Thymoquinone is an active principle of Nigella sativa seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections.

Polyphenols are bioactive molecules exhibiting a lot of scientific attention due to their multiple biological activities. This study compared phenolic contents and antioxidant activity in Cynara cardunculus L. organs and focus on leaf phenolic compounds identification by RP-HPLC and their antibacterial activity. The analyzed organs exhibited different total polyphenol contents (7–14.8 mg GAE g ⁻¹ DW). Leaf and seed phenolic contents were similar and two times higher than those in flowers. The same tendency was observed for the amount of flavonoids and tannins. However, seed extracts displayed the highest DPPH ^⋅ scavenging ability with the lowest IC ₅₀ value (23 μg ml ⁻¹ ), followed by leaves and flowers (over 50 μg ml ⁻¹ ). In contrast, leaves showed the highest capacity to quench superoxide (IC ₅₀ : 1 μg ml ⁻¹ ) as compared to seeds (6 μg ml ⁻¹ ). In addition, cardoon leaves were efficient to inhibit growth of pathogenic bacteria mainly against Staphylococcus aureus and Escherichia coli . The identification of phenolic compounds from leaves revealed that syringic and trans -cinnamic acids were the major molecules.