Abstract:In this study, the optimal conditions for extracting polyphenols from artichoke leaves were investigated using single factor and orthogonal tests. The antioxidant and antibacterial activities of the polyphenol extracts from artichoke leaves before and after the purification by macroporous resins were compared. The results showed the optimal extraction conditions were: extraction solvent, 70% ethanol; sample/solvent ratio, 1:20 (g/mL); ultrasonic time, 40 min. Under these conditions, the total phenol content of the extract from artichoke leaves was 88.36 mg/g. Based on the comparison of static adsorption and desorption of nine macroporous resins, NKA-2 resin was found to be the best option for purification of the polyphenol extract. After such purification, the antioxidant activity of the purified polyphenol extract from artichoke leaves was significantly increased e.g. the IC50 values of 1-diphenyl- 2-trinitrobenzene hydrazine (DPPH) and 2, 2'-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) radical scavenging decreased to 32.30±0.25 μg/mL and 107.98 ± 0.42 μg/mL from 82.79 μg/mL and 251.30 μg/mL, respectively. In addition, the purification process significantly improved the antibacterial effect of the extract from artichoke leaves, including the inhibition of Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Monilia albican, Pseudomonas aeruginosa and Lactobacillus. In summary, this work provides a scientific basis and theoretical foundation for the extraction, purification and application of the polyphenols from artichoke leaf.
