction batch, 5 g of the extract was dissolved in 60 mL of DCM and extracted six times with 25 mL of diluted sulfuric acid R (1M, European Pharmacopoeia Reagent) in a separating funnel. Due to their increased hydrophilicity, the protonated alkaloids concentrate in the aqueous phase, while lipophilic and neutral compounds mainly accumulate in the lipophilic DCM phase. After evaporation, the DCM phase yielded 103.98 g of the lipophilic and neutral fraction (LNB).
The collected acidic water phase was alkalized to a pH value of ≈ 10 with solid sodium hydroxide and subsequently extracted six times with 200 mL of DCM. The deprotonated alkaloids accumulate in the lipophilic phase, while hydrophilic impurities remain in the aqueous phase. Of the alkaloid fraction (ALOF), 4.63 g was obtained from the evaporated DCM phase. According to LC/MS quantification, GBUS and ALOF contained 0.06% (63.43 mg) and 1.14% (52.89 mg) of the target compound1 , respectively, corresponding to an enrichment factor of 19. The recovery rate was 90.6% (note that only 103 of the 112 g GBUS were used).
An acid–base extraction was carried out to enrich the alkaloids from 103 g of the crude extract. For each extraction batch, 5 g of the extract was dissolved in 60 mL of DCM and extracted six times with 25 mL of diluted sulfuric acid R (1M, European Pharmacopoeia Reagent) in a separating funnel. Due to their increased hydrophilicity, the protonated alkaloids concentrate in the aqueous phase, while lipophilic and neutral compounds mainly accumulate in the lipophilic DCM phase. After evaporation, the DCM phase yielded 103.98 g of the lipophilic and neutral fraction (LNB).
The collected acidic water phase was alkalized to a pH value of ≈ 10 with solid sodium hydroxide and subsequently extracted six times with 200 mL of DCM. The deprotonated alkaloids accumulate in the lipophilic phase, while hydrophilic impurities remain in the aqueous phase. Of the alkaloid fraction (ALOF), 4.63 g was obtained from the evaporated DCM phase. According to LC/MS quantification, GBUS and ALOF contained 0.06% (63.43 mg) and 1.14% (52.89 mg) of the target compound
Free full text: Click here
