Comparative anti-herpes simplex virus type 1 and chemical profiling of Thymus capitatus and Artemisia herba-alba collected from North Africa

Herpes simplex virus (HSV) can infect millions of people worldwide causing mild to life-threating infections. The current study demonstrates the first comparative anti-HSV type 1 activity and phytochemical investigation of Artemisia herba-alba and Thymus capitatus collected from Egypt and Libya. Liquid chromatography/mass spectrometry (LC/MS) analysis allowed the identification of 56 and 38 compounds in the Egyptian and Libyan Artemisia herba-alba ethanolic extracts, respectively, in addition to 46 and 50 compounds in the Egyptian and Libyan Thymus capitatus ethanolic extracts, respectively. Gas chromatography/mass spectrometry (GC/MS) analysis of their corresponding essential oils revealed the presence of 15, 17, 17 and 8 compounds in Egyptian and Libyan Artemisia herba-alba and Thymus capitatus, respectively. The major chemical classes of the identified compounds were phenolic acids, flavonoids and oxygenated monoterpenes. Evaluation of the anti-HSV1 activities of the studied extracts showed that the Egyptian Thymus capitatus ethanolic extracts were the most potent extract with more than 200-fold reduction in the viral PFU.

Absolute Affinities from Quantitative Shotgun Glycomics Using Concentration-Independent (COIN) Native Mass Spectrometry

Native mass spectrometry (nMS) screening of natural glycan libraries against glycan-binding proteins (GBPs) is a powerful tool for ligand discovery. However, as the glycan concentrations are unknown, affinities cannot be measured directly from natural libraries. Here, we introduce Concentration-Independent (COIN)-nMS, which enables quantitative screening of natural glycan libraries by exploiting slow mixing of solutions inside a nanoflow electrospray ionization emitter. The affinities (K_d) of detected GBP-glycan interactions are determined, simultaneously, from nMS analysis of their time-dependent relative abundance changes. We establish the reliability of COIN-nMS using interactions between purified glycans and GBPs with known K_d values. We also demonstrate the implementation of COIN-nMS using the catch-and-release (CaR)-nMS assay for glycosylated GBPs. The COIN-CaR-nMS results obtained for plant, fungal, viral, and human lectins with natural libraries containing hundreds of N-glycans and glycopeptides highlight the assay's versatility for discovering new ligands, precisely measuring their affinities, and uncovering "fine" specificities. Notably, the COIN-CaR-nMS results clarify the sialoglycan binding properties of the SARS-CoV-2 receptor binding domain and establish the recognition of monosialylated hybrid and biantennary N-glycans. Moreover, pharmacological depletion of host complex N-glycans reduces both pseudotyped virions and SARS-CoV-2 cell entry, suggesting that complex N-glycans may serve as attachment factors.

In vitro biological activities and in vivo hepatoprotective role of brown algae-isolated fucoidans

Brown seaweeds are rich in polysaccharides, such as fucoidan (FUC) which has shown beneficial effects in several medical conditions. The aim of the present study was to assess the antioxidant, anti-inflammatory, and hepatoprotective properties of Colpomenia sinuosa- and Sargassum prismaticum-isolated FUC in vitro and in vivo. The hot acid extraction method was used to isolate FUC from C. sinuosa (FCS) and S. prismaticum (FSP) species. The antioxidant, anticancer, as well as the effect on neurotransmitter-degrading enzyme and disaccharidase activities were measured using standard protocols. Moreover, the hepatoprotective effect of two FCS doses (100 and 200 mg/kg) on paracetamol-administered rats (one dose of 1 g/kg) were evaluated by measuring blood liver function markers, hepatic pro-oxidants as malondialdehyde (MDA) and nitric oxide (NO), antioxidants as glutathione (GSH) and glutathione peroxidase (GPx), proinflammatory markers as inducible nitric oxide synthase (iNOS), interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), and liver histology. The crude fucoidan yield was 15.6% and 14.8% of C. sinuosa and S. prismaticum dry weights, respectively. The antioxidant effects and cytotoxic activity on hepatic cancer cell were higher for FCS than FSP. Moreover, in vivo data showed that FCS administration at both doses significantly improved liver functions and alleviated histological alterations, hepatic inflammation, and oxidative stress following paracetamol intake. In conclusion, fucoidan exerts anti-inflammatory, antidigestive enzyme activity, antioxidant, anticancer, and hepatoprotective effects.

