Dorra Driss - Academia.edu (original) (raw)

Papers by Dorra Driss

Production of xylooligosaccharides from garlic straw xylan by purified xylanase from Bacillus mojavensis UEB-FK and their in vitro evaluation as prebiotics

Food and Bioproducts Processing, Apr 1, 2015

ABSTRACT A newly isolated Bacterium strain named UEB-FK was selected from Tunisian Sahara, exhibi... more ABSTRACT A newly isolated Bacterium strain named UEB-FK was selected from Tunisian Sahara, exhibiting the highest clear zone on agar plates containing oat spelt xylan by staining with Congo red. On the basis of 16S rDNA sequence analysis, this strain was identified as Bacillus mojavensis. This strain produced extracellular xylanase. Xylanase from the strain was purified to homogeneity and had an apparent molecular weight of 14 kDa. The Km and Vmax values of the purified xylanase on oat spelt xylan were 3.85 mg/mL and 250.02 U/mg, respectively. The optimum pH and temperature for the enzyme were found to be 4.0 and 50 °C, respectively, and the enzyme exhibited significant heat stability even incubated in 60 °C for 90 min. In addition, the enzyme was found to be stable in a wide range of pH (3–9) and in presence of some detergents and organic solvents. The main hydrolysis products yielded from garlic straw extracted xylan were xylobiose and xylotriose. The resulting xylooligosaccharides (XOS) could be used as a special nutrient for lactic bacteria. Therefore, prebiotic effect of XOS was evaluated by in vitro fermentation using known probiotic strains viz. Bifidobacterium adolescentis and Lactobacillus acidophilus.

Potassium Bromate-induced Changes in the Adult Mouse Cerebellum Are Ameliorated by Vanillin

PubMed, Feb 1, 2018

Objective: The current study aimed to elucidate the effect of vanillin on behavioral changes, oxi... more Objective: The current study aimed to elucidate the effect of vanillin on behavioral changes, oxidative stress, and histopathological changes induced by potassium bromate (KBrO3), an environmental pollutant, in the cerebellum of adult mice. Methods: The animals were divided into four groups: group 1 served as a control, group 2 received KBrO3, group 3 received KBrO3 and vanillin, and group 4 received only vanillin. We then measured behavioral changes, oxidative stress, and molecular and histological changes in the cerebellum. Results: We observed significant behavioral changes in KBrO3-exposed mice. When investigating redox homeostasis in the cerebellum, we found that mice treated with KBrO3 had increased lipid peroxidation and protein oxidation in the cerebellum. These effects were accompanied by decreased Na+-K+ and Mg2+ ATPase activity and antioxidant enzyme gene expression when compared to the control group. Additionally, there was a significant increase in cytokine gene expression in KBrO3-treated mice. Microscopy revealed that KBrO3 intoxication resulted in numerous degenerative changes in the cerebellum that were substantially ameliorated by vanillin supplementation. Co-administration of vanillin blocked the biochemical and molecular anomalies induced by KBrO3. Conclusion: Our results demonstrate that vanillin is a potential therapeutic agent for oxidative stress associated with neurodegenerative diseases.

Free Radicals and Antioxidants, Jan 10, 2016

Background: This present research highlight the phytochemical profile, the antioxidant, the antim... more Background: This present research highlight the phytochemical profile, the antioxidant, the antimicrobial, the antimutagenic and the antiproliferative activities of an essential oil extracted from Corchorus olitorius L. flowers and leaf (COFL), an aromatic plant widely distributed in Tunisia and used as a traditional food plant. Results: Gas chromatography/ mass spectrometry was used to determine the composition of the COFL essential oil (COFL-EO). Forty-three components were identified and the main compounds were benzaldehyde (56%), methyl 4-methoxysalicylate (6.55%) and carvacrol (4.75%). The COFL-EO was also found to possess antioxidant activities, as evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method and β-carotene bleaching assay. The antibacterial activities showed good growth inhibition compared to positive controls. The diameter of the inhibition zones reached a maximum of 16.7 ± 0.1 mm when tested against Salmonella typhimurium using just 6 mg extract. On the other hand, the antimutagenic activity was assessed using the Ames Salmonella/microsome mutagenicity test and the COLF-EO exhibited high antimutagenic effects at 0.125, 0.0125 and 0.00125 mg/plate. Antiproliferative activity of this essential oil evaluated in four mammalian cells lines was significantly stronger in Hela cell line (IC 50 =4 ± 0.98 µg/mL). Conclusion: Overall, results presented here suggest that the COFL-EO is a potential new source of active ingredients for food and pharmaceutical industry.

