Phytochemical Composition and Antimicrobial Properties of Burdock (Arctium lappa L.) Roots Extracts

Burdock (Arctium lappa L.) roots were used as a medicinal plant or vegetable worldwide. The research aimed to obtain different fractions by sequential extraction (hexane, chloroform, ethyl acetate water) of burdock roots and to evaluate phytochemical compounds in them. Antioxidant and antimicrobial properties of nonpolar fractions were evaluated. Ethyl acetate fraction contained the highest total phenolics, total flavonoids, and derivatives of caffeic acids. Phenolic acids (mainly chlorogenic, caffeic acid, and p-coumaric acids) were detected only in the ethyl acetate fraction, while in the hexane fraction was found only triterpenes. Due to the high polyphenol content, the ethyl acetate fraction demonstrated the highest antioxidant activity. Three fractions revealed antimicrobial activity against Salmonella sp., Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus, Bacillus cereus, and Candida albicans. The lowest minimum inhibitory concentration (>1 mg/ml) showed an ethyl acetate fraction against Pseudomonas aeruginosa and Bacillus cereus. From the water fraction was isolated inulin-type fructan with a degree of polymerization 20-24 with promising functional properties. This study showed the potential application of burdock root fractions as a rich source of phytochemicals with antimicrobial, antioxidant activities, and potential prebiotic effect due to the 7 g/100 g inulin content in them.