Evaluation of the antiviral activity of new dermaseptin analogs against Zika virus.

Zika virus represents the primary cause of infection during pregnancy and can lead to various neurological disorders such as microcephaly and Guillain-Barré syndrome affecting both children and adults. This infection is also associated with urological and nephrological problems. So far, evidence of mosquito-borne Zika virus infection has been reported in a total of 89 countries and territories. However, surveillance efforts primarily concentrate on outbreaks that this virus can cause, yet the measures implemented are typically limited. Currently, there are no specific treatments or vaccines designed for the prevention or treatment of Zika virus infection or its associated disease. The development of effective therapeutic agents presents an urgent need. Importantly, an alternative for advancing the discovery of new molecules could be dermaseptins, a family of antimicrobial peptides known for their potential antiviral properties. In this study, we carried out the synthesis of dermaseptins and their analogs and subsequently assessed the bioactivity tests against Zika virus (ZIKV PF13) of dermaseptins B2 and S4 and their derivatives. The cytotoxicity of these peptides was investigated on HMC3 cell line and HeLa cells by CellTiter-Glo® Luminescent Cell Viability Assay. Thereafter, we evaluated the antiviral activity caused by the action of our dermaseptins on the viral envelope using the Fluorescence Activated Cell Sorting (FACS). The cytotoxicity of our molecules was concentration-dependent at microgram concentrations Expect for dermaseptin B2 and its derivative which present no toxicity against HeLa and HMC3 cell lines. It was observed that all tested analogs from S4 family exhibited antiviral activity with low concentrations ranging from 3 to 12.5 µg/ml , unlike the native B2 and its derivative which increased the infectivity. Pre-incubating of dermaseptins with ZIKV PF13 before infection revealed that these derivatives inhibit the initial stages of virus infection. In summary, these results suggest that dermaseptins could serve as novel lead structures for the development of potent antiviral agents against Zika virus infections.

Evaluation of the Antibacterial Activity of New Dermaseptin Derivatives against Acinetobacter baumannii.

Nosocomial infections represent one of the biggest health problems nowadays. Acinetobacter baumannii is known as an opportunistic pathogen in humans, affecting people with compromised immune systems, and is becoming increasingly important as a hospital-derived infection. It is known that in recent years, more and more bacteria have become multidrug-resistant (MDR) and, for this reason, the development of new drugs is a priority. However, these products must not affect the human body, and therefore, cytotoxicity studies are mandatory. In this context, antimicrobial peptides with potential antibacterial proprieties could be an alternative. In this research, we describe the synthesis and the bioactivity of dermaseptins and their derivatives against Acinetobacter baumannii. The cytotoxicity of these compounds was investigated on the HEp-2 cell line by MTT cell viability assay. Thereafter, we studied the morphological alterations caused by the action of one of the active peptides on the bacterial membrane using atomic force microscopy (AFM). The cytotoxicity of dermaseptins was concentration-dependent at microgram concentrations. It was observed that all tested analogs exhibited antibacterial activity with Minimum Inhibitory Concentrations (MICs) ranging from 3.125 to 12.5 µg/mL and Minimum Bactericidal Concentrations (MBCs) ranging from 6.25 to 25 µg/mL. Microscopic images obtained by AFM revealed morphological changes on the surface of the treated bacteria caused by K4S4(1-16), as well as significant surface alterations. Overall, these findings demonstrate that dermaseptins might constitute new lead structures for the development of potent antibacterial agents against Acinetobacter baumannii infections.

Phytochemical Analysis and Evaluation of the Antioxidant, Antiproliferative, Antibacterial, and Antibiofilm Effects of Globularia alypum (L.) Leaves.