Materials Chemistry and Physics, Sep 1, 2019

Chemico-Biological Interactions, May 1, 2016

The present study aimed to explore the ability of vanillin to ameliorate the adverse effects indu... more The present study aimed to explore the ability of vanillin to ameliorate the adverse effects induced by potassium bromate (KBrO 3) in the renal tissue. Our results showed a significant increase in hydrogen peroxide, superoxide anion, malondialdehyde, advanced oxidation protein product and protein carbonyl levels in the kidney of KBrO 3 treated mice, compared with the control group. Nephrotoxicity was evidenced by a decrease in plasma uric acid and kidney glutathione levels, Na þ-K þ-ATPase, lactate dehydrogenase and catalase activities. Additionally, creatinine and urea levels significantly increased in the plasma and declined in the urine. Also, Kidney glutathione peroxidase, superoxide dismutase, metallothionein (MT1 and MT2) mRNA expression remarkably increased. These modifications in biochemical and molecular values were substantiated by histopathological data. Co-treatment with vanillin restored these parameters to near control values. Interestingly, vanillin proved to possess, in vitro, a stronger scavenging radical activity than vitamin C and Trolox. Thus, vanillin inhibited KBrO 3-induced damage via its antioxidant and antiradical activities as well as its capacity to protect genes expression and histopathological changes.

Journal of Food Science and Technology, Apr 29, 2015

The water soluble crude polysaccharides were obtained from the aqueous extracts of the carrot pee... more The water soluble crude polysaccharides were obtained from the aqueous extracts of the carrot peels by-product (CWSP) through hot water extraction followed by isopropanol precipitation. Response surface methodology was applied to optimize the extraction of polysaccharides. A three-level, four-variable Box-Behnken design was employed to obtain the best possible combination of extraction time (X1: 60-100 min), ratio of water to raw material (X2: 15:1-25:1, v/ w), extraction temperature (X3: 60-80°C), extraction cycle (X4: 1-3 times) for maximum yield of CWSP. The optimum extraction conditions were as follows: extraction time of 74.86 min, ratio of water to raw material of 24.86, extraction temperature of 60°C and extraction cycles of 3. Under these conditions, the experimental yield was 41.91 %, which is well in close agreement with the theoretical value (42 %) predicted by RSM model. Antioxidant activities and inhibitory activities against the bacteria of CWSP were investigated. CWSP at 1.2 mg/ml was found to scavenge the DPPH radical (80.21 %), to prevent bleaching of β-carotene (65 %) and to chelate iron ion (40.25 %) in vitro systems. CWSP also exhibited the antibacterial activities. CWSP at 200 mg/ml could inhibit the growth of the Gram-negative and Gram-positive bacteria. CWSP have significant antioxidant and high antibacterial activity and may be potential functional food ingredients.

Production and in vitro evaluation of xylooligosaccharides generated from corncobs using immobilized Penicillium occitanis xylanase

Journal of Molecular Catalysis B-enzymatic, Apr 1, 2014

ABSTRACT Penicillium occitanis xylanase 3 expressed in Pichia pastoris, termed PoXyn3, was immobi... more ABSTRACT Penicillium occitanis xylanase 3 expressed in Pichia pastoris, termed PoXyn3, was immobilized on chitosan with glutaraldehyde by covalent coupling reaction. The immobilization yield and the xylanase activity recovery were 98.8 +/- 2.5% and 94.45 +/- 3.5%, respectively. The optimum pH was not affected by immobilization, but the immobilized PoXyn3 exhibited more acidic and large optimum pH range (pH 2.0-4.0) than that of the free PoXyn2 (pH 3.0). The free PoXyn3 had an optimum temperature of 50 degrees C, whereas that of the immobilized enzyme was shifted to 65 degrees C. Immobilization increased both pH stability and thermostability when compared with the free enzyme. It also exhibited high storage stability and retained 70% of its initial activity after 120 days. The main hydrolysis products yielded from corncob extracted xylan were xylobiose and xylotriose. The resulting xylooligosaccharides (XOS) could be used as a special nutrient for lactic bacteria. Therefore, prebiotic effect of XOS was evaluated by in vitro fermentation using known probiotic strains viz. Bifidobacterium adolescentis and Lactobacillus acidophilus. The results of this study revealed better growth of Bifidobacterium spp on XOS as a carbon source than Lactobacillus spp.

