Morphoanatomy, histochemistry, essential oil, and other secondary metabolites of Artemisia copa (Asteraceae)

Abstract

Artemisia copa var. copa, popularly known as “copa”, “copa-copa”, “coa”, “copal” or “tola”, is an aromatic shrub that inhabits the high Andean peaks and the Puna region of Chile, Bolivia, and Argentina. Its aerial parts are sold in the local markets as a sedative, for the treatment of digestive disorders, hypertension, fever, urinary, respiratory infections, and frictions to relieve rheumatism. The morpho-anatomy and the histochemistry of the aerial parts of a native population of A. copa (Catamarca province, Argentina) were described in order to determine diagnostic characters and to identify the site of synthesis and storage of essential oils and other secondary metabolites. A. copa can be differentiated from other Artemisia species by a set of morpho-anatomical features, such as the presence of entire to segmented leaves; ribbed young stems with circular to quadrangular shape; schizogenous secretory ducts distributed (1–2) near the xylem at the midvein of the leaf and the cortex of the stems; non-glandular two-armed “T” shaped trichomes with 2–4 short uniseriated basal cells and biseriate capitate glandular trichomes. Epidermal cells, glandular trichomes, and secretory ducts were associated with the synthesis and accumulation of essential oil, triterpenic and phenolic compounds. Triterpenes (lupeol, α- and β-amyrin); phytosterols βsitosterol, stigmasterol, campesterol, and 24-methyl cholesta-5, 22-dien-3β-ol); sesquiterpene lactones (leucodin and achillin) and flavones (chrysosplenetin and jaceidin,) were identified in the chloroform extract. The essential oil showed chrysanthenone (76.9%), as the main component, accompanied by minor amounts of other mono- and sesquiterpenoids.