Halophytes from lagoons of the North Adriatic Sea: their biological activity and potential application.

Halophytes are salt-tolerant plants adapted to extreme coastal conditions and known to produce high levels of bioactive secondary metabolites, making them attractive candidates for nutraceutical, pharmacological, cosmetic, and biotechnological applications. This study examines thirteen halophytic species from the North Adriatic lagoon system (Venice Lagoon and Po Delta areas) by assessing their biological potential through an integrated analytical workflow. Extracts from different plant organs (leaves, stems, roots, and flowers) were prepared and tested for their in vitro antioxidant activity (DPPH, ABTS, FRAP assays) and for their in vitro inhibitory activity on enzymes linked to human disorders, including tyrosinase, α-glucosidase, α-amylase, and lipase. Total phenolic and flavonoids of the extracts were quantified colorimetrically, and their chemical profile was characterized by UPLC-HRMS to obtain a comprehensive phytochemical overview. Most extracts exhibited notable antioxidant properties, with leaves and flowers generally outperforming stems and roots. Among the species investigated, Oenothera biennis, particularly its leaves and flowers, showed strong antioxidant activities and substantial inhibition of tyrosinase and α-glucosidase. Asparagus maritimus leaf extract and Plantago coronopus root and leaf extracts also displayed remarkable antioxidant activities. α-Amylase inhibition was moderate and mainly associated with Calystegia soldanella and Ammophila littoralis, while lipase inhibition remained weak across all species. Untargeted metabolomic analyses enabled level 2 annotation of 90 features, largely represented by phenylpropanoids, especially flavonoids, together with diverse lipid classes, triterpenoids, dipeptides, nucleosides, and vitamins. The combined interpretation of bioactivity results and metabolomic analyses underscores the central contribution of flavonoids to the observed biological effects and highlights clear species- and organ-specific patterns linked to ecological adaptation. These results demonstrate that halophytes from the North Adriatic lagoons represent valuable sources of bioactive metabolites with antioxidant and enzyme-inhibitory potential, supporting the relevance of future studies across seasons and environmental gradients to further enhance their characterization and valorization.