Natural Product Research, Jul 13, 2015

The aim of the present study was first to ascertain the chemical composition and the physico-chem... more The aim of the present study was first to ascertain the chemical composition and the physico-chemical properties of cereal extracted β-glucan from barley flour. Secondly, to assess the antioxidant properties and the antibacterial properties of extracted β-glucan hydrolysates. The proximate composition, FT-IR and Scanning electron microscopic of extracted β-Glucan were studied. Hydrolysates from extracted β-glucan, obtained by lichenase EG L from Penicillium occitanis, were a mixed linkage betaoligosaccharides (MLBO) of trisaccharides and tetrasaccharides. MLBO showed a DPPH radicalscavenger with IC50 about 1.8±0.01 mg/ml whereas the IC50 of extracted β-glucan was about 5±0.01 mg/ml. MLBO showed a high antioxidative capacity 175 µmol/ml α-tocopherol equivalents at 5 mg/ml. The antimicrobial activity was confirmed against all tested bacteria especially at 20 mg/ml of MLBO while no inhibition was observed for all the strains used after the addition of either EG L or extracted β-glucan.

Energy, Sep 1, 2014

The main objective of this paper is to validate the numerical results developed with the Computat... more The main objective of this paper is to validate the numerical results developed with the Computational Fluid Dynamics (CFD) code. For thus, a small incurved Savonius wind rotor with a height of 300mm and a bucket diameter of 100 mm is designed and built. This rotor is placed in a wind tunnel test section of 400 mm x 400 mm. The prototype is used to estimate the velocity profiles. For thus, a thermal velocity probe anemometer was used to measure the air velocity. The air speed at the tunnel test section was varied between 0 and 17 m.s-1. The Conformity between the numerical and the experimental results validate the numerical method developed elsewhere.

Penicillium occitanis expressed with an His-tag in Pichia pastoris, termed PoXyn2, was immobilize... more Penicillium occitanis expressed with an His-tag in Pichia pastoris, termed PoXyn2, was immobilized on nickel-chelate Eupergit C by covalent coupling reaction with a high immobilization yield up to 93.49%. Characterization of the immobilized PoXyn2 was further evaluated. The optimum pH was not affected by immobilization, but the immobilized PoXyn2 exhibited more acidic and large optimum pH range (pH 2.0-4.0) than that of the free PoXyn2 (pH 3.0). The free PoXyn2 had an optimum temperature of 50 °C, whereas that of the immobilized enzyme was shifted to 65 °C. Immobilization increased both pH stability and thermostability when compared with the free enzyme. Thermodynamically, increase in enthalpy and free energy change after covalent immobilization could be credited to the enhanced stability. Immobilized xylanase could be reused for 10 consecutive cycles retaining 60% of its initial activity. It was found to be effective in releasing reducing sugar from poultry feed. Immobilization on Eupergit C is important due to its mechanical resistance at high pH and temperature. Hence, considerable stability and reusability of bound enzyme may be advantageous for its industrial application.

