Antibacterial and antioxidant properties of rosemary and sage (Rosmarinus officinalis L. and Salvia officinalis L.) essential oils

Use of aromatic plants in phytotherapy is mostly related to different activities of their essential oils, such as antimicrobial, spasmolytic, carminative, hepatoprotective, anticarcinogenic, etc. Many aromatic plants are today considered as the most important sources for the extraction of compounds with strong antioxidant activity [1]. Rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.), Lamiaceae, are two spices widely used in folk medicine, pharmacy and flavoring agents, but also designed as very powerful aromatic plants. In both spices, several phenolic diterpenes and phenolic acids were identified as major antioxidants [2]. However, for the same activity of essential oils very few data are available. Thus, the present study describes antimicrobial and antioxidant activity of rosemary and sage essential oils. Essential oils were obtained by the hydrodistillation and the chemical composition was evaluated by the means of GC-MS and TLC. Antibacterial activity was tested against 13 bacterial and 6 fungal strains by standard antibiogram assay [3]. Antioxidant activity was evaluated using DPPH- (2,2-diphenyl, 1-picrylhydrazyl) and TBA-test, following the effects of essential oils on Fe²⁺/ascorbate and Fe²⁺/H₂O₂ induced lipid peroxidation (LP) [3]. Both examined essential oils expressed strong antibacterial activity, especially on different Escherichia coli strains, Salmonella typhi and Shigella sonei. Rosemary essential oil exhibited stronger antifungal activity on five dermatomycetes and Candida albicans than sage oil. The investigated essential oils reduced the DPPH radical formation (IC₅₀=3.82µg/ml for rosemary and 1.78µg/ml for sage) in dose dependent manner. Strong inhibition of LP in both systems of induction was observed for the rosemary essential oil. Obtained results suggest that both essential oils could serve not only as flavour agents, but also as natural supplements in preventing deterioration of foodstuff, cosmetic and pharmaceutical products.

References: [1] Charalambous G. (Ed.) (1994) Spices, Herbs and Edible Fungi. Developments in Food Science. Elsevier Science, Amsterdam, Netherlands. [2] Loliger, J. (1991) Lipid Technology 3(1): 58–61. [3] Bzin et al. (2006) Journal of Agricultural and Food Chemistry 54: 1822–1828.