HPLC-HESI-MS/MS Analysis of Phenolic Compounds from Cynoglossum tubiflorus Leaf Extracts: An Assessment of Their Cytotoxic, Antioxidant, and Antibacterial Properties.

The current study aimed to investigate the chemical composition, antioxidant, antibacterial, and cytotoxic properties of three extracts (hexane, dichloromethane, and methanol) from Cynoglossum tubiflorus. The composition of the methanolic extract was elucidated using HPLC-HESI-MS/MS analysis. The antioxidant effect was examined using NO, DPPH, FRAP, and TAC assays. Antimicrobial activity was evaluated by broth microdilution using various bacterial strains such as S. aureus, S. epidermidis, P. aeruginosa, E. coli, and K. pneumoniae. Structural disruptions in Gram-positive bacteria were visualized using scanning electron microscopy (SEM). Cytotoxic effects were evaluated on human MRC-5 in culture according to the MTT assay. The outcomes suggest that methanol extract contained a high amount of phenolic compounds (254.35 ± 0.360 mg GAE/g DE and 211.59 ± 0.939 mg QE/g DE). By applying the HPLC-HESI-MS/MS analysis, 32 compounds were identified, including phenolic acids, flavonoids, lignans, and fatty acids. This extract showed strong antioxidant (IC50 = 0.043 ± 0.001 mg/mL) and antimicrobial (MIC = 156 µg/mL) activities. The SEM suggests that cells exhibited membrane distortions characterized by surface depressions and alterations in bacterial shape, including dents, when compared to untreated cells. The in vitro cytotoxicity effect on human MRC-5 cells showed no toxicity effects at a concentration of 600 µg/mL. In silico analysis predicted low toxicity for all tested compounds across four different administration routes. This research indicates that this plant could be explored as a powerful source of natural drugs to target pathogens, with applications in the food, pharmaceutical, and medical industries.

AFM reveals the interaction and nanoscale effects imposed by squalamine on Staphylococcus epidermidis.

The Gram-positive bacterium Staphylococcus epidermidis is responsible for important nosocomial infections. With the continuous emergence of antibiotic-resistant strains, the search for new treatments has been amplified in the last decades. A potential candidate against multidrug-resistant bacteria is squalamine, a natural aminosterol discovered in dogfish sharks. Despite its broad-spectrum efficiency, little is known about squalamine mode of action. Here, we used atomic force microscopy (AFM) imaging to decipher the effect of squalamine on S. epidermidis morphology, revealing the peptidoglycan structure at the bacterial surface after the drug action. Single-molecule force spectroscopy with squalamine-decorated tips shows that squalamine binds to the cell surface via the spermidine motif, most likely through electrostatic interactions between the amine groups of the molecule and the negatively-charged bacterial cell wall. We demonstrated that - although spermidine is sufficient for the initial attachment of squalamine to S. epidermidis - the integrity of the molecule needs to be conserved for its antimicrobial action. A deeper analysis of the AFM force-distance signatures suggests the implication of the accumulation-associated protein (Aap), one of the main adhesins of S. epidermidis, in the initial binding of squalamine to the bacterial cell wall. This work highlights that AFM -combined with microbiological assays at the bacterial suspension scale- is a valuable approach to better understand the molecular mechanisms behind the efficiency of squalamine antibacterial activity.

Synthesis, Photophysical Characterization and Evaluation of Biological Properties of C7, a Novel Symmetric Tetra-Imidazolium-Bis-Heterocycle.

A novel symmetric tetra-imidazolium-bis-heterocycle, called C7, was designed and synthesized in a quick two-step pathway, with the objective to synthesize biologically active supramolecular assembly. The synthesized compound was then analyzed for its photophysical properties, for a potential application in theragnostic (fluorescence) or phototherapy (photodynamic therapy, with the production of reactive oxygen species, such as singlet oxygen 1O2). C7 was thus screened for its biological activity, in particular against important human pathogens of viral origin (respiratory viruses such as adenovirus type 2 and human coronavirus 229E) and of fungal and bacterial origin. The compound showed limited antiviral activity, combined with very good antiproliferative activity against breast cancer, and head and neck squamous cell carcinoma models. Interestingly, the selected compound showed excellent antibacterial activity against a large array of Gram-positive and Gram-negative clinically isolated pathogenic bacteria, with a possible inhibitory mechanism on the bacterial cell wall synthesis studied with electron microscopy and molecular docking tools. Collectively, the newly synthesized compound C7 could be considered as a potential lead for the development of new antibacterial treatment, endowed with basic photophysical properties, opening the door towards the future development of phototherapy approaches.

Phenolamides: Plant specialized metabolites with a wide range of promising pharmacological and health-promoting interests.

