Factors controlling phytoplankton dynamics in an arid reservoir in Tunisia (case of Sidi Saad dam).

Temporal variation of the phytoplankton community and environmental factors were investigated over 8 months: from January 2018 to November 2018 in the Sidi Saad reservoir (central Tunisia): May, June (spring season), July, August (summer season) September, October and November (autumn season), and January (winter season). The relationships between phytoplankton and environmental factors were explored using Canonical Correspondence Analysis (CCA). General linear models (GLMs) were used to predict the phytoplankton abundance. Analysis of variance (ANOVA) was used to test the hypothesis that the abundance of each group of taxa differed between sampling months. The results of chemical analysis of the reservoir showed that the environment was enriched in nitrates, nitrites, ammonium, and orthophosphate, especially in May. Carlson's trophic index using average chemical variables showed that Sidi Saad has a mesotrophic statute. There is temporal phytoplankton succession in the Sidi Saad reservoir. Cyanophyceae dominated over the year except in winter and late autumn (November and January). Chlorophyceae was the dominant group in winter month. The CCA results showed that six environmental factors, orthophosphates (PO43-), total phosphates (TP), Secchi disc depth (SD), total nitrogen (TN), temperature (T), and nitrite (NO2-) had significant influences on the changes in phytoplankton. GLM showed that PO43-, TP, TN, SD, and T were the significant predictors of phytoplankton abundance. Phytoplankton composition is largely dominated by the species Microcystis aeruginosa which formed a bloom with excessive abundance (up to 89.76 billion cell l-1 in spring). We recommend banning the fishing and their consumption during the period of Microcystis bloom and installing a system of biomonitoring of the levels of toxins in the water.

Optimization of extraction with salicylic acid, rheological behavior and antiproliferative activity of pectin from Citrus sinensis peels.

A Box-Behnken design was used to optimize extraction temperature, extraction time and concentration of the salicylic acid to obtain a maximum polysaccharide yield from Citrus sinensis peels. The optimal settings were: extraction time 3 h, extraction temperature 80 °C and concentration of the salicylic acid 1.5%. Under these conditions, the experimental yield and uronic acid content were 11.74% and 66.9% respectively. Preliminary characterization was performed via FT-IR, SEC/MALS/VD/DRI and GC-MS after hydrolysis. SEC analysis showed that the extracted polysaccharide had a weight average molar mass of 350 kDa and an intrinsic viscosity of 640 mL/g. The GC-MS results revealed that the extracted polysaccharide was composed of arabinose 56.7%, galactose 17.8%, xylose 13.8%, rhamnose 5.1%, mannose 2.5% and glucose 1.5% suggested a rhamnogalacturonan pectin type I with a degree of esterification of 50.9% (IRTF). The flow curve and the dynamic frequency sweep were obtained at 10, 20, 30 and 40 g/L in water and at 30 g/L in presence of CaCl2 or NaCl at 1 mol/L. The solutions showed shear-thinning behavior fitted with Ostwald-De Waele model, except 10 g/L with a Newtonian behavior. The apparent viscosity and, the G' and G" moduli increase with PACO concentration in agreement with a slow-down of the dynamic chain. In the presence of CaCl2 or NaCl the reduction of electrostatic repulsions between pectin chains decreases the rheological parameters. The effect is less sensitive with CaCl2 due to intermolecular interactions. The antiproliferative activity of the extracted pectin on human Caco-2 and Hep-2 cells was very interesting with an IC50 1.4 and 1.8 µg/mL respectively.

Anti-oxidant, antibacterial, anti-biofilm, and anti-quorum sensing activities of four essential oils against multidrug-resistant bacterial clinical isolates.

