[Show abstract][Hide abstract] ABSTRACT: In this work, we report the adaptation of bacteria to stress conditions that induce instability of their cultural, morphological, and enzymatic characters, on which the identification of pathogenic bacteria is based. These can raise serious issues during the characterization of bacteria. The timely detection of pathogens is also a subject of great importance. For this reason, our objective is oriented towards developing an immunosensing system for rapid detection and quantification of Staphylococcus aureus. Polyclonal anti-S. aureus are immobilized onto modified gold electrode by self-assembled molecular monolayer (SAM) method. The electrochemical performances of the developed immunosensor were evaluated by impedance spectroscopy through the monitoring of the charge transfer resistance at the modified solid/liquid interface using ferri-/ferrocyanide as redox probe. The developed immunosensor was applied to detect stressed and resuscitate bacteria. As a result, a stable and reproducible immunosensor with sensitivity of 15 kΩ/decade and a detection limit of 10 CFU/mL was obtained for the S. aureus concentrations ranging from 10(1) to 10(7) CFU/mL. A low deviation in the immunosensor response (±10 %) was signed when it is exposed to stressed and not stressed bacteria.
Full-text · Article · Jun 2015 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: Four strains of Staphylococcus aureus were incubated for eight months in seawater microcosms and then tested for their ability to form a biofilm on different surfaces. Our results showed that the stressed strain became safranin and increased their capacity for producing biofilm on polystyrene microplates or glass wells. These bacteria were able to form a biofilm on the surfaces tested and the cell density was the highest on the stainless steel surface followed by polystyrene and the polyethylene surfaces. These properties allow these bacteria to survive, proliferate and persist even after treatment with antibacterial agents.
No preview · Article · Jul 2014 · Journal of Industrial and Engineering Chemistry
[Show abstract][Hide abstract] ABSTRACT: Abstract Hashimoto's thyroiditis (HT) is a complex genetic autoimmune thyroid disease (AITD). Thyroid-stimulating hormone receptor (TSHR) is considered as candidate gene in AITD. IL1RN gene is involved in the pathogenesis of a number of autoimmune diseases. These findings prompted us to investigate the association of TSHR and IL1RN genes polymorphism with the risk and the prognosis of HT in Tunisia. A total of 249 healthy controls and 202 patients with HT were genotyped for TSHR D727E and IL1RN(VNTR) polymorphism. No significant difference was found for D727E polymorphism between HT patients and healthy controls. For IL1RN gene, we found an association between HT and IL1RN(VNTR) polymorphism. The A1A3 genotype was more prevalent in HT patients than in controls. However, the A1A4 genotype was associated with HT as a protective factor. Significant association of the TSHR polymorphism with lower plasma TSH level in HT patients has been detected. We found for the first time an association of IL1RN(VNTR) polymorphism with the production of anti-thyroid peroxidase antibody at the onset of disease. These preliminary results suggest that only the IL1RN(VNTR) polymorphism may be associated with HT susceptibility and that TSHR and IL1RN(VNTR) polymorphisms may represent prognostic factors for predicting the severity of HT.
[Show abstract][Hide abstract] ABSTRACT: Six new benzophenone glycosides, 2,3',4,5',6-pentahydroxybenzophenone 4-O-(6″-benzoyl)-β-d-glucopyranoside (1), 2,3',4,5',6-pentahydroxybenzophenone 4-O-β-d-glucopyranoside (2), 2,3',4,5',6-pentahydroxybenzophenone 2-O-(2″-benzoyl)-α-l-arabinopyranoside (3), 2,3',4,5',6-pentahydroxybenzophenone 2-O-α-l-arabinopyranoside (4), 2,3',4,5',6-pentahydroxybenzophenone 2-O-(4″-acetyl)-β-d-xylopyranoside (5), and 2,3',4,5',6-pentahydroxybenzophenone 3-C-(4″-benzoyl)-β-d-glucopyranoside (6), and five known compounds were isolated from the aerial parts of Hypericum humifusum ssp. austral. The structures of 1-6 were elucidated by mass spectrometry and extensive 1D and 2D NMR spectroscopy.
Full-text · Article · May 2013 · Journal of Natural Products
[Show abstract][Hide abstract] ABSTRACT: A number of bio-active secondary metabolites have been identified and reported for several Hypericum species. Many studies have reported the potential use of the plant extracts against several pathogens. However, Hypericum triquetrifolium is one of the least studied species for its antimicrobial activity. The aim of the present study was to evaluate the cytotoxic effect of the essential oils of Hypericum triquetrifolium as well as their antimicrobial potential against coxsakievirus B3 and a range of bacterial and fungal strains.
The essential oils of Hypericum triquetrifolium harvested from five different Tunisian localities (Fondouk DJedid, Bou Arada, Bahra, Fernana and Dhrea Ben Jouder) were evaluated for their antimicrobial activities by micro-broth dilution methods against bacterial and fungal strains. In addition, the cytotoxic effect and the antiviral activity of these oils were carried out using Vero cell lines and coxsakievirus B3.
