Anatomical, micromorphological and phytochemical characterization of Artemisia chamaemelifolia, a rare plant in the western Italian Alps

Artemisia chamaemelifolia subsp. chamaemelifolia is a perennial herb of Asteraceae, growing in Italy only in Valle d’Aosta and Piedmont and included in the Near Threatened category of the Italian Red List. Samples of the plant were collected at the flowering stage in the locality of Taveronaz (Cogne, AO). Few reports are available on the pharmacognostic characteristics of this species and its subspecies, and there is no data on the populations growing on the Alps. Aim of our study was to investigate anatomy and micromorphology of the aerial portions of this species, to characterize the essential oil (EO), and evaluate its antioxidant properties. Microscopic analysis revealed the presence of both T-shaped non-glandular and glandular trichomes (GTs) on all aerial portions, the latter being mainly abundant on the reproductive portions. Small secretory ducts inside leaves, stem and inflorescence axis were also identified. In EO 39 components were found (99.66% of the total), with α-bisabolol (25.98%), grandisol (15.66%), and fragranyl acetate (12.46%) as the major constituents. EO showed a moderate antioxidant activity, probably related to population, climate, and edaphic condition. This study provides the first pharmacognostic characterization of this rare species of the western Italian Alps.