Objective: To extract and identify the chemical composition of the polysaccharide isolated from the Eucalyptus cultivated in Lebanon and to evaluate its antioxidant activity. Materials: The water-soluble polysaccharide was isolated from Eucalyptus leaves, and its structure was identified by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance. The antioxidant activity of the active ingredient was screened for its radical scavenging ability using 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH) test. Results: The results of the DPPH test have shown that fucoidan, the polysaccharide isolated from Eucalyptus, exhibited almost the same antioxidant activity against DPPH$as the ascorbic acid did at 100 mg/mL. Conclusions: This natural molecule extracted from a medicinal plant has a promising antioxidant activity and could be used in pharmaceutical and medical applications.

Objective To extract and identify the chemical composition of the polysaccharide isolated from the Eucalyptus cultivated in Lebanon and to evaluate its antioxidant activity. Materials The water-soluble polysaccharide was isolated from Eucalyptus leaves, and its structure was identified by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance. The antioxidant activity of the active ingredient was screened for its radical scavenging ability using 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH) test. Results The results of the DPPH test have shown that fucoidan, the polysaccharide isolated from Eucalyptus, exhibited almost the same antioxidant activity against DPPH· as the ascorbic acid did at 100 μg/mL. Conclusions This natural molecule extracted from a medicinal plant has a promising antioxidant activity and could be used in pharmaceutical and medical applications.

Objective: To evaluate the antibacterial activity of the extracts of Laurus nobilis against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis CIP 444) and two Gram-negative bacteria (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853). Also, the antibiofilm activity has been investigated against the biofilm produced by Staphylococcus epidermidis CIP 444. Materials: The polysaccharides, essential oil, and fatty oils extracted from the plant were used in broth microdilution methods to study the minimal inhibitory concentration, and then the minimal bactericidal concentration was determined. Results: The results showed that alginate, fucoidan, fatty oils and essential oil have good antibacterial activities against the 5 bacterial strains, and a negligible biofilm eradication activity of fucoidan, laminaran, fatty oil, and essential oil was observed, but a promising biofilm eradication activity was obtained with alginate, which showed a reduced biofilm mass even at low concentration. Conclusions: The extracts obtained have promising antibacterial capacities which need further investigation for them to be incorporated in medical or nutritional applications.