Mohamed Aymen Chaouch

Depolymerization of polysaccharides from Opuntia ficus indica: Antioxidant and antiglycated activities

The extraction, purification and degradation of polysaccharides from Opuntia ficus indica cladodes, as well as the evaluation of their antioxidant and antiglycated activities in vitro were investigated. The optimization of the extraction showed that extraction by ultrasound at 40 °C presented the best carbohydrates yield. The degradation of the extracted polysaccharides was achieved by free radical depolymerization with H2O2 in the presence of copper(II) acetate for various reaction times. Sugar contents were determined by colorimetric assays. The macromolecular characteristics of the different isolated and degraded carbohydrates were carried by size exclusion chromatography (SEC/MALS/VD/DRI). These experiments showed that all samples are polysaccharides, which are probably pectins and that molecular weight (Mw) has decreased from 6,800,000 to 14,000 g/mol after 3 h of depolymerization without changing the structure. Preliminary antioxidant and antiglycated tests indicated that degraded polysaccharides for 2 and 3 h showed even better antioxidant and antiglycated activities.

Physico-chemical characterization and pharmacological activities of polysaccharides from Opuntia microdasys var. rufida cladodes

The aim of this study is to isolate pectin from peel (WNPE) and pulp (WNPU) of Opuntia microdasys var. rufidas (OMR) cladodes and to characterize these polysaccharides by size exclusion (SEC/MALS/VD/DRI), gas chromatography coupled to mass spectrometer (GC-MS), nuclear magnetic resonance (1H NMR), and Fourier transform infrared spectroscopy (FTIR) analysis. The polysaccharides were extracted in neutral aqueous media followed by ethanol precipitation and dialysis. Both WNPE and WNPU are mainly composed of uronic acids and some neutral sugars such as arabinose, galactose, rhamnose and mannose. Their molecular weight range from 2,180,000 and 4,920,000g/mol. The in-vivo pharmacological activities (anti-inflammatory, analgesic and gastroprotective activities) have been performed. The extracted pectin (50-100mg/kg, i.p. (intraperitoneal)) inhibited, in a dose-related manner, both carrageenan-induced paw edema in rats and Xylene-induced ear edema in mice. A dose-dependent action was obtained against chemical (writhing test) and thermic (hot plate test) stimuli, respectively, with doses of 50 and 100mg/kg. Moreover, a considerable gastroprotective effect was observed with these two biopolymers, the gastric ulcer was attenuated until 67.67% for WNPE and 81.93% for WNPU, at the dose of 100mg/kg.

Effect of ultrasonic degradation of hyaluronic acid extracted from rooster comb on antioxidant and antiglycation activities.

Abstract Content: Recently, low-molecular-weight hyaluronic acid (LMWHA) has been reported to have novel features, such as free radical scavenging activities, antioxidant activities and dietary supplements. Objective: In this study, hyaluronic acid (HA) was extracted from rooster comb and LMWHA was obtained by ultrasonic degradation in order to assess their antioxidant and antiglycation activities. Materials and methods: Molecular weight (Mw) and the content of glucuronic acid (GlcA) were used as the index for comparison of the effect of ultrasonic treatment. The effects on the structure were determined by ultraviolet (UV) spectra and Fourier transform infrared spectra (FTIR). The antioxidant activity was determined by three analytical assays (DPPH, NO and TBARS), and the inhibitory effect against glycated-BSA was also assessed. Results: The GlcA content of HA and LMWHA was estimated at about 48.6% and 47.3%, respectively. The results demonstrate that ultrasonic irradiation decreases the Mw (1090–181 kDa) and intrinsic viscosity (1550–473 mL/g), which indicate the cleavage of the glycosidic bonds. The FTIR and UV spectra did not significantly change before and after degradation. The IC50 value of HA and LWMHA was 1.43, 0.76 and 0.36 mg/mL and 1.20, 0.89 and 0.17 mg/mL toward DPPH, NO and TBARS, respectively. Likewise LMWHA exhibited significant inhibitory effects on the AGEs formation than HA. Discussion and conclusion: The results demonstrated that the ultrasonic irradiation did not damage and change the chemical structure of HA after degradation; furthermore, decreasing Mw and viscosity of LMWHA after degradation may enhance the antioxidant and antiglycation activity.

