Additive effect of the probiotics Lactobacillus exopolysaccharides and the Satureja calamintha extracts on enteropathogenic Escherichia coli adhesion

Abstract This study assessed the inhibitory potential of the probiotics Lactobacillus (LB) exopolysaccharides (EPS) with or without extracts of Satureja calamintha on enteropathogenic Escherichia coli (EPEc) responsible for gastroenteritis. Methanolic and hydromethanolic extracts were prepared by cold maceration and subjected to phytochemical screening. The compounds of the extracts were determined with the colorimetric assays and identified using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). Antioxidant activities of the extracts were also evaluated by using 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging. Antibacterial effect on EPEc was evaluated by using both agar disc diffusion and microdilution methods. The in vitro test of auto-aggregation was investigated. Microbiological analysis showed that 63% of the isolated LB were producing EPS, with the amount ranging from 8.21 to 43.13 mg/L. Chemical analysis of the extracts revealed the presence of polyphenols and flavonoids, more abundant in the hydromethanolic extract, which presented the highest content with 2.11 mg EGA/g of polyphenol and 1.64 mg EC/g of flavonoids and 1.71 mg EGA/g of polyphenol and 1.15 mg EC/g of flavonoids in the methanolic extract. Hydromethanolic extracts and EPS exhibited a more important activity than did the methanolic extract against EPEc. The combined action of EPS and extracts reduced the aggregation ability of EPEc and decreased the rate of their adhesion.

Bacterial ecology and antibiotic resistance mechanisms of isolated resistant strains from diabetic foot infections in the north west of Algeria.

BACKGROUND: In front of the polymorphic bacterial ecology and antibiotic resistance in diabetic patients with foot infections and good patient care, collaboration between clinicians and microbiologists is needed to improve assessment and management of patients with this pathology. OBJECTIVE: This study was designed to characterize the bacterial ecology of diabetic foot infection (DFIs) and to determine the different mechanisms of resistance involved. METHODS: In this study bacterial strains and antibiotic resistance profiles were determined from diabetic foot infections patients (n = 117). The identification of resistance mechanisms, such as penicillinase and/or extended-spectrum ß-lactamase production (ESBL), methicillin-resistant Staphylococcus aureus (MRSA) and efflux pump over-expression were performed. RESULTS: A high prevalence of Gram-negative bacteria (61%) with Escherichia coli, and other Enterobacteriaceae and Pseudomonas aeruginosa being the predominant isolates. Gram positive bacteria mainly represented by Staphylococcus aureus accounted for 39% of the isolates. 93.5% of the Enterobacteriaceae were resistant to, at least, one molecule in the ß-lactam family, while the majority of the Staphylococci were resistant to penicillin G and tetracycline (93.3% and 71.7%). The majority of non-fermenting Gram negative bacteria were also resistant to fluoroquinolones. ß-lactamase detection tests revealed the presence of extended-spectrum ß-lactamase in 43.5% of the Enterobacteriaceae, while methicillin-resistant Staphylococcus aureus represented 18.2% of the isolates. Additionally, 50.9% of non-fermenting Gram negative bacteria were overproducing efflux pumps. CONCLUSION: All Acinetobacter Baumannii were Multidrug-Resistant (MDR), as the majority of Staphylococci, and Enterobacteriaceae. These results should be taken into account by the clinician in the prescription of probabilistic antibiotic therapy in this context.

Purification and characterization of catechol oxidase from Tadela (Phoenix dactylifera L.) date fruit.

