Volatile composition of six horsetails: prospects and perspectives

Six horsetails were investigated for volatile organic compounds (VOC) by GC-MS using organic solvent extraction. Seventy-five VOC biosynthesized from the shikimic, lipidic and terpenic pathways including isoprenoid derivatives were detected from these putative natural resources. E. palustre var. americana contained mainly lipidic derivatives, i.e., 1-octen-3-ol (mushroom-like odor), (E)-2-hexenoic acid (fruity odor) and (E)-2-hexenal (green odor). Many isoprenoid flavour precursors, i.e., 3-oxo-alpha-ionol (spicy odor) and (E,E)-pseudoionone (balsamic odor), as well as odorous benzenic derivatives, i.e, phenylethanal (hyacinth, lilac note) and 2-phenylethanol (rose odor) contributed to the odor of E. arvense. The volatile pattern of E. telmateia is dominated by high amounts of isoprenoids and benzenic derivatives. The complex volatile profiles of E. hyemale and E. ramosissimum are based on ferulic acid isomers, along with either (E)-2-heptenal (green vegetable-like odor) or 4-vinylguaiacol (spicy clove smoky odor) for E. hyemale and E. ramosissimum, respectively. The broad spectrum of E. scirpioides shows the lowest VOC content with high amount of isoprenoids (46.9%), mainly ionone derivatives. Equisetum resources are of great interest as bioactive litter and new potential functional feed ingredients.