Nacim Zouari

A novel hepatopancreatic phospholipase A2 from Hexaplex trunculus with digestive and toxic activities.

A marine snail digestive phospholipase A2 (mSDPL) was purified from delipidated hepatopancreas. Unlike known digestive phospholipases A2, which are 14 kDa proteins, the purified mSDPL has a molecular mass of about 30 kDa. It has a specific activity of about 180 U/mg measured at 50 degrees C and pH 8.5 using phosphatidylcholine liposomes as a substrate in the presence of 4 mM NaTDC and 6mM CaCl2. The N-terminal amino-acid of the purified mSDPL does not share any homology with known phospholipases. Moreover, the mSDPL exhibits hemolytic activity in intact erythrocytes and can penetrate phospholipid monolayers at high surface pressure, comparable to snake venom PLA2. These observations suggest that mSDPL could be toxic to mammal cells. However, mSDPL can be classified as a member of a new family of enzymes. It should be situated between the class of toxic phospholipase A2 from venoms and another class of non toxic pancreatic phospholipase A2 from mammals.

Blue-green algae (Arthrospira platensis) as an ingredient in pasta: free radical scavenging activity, sensory and cooking characteristics evaluation.

The effects of semolina enrichment with blue-green algae (Arthrospira platensis) at three different levels (1, 2 and 3 g/100 g of semolina) on the colour, cooking properties, firmness, free radical scavenging activity and sensory characteristics of pasta are reported. Microalgae addition resulted in higher swelling index and lower cooking loss than the control sample. A significant increase in pasta firmness was evidenced with an increase of added microalgae due to structural reinforcement. In addition to colouring, the use of A. platensis (2 g/100 g of semolina) can enhance the sensory quality and nutraceutical potential as evaluated by free radical scavenging activity of pasta.

Opuntia ficus-indica cladodes as a functional ingredient: bioactive compounds profile and their effect on antioxidant quality of bread

BackgroundIn the context of a balanced diet, the antioxidant-rich food consumption is a preventive way of many degenerative diseases. Consequently, improving the nutraceutical quality of traditional foods such as bakery products is an interesting approach. Considering the present consumer’s demand, cladodes from prickly pear that were traditionally used as a valuable food as well as in folk medicine for the treatment of several chronic diseases were investigated for their use in bread production to improve its functionality.MethodsBioactive substances were determined by liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HRESIMS) analysis. Dough rheological properties were characterized by alveographic measurements. Bread antioxidant quality was evaluated by total phenolics content, DPPH• radical-scavenging, metal (Fe2+) chelating and Fe3+ reducing power determinations.ResultsLC-HRESIMS analysis of the cladodes extract allowed the identification of 9 flavonoids, 2 phenolics, 1 alkaloid and 1 terpenoid compounds. Cladodes powder enrichment induced important modifications on the dough rheological parameters in terms of the extensibility (L) and deformation energy (W) decrease. Moreover, cladodes powder addition to bread resulted in a decrease in both crust and crumb colour parameters (L*, a* and b*). A 5% supplementation resulted in an increase of the bread yield and bread specific volume by 8.9 and 25%, respectively. Interestingly, Bread containing cladodes powder showed enhanced total phenolics content and antioxidant potential as compared to the control.ConclusionsSubstitution of wheat flour by the cladodes powder at 5% level was optimal for improving the total phenolics content and the antioxidant potential of bread without having any negative effect on its sensory acceptability. Cladodes from Opuntia ficus-indica could be considered as a potential health-promoting functional ingredient in bakery products.

