The antioxidant and antimicrobial activities of Echinacea purpurea L. methanolic extracts

The antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by ultrasound-assisted extraction were investigated. The aerial parts of plants were extracted at room temperature with 70% ethanol at a solid:liquid ratio of 1:10 (w/v). Each of the measurements was carried out in three repeated experiments.

Total contents of phenolic compounds and flavonoids were determined by Folin-Ciocalteu [1] and aluminium chloride colorimetric method [2], respectively. Total phenolic and flavonoid content were 46.8±0.29mg gallic acid equivalents (GAE)/g dry extract and 27.0±0.39mg rutin equivalents (RE)/g dry extract, respectively. The antioxidant activity of Echinacea purpurea L. extract was determined using the DPPH free radical method [3]. 2,2-Diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the EC₅₀ concentration for the inhibition of 50% DPPH was 1.88±0.02µg/µg DPPH. Antimicrobial activity of Echinacea purpurea extract was evaluated by an agar well-diffusion method against seven microorganisms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Candida albicans, Saccharomyces cerevisiae and Aspergillus niger. The results indicate that the extract showed a considerable growth inhibition on Candida albicans and Saccharomyces cerevisiae while no growth inhibition zones were observed only for Aspergillus niger.

Acknowledgements: Ministry of science and environmental protection, Republic of Serbia projects OI 142073b.

References: [1] Singleton V. L., Rossi J. A., (1965) Amer. J. Enol. Viticult. 16 (3): 144–158. [2] Chang C. et al.(2002) J. Food Drug Anal. 10 (3): 178–182. [3] Choi C.W. et al. (2002) Plant Sci. 163(6): 1161–1168.