Chemical Composition And Synergistic Effect Of Three Moroccan Lavender Eos With Ciprofloxacin Against Foodborne Bacteria: A Promising Approach To Modulate Antimicrobial Resistance

The aim of this study was to determine the chemical profile of the essential oils (EOs) of three Moroccan lavender species (Lavandula pedunculata, LP; Lavandula angustifolia, LA; and Lavandula maroccana, LM) and to investigate, for the first time, the synergistic effect of the optimal mixture of the EOs with conventional antibiotic ciprofloxacin against three pathogenic foodborne bacteria. Gas chromatography/mass spectrometry analysis showed that eucalyptol (39 center dot 05%), camphor (24 center dot 21%) and borneol (8 center dot 29%) were the dominant compounds of LA-EO. LP-EO was characterized by the abundance of camphor (74 center dot 51%) and fenchone (27 center dot 06%), whereas carvacrol (42 center dot 08%), camphor (17 center dot 95%) and fenchone (12 center dot 05%) were the main constituents of LM-EO. EOs alone or combined showed a remarkable antimicrobial activity against the tested bacteria with minimum inhibitory concentrations (MICs) ranging from 3 center dot 53 to 15 center dot 96 mg ml(-1). The optimal mixture, calculated using a mixture design, corresponded to 19% LA, 38% LP and 43% LM. All combination of the EOs and the best EO mixture with ciprofloxacin exhibited a total synergism with fractional inhibitory concentration index values ranging from 0 center dot 27 to 0 center dot 37. The best EO mixture showed the highest gain of 128-fold, especially against Salmonella spp., more than that found testing the EOs separately. These findings should be taken into consideration for a possible application in the pharmaceutical and food industries.