Cladodes from prickly pear as a functional ingredient: effect on fat retention, oxidative stability, nutritional and sensory properties of cookies

Abstract The stems of Opuntia ficus-indica known as cladodes are rich source of bioactive and functional substances, which make them important candidate for the production of health-promoting food. Cladodes powder was incorporated at different levels of substitution (2.5%, 5% and 7.5%) in cookies (butter/wheat flour: 55/100 m/m). Substitution of wheat flour by cladodes powder improved dietary fiber, ash, potassium, magnesium and calcium contents of enriched cookies. The results also revealed that cladodes supplementation increased hardness; however, it decreased a* and b* values and reduced exudate loss of cookies during storage. Moreover, rising levels of cladodes powder contribute to the increase of antioxidant activity of cookies and decreased their oxidative degradation. Sensory evaluation showed that cladodes supplementation at 5% level remained acceptable at 5-point hedonic scale. The present study suggested that cladodes supplementation in high-fat cookies not only added nutritional value to food, but also improved its functional characteristics.

Digestive amylase of a primitive animal, the scorpion : Purification and biochemical characterization

Scorpion, one of the most ancient invertebrates was chosen, as a model of a primitive animal, to purify and characterize an amylase located in the hepatopancreas. The scorpion digestive amylase (SDA) was purified. Pure SDA was obtained after heat treatment followed by ammonium sulfate fractionation and three steps of chromatography. The pure amylase is not glycosylated and has a molecular mass of 59,101 Da determined by MALDI-TOF MS analysis. The maximal amylase activity was measured at pH 7.0 and 50 degrees C, in the presence of Ca2+ and using potato starch as substrate. The enzyme was able to hydrolyze also, glycogen and amylose. The 23 NH2-terminal amino acid SDA residues were sequenced. The sequence obtained is similar to those of mammalian and avian pancreatic amylases. Nevertheless, polyclonal antibodies directed against SDA failed to recognize classical digestive amylases like the porcine pancreatic one.

Chemical composition and chelating activity of Ruta chalepensis L. (Rutaceae) essential oil as influenced by phenological stages and plant organs

Chemical composition and chelating activity of Ruta chalepensis L. essential oils collected from the south-east of Tunisia at the vegetative and the flowering stages were investigated. Essential oils were extracted by hydrodistillation from different organs (leaves, flowers and stems) and analyzed by gas chromatography–flame ionization detector (GC–FID) and GC–mass spectrometry (GC–MS) techniques. The highest essential oil yields were obtained at the flowering stage with a maximum in the flowers (1.8-1.9%). Twenty-five compounds were identified in different essential oils, where ketones and esters constituted the main chemical classes. 2-Nonanone (17.2–25.9%), 2-undecanone (19–37.2%) and octyl acetate (9.1–30.8%) were found to be the major compounds in all essential oils. The majority of essential oil compounds showed homogeneity with respect to the phenological stage and plant organs. At the flowering stage, stems and flowers essential oils showed the highest metal chelating activity, whose ic50 values ranged between 160 and 180 μg/mL.

Phytochemical, antioxidant and protective effect of cactus cladodes extract against lithium-induced liver injury in rats

Abstract Context: Opuntia ficus-indica (L.) Mill. (Castaceae) (cactus) is used in Tunisian medicine for the treatment of various diseases. Objective: This study determines phytochemical composition of cactus cladode extract (CCE). It also investigates antioxidant activity and hepatoprotective potential of CCE against lithium carbonate (Li2CO3)-induced liver injury in rats. Materials and methods: Twenty-four Wistar male rats were divided into four groups of six each: a control group given distilled water (0.5 mL/100 g b.w.; i.p.), a group injected with Li2CO3 (25 mg/kg b.w.; i.p.; corresponding to 30% of the LD50) twice daily for 30 days, a group receiving only CCE at 100 mg/kg of b.w. for 60 days and then injected with distilled water during the last 30 days of CCE treatment, and a group receiving CCE and then injected with Li2CO3 during the last 30 days of CCE treatment. The bioactive components containing the CCE were identified using chemical assays. Results: Treatment with Li2CO3 caused a significant change of some haematological parameters including red blood cells (RBC), white blood cells (WBC), haemoglobin content (Hb), haematocrit (Ht) and mean corpuscular volume (VCM) compared to the control group. Moreover, significant increases in the levels of glucose, cholesterol, triglycerides and of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) activities were observed in the blood of Li2CO3-treated rats. Furthermore, exposure to Li2CO3 significantly increased the LPO level and decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities in the hepatic tissues. Conclusion: CCE possesses a significant hepatoprotective effect.