Free Radicals and Antioxidants, Jun 23, 2015

Background and aim: Opuntia stricta is belonging to the Cactaceae family. Its fruit is composed o... more Background and aim: Opuntia stricta is belonging to the Cactaceae family. Its fruit is composed of around 69% peels, 21% pulp and 10% seeds. Extracting bioactive compounds from the peels; the major part usually discarded, helps to reduce the cost and environmental concerns associated with their disposal. Many studies have been interested in extracting dyes and phenolics from O. stricta peels, showing their antioxidant properties, but no work was devoted to extract and characterize the non-polar compounds meaning hydrodistillation. Method: O. stricta fruits were collected at ripening, the peels, pulps and seeds were manually separated. Peels were then blended, hydrodistilled, and the non-polar compounds were extracted and identified using gas chromatography-mass spectrometry. Afterwards, the antioxidant and antibacterial activities of the extracted molecules were investigated. Results: The extracted non-polar compounds from O. stricta fruit peels were mainly terpene alcohols. The major components were trans-linalool oxide, cis-linalyl oxide and linalool with 38.3%, 29.6% and 23.4%, respectively. The antioxidant activities showed high inhibition of the DPPH free radicals with 84% at 50 mg/ml, higher reducing power than that of ascorbic acid, and high total antioxidant activity with 309 ± 37 µg ascorbic acid equivalent at 25 mg/ml. The antibacterial activities showed high growth inhibition against Staphylococcus aureus and partial inhibition against Enterococcus faecalis. Conclusion: Non-polar compounds extracted meaning hydrodistillation from O. stricta fruit peels exhibit high antioxidant activities and inhibit the growth of S. aureus. They represent thus a promising way for the valorization of this by-product.

International Agrophysics, Jul 1, 2015

Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Ext... more Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical composition revealed the presence of rhamnose, arabinose, glucose, mannose, galactose and galacturonic acid. The infra-red spectroscopic analysis showed a similar structure to that of Opuntia ficus-indica polysaccharide peels. Additionally, the extracted polysaccharides exhibited high antioxidant activities. In fact, the free radical scavenging activity (half inhibition concentration = 6.5 mg ml-1 with 94.9% inhibition at 50 mg ml-1), the total antioxidant activity (100 μg ascorbic acid equivalent at 50 mg polysaccharides) and the reducing power capacity (absorbance 700 nm = 0.7 at 50 mg ml-1), appeared to be interesting compared to natural and synthetic antioxidants. Therefore, watersoluble polysaccharides from Opuntia stricta Haw. fruit peels could be a natural alternative to replace synthetic antioxidants.

Free Radicals and Antioxidants, Feb 16, 2015

Background and aim: Eruca sativa or most commonly known as rocket is a worldwide herbaceous plant... more Background and aim: Eruca sativa or most commonly known as rocket is a worldwide herbaceous plant usually used for salad preparations due to its astringent properties. The health benefits of its leaves and seeds were widely investigated, however no study has been conducted on its flowers demonstrating these benefits. The aim of this work is to investigate the phytochemical properties of solvent extract from rocket flowers. Method: Rocket flowers were collected at their blooming day and solvent extracts were prepared meaning hydrodistillation. Non-polar compounds were extracted using hexane and the efficiency of the obtained extract was evaluated using antibacterial and antioxidant activities. The antibacterial activities were tested against 11 pathogenic strains, whereas the antioxidant activities were tested through DPPH free radical scavenging activity, total antioxidant capacity and β-carotene bleaching test. Results: The antibacterial activities showed good growth inhibition compared to positive controls. The diameter of the inhibition zones reached a maximum of 16.7 ± 0.1 mm when tested against Salmonella typhimurium using 14 mg extract. The results obtained for the antioxidant activities showed more than 90% DPPH free radical inhibition, 315 µg AAE/ml for 71 mg/ml extract and more than 70% inhibition using β-carotene bleaching assay. Conclusion: The obtained phytochemical properties demonstrated the health benefit features of rocket flowers and their potential uses as feedstock of bioactive molecules.

International Journal of Biological Macromolecules, 2018

A cationic cell-penetrating peptide PEP-NJSM was identified in human virus proteomes by a screeni... more A cationic cell-penetrating peptide PEP-NJSM was identified in human virus proteomes by a screening of charge clusters in protein sequences generating cell penetrating peptides (CPP). PEP-NJSM was selectively active against Gram positive Staphylococcus epidermidis as antibacterial agent with MIC value of 128 µM compared to the Gram-negative Pseudomonas aeruginosa strain with MIC value exceeded 512 µM. The selected peptide exhibited an important anti-biofilm activity even at sub-MIC levels. PEP-NJSM could prevent biofilm formation and increase the mortality of cells inside mature S. epidermidis biofilm. The results demonstrated that PEP-NJSM presented an important anti-adherent activity. It showed a S. epidermidis inhibition of biofilm formation more than 84% at a concentration of 256 µM (2 X MIC) and remained active even at a concentration of 4 µM with 32% of inhibition. The eradication of the established biofilm was observed at a concentration of 256 µM with 55.7% of biofilm eradication. The peptide was active against mature biofilm even at low concentration of 0.5 µM with approximately 22.9% of eradication. PEP-NJSM exhibited low hemolytic activity and cytotoxicity against mammalian cells. Our results demonstrate that PEP-NJSM could have a potential role in the treatment of diseases related to Staphylococcus epidermidis infection.