The results showed a good antibacterial activities against a wide range of bacterial strains, MIC values ranging between 0.39-12.50 mg/ml and MBC values between 1.56-25.0 mg/ml. In addition, the essential oils showed promising antifungal activity with MIC values ranging between 0.39 μg/mL and 12.50 μg/mL; MFC values ranged between 3.12 μg/mL and 25.00 μg/mL; a significant anticandidal activity was noted (MIC values comprised between 0.39 μg/mL and 12.50 μg/mL). Although their low cytotoxic effect (CC50 ranged between 0.58 mg/mL and 12.00 mg/mL), the essential oils did not show antiviral activity against coxsakievirus B3.
The essential oils obtained from Hypericum triquetrifolium can be used as antimicrobial agents and could be safe at non cytotoxic doses. As shown for the tested essential oils, comparative analysis need to be undertaken to better characterize also the antimicrobial activities of Hypericum triquetrifolium extracts with different solvents as well as their purified fractions and their pure secondary metabolites.
Full-text · Article · Jan 2013 · BMC Complementary and Alternative Medicine
[Show abstract][Hide abstract] ABSTRACT: The chemical composition of the essential oils extracted from some Tunisian Hypericum species and their larvicidal activity against Culex pipiens larvae were evaluated. The chemical compositions of the essential oils from the aerial plant parts were analyzed using gas chromatography-mass spectrometry. One hundred and thirty-four compounds were identified, ranging between 85.1 and 95.4 % of the oil's composition. The components were monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, non-terpenic hydrocarbons, and others. The larvicidal activity of the essential oils was evaluated using a method recommended by WHO. Larvicidal tests revealed that essential oils from the Hypericum species have a significant larvicidal activity against C. pipiens, with LC(50) ranging between 102.82 and 194.70 ppm. The most powerful essential oils against these larvae were Hypericum tomentosum and Hypericum humifusum samples, followed by the essential oil of Hypericum perforatum.
Full-text · Article · Nov 2012 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: To study the recombination events among enterovirus strains and the development of specific primers for the detection of enteroviruses in environmental samples.
Nucleotide sequence analysis of enteroviruses deposited in the international database GenBank (www.ncbi.nlm.nih.gov/Genbank) was conducted to develop specific primers for the detection of these viruses. The specificity and sensitivity of the method were tested using coxackievirus B3 strain Nancy, environmental isolate of human hepatitis A virus and human rotavirus strain WA. Seventy sewage samples were analyzed.
Enterovirus genome was detected in all positive samples. The genome of enterovirus was not detected in negative samples. The level of detection of these viruses was 10(2) TCID(50)/mL.
The development of new primers is an important issue for the detection of enteroviruses in the environment and the assessment of risk factors to human health.
Preview · Article · Sep 2012 · Asian Pacific Journal of Tropical Medicine
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to investigate the seroprevalence of Hepatitis A virus antibodies in patients with clinical symptoms of viral hepatitis and molecular characterization of the detected isolates. The present study deals with the seroprevalence and the genetic diversity of HAV in 400 Tunisian patients presenting in dispensaries (160 patients) and in University Hospitals (240 patients) with hepatitis symptoms between 2006 and 2008. The patients with acute hepatitis were mainly from rural regions. However, the total number of patients was decreased over time. The collected samples were from patients with hepatitis symptoms occurring mainly during January-March (36.7, 26, and 35.5%) and September-December (39.4, 43.4, and 35.5%) during the three years of study, respectively. However, HAV infection was established for only 110 among 400 patients. The detected isolates were clustered within sub-genotype IA. The present study constituted another report of the continued surveillance of HAV infection in the region of Monastir and the molecular characterisation of the detected strains.
No preview · Article · Jun 2012 · Indian Journal of Virology
[Show abstract][Hide abstract] ABSTRACT: The natural products are widely used in many fields as pharmaceutical, flavor, industrial, and additive compounds. In many cases, there is a need to evaluate the cytotoxic effect of these products and to determine the non cytotoxic concentration at which they can be used in a safe manner.The objective of the present study was to compare two methods of evaluation the cytotoxic effect of a plant extract. The MTT assay and the PI dye-inclusion assay were used to carry out the experiments. The results were then evaluated by calorimetric and flow cytometry assays. The obtained results showed that a clear difference between the two methods and the cell death using the MTT assay seem to be overestimated. To better evaluate the cytotoxic effect of natural product, we need to carry out several in vitro and in vivo tests before the judgment that a compound is safe to use andat which concentration.