Lithium induced, oxidative stress and related damages in testes and heart in male rats: The protective effects of Malva sylvestris extract

Malva sylvestris is widely used in Mediterranean and European traditional medicine and ethnoveterinary for the treatment of various diseases. This study, carried out on male Wistar rats, evaluates the beneficial effects of Malva sylvestris extract upon lithium carbonate-induced damages in testes and heart. For this purpose, Malva sylvestris extract at a dose of 0.2g/kg was orally administrated, followed by 25mg/kg lithium carbonate (intraperitoneal injection, twice daily). Lithium carbonate treatment significantly (p<0.01) decreased the weight of testes, accessory sex organ and heart, sperm count and motility, and serum testosterone level. In addition, exposure to lithium carbonate significantly (p<0.01) increased lipid peroxidation level (LPO) and decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in testes and heart. Treatment with M. sylvestris extract affords substantial protection in testes and heart by altering all the parameters to near normal levels that were further confirmed by histological examination. The beneficial effect of M. Sylvestris extract in several organs could be attributed to the interaction of antioxidant components, such as complex polysaccharides, as confirmed by phytochemical analysis.

Malva sylvestris extract protects upon lithium carbonate-induced kidney damages in male rat

Malva sylvestris has recently attracted special attention due to its potential activities in many chronic disorders. We aimed to assess the beneficial effects of Malva sylvestris extract against lithium carbonate induced renal damage in male Wistar rats. For this purpose, Malva sylvestris extract at a dose of 0.2g/kg was orally administrated, followed by 25mg/kg of lithium carbonate (intraperitoneal injection) for 30 days. Malva sylvestris extract was proved to contain large amounts of K+, Na+, Ca++ and the existence of phenolic acids and flavonoids shown by the obtained HPLC-based analysis. The antioxidant capacities in vitro showed high level of radical scavenging activity and reducing power. The in vivo results showed that intraperitoneal injection of lithium carbonate exhibited a significant increase (p<0.01) of serum creatinine and urea and reduced serum sodium and potassium concentrations. Lithium carbonate also induced oxidative damage as indicated by a significant raise in LPO level associated with a decrease in superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in the kidney. However, pretreatment with Malva sylvestris extract restored the status of all parameters studied. It can be concluded that lithium carbonate has induced oxidative stress, biochemical changes and histopathological damage but the supplementation with Malva sylvestris extract has prevented such toxicity.

Isolation of polysaccharides from Malva aegyptiaca and evaluation of their antioxidant and antibacterial properties

This study investigated the antioxidant and antibacterial properties of crude water-soluble polysaccharides extracted from the mallow (Malva aegyptiaca) by precipitation with cetylpyridinium chloride (P1) or ethanol (P2). The Polysaccharides fractions were characterized by FTIR spectroscopy, a monosaccharide composition, and antioxidant and antibacterial activities. P1 showed the highest total sugars (81.2%) and sulfated groups (2.9%) contents but with the lowest total proteins content (8.7%). The infrared spectroscopic spectra exhibited the typical bands and peak characteristic of polysaccharides. Monosaccharides analysis revealed the dominance of galactose (40.3-43.7%) and glucuronic acid (25.9-30.9%). Interestingly, P1 displayed an important antioxidant activity as evaluated by the (Fe2+) chelating activity (IC50=1.15mg/ml), (Fe3+) reducing power (EC50=1.22mg/ml), β-carotene bleaching inhibition capacity (IC50=1.56mg/ml) and DPPH-radical scavenging activity (IC50=1.94mg/ml). Furthermore, P1 at 10mg/ml was highly active than P2 against several bacterial strains and especially the Gram-positive bacteria, where the inhibition rate ranged between 84.2 and 90.3%. Obtained results suggest that M. aegyptiaca polysaccharides precipitated by cetylpyridinium chloride could be used as a naural antioxidant and antibacterial agent.