Task Allocation for Heterogeneous Multi-agent System via Game-Based Learning

2021 IEEE 21st International Conference on Communication Technology (ICCT)

The aim of this study was first to ascertain the chemical composition and the physicochemical pro... more The aim of this study was first to ascertain the chemical composition and the physicochemical properties of cereal extracted β-glucan from barley flour. Secondly, to assess the antioxidant properties and the antibacterial properties of extracted β-glucan hydrolysates. The proximate composition, FT-IR and scanning electron microscopy of extracted β-Glucan were studied. Hydrolysates from extracted β-glucan, obtained by lichenase EG<sub>L</sub> from <i>Penicillium occitanis</i>, were a mixed linkage beta-oligosaccharides (MLBO) of trisaccharides and tetrasaccharides. MLBO showed a DPPH radical scavenger with IC50 about 1.8 ± 0.01 mg/mL whereas the IC50 of extracted β-glucan was about 5 ± 0.01 mg/mL. MLBO showed a high antioxidative capacity (175 μmol/mL α-tocopherol equivalents) at 5 mg/mL. The antimicrobial activity was confirmed against all tested bacteria especially at 20 mg/mL of MLBO while no inhibition was observed for all the strains used after the additi...

Materials Chemistry and Physics, 2019

Molecular insights into MYO3A kinase domain variants explain variability in both severity and progression of DFNB30 hearing impairment

Journal of Biomolecular Structure and Dynamics, 2021

Hereditary hearing impairment (HI) is a common disease with the highest incidence among sensory d... more Hereditary hearing impairment (HI) is a common disease with the highest incidence among sensory defects. Several genes have been identified to affect stereocilia structure causing HI, including the unconventional myosin3A. Interestingly, we noticed that variants in MYO3A gene have been previously found to cause variable HI onset and severity. Using clinical exome sequencing, we identified a novel pathogenic variant p.(Lys50Arg) in the MYO3A kinase domain (MYO3A-KD). Previous in vitro studies supported its damaging effect as a 'kinase-dead' mutant. We further analyzed this variation through molecular dynamics which predicts that changes in flexibility of MYO3A structure would influence the protein-ATP binding properties. This Lys50Arg mutation segregated with congenital profound non-syndromic HI. To better investigate this variability, we collected previously identified MYO3A-KDs variants, p.(Tyr129Cys), p.(His142Gln) and p.(Pro189Thr), and built both wild type and mutant 3 D MYO3A-KD models to assess their impact on the protein structure and function. Our results suggest that KD mutations could either cause a congenital profound form of HI, when particularly affecting the kinase activity and preventing the auto-phosphorylation of the motor, or a late onset and progressive form, when partially or completely inactivating the MYO3A protein. In conclusion, we report a novel pathogenic variant affecting the ATP-binding site within the MYO3A-KD causing congenital profound HI. Through computational approaches we provide a deeper understanding on the correlation between the effects of MYO3A-KD mutations and the variable hearing phenotypes. To the best of our knowledge this is the first study to correlate mutations' genotypes with the variable phenotypes of DFNB30.Communicated by Ramaswamy H. Sarma.

Molecular Genetics & Genomic Medicine

Freshly caught Nile Tilapia (Oreochromis niloticus) samples were obtained from Sabiyel Lake in Al... more Freshly caught Nile Tilapia (Oreochromis niloticus) samples were obtained from Sabiyel Lake in Aliero Local Government Area of Kebbi State. Oreochromis niloticus samples were descaled, degutted, cut into chunks and rinsed with clean water at