Chemical Composition and In Vitro Antioxidant Activity of Salvia aratocensis (Lamiaceae) Essential Oils and Extracts

Salvia aratocensis (Lamiaceae) is an endemic shrub from the Chicamocha River Canyon in Santander (Colombia). Its essential oil (EO) was distilled from the aerial parts of the plant via steam distillation and microwave-assisted hydrodistillation and analyzed using GC/MS and GC/FID. Hydroethanolic extracts were isolated from dry plants before distillation and from the residual plant material after distillation. The extracts were characterized via UHPLC-ESI(+/)-Orbitrap-HRMS. The S. aratocensis essential oil was rich in oxygenated sesquiterpenes (60-69%) and presented tau-cadinol (44-48%) and 1,10-di-epi-cubenol (21-24%) as its major components. The in vitro antioxidant activity of the EOs, measured via an ABTS(+center dot) assay, was 32-49 mu mol Trolox((R)) g(-1) and that measured using the ORAC assay was 1520-1610 mu mol Trolox((R)) g(-1). Ursolic acid (28.9-39.8 mg g(-1)) and luteolin-7-O-glucuronide (1.16-25.3 mg g(-1)) were the major S. aratocensis extract constituents. The antioxidant activity of the S. aratocensis extract, obtained from undistilled plant material, was higher (82 +/- 4 mu mol Trolox((R)) g(-1), ABTS(+center dot); 1300 +/- 14 mu mol Trolox((R)) g(-1), ORAC) than that of the extracts obtained from the residual plant material (51-73 mu mol Trolox((R)) g(-1), ABTS(+center dot); 752-1205 mu mol Trolox((R)) g(-1), ORAC). S. aratocensis EO and extract had higher ORAC antioxidant capacity than the reference substances butyl hydroxy toluene (98 mu mol Trolox((R)) g(-1)) and alpha-tocopherol (450 mu mol Trolox((R)) g(-1)). S. aratocensis EOs and extracts have the potential to be used as natural antioxidants for cosmetics and pharmaceutical products.