Sesquiterpenoids from Common Ragweed (Ambrosia artemisiifolia L.), an invasive biological polluter

Common ragweed (Ambrosia artemisiifolia L.) is an invasive species native to North America, nowadays widespread in most temperate regions of the world. Allergy to Ambrosia is increasingly important from a clinical point of view but, surprisingly, little is known on the secondary metabolites of this plant and on their potential involvement in the symptoms associated to the allergic reaction to its pollen. We have isolated eight novel sesquiterpenoids from the aerial parts of A. artemisiifolia, whose structures will be reported in this communication, and evidenced the presence of large amounts of exomethylene-γ-lactones, e.g. damsin (1) and isabelin (2). Since compounds of this type, as well as their acidic precursors, might also be present in pollen, their reactivity with thiols was investigated and correlated to the activation of TRPA1, highly expressed in the aerial pathways and involved in airways sensory irritation, a common complication of allergy to Ambrosia.