Determination of Phenolic Contents, Antioxidant and Antibacterial Activities of Strawberry Tree (Arbutus unedo L.) Leaf Extracts

Aims: This study was designed to evaluate the antibacterial and antioxidant activities of methanolic, ethanolic, ethyl acetate and n-hexanic extract from the leaves of Strawberry tree (Arbutus unedo L.) growing in Morocco.

Study Design: Determination of total phenol and flavonoids content, in vitro antioxidant activity and antibacterial study of extracts.

Place and Duration of Study: Department of Biology (Faculty of Sciences), between July 2015 and November 2015.

Methodology: The extracts were prepared using solid-liquid extraction. The total phenolic content was assessed by the Folin-Ciocalteau assay, total flavonoid content was assessed by aluminium chloride (AlCl3) colorimetric assay. The antibacterial activity of extracts was tested against five reference strains, Escherichia coli K12 MBLA, Staphylococus aureus CECT 976, Listeria monocytogenes serovar 4b CECT 4032 and Pseudomonas aeruginosa IH using the agar well diffusion method and the micro-dilution assays. The antioxidant activity was assessed by measuring the ability of the extracts to scavenge the 2,2-diphenyl-1- picrylhydrazyl (DPPH).

Results: The total phenol content of strawberry tree five extracts ranged between 94.51±0.08 and 141.72±0.56 mg GAE/g extract, and the flavonoid content ranged between 17.48±1.02 and 31.61±0.59 mg QE/g extract. All of the extracts presented antioxidant capacity assessed by DPPH scavenging method, but at different levels depending on the concentration and the extraction solvent are found. In addition, all extracts exhibited an antibacterial activity at different levels against strains reported as the causal agents of food borne diseases.

Conclusion: Results suggest the potential use of tested A. unedo extracts as bio-preservatives in the functional food industry.