Essential oils of Salvia bracteata and Salvia rubifolia from Lebanon: Chemical composition, antimicrobial activity and inhibitory effect on human melanoma cells

Aim of the study: Salvia bracteata Banks et Sol. and Salvia rubifolia Boiss. are known in folk medicine of Lebanon for the treatment of microbial infections, cancer, urinary and pulmonary problems. In the present study the chemical composition and antimicrobial activity of essential oils from aerial parts of Salvia bracteata and Salvia rubifolia collected in Lebanon were evaluated. The oils were also tested for their potential antiproliferative effects against M14 human melanoma cells. Material and methods: The oils were studied by GC and GC-MS and their antibacterial activity (MIC and MBC) was tested against ten bacteria species using the broth dilution method. The inhibitory effect on human melanoma cells (measurement of cell vitality, cell membrane integrity and genomic DNA fragmentation) was studied using MTT assay, calculation of LDH release and COMET assay. Results: The oils showed a good antibacterial activity (MIC = 50 μg/ml) against Gram+ bacteria. They besides exhibited an inhibitory effect on the human cancer cells examined inducing also apoptotic cell death, but the oil of Salvia rubifolia was significantly (p < 0.001) more active as compared to the oil of Salvia bracteata. Conclusion: The results on the pharmacological activities of these Salvia species provide an in vitro scientific support for the use of these plants in traditional herbal preparations.