Catechol oxidase (PPO) was extracted and purified from Tadela (Phoenix dactylifera L.) date fruit, by a procedure that included (NH4)2SO4 precipitation followed by dialysis, Q-Sepharose bb ion-exchange chromatography and HPLC gel filtration chromatography. Some of its biochemical characteristics were studied. The purification rate and the yield were 80% and 20%, respectively. The Tadela date fruit catechol oxidase exhibited a molecular weight of 90 kDa using SDS-PAGE. The catechol oxidase showed only o­diphenolase and triphenolase activities while no monophenolase activity was detected. A better affinity was observed using catechol as substrate (Km = 35 mM) with thus, a higher Vmax/Km ratio (80 U/mM·mL). This enzyme is thermostable in the temperature range (30-60 °C) with optimum activity in acidic range of pH. Four inhibitors were used for the control of enzymatic browning, of which sodium metabisulfite was the most potent (IC50 = 0, 11 mM). The values of KI and mechanism of inhibition were also determined. No significant change on enzyme activity was noticed in the presence of metal ion and detergents. Therefore, thermal inactivation was studied in the temperature range between 60 and 80 °C using catechol as substrate. Their kinetic (K, D, t1/2, Zt, Ea) and thermodynamic (ΔH, ΔG and ΔS) parameters were also estimated.

In vitro study on the activity of essential oil and methanolic extract from Algerian Nigella sativa L. Seeds on the growth kinetics of micro-organisms isolated from the buccal cavities of periodontal patients.

An in vitro evaluation of the antimicrobial activity of essential oil (EO) and methanol extract (ME) from Algerian Nigella sativa L. seeds against microbial strains isolated from the oral cavities of periodontal patients was performed. Twelve Gram-positive bacteria, eleven Gram-negative bacteria and three microscopic fungi strains were isolated and identified. The antimicrobial activities of EO and ME were tested against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, Klebsiella pneumoniae, Proteus sp., Acinetobacter baumannii/calcoaceticus, Porphyromonas sp., Veillonella sp., Candida sp. and Saccharomyces sp.. The total polyphenol and flavonoids contents of ME were higher than those of EO. Thin layer chromatography showed that catechin, gallic acid and quercetin were most likely present in the extracts. Fourier transform infrared spectrometry analysis (FT-IR) indicated the presence of bands from the CO groups of acids, alcohols, phenols, and ethers and the C[bond, double bond]O band of aldehydes. Analysis of the antimicrobial activity of N. sativa extracts obtained by the microdilution method showed excellent bactericidal activity of the essential oil and moderate efficiency of the ME against all the microbes tested. Staphylococcus epidermidis and Porphyromonas sp. were the most sensitive to EO (minimum bactericidal concentration (MBC): 16,500 µg/ml) at 48 h of incubation and, 125,000 µg/ml of ME was the most active against all the microbes tested. However, after18 or 24 h, this efficiency was decreased in some strains. In addition, Saccharomyces sp. and Candida albicans were more sensitive to EO than ME during the incubation, while this efficiency was clearly not visible with the agar well method, and most microbes tested presented remarkable resistance to these extracts.

Phytochemicals, Antioxidant and Antiproliferative Properties of Rosmarinus officinalis L on U937 and CaCo-2 Cells.

Rosmarinus officinalis L., a medicinal herb from the labiates family, has been reported to have potential benefit in the treatment and prevention of several diseases. In particular its phenolics have demonstrated protective effects on various types of cancer through several mechanisms. The present study aimed to determine the effects of rosemary phenolic extracts on human cell functions, with particular regard to their anti-proliferative properties in three cell types U937, CaCo-2 and the peripheral blood mononuclear cells (PBMCs). The radical scavenging and Ferric reducing abilities of the extracts have been assessed as well as their cyto-toxicity and effects on cell cycle distribution and apoptosis. About 13 compounds were identified with dominance of rosmarinic acid in the methanolic extract and phenolic diterpens in the ethyl acetate fraction (Carnosol, Carnosic acid and methyl Carnosate). The total polyphenolic content was important in the first extract with 2.589 ± 0.005 g/100 g in gallic acid equivalent compared to 0.763 ± 0.005 g/100 g. The methanolic fraction displayed higher antioxidant activity (DPPHIC50: 0.510 mg/mL and FRAP: 1.714 ± 0.068 mmol Fe2+/g) while ethyl acetate showed pronounced antiproliferative effects (IC50: 14.85 ± 0.20µg/mL and 14.95 ± 2.32 µg/mL respectively for U937 and CaCo-2 cells). The anti-proliferative effect was associated with a cell cycle arrest in S phase for U937 (62% of the population at 5 µg/mL) with a concomitant decrease in G1 and G2/M phases. Tested extracts displayed in addition early apoptotic effects in U937 and late apoptosis in CaCo-2 cells. The obtained data indicate that the identified phenolics are at least partially responsible for the observed cytotoxicity.