No preview · Article · May 2012 · Journal of Applied Pharmaceutical Science
[Show abstract][Hide abstract] ABSTRACT: Nanoparticles derived from plants known for their high content of flavonoids provide a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on the antiviral activity of Salvia officinalis L. and Washingtonia filifera H.Wendl aqueous extracts and their corresponding nanoparticles. In the present study, antiviral activity of subset extracts obtained from aerial parts of Salvia officinalis L. and Washingtonia filifera H.Wendl and nanoparticles derived from these plants were investigated against coxsackievirus B3 (CVB3). Different concentrations of extracts (7.8, 15.6, 31.25, 62.5, 125, 250, 500, and 1000 μg/mL) were tested for their cytotoxic effect and the antiviral activity was carried out using three non cytotoxic concentrations against CVB3 in Vero cells. The cell viability was carried out using tetrazolium dye (MTT). The experiment was carried out by incubating the extracts with either virus or cells prior to infection. The silver nanoparticles derived from the tested plant extracts enhance antiviral activity at non cytotoxic concentrations. The biosynthesized nanoparticles may be further characterized to better evaluate their antiviral potential against other viral pathogens.
No preview · Article · May 2012 · Journal of Applied Pharmaceutical Science
[Show abstract][Hide abstract] ABSTRACT: The chemical composition of the essential oils of five populations of Hypericum triquetrifolium Turra from Tunisia and their intraspecific variability were analyzed in detail by GC/MS. One hundred seventy-four compounds were identified, representing averages of 87.9 to 98.7% of the oil composition. The components are represented here by homologous series of monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpenes hydrocarbons, oxygenated sesquiterpenes, non-terpenic hydrocarbons, and others. Sesquiterpene hydrocarbons were the most abundant chemical compounds. Multivariate chemometric techniques, such as cluster analysis (CA) and principal-component analysis (PCA), were used to characterize the samples according to the geographical origin. By statistical analysis, the analyzed populations were classified into four chemotype groups.
[Show abstract][Hide abstract] ABSTRACT: The antiviral activities of extracts from Daucus maritimus seeds were investigated against the reverse transcriptase of human immunodeficiency virus (HIV) type 1 and a panel of RNA-dependent RNA polymerases of dengue virus, West Nile virus (WNV) and hepatitis C virus (HCV). The extracts showed moderate to potent inhibition rates against the four viral polymerases. The ethyl acetate extract exhibited a potent inhibitory effect against WNV's RdRp, with an IC₅₀ value of 8 µg mL⁻¹. The F₂ fraction exhibited potent inhibitory activity against WNV and HCV's RdRps, with IC₅₀ values 1 and 5 µg mL⁻¹, respectively. The P₂ fraction also showed potent inhibitory effects on WNV and HCV's RdRps, with IC₅₀ values 2.7 and 4 µg mL⁻¹, respectively. The results suggest that these extracts are candidates for the development of new anti-WNV RpDp and anti-HCV RpDp agents.
No preview · Article · Sep 2011 · Natural product research
[Show abstract][Hide abstract] ABSTRACT: In the present study, epidemiological survey and molecular characterization of hepatitis A virus during an outbreak in five Tunisian childcare centers in El-Mahres during October and November 2006 were carried out. Five well-water and five drinking water samples were included in the present study. Serological investigation and molecular characterization were carried out. All patients were IgM seropositive and the viral genome was detected in all clinical and well-water samples whereas it was not detected in drinking water from the five childcare centers. Sequence analysis showed that all Tunisian strains belong to sub-genotype IA. The genetic profile of the VP1/2A junction showed that the outbreak isolates underwent an amino acid substitution which was absent in virus's strains detected previously in Tunisia. Further studies need to be conducted to evaluate the emergence of the virus's strains in clinical and water samples and more epidemiological data need to be collected about the risk factors which may contribute to acute hepatitis.
[Show abstract][Hide abstract] ABSTRACT: Porcine respiratory coronavirus is related genetically to porcine transmissible gastroenteritis virus with a large deletion in S protein. The respiratory virus is a mutated form that may be a consequence of the gastroenteritis virus's evolution. Intensive passages of the virus in its natural host may enhance the appearance of mutations and therefore may contribute to any attenuated form of the virus. The objective of this study was to characterize the porcine transmissible gastroenteritis virus TMK22 strain after passages in piglets from 1992 until 2007. A typical experimental infection, molecular characterization, and serological analysis were also carried out to further characterize and to evaluate any significant difference between strains. The sequence analysis showed two amino acid deletions and loss of an N-glycosylation site in transmissible gastroenteritis virus S protein after passages in piglets. Although these deletions were positioned at the beginning of the antigenic site B of S protein, no clinical differences were observed in piglets infected experimentally either with the native virus or the mutated one. Serological tests did not show any antibody reactivity difference between the two strains. In this article, we report that the S protein deletion did not affect the virus's pathogenicity. The variety of the virus's evolutionary forms may be a result, not only of the multiple passages in natural hosts, but also of other factors, such as different pathogens co-infection, nutrition, immunity, and others. Further studies need to be carried out to characterize the mutated strain.