Antioxidant activity and evidence for synergism of Cannabis sativa (L.) essential oil with antimicrobial standards

The present work was conducted to study the antioxidant activity and to determine for the first time the antimicrobial potential of Moroccan Cannabis sativa essential oil (EO) singly or in combination with two conventional antibiotics (fluconazol and ciprofloxacin) against some resistant and pathogenic microorganisms. The chemical composition analyzed by means of GC/MS showed that C. sativa EO was characterized by the dominance of (E)-caryophyllene (35.0%), α-humulene (12.8%) and caryophyllene oxide (10.6%). Results from antioxidant tests showed that C. sativa EO exhibit a moderate potency (IC50 = 1.6 ± 0.1 mg/m L for 2,2- diphenyl-1-picrylhydrazyl (DPPH) assay, IC50 = 1.8 ± 0.2 mg/mL for β-carotene/linoleic acid assay, and IC50 = 0.9 ± 0.1 mg/m L for ferric reducing power assay). Regarding antimicrobial assays, the results demonstrated that C. sativa EO displayed interesting antimicrobial activities with minimum inhibitory concentration (MIC) values in the range from (1.2 to 37.8) mg/m L for tested microorganisms. The combination of the studied EO with fluconazol and ciprofloxacin showed a significant decrease in their individual MICs. In fact, at sub-inhibitory concentrations, C. sativa EO contributed to the decrease of ciprofloxacin MICs of bacterial strains by 2- to 64-fold and by16-fold regarding fluconazol MICs against Candida spp. These findings suggest that C. sativa EO can be considered as a potential source of natural antioxidant and antimicrobials, and constitute in combinational treatments a promising strategy to overcome the intense use of antibiotics against some infectious diseases.