Sameh Maktouf

Structural, functional, and antioxidant properties of water-soluble polysaccharides from potatoes peels

Water-soluble polysaccharides were extracted from potato peel waste (PPW). The structure of the polysaccharides from PPW (PPPW) was examined by means of Fourier transform-infrared spectroscopy (FT-IR) analysis, X-ray diffractometry (XRD) and gas chromatography-mass spectrometry (GC-MS). The results suggest that the extracted polysaccharides form a semi-crystalline polymer constituted essentially of the functional groups CO, CH and OH. Acid hydrolysis of this polymer yielded glucose (76.25%) as the dominant sugar functional properties (water holding capacity: WHC, oil holding capacity: OHC, foaming, and emulsion properties) of this polymer were studied. The PPPW showed interesting water-holding and fat-binding capacities which were 4.097 ± 0.537 g/g and 4.398 ± 0.04 g/g, respectively. In addition, it presented good foaming and emulsion properties. The antioxidant activity of this polymer was also studied and revealed that the polysaccharides showed interesting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity (IC50 PPPW=11.578 mg/mL), reducing power and β-carotene bleaching inhibition activities, and also a strong ABTS radical scavenging activity (IC50 PPPW=2mg/mL). Overall, the results suggest that the polysaccharide is a promising source of natural antioxidants and can be used as additive in food, pharmaceutical and cosmetic preparations.

Investigation of Antimicrobial Activity and Statistical Optimization of Bacillus subtilis SPB1 Biosurfactant Production in Solid-State Fermentation

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.

Disruption of erythrocyte antioxidant defense system, hematological parameters, induction of pro-inflammatory cytokines and DNA damage in liver of co-exposed rats to aluminium and acrylamide

The individual toxic effects of aluminium and acrylamide are well known but there are no data on their combined effects. The present study was undertaken to determine (i) hematological parameters during individual and combined chronic exposure to aluminium and acrylamide (ii) correlation of oxidative stress in erythrocytes with pro-inflammatory cytokines expression, DNA damage and histopathological changes in the liver. Rats were exposed to aluminium (50 mg/kg body weight) in drinking water and acrylamide (20 mg/kg body weight) by gavage, either individually or in combination for 3 weeks. Exposure rats to AlCl3 or/and ACR provoked an increase in MDA, AOPP, H2O2 and a decrease in GSH and NPSH levels in erythrocytes. Activities of catalase, glutathione peroxidase and superoxide dismutase were decreased in all treated rats. Our results showed that all treatments induced an increase in WBC, erythrocyte osmotic fragility and a decrease in RBC, Hb and Ht. While MCV, MCH, MCHC remained unchanged. Hepatic pro-inflammatory cytokines expression including tumor necrosis factor-α, interleukin-6, interleukin-1β was increased suggesting leucocytes infiltration in the liver. A random DNA degradation was observed on agarose gel only in the liver of co-exposed rats to AlCl3 and ACR treatment. Interestingly, co-exposure to these toxicants exhibited synergism based on physical and biochemical variables in erythrocytes, pro-inflammatory cytokines and DNA damage in liver.

Co-exposure to aluminum and acrylamide disturbs expression of metallothionein, proinflammatory cytokines and induces genotoxicity: Biochemical and histopathological changes in the kidney of adult rats

The individual toxic effects of aluminum and acrylamide are known but there is no data on their combined effects. The present study investigates the toxic effects after combined exposure to these toxicants on: (i) oxidative stress during combined chronic exposure to aluminum and acrylamide on kidney function (ii) correlation of oxidative stress with metallothionein (MT) and inflammatory cytokines expression, DNA damage, and histopathological changes. Rats were exposed to aluminum (50 mg/kg body weight) in drinking water and acrylamide (20 mg/kg body weight) by gavage either individually or in combination for 3 weeks. Exposure rats to aluminum chloride or acrylamide alone and in combination induced nephrotoxicity, as evidenced by a decrease in the 24‐h urine volume and uric acid levels in plasma and an increase of plasma creatinine, urea, and blood urea nitrogen levels. Nephrotoxicity was objectified by a significant increase in malondialdehyde level, advanced oxidation protein, and protein carbonyl contents, whereas reduced glutathione, nonprotein thiol, vitamin C levels, catalase, and glutathione peroxidase activities showed a significant decline. Superoxide dismutase activity and its gene expression were increased. Aluminum and acrylamide co‐exposure exhibited synergism in various biochemical variables and also in DNA damage. Kidney total MT levels and genes expression of MT1, MT2, and proinflammatory cytokines were increased. All these changes were supported by histopathological observations. Co‐exposure to aluminum and acrylamide exhibited synergism and more pronounced toxic effects compared with their individual effects based on various biochemical variables, genotoxic, and histopathological changes.

Multistage process for the production of bioethanol from almond shell

This work describes the feasibility of using almond shell as feedstock for bioethanol production. A pre-treatment step was carried out using 4% NaOH for 60min at 121°C followed by 1% sulfuric acid for 60min at 121°C. Enzymatic saccharification of the pre-treated almond shell was performed using Penicillium occitanis enzymes. The process was optimized using a hybrid design with four parameters including the incubation time, temperature, enzyme loads, and polyethylene glycol (PEG) concentration. The optimum hydrolysis conditions led to a sugar yield of 13.5%. A detoxification step of the enzymatic hydrolysate was carried out at pH 5 using 1U/ml of laccase enzyme produced by Polyporus ciliatus. Fermenting efficiency of the hydrolysates was greatly improved by laccase treatment, increasing the ethanol yield from 30% to 84%. These results demonstrated the efficiency of using almond shell as a promising source for bioethanol production.

Structural, functional, and biological properties of potato peel oligosaccharides

Enzymatic hydrolysis of water-soluble polysaccharides from potato peel waste (PPPW) generates low molecular weight oligosaccharides with a yield of 63%. The oligosaccharides generated from potato peel polysaccharides (OPPP) were purified by Superdex-30 column. The results showed the presence of 8 peaks (OPPP1-OPPP8). The identification of all the fractions by chromatography analysis (GC-FID) illustrated that the most prominent residues were glucose with traces of galactose, arabinose and rhamnose. Finally, mass spectrometry (MALDI-ToF-ToF) analysis showed that the generated oligosaccharides were heterogeneous and contained different degree of polymerization (DP). Indeed, the obtained oligosaccharides fractions OPPP3, OPPP4, OPPP5, OPPP6 and OPPP7 were compose of the following degree of polymerization DP5; DP4; DP2; DP1 and DP1, respectively. Potato peel oligosaccharides (OPPP) efficiency were tested using different concentrations in functional properties. The results showed good foaming and emulsion properties. This study also aimed to investigate the antioxidant activity of OPPP. The items explored included the DPPH radical-scavenging capacity (IC50 OPPP=2.5mg/mL), reducing power (OD: 0.622±0.032 at a concentration of 20mg/mL), β-carotene bleaching inhibition activity (45.335±3.653%), and also the ABTS radical scavenging activity (14.835±0.1%).These findings indicate that potato peel oligosaccharides have potent antioxidant activities. Hence, one can suggest that these oligosaccharides might contribute as additives in food, pharmaceutical and cosmetic preparations.