In vitro and in vivo antimicrobial activity of Algerian Hoggar Salvadora persica L. extracts against microbial strains from children's oral cavity.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvadora persica L. (miswak) is traditionally used to ensure oral hygiene Muslim people in developing countries where it is growing. The antibacterial properties of Salvadora persica L. originating from various geographic areas have already been reported. However, they have never been tested for samples originating from Hoggar, where extreme weather conditions could lead to different properties for this Salvadora persica L. ecotype. AIM OF THE STUDY: To assess the in vitro and in vivo antimicrobial activities of methanolic extract of Algerian Hoggar Salvadora persica L. (miswak) on some isolated and identified strains from the oral cavity of school children aged from 6 to 12 with (n=20) and without (n=20) caries. MATERIALS AND METHODS: After a qualitative and quantitative analysis of dental plaque samples from the selected children, the effect of methanolic extract of Hoggar miswak against oral bacterial and fungal strains isolated from the oral cavity of children with caries was tested by both agar disc diffusion and microdilution methods. The stability and physicochemical parameters of Hoggar Salvadora persica L. mouthwash were also assessed compared. The in vivo antimicrobial effect of Hoggar miswak rinse on dental plaque samples was also tested over a week. RESULTS: Four bacterial genera (Staphylococcus, Streptococcus, Escherichia and Lactobacillus) were commonly identified in all subjects at different colonization levels. A statistically significant difference in colonization levels between the two groups of children was recorded. Hoggar miswak extract more significantly inhibited the growth of Gram negative bacteria from the dental plaque than Gram positive ones. Hoggar Salvadora persica L. mouthwash was stable at 4 °C and 25 °C over the period of conservation (one week) while a temperature of 40 °C induced variations in the physicochemical parameters and considered not suitable for preservation. The in vivo study revealed a significant reduction in bacteria of the oral cavity using miswak mouthwash as compared to placebo. CONCLUSION: Hoggar miswak extract displayed a strong antimicrobial effect both in vitro and in vivo. Its use as a mouthrinse could therefore be recommended as a preventive measure to preserve from tooth decay.

The sorption of lead, cadmium, copper and zinc ions from aqueous solutions on a raw diatomite from Algeria.

The adsorption of Cu(2+), Zn(2+), Cd(2+) and Pb(2+) ions from aqueous solution by Algerian raw diatomite was studied. The influences of different sorption parameters such as contact pH solution, contact time and initial metal ions concentration were studied to optimize the reaction conditions. The metals ions adsorption was strictly pH dependent. The maximum adsorption capacities towards Cu(2+), Zn(2+), Cd(2+) and Pb(2+) were 0.319, 0.311, 0.18 and 0.096 mmol g(-1), respectively. The kinetic data were modelled using the pseudo-first-order and pseudo-second-order kinetic equations. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. Equilibrium isotherm data were analysed using the Langmuir and the Freundlich isotherms; the results showed that the adsorption equilibrium was well described by both model isotherms. The negative value of free energy change ΔG indicates feasible and spontaneous adsorption of four metal ions on raw diatomite. According to these results, the high exchange capacities of different metal ions at high and low concentration levels, and given the low cost of the investigated adsorbent in this work, Algerian diatomite was considered to be an excellent adsorbent.