**4. Conclusions**

The results obtained in this work indicate that cladodes of *Opuntia ficus-indica* are rich in phenolic compounds, particularly *p*-hydroxybenzoic acid derivatives, and possess in vitro antioxidant activity which results higher in the immature cladodes. The extracts exhibited in vivo antioxidant capacity with a strong anti-hemolytic effect. A selective inhibition against potentially pathogenic bacteria and a significant inhibition of the biofilm formation were shown by the cladodes at both developmental stages. To our knowledge, this is the first report on the characterization of *Opuntia ficus-indica* cladodes

extracts for their antimicrobial and anti-biofilm properties. In conclusion, our results indicate that *Opuntia ficus-indica* cladode extracts, especially the immature ones, could be used for food purpose as functional food (being comparable to the antioxidant value of blueberries), as well as for food process control and food safety as recently proposed by Rocchetti et al. [26].

**Author Contributions:** Conceptualization, methodology, investigation, writing—original draft preparation: F.B. and S.F.; methodology, investigation, formal analysis: R.R., C.N.; writing—review and editing: L.D.B.

**Funding:** This research received no external funding

**Conflicts of Interest:** The authors declare no conflicts of interest.