Enhancement of phenolic content, antioxidant and cytotoxic activities of Moringa oleifera leaf and seed by suspension culture

Moringa oleifera Lam. family Moringaceae is well known for a wide range of biological activities and a complex phytochemical composition. The current study investigates tissue culture protocols for Moringa oleifera leaves and seeds. For static culture initiation, Murashige and skooge (MS) as a basal medium with hormonal supply of (0-10 µM) of 2,4-dicholorophenoxy acetic acid and 6-benzyl aminopurine for Moringa oleifera seeds and leaves was employed. Suspension cultures with the optimum hormonal combination was initiated for both seeds and leaves calli. Liquid chromatography/mass spectroscopy (LC/MS) analysis performed, for the first time, on the methanolic extracts of plant parts and the produced calli revealed varying concentrations of nine major components (six flavonoids and three phenolic acids). Antioxidant and cytotoxic activities, against three cell lines, were evaluated for the obtained methanolic extracts. In general, superior biological activities were identified for the produced calli when compared to plant parts.

Antibacterial activity of Centaurea pumilio L. root and aerial part extracts against some multidrug resistant bacteria

Background

In the context of searching for potent, safe, natural antimicrobial agents to combate the global antimicrobial resistance (AMR) phenomenon, the current study evaluates for the first time ever, the broad-spectrum antimicrobial activity of essential oil (EO) and extracts from the rare wild plant Centaurea pumilio L.. It has tremendous ethnomedicinal values; its dried root is used as a fattening agent, a treatment for bad breath and diabetes, and screened for schistosomicidal activity.

Methods

C. pumilio EO was extracted by hydrodistillation using a Clevenger apparatus. Chemical constituents of aerial part were extracted using a sequential solvent/solvent procedure employing four solvents with increasing polarities in the following order: petroleum ether, chloroform, ethyl acetate, and n-butanol. The chemical constituents were identified by GC-MS. Fifty-two microbial strains were used; twenty-six multidrug resistant (MDR), sixteen clinical, and ten reference strains. The identification of the microbial strains was performed by MALDI-TOF-MS. The antimicrobial activity of the EO and the aerial part and the root extracts was assessed through disc diffusion assay. A minimum inhibitory concentration (MIC) of the EO and extracts was determined using the broth micro-dilution method.

Results

The growth of reference and clinical strains was inhibited by EO, methanol, chloroform, and ethyl acetate aerial part extracts and chloroform root extract. The MDR strains growth, however, was inhibited only by EO and chloroform aerial part extract. GC-MS identified for the first time eighteen constituents from aerial part EO and chloroform extract each. EO showed antimicrobial activity against the reference, clinical, and MDR strains with MIC values of 31.25–125, 31.25–125, and 62.50–250 μg/mL, respectively. Methanol aerial part extract exhibited high antimicrobial activities with MIC values of 62.50–250 μg/mL against reference and clinical strains. Chloroform root extract displayed strong antimicrobial activity against reference and clinical strains recording MIC values of 62.50–250 μg/mL and 62.50–125 μg/mL, respectively. The chloroform aerial part extract demonstrated potent antimicrobial activity against the reference, clinical, and MDR strains with 31.25, 31.25, and 15.62 μg/mL MIC values, respectively.

Conclusions

Present data unravel the C. pumilio pharmacological magnitude to discover eco-friendly potent antimicrobial agents to fight AMR phenomenon.

Screening natural libraries of human milk oligosaccharides against lectins using CaR-ESI-MS

