Antimicrobial Activity and Multi-therapeutic Potential of Salvia officinalis and Mentha longifolia Essential Oils in Leaves

The objective of the current work was to test the antimicrobial impact of Salvia officinalis and Mentha longifolia collected from Al-Madinah city in Saudi Arabia and extracted by hydrodistillation versus Escherichia coli (ATCC25922), Enterobacter cloacae (ATCC13047), Candida tropicalis (ATCC 13803), and Aspergillus fumigates (ATCC46645). M. longifolia essential oils showed higher inhibition zones versus tested microorganisms, especially against E. coli and C. tropicalis. Minimal inhibitory concentrations of M. longifolia essential oils were determined for M. longifolia, where 3.9 and 62.5 µg/ml were the resulted values of the essential oils versus E. coli and C. tropicalis, respectively. Antioxidant impact of essential oils from both plants was compared using a DPPH assay where, M. longifolia showed the most promising antioxidant action with an IC50 of 88.73 ± 2.59 µg/ml. Transmission electron microscopic examination was applied after treatment of E. coli and C. tropicalis using M. longifolia essential oils, which showed their impact to destroy tested bacterial and fungal microbes as standard drugs. M. longifolia essential oils were further tested versus colorectal cancer cells, showed their cytotoxic impact versus cancer cells with an IC50 of 97.61 ± 1.8 μg/ml and confirmed by flow cytometric analysis, which showed that treated cells by M. longifolia essential oils dramatically elevated their apoptotic rate (P< 0.05) compared to untreated Caco-2 cells. M. longifolia essential oils showed minimal cytopathic action versus Vero cells, which revealed their potency. These results illustrated the possible pleiotropic experimental roles of M. longifolia growing in Al-Madinah City to be applied in pharmaceutical applications after in vivo confirmation of results.