Chemical Composition of Different Extracts from Echinacea purpurea (L.) Moench Roots and Evaluation of Their Antimicrobial Activity

Abstract

This research aimed to reveal the chemical composition of different fractions obtained by sequential extraction of purple coneflower (Echinacea purpurea) roots and to evaluate the antimicrobial activity of some of them. Hexane, chloroform, ethyl acetate, and water were used as solvents to obtain the corresponding extracts. A GC-MS analysis was employed to reveal the chemical composition of hexane, chloroform, and ethyl acetate fractions. Conventional and ultrasound-assisted water extraction was performed to isolate inulin-type polysaccharides. Eighteen microorganisms were used for testing the antimicrobial activity of the obtained organic extracts. From GC-MS analysis more than forty compounds were detected in the fractions, including fatty acids, organic acids, fatty alcohols, sterols, and terpenes. Only in ethyl acetate extract were found mannitol and fructose isomers, while in chloroform extract were detected α- and β-amyrin, and betulin. Ethyl acetate fraction demonstrated the highest antimicrobial activity against 11 microorganisms (Bacillus cereus, B. amyloliquefaciens, Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritis, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, Saccharomices cerevisiae, and Peniclium sp.). The polysaccharide fractions were structurally characterized by FT-IR and NMR studies as linear inulin having β-(2→1)-linked Fru units and a T-Glc unit linked α-(1→2). Inulin from coneflower roots showed poor flowability, promising bulk and tapped density, swelling properties, and better oil-holding than water-holding capacity. This study demonstrated the potential of coneflower root fractions as a rich source of phytochemicals with antimicrobial activities and potential prebiotic activity due to inulin content (15% yield) and echinacea root as a useful biobased industrial crop/material.