Globularia alypum L. (GA) is a Mediterranean plant of the Globulariaceae family which is widely used in traditional Tunisian medicine. The main goal of this study was to evaluate the phytochemical composition, antioxidant, antibacterial, and antibiofilm activities, and the antiproliferative potential of different extracts of this plant. The identification and the quantification of the different constituents of extracts were determined using gas chromatography-mass spectrometry (GC-MS). The antioxidant activities were evaluated using spectrophotometric methods and chemical tests. The antiproliferative study was based on the use of colorectal cancer SW620 cells, including an antibacterial assessment with the microdilution method and analysis of the antibiofilm effects via the crystal violet assay. All extracts presented several components, mainly sesquiterpenes, hydrocarbon, and oxygenated monoterpenes. The results revealed that the maceration extract had the most important antioxidant effect (IC50 = 0.04 and 0.15 mg/mL), followed by the sonication extract (IC50 = 0.18 and 0.28 mg/mL). However, the sonication extract demonstrated significant antiproliferative (IC50 = 20 µg/mL), antibacterial (MIC = 6.25 mg/mLand MBC > 25 mg/mL), and antibiofilm (35.78% at 25 mg/mL) properties against S. aureus. The results achieved confirm the important role of this plant as a source of therapeutic activities.

Phytochemical profile, cytotoxic, antioxidant, and allelopathic potentials of aqueous leaf extracts of Olea europaea.

Although bioactivities of Olea europaea (OE) have been widely described, most of them were related to its methanolic extracts or its essential oils, While data related to aqueous extracts still very scarce. Thus, in this study, the phytochemical composition, the antioxidant activity, the cytotoxic potential, and the allelopathic potential of aqueous leaf extracts from two varieties of Olea europaea were investigated and compared. High-performance liquid chromatography (HPLC) was used to identify and quantify the constituents of the tested plants, and spectrophotometric methods to evaluate antioxidant activities. The cytotoxic potential was investigated using murine oligodendrocytes (158N) while germination seeds' test was used for allelopathic activity. HPLC analysis showed the presence of 10 phenolic compounds in both extracts. Chemlali variety showed the highest antioxidant and allelopathic activities. Regarding the cytotoxicity effect, a significant increase in cell viability was observed with both of our extracts compared to untreated cells. These results confirm that aqueous extracts from OE produce a range of substances with potential antioxidant, antifungal, and allelopathic effects without toxic effects. Thus, they could be used as an alternative of chemical compounds.

Phytochemical Analysis and Assessment of Biological Properties of Essential Oils Obtained from Thyme and Rosmarinus Species.

BACKGROUND: The plant species Thymus algeriensis (TA); Thymus capitatus (TC) and Rosmarinus officinalis (RO), are widely used in traditional medicine in Tunisia. The bioactivities of their essential oils have also been reported previously. The main objective of this work was to assess the phytochemical composition, the antioxidant activity, cytotoxic potential and the antibacterial, antifungal, of the essential oil (EO) of these plants. METHODS: Gas Chromatography-Mass Spectrometry (GC-MS) was used to identify and quantify the constituents of the tested EO. Chemical tests, and spectrophotometric methods were used for antioxidant activities and for the screening and quantification of phytochemicals. The cytotoxic potential of the EO was checked using HCT 116 cultures. The extracts were evaluated for their antibacterial potential by the microdilution method. Antifungal activities were tested using the Poisoned food technique against Aspergillus niger and Aspergillus flavus. RESULTS: The EO of tested plants presented several components, mainly monoterpenes and sesquiterpenes. The results revealed that T. capitatus EO is not toxic compared to the other tested samples. Phenolic compounds were detected and this EO showed excellent antioxidant activity presenting dosedependent relationship. Regarding antimicrobial activity, T. capitatus EO, also had the highest inhibition against all tested bacteria and fungi. CONCLUSION: This study showed the importance of the bioactivities (antioxidant, antimicrobial, and safety potential) of EOs of the plant species TC, RO, and TA used in traditional medicine.

Chemical composition, Fatty acids profile and Biological properties of Thymus capitatus (L.) Hoffmanns, essential Oil.

T. capitatus is widely used in traditional medicine in Tunisia. The main goal of this study was to evaluate the phytochemical composition, the fatty acids profile, the antioxidant, antibacterial, and antifungal activities as well as the cytotoxic potential of the essential oil (EO) of this plant. The identification and the quantification of the different constituents of the tested EO was determined by gas chromatography-mass spectrometry (GC-MS). Antioxidant activities were evaluated by spectrophotometric methods and chemical tests. HCT 116 cells were used to evaluate the cytotoxic effect of the EO. The microdilution method was conducted to evaluate the antibacterial activity. Poisoned food method was used to test the antifungal activities against fungi species such Aspergillus niger and Aspergillus flavus. The EO presented several components, mainly monoterpenes. Results revealed that T. capitatus EO is not cytotoxic and showed excellent antioxidant activity with a dose dependent manner. Regarding antimicrobial activity, T. capitatus EO was efficient against all tested bacteria and fungi.