PURPOSE OF THE STUDY: Outbreaks of multidrug-resistant bacteria are increasingly reported at the clinical setting. The antimicrobial, anti-biofilm, anti-quorum sensing, and anti-oxidant activities of four essential oils extracted from Cinnamomum verum, Origanum majorana, Thymus vulgaris, and Eugenia caryophyllata against Gram-positive and Gram-negative multidrug-resistant bacteria were evaluated in vitro. MATERIALS AND METHODS: This study was conducted on 105 multidrug resistant clinical strains. Inhibition diameter zone, minimum inhibitory concentration, and minimum bactericide concentration of the oils were determined using agar disc diffusion method and microdilution. The ability of the 4 essential oils to inhibit the production of bacterial biofilms was tested on polystyrene plates, as well as their inhibitory effect on the production of violacein by Chromobacterium violaceum CV026. The anti-oxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl scavenging method. RESULTS: Essential oils of Cinnamomum verum, Thymus vulgaris and Eugenia caryophyllata showed an important antibacterial activity. The inhibition diameter zone was higher than 20 mm for 90.24 %, 85.71 % and 60.95 % of strains respectively. These essential oils have a remarkable anti-biofilm and anti-quorum sensing activities against almost all the species studied. Clove extract revealed the highest anti-oxidant activity (Pourcentage of inhibtion of DPPH = 90.3 %). CONCLUSION: These results supported the use of the 4 essential oils as alternative or complementary agents to treat infections caused by multidrug-resistant bacteria, and to prevent biofilm formation and quorum sensing signaling. They might be used as a safe anti-oxidants instead of harmful artificial ones.

Plasticizers and BPA Residues in Tunisian and Italian Culinary Herbs and Spices.

In the present study, 18 plasticizers and residues in 10 different Tunisian and Italian culinary herbs and spices (black pepper, mint, caraway, coriander, oregano, rosemary, thyme, fennel, verbena, and laurel) were determined by GC/MS. Di-methylphthalate, di-(2-methylpropyl)adipate, di-n-butyladipate, di-propylphthalate, benzylbenzoate, di-phenylphthalate, and bisphenol A were lower than their LOQ in all 118 samples. Among the Tunisian samples, di-(2-ethylhexyl)phthalate was found in all types of samples and di-butylphthalate in 50% of types; all other phthalates were rarely dectected. Among the adipates, only di-methyladipate was found in 90% of types; di-ethyladipate was seldom found and di-(2-ethylhexyl)adipate only in samples of caraway. Di-(2-ethylhexyl)terephthalate was found in all types of samples; di-(2-ethylhexyl)sebacate was detected rarely but with high values. Among the Sicilian samples, di-ethylphthalate and di-(2-methylpropyl)phthalate were detected only in samples of mint; di-methyladipate, di-butylphthalate, and benzylbutylphthalate were identified in oregano and laurel; di-(2-ethylhexyl)terephthalate and di-(2-ethylhexyl)sebacate only in oregano. In any case, the results suggested that intake of these contaminants through spices and herbs is not a dangerous risk to the consumers. Probably, as already observed for the other food, these contaminants could result from pollution of the environment (air, water, and/or soil) and/or farming methods. PRACTICAL APPLICATION: Plasticizers and BPA in Tunisian and Italian spices were determined by GC/MS. Tunisian spices seem to contain more residues than Italian samples. Intake of these contaminants by spices is not a dangerous risk to the consumers. These pollutants could result from environmental pollution or agricultural practices.

Analgesic and antibutyrylcholinestrasic activities of the venom prepared from the Mediterranean jellyfish Pelagia noctiluca (Forsskal, 1775).

BACKGROUND: Toxins derived from jellyfishes have been exploited as a model for the development of new drug promising applications to treat neurodegenerative diseases. The present work is aimed to evaluate the acute toxicity of crude venom of Pelagia noctiluca and then to screen the analgesic and antibutyrylcholinestrasic (anti-BuChE) activities of the crude venom and its fractions. METHODS: Sephadex G75 gel was used to separate crude venom of Pelagia noctiluca, which led to some fractions. In addition, in vivo analgesic and in vitro plasma antibutyrylcholinestrasic activities were carried out with Pelagia crude venom and its fractions respectively. RESULTS: The crude venom and its fractions displayed analgesic and anti-BuChE activities at different doses without inducing acute toxicity. Fraction 2 possesses the highest analgesic and antibutyrylcholinestrasic properties. The crude venom and fraction 1 had shown to possess less significant inhibitory activity against analgesic and antibutyrylcholinestrasic models. CONCLUSIONS: Based on this study, the crude venom of Pelagia noctiluca is found to be a useful tool for probing pharmacological activity. The purification and the determination of chemical structures of compounds of active fractions of the venom are under investigation.

Polar extracts from (Tunisian) Acacia salicina Lindl. Study of the antimicrobial and antigenotoxic activities.

