Ailanthus altissima and Amorpha fruticosa – invasive arboreal alien plants as cheap sources of valuable essential oils

The high tolerance of various habitat conditions and potent propagation ability of Ailanthus altissima (Mill.) Swingle (Simaroubaceae) and Amorpha fruticosa L. (Fabaceae) promote their aggressive invasive behaviour. Additionally, they not only over-compete the local vegetation but suppress the seed development. In the newly invaded habitats they might not have suitable herbivores to control their populations. The aim of this review is to evaluate the potential of A. altissima and A. fruticosa, as cheap sources of valuable essential oils. The essential oils yield and compostion of both plant species vary significantly depending on plant parts, origin and time of collection. The main constituents of A. altissima essential oil are α-curcumene, α-gurjunene, γ-cadinene, α-humulene β-caryophyllene caryophyllene oxide, germacrene D etc. The main constituents of A. fruticosa are δ-cadinene, γ-cadinene, β-caryophyllene γ-muurolene +, ar-curcumene, myrcene etc. These essential oils have been reported to possess different activities such as antimicrobial, insect repellent, insecticidal and herbicidal activity. Due to the fact that these are aggressive invasive species, they can provide abundant and cheap resources. Additionally, future industrial exploitation of the biomass of these invasive plants for essential oils' extraction might contribute to biodiversity conservation by relieving their destructive impact on the natural habitats.