Chemical composition, antioxidant, antimicrobial and antibiofilm activities of essential oil from the Moroccan endemic Plant, Calendula maroccana (Ball) B. D. Jacks.

The chemical characterization of the essential oil of the endemic Moroccan species, Calendula maroccana, was achieved by GC and GC-MS methods. The antioxidant, antimicrobial and antibiofilm activities of this essential oil were also studied. Eighty-one compounds were identified in the essential oil, representing 94.82% of the total. Sesquiterpenes predominate in the essential oil; 2-Methoxy-4-vinylphenol (16.13%), delta-amorphene (13.56%), alpha-cedrene (6.23%), gamma-curcumene (5.10%) and alpha-bisabolol (4.94%) were the main constituents. The antioxidant potential was evaluated by DPPH, FRAP and ABTS assays: the essential oil exhibited antioxidant effectiveness with IC50 values of 0.92, 0.3 and 1.7 mg/mL, respectively. Moreover, the essential oil showed potent antimicrobial activity as revealed by inhibition zone values against selected clinically important pathogenic microorganisms. Inhibition zone values of 15.33 +/- 0.19, 23 +/- 0.05 and 15.33 +/- 0.33 mm were observed against Staphylococcus aureus, Candida albicans and C. tropicalis, respectively. The maximal and minimal inhibition concentration values were in the range of 0.25 +/- 0.17 - 4.68 +/- 0.10 mg/mL for bacteria and 0.06 +/- 0.03 - 0.12 +/- 0.14 mg/mL, for Candida. The essential oil showed potent anti-biofilm activity with dual actions, inhibiting (69 - 88%) and eradicating (75 - 92%) the biofilms formed by the three tested bacteria strains. Based on these results, this essential oil can be considered as a natural antioxidant, antibacterial and antibiofilm agent that could be applied in phytotherapy, pharmaceutical and food sectors.