BACKGROUND: Methanolic, aqueous and Total Oligomer Flavonoids (TOF)-enriched extracts obtained from the leaves of Acacia salicina 'Lindl.' were investigated for antibacterial, antimutagenic and antioxidant activities. METHODS: The antimicrobial activity was tested on the Gram positive and Gram negative reference bacterial strains. The Mutagenic and antimutagenic activities against direct acting mutagens, methylmethane sulfonate (MMS) and 4-nitro-o-phenylenediamine (NOPD), and indirect acting mutagens, 2-aminoanthracene (2-AA) and benzo[a]pyrene (B(a)P) were performed with S. typhimurium TA102 and TA98 assay systems. In addition, the enzymatic and nonenzymatic methods were employed to evaluate the anti-oxidative effects of the tested extracts. RESULTS: A significant effect against the Gram positive and Gram negative reference bacterial strains was observed with all the extracts. The mutagenic and antimutagenic studies revealed that all the extracts decreased the mutagenicity induced by B(a)P (7.5 µg/plate), 2-AA (5 µg/plate), MMS (1.3 mg/plate) and NOPD (10 µg/plate). Likewise, all the extracts showed an important free radical scavenging activity towards the superoxide anion generated by the xanthine/xanthine oxidase assay system, as well as high Trolox Equivalent Antioxidant Capacity (TEAC), against the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)⁺• radical. TOF-enriched extract exhibited the highest protective effect against free radicals, direct acting-mutagen and metabolically activated S9-dependent mutagens. CONCLUSIONS: The present study indicates that the extracts from A. salicina leaves are a significant source of compounds with the antimutagenic and antioxidant activities, and this may be useful for developing potential chemopreventive substances.

Correlation between antibutyrylcholinesterasic and antioxidant activities of three aqueous extracts from Tunisian Rhus pentaphyllum.

For centuries, plants have been used in traditional medicines and there has been recent interest in the chemopreventive properties of compounds derived from plants. In the present study, we investigated the antibutyrylcholinestrasic (anti-BuChE) and antioxidant (against some free radicals) activities of extracts from Rhus pentaphyllum. Aqueous extracts were prepared from powdered R. pentaphyllum roots, leaves and seeds and characterized for the presence of tannins, flavonoids and coumarins. Seeds aqueous extract contained the highest quantities of both flavonoids and tannins (21.12% and 17.45% respectively). In the same way, seeds extracts displayed remarkable inhibition against BuChE over 95%, at 100 µg/ml and with IC50 0.74 µg/ml. In addition, compared to leaves and roots extracts, seeds aqueous extract revealed relatively strong antiradical activity towards the ABTS.+ (IC50 = 0.25 µg/ml) and DPPH (IC50 = 2.71 µg/ml) free radicals and decreased significantly the reactive oxygen species such O2.- (IC50 = 2.9 µg/ml) formation evaluated by the non-enzymatic generating O2.- system (Nitroblue tetrazolium/riboflavine). These data suggest that the anti-BuChE activities mechanism of these extracts occurs through a free radical scavenging capacities.The present study indicates that extracts of Rhus pentaphyllum leaves, seeds and roots are a significant source of compounds, such as tannins, flavonoids and coumarins, with anti-BuChE and antioxidant activities, and thus may be useful for chemoprevention.

Phytochemical, antibacterial, antiproliferative, and antioxidant potentials and DNA damage-protecting activity of Acacia salicina extracts.

The extract enriched in total oligomer flavonoids (TOF), and the aqueous, methanol, and ethyl acetate extracts of Acacia salicina were investigated for their polyphenolic compound content, antioxidative activity in the nitro blue tetrazolium/riboflavin assay system, antibacterial activity against Gram-positive and Gram-negative bacterial reference strains, antigenotoxic activity tested with the Ames assay, and cytotoxic activity against the K562 human chronic myelogenous leukemia cell line and L1210 leukemia murine cells. TOF extract was effective at inhibiting nitro blue tetrazolium reduction by superoxide radical in a nonenzymatic O(2)(*-)-generating system. Significant activity against bacterial reference strains Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis, and Salmonella typhimurium was shown with all the tested extracts. These extracts significantly decreased the genotoxicity induced by sodium azide and 4-nitro-o-phenylenediamine. A pronounced cytotoxic effect on both leukemia cell lines was detected in TOF, methanolic and ethyl acetate extracts. The antioxidant, antimicrobial, antigenotoxic, and cytotoxic activities exhibited by A. salicina depended on the chemical composition of the tested extracts.