## 3 Results and Discussion
### Cell Viability and Oxidative Stress
The protection against oxidative stress observed following treatment with methanolic extracts from the stems and SFH of the three artichoke genotypes analyzed in this study was correlated with reduced ROS levels and restored GSH levels. To exhibit their antioxidant effects in a cellular model the compounds can break the peroxyl radical chain reactions at the cell membrane surface, or they can be taken up by the cell and react with ROS intracellularly [2 ]. Among the bioactive compounds present in various parts of the artichoke plant, polyphenols may play a pivotal role in the observed antioxidant activity, particularly 5-O-caffeoylquinic acid (chlorogenic acid) and 3,5- and 1,5-di-O-caffeoylquinic acids, which were the predominant polyphenols identified in the analyzed methanolic extracts. Consistent with our findings, the protective effects of bract and residual leaf extracts against oxidative stress-induced liver damage, evaluated using a hepatocarcinoma cellular model (human HepG2 cells), were primarily attributed to chlorogenic acid, as well as 3,5- and 1,5-di-O-caffeoylquinic acids. Notably, the results demonstrated a strong correlation between polyphenic content and antioxidant efficacy, with 1,5-di-O-caffeoylquinic acid exhibiting the highest antioxidant activity [27 ]. Similar findings were reported for a 60% \(v/v\) methanolic extract fraction derived from artichoke by-products (bracts, leaves, and stems), which were particularly rich in hydroxycinamic acids. This extract significantly reduced ROS production in Caco-2 cells, a model used to evaluate antioxidant capacity against hydrogen peroxide-induced damage in intestinal cells [27 ]. A restoration of ROS levels after treatment with Grato 1 SFH and Orte 2 F7 P2 stem extracts the values observed in control cells was similarly shown by [PERSON] and colleagues [2 ]. They investigated the ability of 4,5-O-dicaffeoyl-1-O-(malic acid methyl ester)-quinic acid (MDCQA) to counteract H\({}_{2}\)O\({}_{2}\)-induced intracellular ROS production in SH-SYSY cells by DCFHDA assay and observed that ROS generation tended to decrease significantly with pretreatment in a dose-dependent manner, restoring ROS levels to the control value, similarly to the N-acetyl-L-cysteine used as an antioxidant drug [27 ]. The antioxidant activity of polyphenols present in artichoke can be explained through several mechanisms. Polyphenols are known to prevent lipid peroxidation and scavenge reactive oxygen species (ROS) through their ability to chelate metal ions [27 ]. Additionally, the antioxidant capacity of caffeoylquinic acids and flavonoids is linked to their hydrogen-donating capacity, which arise from their unique structural features [27 ]. However, their modulatory effects are primarily associated with the interception of free radicals and ROS within critical signaling pathways involving various transcription factors, protein kinases, and phosphatases [27 ]. Notably, antioxidants can modulate the nuclear factor E2-related factor 2 (Nrf2) signaling pathway. Studies have shown that polyphenols regulate Nrf genetically and epigenetically at transcriptional, post-transcriptional, and translational levels, thereby increasing the cytoplasmic concentration of this protein [27 ]. The primary role of Nrf2 is to activate the transcription of genes involved in the synthesis of antioxidant enzymes, such as NADPH quinone oxidoreductase, heme oxygenase, catalase, and superoxide dismutase. It also regulates genes encoding enzymes within the glutathione system, including glutathione peroxidase, glutathione S-transferases, \(\gamma\)-glutamylcysteine synthetase, and glutathione synthetase, the latter two being directly involved in glutathione synthesis [17 ]. Additionally, Nrf controls the expression of inflammatory genes such as nuclear factor-kappa B (NF-\(\kappa\)B) and transforming growth factor-\(\beta\) (TGF-\(\beta\)) [18 ].