Phytochemical Composition, Antioxidant, Antibacterial and Allelopathic Activities of Various Solvent Extracts of <i>Cynara cardunculus</i> Stalks

Abstract

The aim of this study was to assess the phytochemical content, antioxidant, antibacterial and allelopathic properties of various solvent extracts of  Cynara cardunculus (L.) stalks. Dichloromethane, chloroform, ethyl acetate and ethanol were used for the preparation of extracts. The results revealed that the ethyl acetate extract has large amounts of polyphenols (180.35 ± 2.97 mg EAG/g DW), flavonoids (74.32 ± 4.46 mg QE/g DW), and flavonols (7.79 ± 0.00 mg QE/g DW). Furthermore, the ethanol extract of C. cardunculus was the richest in condensed tannin content (45.24 ± 0.36 mg CE/ g DW). The antioxidant effects of the extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay method, which showed that the ethyl acetate extract possesses the strongest activity (IC50 = 0.13 ± 0.02 mg/ml). The extracts were also tested against Gram-positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) microorganisms using the microdilution assay. Among the tested extracts, the ethyl acetate and ethanol extracts exhibited the strongest antibacterial activity against B. subtilis, with minimum inhibitory concentration (MIC) values of 0.019 and 0.039 mg/ml, respectively. The allelopathic activity results demonstrated that the ethyl acetate extract at the highest concentration of 1 mg/ ml induces maximum reduction, showing 100% inhibition of Coriandrum sativum (L.) and Cuminum cyminum (L.) seeds. Thus, these findings suggest that C. cardunculus extracts may serve as potential sources for new antioxidant, antibacterial phytochemicals and natural herbicides.

Keywords: Cynara cardunculus, phytochemical profile, antioxidant effect, antibacterial activity, allelopathic potential