Ailanthus altissima Swingle: beyond invasiveness and biodiversity threat. A phytochemical and functional characterization

Ailanthus altissima Swingle is a tree species native to Asian countries, but its vigorous nature has led to a worldwide spread, with important ecological and social consequences. Moreover, ailanthus tree holds great potential in terms of biomass with underexplored functional value. Aiming at investigating possible applications, we profiled primary/secondary chemistry and bioactivity of leaves (AL) and flowers (AF) of A. altissima. Antioxidant constituents (phenolics, flavonoids, tannins, ascorbate), starch, pigments, free amino acids, and micro-macronutrients were quantified by spectrophotometry, HPLC–DAD, and portable XRF, respectively. Then, aqueous and hydroalcoholic extracts of AL and AF were prepared and screened for phenolics, flavonoids, triterpenes contents, antioxidant capacity (FRAP), and analysed by HPLC–DAD. Human keratinocytes (HaCaT) were employed to assess cytotoxicity and protection from H2O2-induced reactive oxygen species (ROS). The results showed that AL was higher in phenolics, flavonoids and radical-scavenging activity than AF. Amino-acid profiles diverged, with AL enriched in alanine and γ-aminobutyric acid, while AF in proline, glutamate, and aspartate, and also the mineral allocation differed (AL: Ca, S, Fe; AF: P, K, Cu, Zn). Ethanol extraction improved recovery of phenolics, flavonoids, and triterpenes and enhanced reducing power, while chromatographic separation highlighted substantial quali-quantitative discrepancies in the extracts and plant parts. When tested in HaCaT cells, all samples did not influence viability at ≤ 50 µg/mL. Moreover, hydroalcoholic extracts attenuated ROS production dose-dependently, with AF outperforming AL. Overall, A. altissima yields non-toxic antioxidant-rich extracts, which may support evidence for its management and cosmetic applications.