Co-immobilization of chitosan and dermatan sulfate from Raja montagui skin on polyethylene terephthalate surfaces: Characterization and antibiofilm activity

ABSTRACT In this work, polyethylene terephthalate (PET) was chemically modified by covalent co-immobilization of two separate layers of bioactive polymers composed of chitosan and a new dermatan sulfate isolated from Raja montagui skin. The new materials obtained were characterized by determination of carboxyl groups, ATR-FTIR spectroscopy, drop water contact angle, SEM, and TGA measurements. The different immobilizations modified the surface characteristics; especially when the first layer was dermatan sulfate (PET–DS–Chito) which presented the best surface wettability (71 ± 3°). It also reduced the ability of Staphylococcus epidermidis to form biofilm on PET surfaces which could decrease the virulence of vascular prosthesis infections. GRAPHICAL ABSTRACT

Access to new anticoagulant by sulfation of pectin-like polysaccharides isolated from Opuntia ficus indica cladodes

In order to develop new and low cost anticoagulants as potential heparin alternatives, sulfation of a pectin-like polysaccharide from Opuntia ficus indica cladodes using SO3-DMF complex was performed with a significant sulfate content (7%). FTIR and NMR assays indicated that the sulfation reaction had occurred. In addition, GC-MS analyses demonstrated that sulfation was carried out on the arabinose units of native polysaccharide. Moreover, Physico-chemical characterization indicated an evident decrease of the average molecular weight (Mw) and sugar rates after sulfation. Finally, anticoagulant assays demonstrated that the anticoagulant activity was significantly enhanced by the addition of sulfate groups. Thus, sulfated polysaccharides exhibited the most potent anticoagulant activity by prolonging activated partial thromboplastin time (APTT) and thrombin time (TT).

Optimization of antioxidant and antiglycated activities of polysaccharides from Arthrocnemum indicum leaves

Central composite design was performed to optimize uronic acid rate, esterification degree, total antioxidant ability and antiglycation capacity of carbohydrates from Arthrocnemum indicum leaves. Three independent variables were opted: extraction temperature, time and ratio (solvent/material). The optimal settings were: extraction temperature of 80°C, time of 288min and (solvent/solid) ratio of 40mL/g. Under these settings, uronic acid rate and esterification degree were 49.29%, 30.24%, respectively, whereas total antioxidant activity and antiglycation capacity was 35.81mg ascorbic acid equivalents/g matter and 69.81%, respectively. Colorimetric assays showed that total sugar and uronic acid contents for polysaccharide were 71.78% and 49.24%, respectively. Furthermore, Preliminary structure study was performed via various methods including FT-IR, NMR and UV-vis analysis. SEC analyzes revealed that polysaccharide had an average molecular weight of 2179kDa. Moreover, GC-MS analyzes showed that extracted polysaccharide was a pectic polysaccharide which formed of arabinose, mannose, galactose, rhamnose, glucose and xylose in the molar percentage of 66.68%, 3.93%, 12.71%, 6.31%, 6.08% and 4.29%, respectively. This results revealed that extracted polysaccharide can be employed as source of natural antioxidants and as possible antiglycated agents.

Green Corrosion Inhibitor for Carbon Steel in 1 M HCl: A Comparative Study of Polysaccharides Extracted from Prickly Pear Nopals of Opuntia Ficus-Indica (Peel and Pulp)

Corrosion control of metal, particularly in acidic media, appears to draw a critical importance from an economic, environmental and aesthetical prspective.

An AFM Study of the Surface Propriety and Corrosion Inhibition on Carbon Steel in Acidic Media

Atomic Force Microscopy is undoubtedly the most adaptable and dominant microscopic technology for studying nanoscale samples.

Electrochemical and Surface Morphological Studies of a Carbon Steel Corrosion by Natural Product in Acidic Solution

Acid cleaning, acid pickling, acid descaling and oil well acidizing need the use of corrosion inhibitors to stop their corrosion attack.