Human milk oligosaccharides (HMOs) afford many health benefits to breast-fed infants, such as protection against infection and regulation of the immune system, through the formation of non-covalent interactions with protein receptors. However, the molecular details of these interactions are poorly understood. Here, we describe the application of catch-and-release electrospray ionization mass spectrometry (CaR-ESI-MS) for screening natural libraries of HMOs against lectins. The HMOs in the libraries were first identified based on molecular weights (MWs), ion mobility separation arrival times (IMS-ATs) and collision-induced dissociation (CID) fingerprints of their deprotonated anions. The libraries were then screened against lectins and the ligands identified from the MWs, IMS-ATs and CID fingerprints of HMOs released from the lectin in the gas phase. To demonstrate the assay, four fractions, extracted from pooled human milk and containing ≥35 different HMOs, were screened against a C-terminal fragment of human galectin-3 (hGal-3C), for which the HMOs specificities have been previously investigated, and a fragment of the blood group antigen-binding adhesin (BabA) from Helicobacter pylori, for which the HMO specificities have not been previously established. The structures of twenty-one ligands, corresponding to both neutral and acidic HMOs, of hGal-3C were identified; all twenty-one were previously shown to be ligands for this lectin. The presence of HMO ligands at six other MWs was also ascertained. Application of the assay to BabA revealed nineteen specific HMO structures that are recognized by the protein and HMO ligands at two other MWs. Notably, it was found that BabA exhibits broad specificity for HMOs, and recognizes both neutral HMOs, including non-fucosylated ones, and acidic HMOs. The results of competitive binding experiments indicate that HMOs can interact with BabA at previously unknown binding sites. The affinities of eight purified HMOs for BabA were measured by ESI-MS and found to be in the 10³ M^-1 to 10⁴ M^-1 range.

A novel purified Lactobacillus acidophilus 20079 exopolysaccharide, LA-EPS-20079, molecularly regulates both apoptotic and NF-κB inflammatory pathways in human colon cancer

BACKGROUND

The direct link between inflammatory bowel diseases and colorectal cancer is well documented. Previous studies have reported that some lactic acid bacterial strains could inhibit colon cancer progression however; the exact molecules involved have not yet been identified. So, in the current study, we illustrated the tumor suppressive effects of the newly identified Lactobacillus acidophilus DSMZ 20079 cell-free pentasaccharide against colon cancer cells. The chemical structure of the purified pentasaccharide was investigated by MALDI-TOF mass spectrum, 1D and 2D Nuclear Magnetic Resonance (NMR). The anticancer potentiality of the purified pentasaccharide against both Human colon cancer (CaCo-2) and Human breast cancer (MCF7) cell lines with its safety usage pattern were evaluated using cytotoxicity, annexin V quantification and BrdU incorporation assays. Also, the immunomodulatory effects of the identified compound were quantified on both LPS-induced PBMC cell model and cancer cells with monitoring the immunophenotyping of T and dendritic cell surface marker. At molecular level, the alteration in gene expression of both inflammatory and apoptotic pathways were quantified upon pentasaccharide-cellular treatment by RTqPCR.

RESULTS

The obtained data of the spectroscopic analysis, confirmed the structure of the newly extracted pentasaccharide; (LA-EPS-20079) to be: α-D-Glc (1→2)][α-L-Fuc(1→4)] α-D-GlcA(1→2) α-D-GlcA(1→2) α-D-GlcA. This pentasaccharide, recorded safe dose on normal mammalian cells ranged from 2 to 5 mg/ml with cancer cells selectivity index, ranged of 1.96-51.3. Upon CaCo-2 cell treatment with the non-toxic dose of LA-EPS-20079, the inhibition percentage in CaCo-2 cellular viability, reached 80.65 with an increase in the ratio of the apoptotic cells in sub-G0/G1 cell cycle phase. Also, this pentasaccharide showed potentialities to up-regulate the expression of IKbα, P53 and TGF genes.

CONCLUSION

The anticancer potentialities of LA-EPS-20079 oligosaccharides against human colon cancer represented through its regulatory effects on both apoptotic and NF-κB inflammatory pathways.

High-Throughput Label- and Immobilization-Free Screening of Human Milk Oligosaccharides Against Lectins

