Seasonal variation of bioactive properties and phenolic composition of Cynara cardunculus var. altilis

Cynara cardunculus L. (cardoon) has several health benefits mainly attributed to its abundance in polyphenols. In this study, cardoon heads (capitula) were harvested in Greece during the flowering stage, and the hydroethanolic extracts were assessed in terms of phenolic compounds composition and antioxidant, cytotoxic, anti-inflammatory, and antimicrobial activities. The phenolic profile was evaluated by HPLC-DAD-ESI/MS to better understand the seasonal changes in the individual compound levels and how these changes correlate with bioactive properties. The main phenolic compounds identified were caffeoylquinic and dicaffeoylquinic acid derivatives. Immature heads (Car A: principal growth stage (PGS) 5) had the highest phenolic content (34.3 mg/g) and cytotoxic (GI₅₀ of 69-268 µg/mL) and anti-inflammatory (IC₅₀ of 183 µg/mL) activities. Sample Car D (PGS 6/7) revealed the highest antioxidant (IC₅₀ of 23-227 µg/mL) and antifungal (MIC of 0.26-0.51 mg/mL) potential. Regarding the antibacterial activity, Car E (PGS 7) revealed the best results (MIC of 0.59-1.18 mg/mL). This study suggests that the maturity stage of the plant influences the phenolic composition and bioactivity.

Keywords: Anti-inflammatory activity; Antimicrobial properties; Bioactive properties; Cynara cardunculus (L.); Phenolic compounds; Seasonal variation.