Screening of Italian Flora: Identification, Bioavailability, and Intracellular Antioxidant Activity of Novel Secondary Metabolites

The balance between reactive oxygen species (ROS) production and antioxidant defenses is crucial for maintaining cellular homeostasis. Natural products rep- resent a rich source of novel antioxidants. In this PhD project, we investigated extracts from a collection of Italian flora to identify new bioactive molecules. A selection of plant extracts was performed, and 19 species of interest were identi- fied based on the diversity of their metabolic profiles and the scarcity of existing literature on these species. Plant extracts were first evaluated for cell-free radical scavenging through the Fenton reaction assay. Subsequently, we examined the effect of plant extracts on the cell viability of THP-1 and Human Intestinal Ep- ithelial Cells (HIEC). The protection of plant extracts against ROS and lipid per- oxidation induced by tert-butyl hydroperoxide (TBHP) was assessed using flow cytometry. Among the extracts, Eryngium maritimum and Aquilegia atrata exhib- ited the most potent antioxidant properties, demonstrating a dose-dependent re- duction of TBHP-induced ROS production and lipid peroxidation in THP-1 cells. The most active extracts were further tested in HIEC models, yielding consistent results. Bioavailability analyses, by UPLC-MS/MS, revealed that metabolites of Eryngium maritimum and Aquilegia atrata can permeate THP-1 cells. In particular, swertisin was validated as a key intracellular antioxidant compound from Aqui- legia atrata in THP-1 cells. This work identifies Eryngium maritimum and Aquilegia atrata as promising sources of antioxidant compounds, highlighting their ability to reduce oxidative stress, and validates swertisin as a novel bioactive molecule. Future efforts will focus on the in vitro validation of isolated compounds to es- tablish their potential as novel antioxidants.