Publications by authors named "Olfa Tabbene"

Article Synopsis
  • This study evaluated the antioxidant and antileishmanial effects of essential oil from Ballota (B.) hirsuta leaves, identifying spathulenol and germacrene D as its main components.
  • The essential oil demonstrated moderate antioxidant activity and high antileishmanial effectiveness against both promastigote and amastigote forms of Leishmania, with specific IC values indicating its potency.
  • The study also revealed that B. hirsuta EO primarily inhibits the sterol synthesis pathway and suggested that its main compounds may be promising candidates for developing treatments against leishmaniasis.
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As part of the development of alternative and environmentally friendly control against phytopathogenic fungi, could be a useful species notably via the generation of hydrolytic enzymes like chitinases, which can act as a biological control agent. Here, a S614 strain exhibiting chitinase activity was isolated from a soil in southern Tunisia. Then, response surface methodology (RSM) with a central composite design (CCD) was used to assess the impact of five factors (colloidal chitin, magnesium sulfate, dipotassium phosphate, yeast extract, and ammonium sulfate) on chitinase activity.

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  • Antibiotic resistance and biofilm formation in Gram-negative bacteria pose significant challenges for infection control, particularly through the Quorum Sensing (QS) mechanism.
  • Myrtle leaf extract demonstrated a potent anti-QS effect, inhibiting 80% of violacein production and significantly reducing various virulence factors like biofilm formation and protease activity at sub-MIC concentrations.
  • The study identified three phenolic compounds from the extract, with 3,5-di-galloylquinic acid showing the strongest interaction with the CviR QS receptor, indicating potential for developing new QS inhibitors against resistant pathogens.
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  • * Major compounds identified in the EO included α-pinene and -cadinol, but the oil showed limited antioxidant activity, failing to neutralize certain free radicals effectively.
  • * The EO demonstrated strong leishmanicidal effects against promastigote and amastigote forms, with the components showing better binding to the enzyme CYP51 compared to the conventional drug fluconazole, suggesting it could be a promising alternative treatment for leishmaniasis.
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Combination therapy at appropriately suitable doses presents a promising alternative to monotherapeutic drugs. In this study, and essential oils and their major compounds have exhibited substantial leishmaniacidal potential against both promastigote and amastigote forms of . However, they displayed high cytotoxicity against Raw264.

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Nanoencapsulation is widely considered as a highly effective strategy to enhance essential oils' (EO) stability by protecting them from oxidative deterioration and evaporation. The present study aims to optimize and characterize an efficient technique for encapsulating essential oil into chitosan nanoparticles using response surface methodology (RSM). Moreover, the optimized EO nanoparticle was investigated for its antibacterial (against Gram-positive and Gram-negative bacteria), antifungal (against ), and antiparasitic activity (against parasites).

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  • - The study evaluated the antioxidant, antibacterial, antiviral, and anti-inflammatory properties of various parts (flowers, leaves, seeds) of a specific plant using 80% methanol extraction and microdilution techniques.
  • - Flower extracts demonstrated significant antimicrobial effectiveness against Gram-positive bacteria, as well as strong antioxidant and anti-inflammatory properties, with no toxic effects on macrophage cells.
  • - Two beneficial molecules, 12α-hydroxydaturametelin B and daturametelin B, were identified from the flower extract, showing promising potential for treating inflammatory disorders through effective binding with pro-inflammatory agents.
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  • - The study explored the antibacterial and antileishmanial effects of Micromeria nervosa extracts, identifying ursolic acid as the active compound and examining its molecular mechanism of action.
  • - Ethanol and diethyl ether extracts of the plant were tested, with the diethyl ether extract showing strong antibacterial activity against certain resistant bacteria and significant antileishmanial effects against Leishmania species.
  • - Results suggest that M. nervosa extracts and the identified ursolic acid could serve as potential natural alternatives for treating infections, demonstrating low toxicity against host cells and targeting specific gene expressions in pathogens.
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  • * A study analyzed the antibacterial and antibiofilm effects of Peganum harmala seed extract, revealing that its n-butanol extract was more effective against drug-resistant strains than traditional antibiotics.
  • * The active compound identified as harmaline demonstrated both strong antibacterial properties and significant biofilm inhibition, making it a promising candidate for treating P. aeruginosa-related infections.
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The aim of this study was to investigate antimicrobial and antioxidant activities of different fractions obtained from edible Tunisian Ziziphus Lotus leaves of Tozeur region. Different organic extracts were tested: cyclohexane, dichloromethane, ethyl acetate, n-butanol and water. Bio-guided fractionation revealed that dichloromethane fraction is the most active against S.

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Cyclic lipopeptides produced by Bacillus species exhibit interesting therapeutic potential. However, their clinical use remains limited due to their low stability, undesirable interactions with host macromolecules, and their potential toxicity to mammalian cells. The present work aims to develop suitable lipopeptide-loaded chitosan nanoparticles with improved biological properties and reduced toxicity.

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Exopolysaccharide (EPS) from marine microalgae are promising sources of a new generation of drugs. However, lot of them remain to be discovered and tested. In this study, EPS produced by and its oligomers prepared by High Pressure Homogenizer have been tested for different biological activities, i.

