Thiazolotriazoles As Anti-infectives: Design, Synthesis, Biological Evaluation and In Silico Studies.

The rational design of novel thiazolo[2,3-c][1,2,4]triazole derivatives was carried out based on previously identified antitubercular hit molecule H127 for discovering potent compounds showing antimicrobial activity. The designed compounds were screened for their binding efficacies against the antibacterial drug target enoyl-[acyl-carrier-protein] reductase, followed by prediction of drug-likeness and ADME properties. The designed analogues were chemically synthesized, characterized by spectroscopic techniques, followed by evaluation of antimicrobial activity against bacterial and fungal strains, as well as antitubercular activity against M. tuberculosis and M. bovis strains. Among the synthesized compounds, five compounds, 10, 11, 35, 37 and 38, revealed antimicrobial activity, albeit with differential potency against various microbial strains. Compounds 10 and 37 were the most active against S. mutans (MIC: 8 µg/mL), while compounds 11 and 37 showed the highest activity against B. subtillis (MIC: 16 µg/mL), whereas compounds 10, 11 and 37 displayed activities against E. coli (MIC: 16 µg/mL). Meanwhile, compounds 10 and 35 depicted activities against S. typhi (MIC: 16 µg/mL) and compound 10 showed antifungal activity against C. albicans (MIC: 32 µg/mL). The current study has identified two broad-spectrum antibacterial hit compounds (10 and 37). Further structural investigation on these molecules is underway to enhance their potency.

Characterizing fibril morphological changes by spirooxindoles for neurodegenerative disease application.

Fibrillation of proteins and polypeptides, which leads to the deposition of plaques in cells and tissues has been widely associated with many neuropathological diseases. Inhibition of protein misfolding and aggregation is crucial for the prevention and treatment of these conditions. The growing interest in identifying inhibitor molecules to prevent the formation of fibrils in vivo has led to the results highlighted in this study. Due to their hydrophobic structure and potential to readily cross the blood brain barrier, a library of spirooxindole compounds were synthesized with those labelled Hd-63, Hd-66 and Hd-74 proving to be the most potent against fibril formation. Our spectroscopic analysis provides detailed insight, that the introduction of these spirooxindole compounds leads to morphological changes in the mechanism of fibril formation which prevent the formation of highly ordered fibrils, instead results in the formation of disordered aggregates which are not fibrillar in nature.

Identifying Chemical Differences in Cheddar Cheese Based on Maturity Level and Manufacturer Using Vibrational Spectroscopy and Chemometrics.

Cheese is a nutritious dairy product and a valuable commodity. Internationally, cheddar cheese is produced and consumed in large quantities, and it is the main cheese variety that is exported from Australia. Despite its importance, the analytical methods to that are used to determine cheese quality rely on traditional approaches that require time, are invasive, and which involve potentially hazardous chemicals. In contrast, spectroscopic techniques can rapidly provide molecular information and are non-destructive, fast, and chemical-free methods. Combined with partner recognition methods (chemometrics), they can identify small changes in the composition or condition of cheeses. In this work, we combined FTIR and Raman spectroscopies with principal component analysis (PCA) to investigate the effects of aging in commercial cheddar cheeses. Changes in the amide I and II bands were the main spectral characteristics responsible for classifying commercial cheddar cheeses based on the ripening time and manufacturer using FTIR, and bands from lipids, including ß'-polymorph of fat crystals, were more clearly determined through changes in the Raman spectra.

Small angle X-ray scattering investigation of ionic liquid effect on the aggregation behavior of globular proteins.

Globular proteins are well-folded model proteins, where ions can substantially influence their structure and aggregation. Ionic liquids (ILs) are salts in the liquid state with versatile ion combinations. Understanding the IL effect on protein behavior remains a major challenge. Here, we employed small angle X-ray scattering to investigate the effect of aqueous ILs on the structure and aggregation of globular proteins, namely, hen egg white lysozyme (Lys), human lysozyme (HLys), myoglobin (Mb), ß-lactoglobulin (ßLg), trypsin (Tryp) and superfolder green fluorescent protein (sfGFP). The ILs contain ammonium-based cations paired with the mesylate, acetate or nitrate anion. Results showed that only Lys was monomeric, whereas the other proteins formed small or large aggregates in buffer. Solutions with over 17 mol% IL resulted in significant changes in the protein structure and aggregation. The Lys structure was expanded at 1 mol% but compact at 17 mol% with structural changes in loop regions. HLys formed small aggregates, with the IL effect similar to Lys. Mb and ßLg mostly had distinct monomer and dimer distributions depending on IL type and IL concentration. Complex aggregation was noted for Tryp and sfGFP. While the anion had the largest ion effect, changing the cation also induced the structural expansion and protein aggregation.

Quantitation of carotenoids and fatty acids from Atlantic salmon using a portable Raman device.

