[Show abstract][Hide abstract] ABSTRACT: Olive mill wastewater (OMWW), the main waste product of olive oil extraction process, was investigated as a source of polysaccharides. The yield of alcohol insoluble residue (AIR) was 20.5 % based on the dry matter of OMWW. Extraction with water gave water soluble (WSF) and insoluble (WIF) fractions from AIR with yields of 13.3 % (w/w) and 3.7 % (w/w) based on the dry matter, respectively. Chemical composition and monosaccharide analysis indicated that glucose was the main monosaccharide of these extracts in addition to galactose, arabinose, rhamnose, and galacturonic acid. Prebiotic and antioxidant activities of polysaccharidic fractions from OMWW were evaluated. Results gave evidence for their scavenging capacity toward the 2,2'-diphenyl-1-picrylhydrazyle (DPPH) (IC50 value of 89.43 μg/mL) and hydroxyl radicals (IC50 value of 158.70 μg/mL), resistance toward artificial human gastric juice, and ability to be fermented by Lactobacilli strains.
[Show abstract][Hide abstract] ABSTRACT: Physico-chemical and biological properties of native polysaccharides could be greatly improved by changing their primary structure, conformation, water solubility or acidity. Chitosan is well-known for its biological properties. Nevertheless, its poor water solubility and its high molecular weight limit its potential uses as biological agent. Enzymatic hydrolysis or regioselective oxidation can be used to overcome these limitations and give birth to new active oligosaccharides.
Firstly, chitosan was C-6 oxidized with NaOCl/NaBr in the presence of TEMPO. 13C NMR, FT-IR and conductimetry analyses confirmed the C-6 oxidation. The production yield was closed to 11 % (w/w) and the molecular weight estimated to 2 kDa by SEC-MALLS experiments. The potential degradability of the derivative was investigated by glycoside hydrolases and polysaccharide lyases. Macerozyme R-10, Glucanex® and a crude extract from Trichoderma reesei IHEM 4122 showed the best degradation results. Finally, the antiparasite activity of the derivative was evaluated against Leishmania infantum LIPA 137. The toxicity of C-6 oxidized chitosan (IC50 = 125µg/mL) was one hundred times higher than current products used against promastigotes.
TEMPO chemistry highlighted the possibility to produce short size, soluble and non-sulfated hyaluronan-like mimetics. These derivatives will be of great interest to design new drugs in leishmaniosis treatment.
3rd EPNOE International Polysaccharide Conference, Nice, France; 10/2013
[Show abstract][Hide abstract] ABSTRACT: The olive mill waste generated from olive oil extraction is a major environmental issue, particularly in Mediterranean areas. The extraction of olive oil is achieved through discontinuous or continuous processes. The two processes yield three fractions: a solid residue and two liquid phases (oil and olive mill wastewater). The characterization of these two by-products showed that they are mainly composed of phenolic compounds, carbohydrates, organic acids and mineral nutrients variably distributed depending on the process employed and the agronomic practices. Untreated olive by-products discharged between November and March into the environment are a major ecological issue for olive oil-producing countries due to their high toxic organic loads, low pH, and high chemical and biological demands. In this context, recent research studies highlight on the treatment approaches and valorization options for dealing with olive mill waste residues, predominantly those allowing for the recovery of valuable natural components such as phenolic compounds, dietary fibers, animal feed, biofuel, biogaz, enzymes, polymers and other. The impact of the chemical heterogeneity and water content of olive mill by-products about these processes of valorization and bioconversion is discussed.
PROCESS BIOCHEMISTRY 10/2013; 48(10-10):1532-1552. DOI:10.1016/j.procbio.2013.07.010 · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: C-6 oxidized chitosan was produced from chitosan by performing selective oxidation with NaOCl and NaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. Endocellulase, Celluclast 1.5 L, Glucanex®, Macerozyme R-10, hyaluronidase, hyaluronate lyase, red scorpionfish chitinase, glucuronan lyase and a protein mix from Trichoderma reseei were used to degrade the C-6 oxidized chitosan. Glucanex®, the crude extract from Trichoderma reesei IHEM 4122 and Macerozyme R-10 validated the enzymatic degradation through final hydrolysis yields of the derivative respectively close to 36.4, 20.3 and 12.9% (w/w). The best initial reaction velocity (2.41 U.mL(-1)) was observed for Glucanex®. The antileishmanial activity of the derivative was evaluated against Leishmania infantum LIPA 137. The antibacterial activities against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were also tested. Results showed an antileishmanial activity (IC50: 125μg/mL) of the obtained derivatives against Leishmania infantum LIPA 137.
