ALBERT

Description: Atriplex semibaccata R.Br. is a perennial halophyte that has received much attention for studies of revegetation of marginal lands in arid and semi-arid environments. It was, recently, demonstrated that there are no risks in terms of contamination of essential oil (EO) from growing plant on such land. Interest in exploring the antibacterial and antioxidant potential of A. semibaccata EO has consequently been renewed. The objective of this study was to investigate the chemical composition, as well as the antioxidant and antibacterial activities of A. semibaccata EO. The antibacterial activity was evaluated against native (drug-sensitive) and multidrug-resistant (MDR) bacteria by testing the EO alone and in combination with conventional antibiotics. The chemical composition of EO was analyzed by gas chromatography/mass spectrometry, 52 chemical compounds were identified, and 2-Methoxy-4-vinyl phenol (48.9%), benzaldehyde (6.7%), and benzyl alcohol (6.3%) were found to be the main constituents of EO. Furthermore, the antioxidant activity was evaluated using a 2,2-diphenyl-1-picrylhydrazyl reducing–scavenging test. The EO from this species possessed high antioxidant activity (938.65 μg TE/g EO). The antibacterial test demonstrated an inhibitory effect on six native and MDR bacterial strains. We found that Staphylococcus aureus (Gram+), Klebsiella pneumoniae (Gram−), and Escherichia coli (Gram−) were more sensitive than MDR strains, with an inhibition zone ranging from 11.16 mm to 12 mm. Moreover, the minimum inhibitory concentration ranged from 3.12 mg/mL to 6.25 mg/mL. The combination of gentamicin and EO revealed a high synergistic effect. The effect on S. aureus and K. pneumoniae showed lower fractional inhibitory concentration indices of 0.39 and 0.27, respectively. The results also revealed that A. semibaccata EO contained compounds with antibacterial potential against MDR bacteria, with antioxidant properties, and with a moderate synergistic effect in combination with gentamicin. The EO from A. semibaccata could be considered a new and potential source of natural antioxidant and antibacterial agents. These findings make A. semibaccata an excellent choice for the revegetation of marginal lands with the subsequent use of biomass for the production of EO with significant potential in the control of microbial infection.

Description: The abandoned Kettara pyrrhotite mine, located near Marrakech, Morocco, is an acid mine drainage (AMD) producer site. A store-and-release cover system made of phosphate wastes was built to prevent water infiltration and the formation of AMD. This cover system should be vegetated with appropriate plants to ensure its long-term sustainability and allow its reintegration in the surrounding ecosystem. Several indigenous plant species were studied. The choice of plant species was based mainly on their tolerance to trace elements contained in the phosphate wastes, and their low capacity to translocate these metals to their aboveground parts in order to limit the risk of pollutants transfer along the food chain. The main metals and metalloids (As, Cd, Co, Cu, Pb, Zn, Ni, Cr) are determined in 13 dominant plants naturally colonizing the store-and-release cover and their rhizospheric soils. The results showed that the phosphate cover contained high concentrations of Cr (138.04 mg/kg), Cu (119.86 mg/kg) and Cd (10.67 mg/kg) exceeding the regulatory thresholds values (Cr 〉 100 mg/kg, Cu 〉 100 mg/kg, Cd 〉 3 mg/kg). The studied plants revealed no hyper-accumulation of metals and metalloids, and lower concentrations in shoots than in roots. Six species (Plantago afra, Festuca ovina, Aizoon hispanicum, Herniaria cinerea, Echium plantagineum and Asphodelus tenuifolius) have bioconcentration factors greater than 1, and weak translocation factors, identifying them as appropriate candidates for phytostabilization of the phosphate cover.