Raman spectroscopy can be a useful tool for performing non-destructive subsurface measurements, allowing for investigations on intact foods that would otherwise require food products to be prepared for analysis, thus creating food waste, and often requiring the addition of chemicals. To overcome this, we have developed a method to measure the concentration of pigment (astaxanthin) and fatty acids in whole, unfilleted Atlantic salmon through the skin using defocused Raman spectroscopy. Subsurface measurements were performed across different regions of Atlantic salmon. PLS regression of the measured spectra gave a moderate correlation between Raman bands and astaxanthin concentration (R2 = 0.5797) and good correlations for fatty acid concentrations (total, saturated, monounsaturated, polyunsaturated, trans; R2 = 0.7457 to 0.8249). This work shows that subsurface Raman measurements can provide useful quantitative information regarding important quality parameters (pigment and fatty acid concentrations) that can aid with production in aquaculture.

Regioselective pyrrolizidine bis-spirooxindoles as efficient anti-amyloidogenic agents.

Here, we report a microwave-assisted, one-pot, three-component, 1,3-dipolar cycloaddition reaction to produce highly regioselective and stereoselective bis-spirooxindoles as potential inhibitors against amyloid-ß fibrillation. Ease of synthesis, promising anti-amyloidogenic activity, low toxicity, and in vitro blood brain barrier permeability makes these compounds attractive therapeutic leads to treat Alzheimer's disease.

Chemoselective [3 + 2] annulation of oxime acetate with 2-aryl-3-ethoxycarbonyl-pyrroline-4,5-dione: an entry to pyrrolo[2,3-b]pyrrole derivatives.

A novel chemoselective [3 + 2] annulation reaction of easily accessible ketoxime acetate with 2-aryl-3-ethoxycarbonyl pyrroline-4,5-dione has been developed for the synthesis of unknown pyrrolo[2,3-b]pyrrole frameworks. This method involves copper-mediated N-O bond cleavage followed by the formation of carbon-carbon and carbon-nitrogen bonds. This operationally simple protocol provides broader functional group compatibility and good yields.

Microwave-assisted rapid synthesis of spirooxindole-pyrrolizidine analogues and their activity as anti-amyloidogenic agents.

A library of Sox-pyrrolizidines was rapidly prepared by microwave-assisted, one-pot, three-component, 1,3-dipolar cycloaddition of azomethine ylides from l-proline and isatin, with various ß-nitrostyrenes. Nitro-Sox compounds, 4b, 4d and 4e inhibit HEWL amyloid fibril formation by ThT studies with percentages of fluorescence intensity of 55.4, 42.9 and 40.3%, respectively. Further studies with MTT assay, Raman spectroscopy, TEM and molecular docking supported these promising candidates for activity against amyloid misfolding, a phenomenon leading to Alzheimer's disease pathology.

Natural spirocyclic alkaloids and polyphenols as multi target dementia leads.

The U rhynchophylla, U tomentosa, Isatis indigotica Fortune, Voacanga Africana, herbal constituents, fungal extracts from Aspergillus duricaulis culture media, include spirooxindoles, polyphenols or bridged spirocyclic alkaloids. Their constituents exhibit specific and synergistic multiple neuroprotective properties including inhibiting of Aß fibril induced cytotoxicity, NMDA receptor inhibition in mice models of Alzheimer's disease (AD). The pioneering research from Woodward to Waldmann has advanced the synthesis of spirocyclic alkaloids. Furthermore, the elucidation of the genetic analysis, biochemical pathways that links strictosidine to the alkaloids akuammicine, stemmadenine, tabersonine, catharanthine, will now enable the biotechnological generation, also stimulate synthesis of related bridged spirocyclic alkaloids for medicinal investigations. From the value of spirocyclic structures as multi target dementia leads, we hypothesise that simpler Lipinski-like natural/synthetic alkaloid analogues may likewise be discovered that provide neurocognitive enhancing activities against dementia and AD.

Delivery of antimicrobial peptides to model membranes by cubosome nanocarriers.

Antimicrobial peptides (AMPs), which typically disrupt the bacterial wall prompting leakage or lysis of the cell, form a growing contingent in the arsenal against antibiotic resistant bacteria. The effectiveness of AMPs is, however, hampered by their low solubility, general chemical and physical instability, and short half-life in vivo. Lipid nanocarriers such as cubosomes are effective at encapsulating and protecting proteins while simultaneously showing promise in delivery applications. Here, the efficacy of cubosome mediated delivery of AMPs is evaluated by the in-situ surface characterization of model membranes with varying composition. The cubosomes were observed to initially fuse with the membranes, with subsequent membrane disruption observed after approximately 20 - 60 min. The time for the disruption was sensitive to the charge of the cubosome as well as the composition of the bilayer. More physiologically relevant bilayers including lipids with phospho-(1'-rac-glycerol) (PG) or phosphoethanolamine (PE) headgroups were more vulnerable than those of neat phosphocholine (PC). Notably, disruption to the bilayer occurred an order of magnitude faster for encapsulated AMP compared to free AMP.

