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.

Anticoagulant and antibacterial activities of polysaccharides of red algae Corallina collected from Lebanese coast.

In this work, we studied another species of red algae, Corallina, growing on the Lebanese coast of Batroun. The analysis of trace elements showed that Corallina was rich in K, Ca, Mg, Na, Si, Sr, P and Fe. Corallina was composed of 70.81% of saturated fatty acids, 25.54% of monounsaturated fatty acids and 3.65% of polyunsaturated fatty acids with palmitic acid as the main component. Moreover, the total yield of sulfated galactans and carrageenan was 2.5% and 10%, respectively. Both extracts exhibited anticoagulant effect but sulfated galactans were less potent than carrageenan. Sulfated galactans possessed inhibitory activity as well as bactericidal activity against all Gram-positive strains tested (Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis CIP 444). But, carrageenan was only able to inhibit the growth of S. epidermidis with a minimal inhibitory concentration (MIC) of 0.325 mg/mL. Furthermore, infrared spectroscopy (IR) revealed that the isolated carrageenan was of Lambda-type. Corallina could therefore be considered as a potential source of bioactive molecules that may be useful for the development of new pharmaceutical agents.

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.