Recovery and antioxidant activity of extracts from leptocarpha rivularis by supercritical carbon dioxide extraction

• The highest recovery and antioxidant activity of the extract were obtained at 40 °C and 15 MPa.
• Recovery of essential oil with supercritical extraction was 2.5 times higher than with hydrodistillation.
• Supercritical extract presented up to 5 times higher antioxidant activity than hydrodistilled extract.
• Positive correlation between extraction yield and antioxidant activity was achieved.
• Three terpenoids were screened: caryophyllene oxide, β-caryophyllene and α-thujone.

We studied the effects of temperature (40, 50, and 60 °C) and pressure (9, 12, and 15 MPa) on the recovery and antioxidant activity of the essential oil from Leptocarpha rivularis leaves by supercritical CO2 using a 32 factorial design. Experimental data were analyzed with the response surface methodology. Extraction yield varied from 23.5 to 42.6 g/kg d.s., and the resultant antioxidant activity (DPPH assay) varied from 0.60 to 1.84 mmol TE/kg. The highest extraction yield and antioxidant activity in the supercritical extract at 40 °C and 15 MPa, respectively 2.5 and 5 times higher than in hydrodistilled extract. However, the extraction yield and antioxidant activity of a hydroethanolic extract were higher than those of supercritical extracts. Three target terpenoids of L. rivularis (α-thujone, β-caryophyllene and caryophyllene oxide) were quantified in the supercritical extract using GC/FID; they were not detected in the hydroethanolic extract.

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