Effect of extraction procedures on the chemical structure, antitumor and anticoagulant properties of ulvan from Ulva lactuca of Tunisia coast.

The effect of extraction procedures on chemical composition, structural, antitumor and anticoagulant properties of the sulphated polysaccharide 'ulvan' from the green seaweed Ulva lactuca were investigated. The structural features of ulvans were carried out by FTIR and by one- and two- dimensional 1H and 13C NMR spectroscopic. The ulvans were mainly composed of rhamnose, xylose, and uronic acid. Chemical and spectroscopic analyses demonstrated that ulvans were constituted of (1→4)-ß-glucuronic acid, (1→3,4)-α-L-rhamnose-3-sulphate and (1→4)-α-xylose. The extraction procedures effect were observed in chemical structure, Mw and biological activities. Cytotoxic activity of enzymatic-chemical extract on cervical cancer cells (HeLa) (IC50 = 1000 µg/mL) was higher than on normal peripheral blood lymphocytes cells (PBL). Acid extracts promoted to reduce HeLa cells and to grow PBL cells. At high concentrations, acid extracts showed the highest APTT and TT clotting time. Antitumoral and anticoagulant activities of ulvans from Ulva lactuca promote their use as effective therapeutic agent.

Smart ulvan films responsive to stimuli of plasticizer and extraction condition in physico-chemical, optical, barrier and mechanical properties.

Smart films were produced with ulvan extracted from the green seaweed Ulva. lactuca at different extraction conditions, by varying the glycerol or sorbitol in specific plasticizer concentration. Chemical composition and molecular weight characteristics of ulvans were carried out by GLC and HPSEC analysis, respectively. Regardless of the extraction procedure, the investigation revealed that ulvans were selected as reproducible and suitable materials of stimuli-responsive due to its peculiar chemical composition and self-aggregation molecular behavior. When using the terminology of stimuli-responsive system, we declare that the physico-chemical, barrier, optical, and mechanical characteristics of ulvan films system are strongly responsive to extraction conditions and to plasticizer type and concentration. As plasticizer concentration increased, thickness, moisture content (MC), water solubility, water vapor permeability (WVP), transparency, elongation at break (EAB), usually UV and visible light protection of ulvan films increased, while, their tensile strength (TS) decreased significantly. The films prepared with glycerol exhibited better solubility, transparency and mechanical properties, than those with sorbitol. However, the films formed with sorbitol had the greatest moisture resistance and more effective vapor, visible and UV light barrier as well as the lowest solubility. The FTIR spectra evidenced the expected outcome of the chemical interaction and miscibility kind between polysaccharides and plasticizers.

Effects of extraction procedures and plasticizer concentration on the optical, thermal, structural and antioxidant properties of novel ulvan films.

Active films were produced with sulphated polysaccharides "ulvan", extracted from the green seaweed Ulva lactuca with different extraction procedures, by varying the glycerol or sorbitol plasticizer concentration at 1% and 2% (w/v). The surface charge and glass transition temperature (Tg) of ulvans were carried out by zeta (ζ)-potential and DSC analysis, respectively. The investigation revealed that ulvans were anionic stable polymers and they had great Tg values. Regardless of the extraction procedure, ulvans can give successful films formulations. However, the optical, thermal, structural and antioxidant characteristics of ulvan films were strongly affected by extraction conditions and by the variation of the type and concentration of plasticizer. In general, as plasticizer concentration increased, ferrous chelating activity and compact structure increased as well, while, Tg, lightness and DPPH radical-scavenging activity decreased. Interestingly, the films plasticized with glycerol exhibited better compact structure, more negative temperature of transition, and greater free radical scavenging ability than with sorbitol. However, the films prepared with sorbitol had the highest L* values and chelating ability. The current study revealed a high correlation between zeta (ζ)-potential of ulvans and their Tg (R2 = 0.98), as well as with scavenging activity of ulvan films (R2 = 0.8-0.99).