Chenopodium ambrosioides var. ambrosioides used in Moroccan traditional medicine can enhance the antimicrobial activity of conventional antibiotics.

Chenopodium ambrosioides var. ambrosioides is used in the folk medicine as analgesic, antipyretic, antioxidant and to cure gastrointestinal disease, typhoid and dysentery. The chemical composition of the aerial part essential oil was assessed by GC/MS analysis and the main constituents found were: α-terpinene (23.77%), ascaridole (14.48%), p -cymene (12.22%), neral (8.08%), geraniol (5.60%), isoascaridole (2.96%) and 2-carene (2.77%). The antioxidant assays using (DPPH) free radical, β-carotene-linoleic acid and reducing power assays showed that C. ambrosioides var. ambrosioides essential oil presents a moderate antioxidant effect using DPPH assay and a high effect using both β-carotene/linoleic acid bleaching (IC 50 = 3.03 μg/ml) and reducing power assay (IC 50 = 6.02 μg/ml). The antimicrobial properties of the essential oil against a large panel of Gram-positive and Gram-negative bacteria and Candida strains showed an inhibitory effect against all tested strains. Gram-positive bacteria ( Bacillus cereus , Micrococcus luteus ) were generally found to be more sensitive than Gram-negative ones. Moreover, Candia albicans was the most sensitive for Candida strains. The in vitro association of essential oil and some commercial antibiotics showed a synergistic effect between studied essential oil and antibiotics. The lowest FICi values observed were obtained with the combination essential oil and cefixime (FICi = 0,37–0,50) and essential oil-ciprofloxacin (FICi = 0,28–0,75), respectively, for Gram-positive and Gram-negative bacteria. Whereas, the association essential oil-fluconazole showed total synergistic effect for the most used yeast. These results showed that the essential oil exhibited a high antimicrobial and antioxidant activities and a synergistic interaction between antibiotics. These findings are very promising and it can be useful for pharmaceutical treatment and natural therapies. [ABSTRACT FROM AUTHOR]