The current study aimed to investigate ethanolic extracts from the following medicinal plant species cultivated in western Romania: Melissa officinalis L., Rosmarinus officinalis L. (RO) and Salvia officinalis L. (SO). Antioxidant activity, total phenolics content and a profile of the main hydroxycinnamic acids (HCAs), including caffeic, ferulic, coumaric and rosmarinic acids, was determined for each plant extract. The in vitro antimicrobial activity against four bacterial strains (Escherichia coli, Listeria-, Pseudomonas aeruginosa and Staphylococcus aureus), and the effect on cell viability in two melanoma cell lines (B164A5 murine melanoma and A375 human melanoma) was also assessed. The results indicated that total phenolics content was 73.76-274.73 mg GAE·g-1 and the antioxidant activity was 2.32-2.87 mM Fe2+·100 g-1. There was found a strong positive correlation (R=0.9691) between total phenolics content and the antioxidant activity in the investigated samples. Regarding the HCA profile obtained by high performance liquid chromatography, the results demonstrated that rosmarinic acid represents the main identified compound. The ethanolic extracts of RO and SO exhibited antibacterial activity against Gram positive and Gram negative bacteria. RO was the most effective in terms of decreasing the cell viability of murine and human melanoma cell lines, while the HCAs did not exhibit any effect on cell viability. These findings suggest that plant extracts from the Lamiaceae family may used in the clinic as natural antibacterial agents.
Keywords: A375 human melanoma; B16 4A5 murine melanoma; Melissa officinalis L.; Rosmarinus officinalis L.; Salvia officinalis L.; antibacterial; antioxidant; hydroxycinnamic acids; total polyphenols.