The intense interest in the mechanisms responsible for the beneficial effects of breast-feeding on infant health has created a significant need for analytical methods capable of rapidly identifying interactions between human milk oligosaccharides (HMOs) and their protein receptors. Currently, there are no established, high-throughput assays for the screening libraries of free (unmodified) HMOs against lectins. The present work describes a rapid and label- and immobilization-free assay, based on catch-and-release electrospray ionization mass spectrometry (CaR-ESI-MS), capable of simultaneously screening mixtures of free HMOs of known concentration for binding to lectins in vitro. Ligand identification relies on the molecular weights (MWs), ion mobility separation arrival times, and collision-induced dissociation fingerprints of HMO anions released from the target protein in the gas phase. To establish the reliability of the assay, a library of 31 free HMOs, ranging in size from tri- to octasaccharide, was screened against three human galectin (hGal) proteins (a stable mutant of hGal1 (hGal-1), a C-terminal fragment of hGal-3 (hGal-3C) and hGal-7), with known HMO affinities. When implemented using an equimolar concentration library, the CaR-ESI-MS assay identified 100% of ligands with affinities >500 M^-1 and ≥93% of all HMO ligands (hGal-1-31 of 31 ligands; hGal-3C-25 of 25; hGal-7-28 of 30); no false positives were detected. The assay also successfully identified the majority of the highest affinity HMO ligands (or isomer sets that contain the highest affinity ligands) in the library for each of the three hGal. Notably, for each lectin, CaR-ESI-MS screening required <1 h to complete and consumed <5 ng of each HMO and <0.5 μg of protein.

Evaluation of a focused virtual library of heterobifunctional ligands for Clostridium difficile toxins

Higher activity glycopeptoid ligands for two largeClostridium difficiletoxins TcdA and TcdB were discoveredviamodular fragment-based design and virtual screening.

Mycobacteriophage cell binding proteins for the capture of mycobacteria

Slow growing Mycobacteriumavium subsp. paratuberculosis (MAP) causes a deadly condition in cattle known as Johne's disease where asymptomatic carriers are the major source of disease transmission. MAP was also shown to be associated with chronic Crohn's disease in humans. Mycobacterium smegmatis is a model mycobacterium that can cause opportunistic infections in a number of human tissues and, rarely, a respiratory disease. Currently, there are no rapid, culture-independent, reliable and inexpensive tests for the diagnostics of MAP or M. smegmatis infections. Bacteriophages are viruses producing a number of proteins that effectively and specifically recognize the cell envelopes of their bacterial hosts. We demonstrate that the mycobacterial phage L5 minor tail protein Gp6 and lysin Gp10 are useful tools for the rapid capture of mycobacteria. Immobilized Gp10 was able to bind both MAP and M. smegmatis cells whereas Gp6 was M. smegmatis specific. Neither of the 2 proteins was able to capture E. coli, salmonella, campylobacter or Mycobacterium marinum cells. Gp6 was detected previously as a component of the phage particle and shows no homology to proteins with known function. Therefore, electrospray ionization mass spectrometry was used to determine whether recombinant Gp6 could bind to a number of chemically synthesized fragments of mycobacterial surface glycans. These findings demonstrate that mycobacteriophage proteins could be used as a pathogen capturing platform that can potentially improve the effectiveness of existing diagnostic methods.

Screening carbohydrate libraries for protein interactions using the direct ESI-MS assay. Applications to libraries of unknown concentration

A semiquantitative electrospray ionization mass spectrometry (ESI-MS) binding assay suitable for analyzing mixtures of oligosaccharides, at unknown concentrations, for interactions with target proteins is described. The assay relies on the differences in the ratio of the relative abundances of the ligand-bound and free protein ions measured by ESI-MS at two or more initial protein concentrations to distinguish low affinity (≤10(3) M(-1)) ligands from moderate and high affinity (>10(5) M(-1)) ligands present in the library and to rank their affinities. Control experiments were performed on solutions of a single chain antibody and a mixture of synthetic oligosaccharides, with known affinities, in the absence and presence of a 40-component carbohydrate library to demonstrate the implementation and reliability of the assay. The application of the assay for screening natural libraries of carbohydrates against proteins is also demonstrated using mixtures of human milk oligosaccharides, isolated from breast milk, and fragments of a bacterial toxin and human galectin 3.

Reliable determinations of protein-ligand interactions by direct ESI-MS measurements. Are we there yet?

The association-dissociation of noncovalent interactions between protein and ligands, such as other proteins, carbohydrates, lipids, DNA, or small molecules, are critical events in many biological processes. The discovery and characterization of these interactions is essential to a complete understanding of biochemical reactions and pathways and to the design of novel therapeutic agents that may be used to treat a variety of diseases and infections. Over the last 20 y, electrospray ionization mass spectrometry (ESI-MS) has emerged as a versatile tool for the identification and quantification of protein-ligand interactions in vitro. Here, we describe the implementation of the direct ESI-MS assay for the determination of protein-ligand binding stoichiometry and affinity. Additionally, we outline common sources of error encountered with these measurements and various strategies to overcome them. Finally, we comment on some of the outstanding challenges associated with the implementation of the assay and highlight new areas where direct ESI-MS measurements are expected to make significant contributions in the future.

