Antioxidant activity of water-soluble polysaccharide extracted from Eucalyptus cultivated in Lebanon

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.

The antioxidant and anticoagulant activities of polysaccharides isolated from the brown algae Dictyopteris polypodioides growing on the Lebanese coast.

In this study, we attempt to isolate the polysaccharides from the brown seaweed Dictyopteris polypodioides (Dp) growing on the Lebanese coast. The percentages of the main polysaccharide alginic acid were 4.6% in May and 6.25% in July. The extracted yields of Fucoidan, Laminaran and Mannuronan (FLM) and Mannuronan (M) alone were respectively 0.75% and 0.38% in May and 1.15% and 0.67% in July. We performed the infrared spectroscopy in order to reveal the functional groups of alginate and mannuronan. Moreover, a non-destructive technique ¹ H NMR was used to determine the structure of alginate and the distribution of guluronic (G) and mannuronic acid (M) in the chain, allowing us therefore to calculate the ratio M/G. The latter was 0.96 showing a strong ability of alginate to capture heavy metals. The analysis of trace elements showed great amounts of K, Si, Na and Mg in both seasons. Moreover, Dictyopteris appears to be rich in fatty acids (10 items) with palmitic and oleic acids as main fatty acids. Furthermore, the anticoagulant activity of polysaccharides was investigated by activated partial thromboplastin time (APTT) clotting assay and the antioxidant activity was studied by electrolysis method. It has been shown that the FLM and M fractions of Dictyopteris polypodioides have a significant antioxidant and anticoagulant activities. Further investigations are imperative in order to develop new molecules based on these polysaccharides to be used as drugs or for healthcare in general.