Thymic epithelium determines a spontaneous chronic neuritis in Icam1(tm1Jcgr)NOD mice.

The NOD mouse strain spontaneously develops autoimmune diabetes. A deficiency in costimulatory molecules, such as B7-2, on the NOD genetic background prevents diabetes but instead triggers an inflammatory peripheral neuropathy. This constitutes a shift in the target of autoimmunity, but the underlying mechanism remains unknown. In this study, we demonstrate that NOD mice deficient for isoforms of ICAM-1, which comediate costimulatory functions, spontaneously develop a chronic autoimmune peripheral neuritis instead of diabetes. The disease is transferred by CD4(+) T cells, which infiltrate peripheral nerves together with macrophages and B cells and are autoreactive against peripheral myelin protein zero. These Icam1(tm1Jcgr)NOD mice exhibit unaltered numbers of regulatory T cells, but increased IL-17-producing T cells, which determine the severity, but not the target specificity, of autoimmunity. Ab-mediated ICAM-1 blockade triggers neuritis only in young NOD mice. Thymic epithelium from Icam1(tm1Jcgr)NOD mice features an altered expression of costimulatory molecules and induces neuritis and myelin autoreactivity after transplantation into nude mice in vivo. Icam1(tm1Jcgr)NOD mice exhibit a specifically altered TCR repertoire. Our findings introduce a novel animal model of chronic inflammatory neuropathies and indicate that altered expression of ICAM-1 on thymic epithelium shifts autoimmunity specifically toward peripheral nerves. This improves our understanding of autoimmunity in the peripheral nervous system with potential relevance for human diseases.

Characterization of TtALV2, an essential charged repeat motif protein of the Tetrahymena thermophila membrane skeleton.

Alveolins are a recently described class of proteins common to all members of the superphylum Alveolata that are characterized by conserved charged repeat motifs (CRMs) but whose exact function remains unknown. We have analyzed the smaller of the two alveolins of Tetrahymena thermophila, TtALV2. The protein localizes to dispersed, broken patches arranged between the rows of the longitudinal microtubules. Macronuclear knockdown of Ttalv2 leads to multinuclear cells with no apparent cell polarity and randomly occurring cell protrusions, either by interrupting pellicle integrity or by disturbing cytokinesis. Correct association of TtALV2 with the alveoli or the pellicle is complex and depends on both the termini as well as the charged repeat motifs of the protein. Proteins containing similar CRMs are a dominant part of the ciliate membrane cytoskeleton, suggesting that these motifs may play a more general role in mediating membrane attachment and/or cytoskeletal association. To better understand their integration into the cytoskeleton, we localized a range of CRM-based fusion proteins, which suggested there is an inherent tendency for proteins with CRMs to be located in the peripheral cytoskeleton, some nucleating as filaments at the basal bodies. Even a synthetic protein, mimicking the charge and repeat pattern of these proteins, directed a reporter protein to a variety of peripheral cytoskeletal structures in Tetrahymena. These motifs might provide a blueprint for membrane and cytoskeleton affiliation in the complex pellicles of Alveolata.

Active immunization induces toxicity of diphtheria toxin in diphtheria resistant mice--implications for neuroinflammatory models.

Cell-type specific expression of the human diphtheria toxin receptor in generally toxin resistant mice represents an innovative approach for the selective depletion of pre-defined cell populations. We demonstrate that in wildtype mice diphtheria toxin--in concentrations otherwise well tolerated--is highly toxic and lethal together with active immunization irrespective of the immunogenic peptide applied. We found increased lung cellularity as only pathological abnormality. Animal models of inflammatory diseases requiring active immunization including experimental autoimmune encephalomyelitis may thus not be applicable in diphtheria receptor transgenic mice pointing to a major limitation of this otherwise technically interesting approach.