Extraction of bioactive components from Centella asiatica using subcritical water

Abstract

Bioactive components, asiatic acid and asiaticoside, were extracted from Centella asiatica using subcritical water as an extraction solvent. Extraction yields of asiatic acid and asiaticoside were measured using high-performance liquid chromatography (HPLC) at temperatures from 100 to 250 degrees C and pressures from 10 to 40 MPa. As temperature or pressure increased, the extraction yield of asiatic acid and asiaticoside increased. At the optimal extraction conditions of 40 MPa and 250 degrees C, the extraction yield of asiatic acid was 7.8 mg/g and the extraction yield of asiaticoside was 10.0 mg/g. Extracted asiatic acid and asiaticoside could be collected from water as particles with a simple filtering process. Dynamic light scattering (DLS) was used to characterize particle size. Particles containing asiatic acid were larger (1.21 mu m) than particles containing asiaticoside (0.76 mu m). The extraction yields of asiatic acid and asiaticoside using subcritical water at 40 MPa and 250 degrees C were higherthan extraction yields using conventional liquid solvent extraction with methanol or ethanol at room temperature while the subcritical water extraction yields were lower than extraction yields with methanol or ethanol at its boiling point temperature.