Applications of a catch and release electrospray ionization mass spectrometry assay for carbohydrate library screening

Applications of a catch and release electrospray ionization mass spectrometry (CaR-ESI-MS) assay for screening carbohydrate libraries against target proteins are described. Direct ESI-MS measurements were performed on solutions containing a target protein (a single chain antibody, an antigen binding fragment, or a fragment of a bacterial toxin) and a library of carbohydrates containing multiple specific ligands with affinities in the 10(3) to 10(6) M(-1) range. Ligands with moderate affinity (10(4) to 10(6) M(-1)) were successfully detected from mixtures containing >200 carbohydrates (at concentrations as low as 0.25 μM each). Additionally, the absolute affinities were estimated from the abundance of free and ligand-bound protein ions determined from the ESI mass spectrum. Multiple low affinity ligands (~10(3) M(-1)) were successfully detected in mixtures containing >20 carbohydrates (at concentrations of ~10 μM each). However, identification of specific interactions required the use of the reference protein method to correct the mass spectrum for the occurrence of nonspecific carbohydrate-protein binding during the ESI process. The release of the carbohydrate ligands, as ions, was successfully demonstrated using collision-induced dissociation performed on the deprotonated ions of the protein-carbohydrate complexes. The use of ion mobility separation, performed on deprotonated carbohydrate ions following their release from the complex, allowed for the positive identification of isomeric ligands.

Binding of Clostridium difficile toxins to human milk oligosaccharides

The binding of recombinant fragments of the C-terminal cell-binding domains of the two large exotoxins, toxin A (TcdA) and toxin B (TcdB), expressed by Clostridium difficile and a library consisting of the most abundant neutral and acidic human milk oligosaccharides (HMOs) was examined quantitatively at 25°C and pH 7 using the direct electrospray ionization mass spectrometry (ES-MS) assay. The results of the ES-MS measurements indicate that both toxin fragments investigated, TcdB-B1 and TcdA-A2, which possess one and two carbohydrate binding sites, respectively, bind specifically to HMOs ranging in size from tri- to heptasaccharides. Notably, five of the HMOs tested bind to both toxins: Fuc(α1-2)Gal(β1-4)Glc, Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc, Fuc(α1-2)Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc, Gal(β1-3)[Fuc(α1-4)]GlcNAc(β1-3)Gal(β1-4)Glc and Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)Glc. However, the binding of the HMOs is uniformly weak, with apparent affinities ≤10(3 )M(-1). The results of molecular docking simulations, taken together with the experimental binding data, suggest that a disaccharide moiety (lactose or lactosamine) represents the core HMO recognition element for both toxin fragments. The results of a Verocytotoxicity neutralization assay reveal that HMOs do not significantly inhibit the cytotoxic effects of TcdA or TcdB. The absence of protection is attributed to the very weak intrinsic affinities that the toxins exhibit towards the HMOs.

Quantifying labile protein-ligand interactions using electrospray ionization mass spectrometry

A new electrospray ionization mass spectrometry (ES-MS) approach for quantifying protein-ligand complexes that are prone to in-source (gas-phase) dissociation is described. The method, referred to here as the reference ligand ES-MS method, is based on the direct ES-MS assay and competitive ligand binding. A reference ligand (L(ref)), which binds specifically to the protein (P), at the same binding site as the ligand (L) of interest, with known affinity and forms a stable protein-ligand complex in the gas phase, is added to the solution. The fraction of P bound to L(ref), which is determined directly from the ES mass spectrum, is sensitive to the fraction of P bound to L in solution and enables the affinity of P for L to be determined. A mathematical framework for the implementation of the method in cases where P has one or two specific ligand binding sites is given. Affinities of two carbohydrate-binding proteins, a single chain fragment of a monoclonal antibody and the lectin concanavalin A, for monosaccharide ligands are reported and the results are shown to agree with values obtained using isothermal titration calorimetry.