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  • A study evaluated 450 bacterial strains for their ability to combat bacterial soft rot in potatoes caused by Pectobacterium carotovorum, identifying strain Ar10 as a strong antagonist.
  • Strain Ar10, identified as Bacillus amyloliquefaciens, produced a cell-free supernatant with significant antibacterial activity against various bacteria, showing a killing rate of up to 96% against P. carotovorum.
  • Treatment of potato tubers with strain Ar10 or its supernatant significantly reduced disease symptoms, indicating that the glycolipid compound produced by Ar10 could be a promising alternative for managing potato soft rot.
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  • Researchers isolated a strain of Bacillus amyloliquefaciens, named C5, from olive tree roots, which produces antibacterial biosurfactant lipopeptides.
  • They optimized its antibacterial activity using grape seed flour (GSF) at different concentrations, finding 0.2% GSF yielded the best growth and antimicrobial results, with an MIC of 60 μg/ml.
  • Thin layer chromatography and MALDI-TOF/MS analyses indicated the production of multiple lipopeptides, including surfactin and bacillomycin D, highlighting GSF as an effective and affordable medium supplement for biosurfactant production.
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A Trichoderma orientale strain LSBA1 was isolated from the Mediterranean marine sponge Cymbaxinella damicornis. The crude extract of T. orientale mycelium showed inhibitory activity against growth of Gram-positive and Gram-negative bacteria as well as clinical isolates of Candida albicans.

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The present work was developed to evaluate the in vitro antioxidant, antibacterial, antileishmanial and cytotoxic activities of Echium arenarium (Guss) extracts, and to analyze their phytochemical composition. The highest content of total phenolic compounds was obtained in the ethyl acetate extract which showed the best DPPH scavenging activity and β-carotene bleaching inhibition (IC = 1.1 and 9.

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A novel actinomycete strain designated S2 was isolated from Tunisian rhizosphere soil of Lavandula officinalis. This isolate exhibited broad spectrum antibacterial activity against several Gram-positive and Gram-negative bacteria and also antifungal activity against yeast and filamentous fungi. The isolate S2 presents morphological and chemotaxonomic characteristics typical of the members of the genus Streptomyces.

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A protease-producing strain CT2 isolated from Tunisian potatoes, exhibiting a potent protease activity (prot CT2), was identified as Bacillus halotolerans according to 16S ribosomal DNA sequence analysis. Maximum prot CT2 production was obtained in medium supplemented with bean seed proteins. Proteolytic activity was purified by ammonium sulphate precipitation, Sephacryl S-200 gel filtration and SP-sepharose cation-exchange chromatography.

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Article Synopsis
  • * Cinnamomum verum and Pelargonium graveolens showed the best results, with significant inhibition of Candida's secreted aspartic protease (SAP) activity and a strong reduction in ergosterol levels, essential for fungal cell membranes.
  • * The findings suggest that combining these essential oils with fluconazole could enhance treatment effectiveness for Candida infections, potentially leading to better therapeutic options for patients.
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A strain producing chitinase, isolated from potato stem tissue, was identified as Bacillus licheniformis by biochemical properties and 16S RNA sequence analysis. Statistical experimental designs were used to optimize nine independent variables for chitinase production by B. licheniformis AT6 strain in submerged fermentation.

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In the present study, the synergism of the lipopeptide bacillomycin D in combination with the polyene amphotericin B against pathogenic Candida species is described along with their potential cytotoxicity against mammalian cells. Bacillomycin D inhibited the growth of various Candida species at minimal concentrations from 12.5 to 25 μg ml(-1).

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Among nine chitinase-producing strains isolated from Tunisian soil, one isolate called S213 exhibited a potent chitinolytic activity. S213 strain was identified as Bacillus licheniformis by API 50CH system and sequence analysis of its partial 16S ribosomal DNA. Chitinolytic activity was induced either by colloidal chitin or fungal cell walls, and the highest chitinase activity reached at the late stationary phase exhibiting optimal temperature and pH of 50-60 °C and pH 6.

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In the present study, we evaluated the antioxidant and the scavenging ability of C14, C15 and C16 bacillomycin D-like lipopeptides produced by B38 strain. They all displayed strong reducing power activity, hydroxyl and superoxide anion radicals scavenging activities and inhibition of lipid peroxidation. In addition, they were found to protect plasmid DNA damage from hydroxyl radical oxidation.

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An antagonist L194 strain against Phoma medicaginis pathogenic fungi was isolated from Tunisian soil (vicinity of Tunis) and identified as Bacillus subtilis based on biochemical characteristics and partial 16S rDNA sequence. When cells were grown in a minimal medium for 24 h, spore culture supernatant exhibited 2-fold higher antifungal activity than vegetative cells. MALDI-TOF mass spectrometry analysis showed that L194 spores produced mainly iturins, surfactins and fengycins with long-chain fatty acids, and other not yet identified compounds.

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In continuation of our search for bioactive secondary metabolites from terrestrial Bacillus spp., a new microbial diketopiperazine, cis-cyclo-(His,Leu) (1) was isolated from the ethyl acetate extract of a strain B. subtilis B38, together with cis-cyclo-(Phe,Phe) (2), tryptophane (3), cis-cyclo-(Leu,Tyr) (4), cis-cyclo-(Trp,Tyr) (5) and macrolactin A (6).

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