## 4 Discussion
### Evaluation of the Effect of Fucus vesicusus Extract on Peritoneal Macrophages Vitality  
The effect of _F. vesicusus_ extract on cell viability is a topic of interest due to the potential therapeutic applications and safety concerns associated with its use. Our results on mouse peritoneal macrophages disclosed that exposure to different concentrations of algal extract reduces viability as the dose tested increases. The cytotoxic effects of these extracts may vary depending on the specific compounds present and their concentrations, particularly the fucoidan molecule, which is closely related to this effect. Research indicates that low-molecular-weight (LMW) fucans derived from _Fucus vesicusus_ can inhibit the growth of certain cell lines. For instance, studies have shown that these fucans can inhibit the proliferation of Chinese hamster fibroblasts by up to 80% at a concentration of 1000 \(\upmu\)g/mL while exhibiting less than 50% inhibition on human colon adenocarcinoma cells at the same concentration [69]. Additionally, other studies have reported dose-dependent cytotoxic effects of fucoidan, particularly in the 100-1000 \(\upmu\)g/mL concentration range, on macrophage cell lines, such as RAW 264.7 cells [70,71]. This evidence suggests that the cytotoxic effect is context-dependent and can vary based on factors such as concentration, highlighting, however, that _Fucus vesicusus_ extract may be beneficial in targeting specific cell types. In the context of peritoneal macrophages, the extract's influence on cell viability and function is crucial, and it is essential to consider the balance between its cytotoxic and protective effects under stressed conditions. In fact, our study also highlighted that when macrophages are pre-treated with H2O2 leading to oxidative stress, concentrations of 50 and 100 \(\upmu\)g/mL of _F. vesicusus_ extract protect macrophages from cellular damage, increasing their vitality. As reported before, _Fucus vesicusus_ exhibits notable antioxidant properties, which can mitigate the damaging effects of oxidative stress. The extracts from this seaweed have demonstrated the ability to enhance the antioxidant status in various biological systems, including activated macrophages [72]. Specifically, studies have shown that _Fucus vesicusus_ extracts can scavenge free radicals and reduce oxidative damage in cellular models, suggesting a protective role against H2O2-induced injury [73,74]. The mechanism by which _Fucus vesicusus_ exerts its protective effects may involve modulating inflammatory responses and enhancing cellular antioxidant defenses. Peritoneal macrophages, which are crucial in the immune response, can release H2O2 as part of their antimicrobial activity [75]. However, excessive H2O2 can lead to cellular dysfunction and apoptosis. The bioactive compounds found in _Fucus vesicusus_ are believed to play a significant role in counteracting this oxidative stress by neutralizing reactive oxygen species and supporting the activity of endogenous antioxidant enzymes [76, 77, 78]. Furthermore, the extracts have been shown to enhance the activity of key antioxidant enzymes, such as superoxide dismutase and catalase, which are vital for maintaining cellular integrity in the face of oxidative challenges [38]. Thus, our results, supported by those found in the literature, highlight that the protective role of _Fucus vesicusus_ extract on peritoneal macrophages stressed with H2O2 is supported by its antioxidant properties, which help mitigate oxidative damage and modulate inflammatory responses, suggesting that _Fucus vesicusus_ could be a valuable dietary supplement for enhancing cellular resilience against oxidative stress.