International journal of biological macromolecules 06/2013; DOI:10.1016/j.ijbiomac.2013.06.025 · 2.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polysaccharides are abundant biopolymers exhibiting various functional activities owing to their structural diversity. These macromolecules, easily renewable, are commonly used in food, oil, cosmetic or pharmaceutical industries. The use of native polysaccharides could be greatly improved by enhancing their properties. In this way, changes in the primary structure of polysaccharides through the addition of anionic/cationic charges, alkyl or sulfated groups modify their conformation, water solubility or acidity. The field of applications of these biopolymers is very wide but closely dependent on their solubility at neutral pH values, on their viscosity in aqueous solutions and on their molecular weight. Chitosan, which is a biopolymer composed of N¬-acetyl-D-glucosamine and D-glucosamine units linked by β-(1-4) bonds, is one example of bioactive polysaccharide insoluble in water at pH 7. Its poor water solubility limits its uses as biological agent. Besides, chitosan is an excellent candidate for chemical modifications, especially to produce glycosaminoglycan mimetics (GAGs), which are known for their dietary or cosmetic properties as the hyaluronic acid. The production of GAGs mimetics from a low cost biopolymer, such as chitosan, highlights major healthy and economic interests.
The first goal of this work was to produce oligoglycosaminoglycans (oligoGAGs) from chitosan by performing its oxidation through the use of 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO). Chitosan (90 % deacetylated and with a molecular weight of 150 kDa) was oxidized regiospecifically at C6 with NaOCl and NaBr for approximately 1 h at 4°C in the presence of TEMPO as a catalyst. 13C NMR analyses were carried out and confirmed the regioselective oxidation. Conductivity experiments showed an oxidation degree closed to 94 %. The production yield of these oligoGAGs mimetics was closed to 10.9 % ± 1.4 (w/w) by using this preparation process and their molecular weight closed to 2 KDa. The second aim was to evaluate the potential degradability of these oligoGAGs by glycoside hydrolases (GHs) and polysaccharide lyases (PLs). Cellulase, Celluclast 1.5 L, Glucanex, Macerozyme R-10, glucuronan lyase, rockfish chitinase and enzymatic mix from Trichoderma reseei were used to degrade the oligoGAGs mimetics. Effects of pH and temperature were also studied. Enzymatic degradations were followed by colorimetric assays and the use of Macerozyme R-10 and Glucanex showed the best degradation results.
Finally, TEMPO chemistry showed the possibility to easily produce soluble oligoGAGs mimetics. The short size of the oligoGAGs decreased the amount of enzymes required for the degradation but the biodegradability of these anionic chitosans was validated.
5th European Symposium POLYMERIX 2012, Rennes, France; 06/2012
[Show abstract][Hide abstract] ABSTRACT: The antioxidant properties of phenolic compounds from olive pulp (PCO) of chamlal variety and those of individual phenolic compounds were evaluated and compared with that of vitamin C (Vit C). The antioxidant activity was measured by the tests of iron reduction and scavenging hydrogen peroxide (H(2)O(2)). Results showed that all the substances tested exhibit a reducing power. The PCO present activities of iron reduction and H(2)O(2) scavenging higher than those of Vit C. The protective effect of PCO against oxidation of lipids and proteins from erythrocyte membranes was studied. The measurement of malondialdehyde generated under oxidative stress conditions induced by hydroxyl radicals generating system revealed that PCO have the most significant protective activity against lipid peroxidation (IC(50) = 49.27 ± 1.91 μg mL(-1)). Paradoxically, Vit C revealed a pro-oxidant effect. Proteins oxidation was evaluated using the H(2)O(2)/FeSO(4) system and electrophoresis. In the presence of PCO at 1 mg mL(-1), proteins of erythrocyte membranes were protected contrary to those treated with Vit C at the same concentration.
[Show abstract][Hide abstract] ABSTRACT: Crude enzymatic extract obtained from five fermentations (300 g of wheat bran) was characterized by a clotting activity of 0.34 ± 0.08 UP/ml with a strength ratio of 1/1: 200. The comparative study of the summaries from 2 purification protocols showed that it is possible to recover 6% of the initial proteins with a 44.54% activity after gel filtration (protocol I), which appeared more technically sound when compared to ion-exchange (1.80% of total proteins with a 23% performance) (protocol II). The protein homogeneity (a single electrophoretic band) of the monomeric protease was confirmed by both methods after precipitation with 80% saturated ammonium sulphate. Moreover, the fractional precipitation technique with this salt (40 and 80%) was useless in the experimental conditions employed and an important loss of activity was observed (28.53%) with a 3-fold purification. In another part of the study, without ammonium sulphate precipitation, the gel filtration enabled the elimination of almost 97% of the inactive proteins and improved the activity performance by 55.13%, while multiplying the specific activity of the coagulant by a factor of 20.88 against a 6.75-fold purification with ion-exchange and the appearance of a more or less 20 kDa peptide after electrophoresis. The proteolytic activity of the purified extracts had a similar appearance to a more pronounced kinetic when compared with the reference rennet. The purification protocols did not seem to have an impact on the isolated protease activity.
AFRICAN JOURNAL OF BIOTECHNOLOGY 03/2011; 10(9):1655-1665. · 0.57 Impact Factor