Phenolamides constitute a family of metabolites, widely represented in the plant kingdom, that can be found in all plant organs with a predominance in flowers and pollen grains. They represent a large and structurally diverse family, resulting from the association of phenolic acids with aliphatic or aromatic amines. Initially revealed as active compounds in several medicinal plant extracts, phenolamides have been extensively studied for their health-promoting and pharmacological properties. Indeed, phenolamides have been shown to exhibit antioxidant, anti-inflammatory, anti-cancer and antimicrobial properties, but also protective effects against metabolic syndrome and neurodegenerative diseases. The purpose of this review is to summarise this large body of literature, including in vitro and in vivo studies, by describing the diversity of their biological properties and our actual knowledge of the molecular mechanisms behind them. With regard to their considerable pharmacological interest, the question of industrial production is also tackled through chemical and biological syntheses in engineered microorganisms. The diversity of biological activities already described, together with the active discovery of the broad structural diversity of this metabolite family, make phenolamides a promising source of new active compounds on which future studies should be focused.

Evaluation of Antioxidant and Antibacterial Activities, Cytotoxicity of Acacia seyal Del Bark Extracts and Isolated Compounds.

Water extract of Acacia seyal bark is used traditionally by the population in Djibouti for its anti-infectious activity. The evaluation of in vitro antibacterial, antioxidant activities and cytotoxicity as well as chemical characterization of Acacia seyal bark water and methanolic extracts were presented. The water extract has a toxicity against the MRC-5 cells at 256 µg/mL while the methanolic extract has a weak toxicity at the same concentration. The methanolic extract has a strong antioxidant activity with half maximal inhibitory concentration (IC50) of 150 ± 2.2 µg/mL using 1-diphenyl-2-picrylhydrazyl (DPPH) and IC50 of 27 ± 1.3 µg/mL using 2,2'-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical methods. For ferric reducing/antioxidant power (FRAP) assay, the result is 45.74 ± 5.96 µg Vitamin C Equivalent (VCE)/g of dry weight (DW). The precipitation of tannins from methanol crude extract decreases the MIC from 64 µg/mL to 32 µg/mL against Staphylococcus aureus and Corynebacterium urealyticum. However, the antioxidant activity is higher before tannins precipitation than after (IC50 = 150 µg/mL for methanolic crude extract and 250 µg/mL after tannins precipitation determined by DPPH method). By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, the results showed that the condensed tannins consist of two types of catechin and gallocatechin-based oligomers. The fractionation led to the identification of three pure compounds: two flavanols catechin and epicatechin; one triterpene as lupeol; and a mixture of three steroids and one fatty acid: campesterol, stigmasterol, clionasterol, and oleamide.

Advances on Antiviral Activity of Morus spp. Plant Extracts: Human Coronavirus and Virus-Related Respiratory Tract Infections in the Spotlight.

(1) Background: Viral respiratory infections cause life-threatening diseases in millions of people worldwide every year. Human coronavirus and several picornaviruses are responsible for worldwide epidemic outbreaks, thus representing a heavy burden to their hosts. In the absence of specific treatments for human viral infections, natural products offer an alternative in terms of innovative drug therapies. (2) Methods: We analyzed the antiviral properties of the leaves and stem bark of the mulberry tree (Morus spp.). We compared the antiviral activity of Morus spp. on enveloped and nonenveloped viral pathogens, such as human coronavirus (HCoV 229E) and different members of the Picornaviridae family-human poliovirus 1, human parechovirus 1 and 3, and human echovirus 11. The antiviral activity of 12 water and water-alcohol plant extracts of the leaves and stem bark of three different species of mulberry-Morus alba var. alba, Morus alba var. rosa, and Morus rubra-were evaluated. We also evaluated the antiviral activities of kuwanon G against HCoV-229E. (3) Results: Our results showed that several extracts reduced the viral titer and cytopathogenic effects (CPE). Leaves' water-alcohol extracts exhibited maximum antiviral activity on human coronavirus, while stem bark and leaves' water and water-alcohol extracts were the most effective on picornaviruses. (4) Conclusions: The analysis of the antiviral activities of Morus spp. offer promising applications in antiviral strategies.

Dual 0.02% chlorhexidine digluconate - 0.1% disodium EDTA loaded thermosensitive ocular gel for Acanthamoeba keratitis treatment.

