Phenolic Constituents, Antioxidant and Antimicrobial Activities of Globe Artichoke (Cynara scolymus L.) Aqueous Extracts

Abstract

Globe artichoke (Cynara scolymus L.) is a promising herbal plant, rich in bioactive compounds. The present study aimed to determine the phenolic profile, antioxidants and antimicrobial activities of globe artichoke bracts and receptacles aqueous extracts. Phenolic compounds in artichoke bracts and receptacles aqueous extracts were determined by high performance liquid chromatography (HPLC). The antioxidant activity was assayed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging and ferric ion reducing antioxidant power (FRAP), and the antimicrobial activity was determined using disc-diffusion assay. The total phenolic and flavonoid contents of the bracts extract (24.04 µg GAE mg-1 and 194.07 µg QE mg-1, respectively) were higher than in the receptacles (15.1 µg GAE mg-1 and 52.07 µg QE mg-1, respectively). The bracts extract contained ten phenolic compounds, of which the major one was p-hydroxybenzoic (9.88 mg g-1), while the receptacles extract contained five compounds, with Gentisic acid (6.36 mg g-1) as the major compound. The bracts extract showed higher antioxidant activity (26.05% and 20.21% at 10ppm for DPPH and ABTS, and 14.05 µmol/L at 100 ppm for FRAP) compared to that of the receptacles. The aqueous extracts of bracts and receptacles showed antimicrobial activity against all tested foodborne pathogenic bacteria and mycotoxigenic fungi with inhibition zone diameters ranging from 7.2 to 11.2 mm and minimum inhibitory concentration (MIC) values ranging between 0.04 and 4.2 mg mL-1. The results revealed that globe artichoke bracts and receptacles could possess important antioxidant and antimicrobial properties that may improve its quality as a functional food.