Glandular trichome disruption by rapid CO sub(2) depressurization as pretreatment for recovery of essential oil from Leptocarpha rivularis leaves

Leptocarpha rivularis is a medicinal plant used as a treatment for different illnesses. These properties are related to its essential oils. Trichomes are specialized structures located on the leaf surface and are responsible for secreting essential oils. Disruption of trichomes by CO sub(2) rapid depressurization was studied as pretreatment of L. rivularis leaves for subsequent extraction of essential oil with supercritical CO sub(2) at 40 degree C and 10 MPa. The effect of temperature (21-49 degree C) and pressure (6-13 MPa) of static compression on extract recovery was studied. Low temperature and high pressure favored the highest extract recovery, with the pressure effect being more important than the temperature effect. Disruption of trichomes was evidenced by light microscopy images of pretreated leaves. Antioxidant activity in the selected extract, measured as Trolox equivalent (TE) and beta -carotene bleaching (IC sub(50) value), were 1.85 mmol TE/kg and 8.7 mg/mL respectively. The anti-inflammatory activity (IC sub(50) value) was 1.12 mg/mL. Three target terpenoids of L. rivularis ( alpha -thujone, beta -caryophyllene and caryophyllene oxide) were quantified in the selected extract using GC/FID. Pretreatment by CO sub(2) rapid depressurization can improve the recovery of important compounds from L. rivularis leaves, and since this is performed at a low temperature, this protects heat-sensitive compounds.