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 CO2 rapid depressurization was studied as pretreatment of L. rivularis leaves for subsequent extraction of essential oil with supercritical CO2 at 40 degrees C and 10 MPa. The effect of temperature (21-49 degrees 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 (IC50 value), were 1.85 mmol TE/kg and 8.7 mg/mL respectively. The anti-inflammatory activity (IC50 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 CO2 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. (C) 2015 Elsevier B.V. All rights reserved.