Antibacterial and Antioxidant Activity of Traditional Medicinal Plants from the Balkan Peninsula

Abstract

Negative effects of available antibiotics and the constant development of bacterial resistance motivate a search for new antimicrobial agents. Aromatics plants have traditionally been used as antibacterial agents and are well accepted today as a source of antioxidants. The present study evaluated the antibacterial activities and antioxidant capacity of eight aromatic plants, indigenous to the flora of the Balkan Peninsula, which are used as medicinal plants in traditional medicine. The plants studied were Hyssopus officinalis, Angelica pancicii, Angelica sylvestris, Laserpitium latifolium, Achillea grandifolia, Achillea crithmifolia, Artemisia absinthium and Tanacetum parthenium. The antimicrobial activities of methanolic extracts of the plant tissues against 16 bacterial isolates of Escherichia coli, Pseudomonas aeruginosa, Klebsiella sp., Proteus mirabilis, Acinetobacter sp., Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae and Enterococcus faecalis were investigated using a microwell dilution assay. Minimal inhibitory concentration (MIC) of the extracts ranged from 6.3 to 100 mg mL^-1, and minimal bactericidal concentration (MBC) ranged from 12.5 to 100 mg mL^-1. Antioxidant potential of the extracts was analyzed as contents of total phenols and flavonoids; radical scavenging activity by the ABTS⁺ and DPPH methods, and reducing power by the iron (III) to iron (II) reduction assay, and the ferric reducing antioxidant power assay (FRAP). Results of antioxidative activities from the 4 methods demonstrated similar sequence of activity: A. crithmifolia > A. grandifolia > H. officinalis > A. absinthium > T. parthenium > L. latifolium > A. pancicii > A. sylvestris. The total content of polyphenols and flavonoids in the methanol extracts of the studied species positively correlated with their antioxidant properties, confirming their major role in antioxidant activity of these species.