Protective potential effects of fucoidan in hepatic cold ischemia-rerfusion injury in rats.

The necessity to increase the efficiency of organ preservation has pushed physicians to consider the use of pharmacological additives in preservation solutions to minimize ischemia reperfusion injury. Here, we evaluated the effect of fucoidan, sulfated polysaccharide from brown seaweed, as an additive to IGL-1 (Institut Georges Lopez) preservation solution. Livers from Wistar rats were preserved for 24 h at 4 °C in IGL-1 solution, enriched or not with fucoidan (100 mg/L). Thereafter, they were subjected to reperfusion (2 h, at 37 °C) using an isolated perfused rat liver model. The addition of fucoidan to IGL-1 solution reduced hepatic injury (AST, ALT) and improved liver function compared to IGL-1 solution without fucoidan. In addition, we noted a significant increase in the phosphorylation of AMPK, AKT protein kinase and GSK3-ß, leading to a reduction in VDAC phosphorylation, as well as a reduction in apoptosis (caspase 3), mitochondrial damage, oxidative stress and endoplasmic reticulum (ER) stress markers. Furthermore, ERK1/2 and P38 MAPKs phosphorylation significantly decreased after supplementation of IGL-1 solution with fucoidan. In conclusion, the supplementation of IGL-1 solution with fucoidan maintained liver graft integrity and function through the prevention of the ER stress, oxidative stress and mitochondrial dysfunction. Fucoidan could be considered as potential natural therapeutic agent to alleviate graft injury.

Characterization of sulfated polysaccharide from Laurencia obtusa and its apoptotic, gastroprotective and antioxidant activities.

This study was designed to characterize the physico-chemical properties of the sulfated polysaccharide (SP) isolated from the red alga Laurencia obtusa and to evaluate its apoptotic, gastroprotective and antioxidant activities. The different macromolecular characteristics of SP were determined by size exclusion chromatography combined with multi-angle laser light-scattering detection (SEC-MALLS), Fourier transform infrared spectroscopy (FTIR) analysis and nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). The native molecular weight of the extracted polysaccharide is high (≥336,900 g·mol-1). It showed high amounts of sulfated groups (28.2%) and low levels of proteins. It was found to be a potent inducer of apoptosis on acute monocytic leukaemia THP-1cell lines with EC50 value of 53 µg·mL-1. Furthermore, a significant gastroprotective effect (p < 0.01) was also observed with a gastric ulcer inhibition of 63.44%, 78.42% and 82.15% at the doses 25, 50 and 100 mg·kg-1, respectively. In addition, SP significantly increased glutathione levels (GSH) and decreased the concentration of thiobarbituric acid-reactive substances (TBARS) in EtOH/HCl-damaged gastric mucosa in rats; it also exhibited an important antioxidant activity in vitro. Therefore, SP, derived from the red alga Laurencia obtusa, may have a potential therapeutic effect against acute myeloid leukaemia and a beneficial potential as gastroprotective and antioxidant natural product.

Influence of the uronic acid composition on the gastroprotective activity of alginates from three different genus of Tunisian brown algae.

Alginates from three genus of Tunisian brown algae were isolated and characterized by size exclusion chromatography and Solid-state NMR spectroscopy. Alginate from Padina pavonica (APP) had the highest molecular weight (Mw) with 147,000g/mol while it was 85,000g/mol for alginate from Cystoseira compressa (ACC) and 58,000g/mol for alginate from Dictyopteris membranaceae (ADM). The mannuronate (M) to guluronate (G) ratios were estimated from spectral deconvolution of the 13C CP/MAS spectra and the results has shown that all the extracts are mannuronic acid-rich alginates with M/G ratio increased in the order ADM - ACC - APP. An interesting gastroprotective effect was observed for the extracts; ADM and ACC exhibited the highest inhibition of gastric lesions, at 50mg/kg, with 83.41% and 75.39% respectively. Otherwise, it has been shown that the gastroprotective effect of alginates depends mainly on their uronic acid composition.