Poor bioavailability and low residence time limit the efficiency of conventional biguanide-based eye drops against Acanthamoeba keratitis. The aim of this work was to formulate an original anti-amoebic thermoreversible ocular gel combining biguanide and metalloproteases inhibitor - chelating agent. Chlorhexidine digluconate (CHX)-ethylenediaminetetraacetic acid disodium salt (Na2EDTA) were compounded in poloxamer 407 saline solution. 0.02% CHX - 0.1% Na2EDTA loaded thermosensitive ocular gel exhibited appropriate pH (5.73 ±â€¯0.06), iso-osmolality (314 ±â€¯5 mOsm/kg), viscosity (ranged between 15 and 25 mPa.s) and thermal gelation (26.5 °C and 33 °C) properties. Bioadhesion of gel was successfully tested onto isolated bovine eyes as well as the assessment of CHX penetration into the cornea. Intracorneal CHX concentration was found greater than trophozoite minimum amoebicidal concentration and minimal cysticidal concentration after 15-min and 2-h ocular exposure, respectively, while any CHX permeation through the cornea was detected (<51 ng/cm2/h). Improvement of CHX ocular bioavailability was attributed to probable solubilization of tear film lipid layer by poloxamer. In vitro efficiency of CHX-Na2EDTA ocular gel was confirmed from the drastic reduction of trophozoite and cyst survival (to 25% and 2%, respectively), confirming the potential of the multicomponent pharmaceutical material strategy for the treatment of Acanthamoeba keratitis.

Genotyping and phylogenetic analysis of Acanthamoeba isolates associated with keratitis.

We examined a partial SSU-rDNA sequence from 20 Acanthamoeba isolates associated with keratitis infections. The phylogenetic tree inferred from this partial sequence allowed to assign isolates to genotypes. Among the 20 isolates examined, 16 were found to be of the T4 genotype, 2 were T3, 1 was a T5, and 1 was a T2, confirming the predominance of T4 in infections. However, the study highlighted other genotypes more rarely associated with infections, particularly the T2 genotype. Our study is the second one to detect that this genotype is associated with keratitis. Additionally, the phylogenetic analyses showed five main emerging clusters, T4/T3/T11, T2/T6, T10/T12/T14, T13/T16, and T7/T8/T9/T17, regularly obtained whichever method was used. A similar branching pattern was found when the full rDNA sequence was investigated.

Micriamoeba tesseris nov. gen. nov. sp.: a new taxon of free-living small-sized Amoebae non-permissive to virulent Legionellae.

Investigation of soil amoebae in 11 cooling towers allowed us to isolate a major unknown small-sized amoeba population (SZA). However, SZA did not appear to be specific to cooling tower ecosystems since they are also a major amoeba population found in muds isolated from different points of a water treatment plant. The SSU-rDNA sequences from SZA strains did not match any known database sequences, suggesting that SZA constitutes a new amoeba taxon. We isolated and further described one of the SZA that we named Micriamoeba tesseris. The phylogenetic analyses showed that Micriamoeba tesseris belongs to the Amebozoa and branched together with genus Echinamoeba+Vermamoeba vermiformis. Phylogenetic analyses within the Micriamoeba group distinguished different subgroups of Micriamoeba strains according to their origin, i.e. cooling tower or mud. Although Micriamoeba are able to feed on viable E. coli cells, they do not uptake virulent Legionella pneumophila strains, thus enabling them to avoid infection by Legionella. Consequently, Micriamoeba is not directly involved in L. pneumophila multiplication. However, an indirect role of Micriamoeba in Legionella risk is discussed.

On the photobiological properties of chimeras combining quaternary ammonium derivatives of retinoic amides and psoralen. A study with cultured human keratinocytes.

The effectiveness of the combination of retinoids with 8-methoxypsoralen (8-MOP) and ultraviolet-A (UV-A) light in the treatment of some cutaneous proliferative diseases has motivated the synthesis of new "chimera-type" molecules built from psoralen derivatives and retinoic amides and related molecules. The chimeras result from the combination of 8-(3-bromopropyloxy)-psoralen with amides prepared by reacting 4-amino-pyridine with 13E- and 13Z-retinoic acids or a "retinoid-like" derivative with an alkene chain of only three double bonds. The synthesis of chimeras built with the 8-(3-bromopropyloxy)-psoralen and the amide of cinnamic acid or its 4-methoxy derivative has also been carried out. In contrast to 8-MOP, all the chimeras exhibit strong molar absorptivities in the range 20 000-40 000 M(-1) cm(-1) in the 340-390 nm UV-A region. The "retinoid-like"- and retinoid-psoralen chimeras are characterized by a marked dark toxicity toward proliferating NCTC 2544 keratinocytes (with a lethal dose corresponding to 50% cell survival [LD50] of 1-5 microM) as compared with that of the cinnamic acid derivative-psoralen chimeras (LD50 > or = 50 microM). This toxicity leads to alteration of the mitochondrial membrane potential. At nontoxic concentrations, the chimeras demonstrate effective psoralens + UV-A-induced photocytotoxicity. They are moderate photosensitizers of membrane lipid peroxidation. Cell apoptosis is a major photocytotoxic process as suggested by the fluorescence-activated cell-sorting technique using annexin-fluorescein isothiocyanate and propidium iodide as apoptotic markers.