International audiencePurified sodium alginate (PS alginate) was isolated from the brown seaweed Sargassum vulgare collected from the Lebanese Mediterranean coast and then depolymerized into homopolymeric polyguluronate (PolyG) and polymannuronate (PolyM) blocks by controlled acid hydrolysis. These fractions of PS alginate issued from S. vulgare were characterized in terms of composition and structure by SEC, elemental analysis, FTIR and 1H and 13C NMR spectroscopy. An alginate with a low content of protein (\textless0.62 %) and a molecular weight of 110 200 g mol-1 was identified as sole polysaccharide. Depolymerized PS alginate fractions, PolyG (32.6 %) and PolyM (22.3 %), were found to have close molecular weights, of 7500 and 6900 g mol-1, respectively. From NMR analysis, values of F G, F M, M/G ratio, F GG, F MM, and F GM (or F MG) blocks were determined and compared with those of alginates from S. vulgare of Brazilian origin and other Sargassum species. Our PS alginate appeared different from the Brazilian S. vulgare alginate, with a lower M/G ratio (0.785 instead of 1.27), a predominance of the G blocks (F G and F GG \textgreater 0.5) instead of the M blocks, and it showed more similarity to the composition of some alginates extracted from other species of Sargassum. High G or M contents (≥80 %) were measured from PolyG and PolyM blocks, respectively. The viscosity of the PS alginate and its fractions PolyG and PolyM was determined. PS alginate from S. vulgare of Lebanese origin showed a Newtonian flow behavior for concentration lower than 0.5 % in 0.1 M NaCl solution, while a shear-thinning pseudoplastic behavior is observed for concentration range between 0.75 and 10 %. Also, storage (G′) and loss (G″) moduli were studied for two concentrations of PS alginate solutions (5 and 10 %). Antioxidant properties of the non-depolymerized and depolymerized alginates were evaluated by determining the scavenging ability of the stable radical DPPH (2,2-diphenyl-1 picrylhydrazyl). Clearly, the results demonstrated differences in radical scavenging efficacy between PolyG and PolyM fractions. The higher hydroxyl radical scavenging activity was observed for the PolyG fractions (~92 % at 2 mg mL-1) and this activity was comparable with those of standard antioxidants. These PolyG fractions could be valuable in foods or pharmaceutical products as alternatives to synthetic antioxidant
Colon carcinogenesis is ranked second globally among human diseases after cardiovascular failures. Bee venom (BV) has been shown to possess in vitro anticancer effects against several types of cancer cells. The two main biopeptides of Apis mellifera BV, namely, melittin (MEL) and phospholipase A2 (PLA2), are suspected to be the biomolecules responsible for the anticancer activity. The present work aims to evaluate the cytotoxic effect of the A. mellifera venom on human colon carcinoma cells (HCT116), and to assess the synergistic effect of MEL and PLA2 on these cells. After analyzing, through high-pressure liquid chromatography, the proportions of MEL and PLA2 on BV, we have established a cell viability assay to evaluate the effect of BV, MEL, PLA2, and a mixture of MEL and PLA2 on the HCT116 cells. Results obtained showed a strong cytotoxicity effect induced by the A. mellifera venom and to a lower extent MEL or PLA2 alone. Remarkably, when MEL and PLA2 were added together, their cytotoxic effect was greatly improved, suggesting a synergistic activity on HCT116 cells. These findings confirm the cytotoxic effect of the A. mellifera venom and highlight the presence of synergistic potential activities between MEL and PLA2, possibly inducing membrane disruption of HCT116 cancer cells. Altogether, these results could serve as a basis for the development of new anticancer treatments.
Chickpea flour is known to have good nutritional values. Nevertheless, it is commonly made from ground grains, and characterized by an “off-flavor”. Processing of chickpea grains before flour formation reduces the intensity of the off-flavor. Therefore, two experiments were conducted: first to examine the effect of conventional processing (soaking, boiling, and drying) on the nutritional composition of the chickpea flour; and second, to investigate the impact of processed chickpea flour incorporation with different ratios on the sensory properties of mankoushe zaatar, a popular Lebanese pastry, usually made up of refined wheat flour. Chickpea flour was found to be nutritionally superior compared to refined wheat flour, and conventional processing of the flour was found not to affect its content of protein, fats, carbohydrates, and phosphorus, while total dietary and crude fibers were significantly increased. The fatty acid profile was minimally affected, while magnesium and potassium were reduced. The sensory test conducted among panelists (n = 60) showed that the incorporation of processed chickpea flour into the dough of mankoushe zaatar with ratios of 30% and 50% provided an end-product with better taste and overall acceptability compared to the regular mankoushe. Hence, conventionally processed chickpea flour can be used as a fortifier to improve the nutritional quality of bakery products without negatively affecting their sensory properties.
Supplementary InformaƟon (ESI) available: Supplementary data include 1 H NMR, 13 C (JMod) of guluronate monomers 1-3 and fractions enriched in α or β furanosides or pyranosides in the D-mannuronamide or L-guluronamide series, isolated after silica gel column chromatography of the GulC4N12, GulC4N18, AlgC4N12 and AlgC4N18 compositions.We describe here an efficient one-pot process for the synthesis of 100% bio-based L-guluronic acid based surfactant compositions as emulsion stabilizers, directly from L-polyguluronate or whole alginate, a renewable polysaccharide extracted from brown seaweeds. The transformation of these polymers into long-chain alkyl-L-guluronamides associated with D-mannuronamides when alginate was used, has been achieved through the prepararation of n-butyl uronate monosaccharide intermediates involving methane sulfonic acic-promoted hydrolysis, Fisher glycosylation and esterification reactions, followed by in situ solvent-free aminolysis reaction with fatty amines.
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