Antioxidant and Antibacterial Activity of Extracts from Selected Plant Material

Plants are a valuable source of biologically active molecules, mainly phenolic compounds. In the present study, the total phenolic content (TPC), DPPH center dot and ABTS(+) scavenging activity as well as ferric reducing ability (FRAP) of aqueous ethanolic (70%) extracts of Cistus incanus L. and Asarum europaeum L. herb, Geum urbanum L. rhizome, Angelica archangelica L. root, white mulberry (Morus alba L.), lemon balm (Melisa officinalis L.), red raspberry (Rubus idaeus L.) and Betula pendula Roth. leaves were determined. In addition, the phenolic profiles of the studied plant extracts and antibacterial activity have been investigated. The extracts from C. incanus and G. urbanum demonstrated the highest TPC and antioxidant capacity, while the extracts from A. archangelica and white mulberry were characterized by the lowest values. A remarkable correlation was also found between the TPC and antioxidant activity of the examined extracts. HPLC analysis showed that the studied extracts were sources of both phenolic acids and flavonoids. More flavonoids than phenolic acids were identified in the extracts of C. incanus, M. alba, R. idaeus and B. pendula compared to the other extracts tested. Not all extracts showed a significant impact on the growth of the tested bacterial strains. Escherichia coli was the most sensitive strain to lemon balm extract (MIC, 0.125 mg/mL), whereas the strains of Acinetobacter baumannii and Bordetella bronchiseptica were sensitive to the G. urbanum extract (MIC, 0.125 mg/mL). Among Gram-positive bacteria, Enterococcus faecalis was the most sensitive to G. urbanum extract. In turn, Staphylococcus aureus and Staphylococcus epidermidis were sensitive to the extracts from C. incanus herb (MIC, 0.125 mg/mL), red raspberry (MIC, 0.125 mg/mL) and lemon balm leaves (MIC. 0.25 mg/mL). Based on the obtained results, the applicability of the studied plant extracts as additives to food and cosmetic products may be considered in the future.