Comparative Analysis Of Chemical Composition, Antioxidant And Antibacterial Activities Of Mentha Rotundifolia Essential Oils From Algeria Extracted By Microwave And Hydrodistillation

The essential oil of Mentha rotundifolia (L.) Huds growing wild from East Algeria (Naciria at 60Km in East of Algiers) obtained by hydrodistillation (HD° and a microwave distillation process (MD) have been analysed by means of GC-FID and GC/MS in combination with retention indices. In total, 54 constituents were identified (accounting for 96.7 and 95.6% in HD and MD oils, respectively). The main components were piperitone oxide (25.1 and 29.1% in HD and MD oils, respectively), piperitenone oxide (8.9 – 11.8%), terpinen-4-ol (9.3 – 3.4%), β-caryophyllene (5.4 – 7.3%), allo-aromadendrene (5.3 - 6.4%) and Dgermacrène (5.4 – 7.1%). In comparison with HD, MD allows to obtain oil in a very short time, with the reduction of solvent used similar yields, comparable qualities and substantial savings of energy. The antioxidant activity was determined according to the ability of the tested samples to scavenge the free radicals 2,2- diphenyl-1-picrylhydrazyl (DPPH*). The essential oil were slightly active (32.6 and 21.8% in HD and MD oils, respectively) comparing with BHT (64.7%). The antibacterial activities of the essential oils indicated that Staphylococcus aureus was the more sensitive strain tested to the oils of Mentha rotundifolia with the strongest inhibition zone 28.3 for HD and 26.5 mm for MO.