Insight into the Mechanism of Action and Peptide-Membrane Interactions of Aib-Rich Peptides: Multitechnique Experimental and Theoretical Analysis.

The increase in resistant bacterial strains necessitates the identification of new antimicrobial molecules. Antimicrobial peptides (AMPs) are an attractive option because of evidence that bacteria cannot easily develop resistance to AMPs. The peptaibols, a class of naturally occurring AMPs, have shown particular promise as antimicrobial drugs, but their development has been hindered by their mechanism of action not being clearly understood. To explore how peptaibols might interact with membranes, circular dichroism, vibrational circular dichroism, linear dichroism, Raman spectroscopy, Raman optical activity, neutron reflectivity and molecular dynamics simulations have been used to study a small library of peptaibol mimics, the Aib-rich peptides. All the peptides studied quickly partitioned and oriented in membranes, and we found evidence of chiral interactions between the phospholipids and membrane-embedded peptides. The protocols presented in this paper open new ground by showing how chiro-optical spectroscopies can throw light on the mechanism of action of AMPs.

Detection of Biomarkers Relating to Quality and Differentiation of Some Commercially Significant Whole Fish Using Spatially Off-Set Raman Spectroscopy.

Aquaculture represents a major part of the world's food supply. This area of food production is developing rapidly, and as such the tools and analytical techniques used to monitor and assess the quality of fish need to also develop and improve. The use of spatially off-set Raman spectroscopy (SORS) is particularly well-suited for these applications, given the ability of this technique to take subsurface measurements as well as being rapid, non-destructive and label-free compared to classical chemical analysis techniques. To explore this technique for analysing fish, SORS measurements were taken on commercially significant whole fish through the skin in different locations. The resulting spectra were of high quality with subsurface components such as lipids, carotenoids, proteins and guanine from iridophore cells clearly visible in the spectra. These spectral features were characterised and major bands identified. Chemometric analysis additionally showed that clear differences are present in spectra not only from different sections of a fish but also between different species. These results highlight the potential application for SORS analysis for rapid quality assessment and species identification in the aquaculture industry by taking through-skin measurements.

Surface Enhanced Raman Spectroscopy in environmental analysis, monitoring and assessment.

Environmental pollution is usually monitored via mass spectrometry-based approaches. Such techniques are extremely sensitive but have several disadvantages. The instruments themselves are expensive, require specialized training to use and usually cannot be taken into the field. Samples also usually require extensive pre-treatment prior to analysis which can affect the final result. The development of analytical methods that matched the sensitively of mass spectrometry but that could be deployed in the field and require minimal sample processing would be highly advantageous for environmental monitoring. One method that may meet these criteria is Surface Enhanced Raman Spectroscopy (SERS). This is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough nanostructure surfaces such as gold or silver nanoparticles. SERS gives selective spectral enhancement such that increases in sensitivity of 1010 to 1014 have been reported. While this means SERS is, theoretically at least, capable of single molecule detection such a signal enhancement is hard to achieve in practice. In this review the background of SERS is introduced for the environmental scientist and the recent literature on the detection of several classes of environmental pollutants using this technique is discussed. For heavy metals the lowest limit of detection reported was 0.45 µg/L for Mercury; for pharmaceuticals, 2.4 µg/L for propranolol; for endocrine disruptors, 0.35 µg/L for 17ß-estradiol; for perfluorinated compounds, 500 µg/L for perfluorooctanoic acid and for inorganic pollutants, 37g/L for general pesticide markers. The signal enhancements achieved in each case show great promise for the detection of pollutants at environmentally relevant concentrations and, although it does not yet routinely match the sensitivity of mass spectrometry. Further work to develop SERS methods and apply them for the detection of contaminants could be of wide benefit for environmental science.

Quantifying factors related to urban metal contamination in vegetable garden soils of the west and north of Melbourne, Australia.

Vegetable gardens in cities provide communities with fresh vegetables but also may contribute towards public exposure to metals present in soil from historical pollution. Contamination of some Melbourne garden soils with Pb (range 12.9-773 mg kg-1 in soil) was found with some soils exceeding the Australian human health screening criteria for residential land use of 300 mg kg-1. Cadmium concentrations (0.12-1.04 mg kg-1) were above the ambient background soil concentrations of <1 mg kg-1. Nickel concentrations (7.6-40.5 mg kg-1) and Cr (11.6-49.4 mg kg-1) were within the range of expected ambient background concentrations. Distance from the nearest arterial road, house age and the likely use of lead-based paints were the main factors explaining approximately 75% of soil Pb variability in garden soils. Metal concentrations in garden soils of wooden houses were found to be significantly higher than the garden soil of brick and concrete houses (Pb (p < 0.0001)) and Cd (p < 0.001)). Significant correlations were found between backyard garden soil metal concentration and house age for Pb (R2 = 0.83, p < 0.0001) and Cd (R2 = 0.40, p < 0.0002) and the distance from arterial roads for Pb (R2 = 0.38, p < 0.002), while Cr and Ni are related to soil characteristics cation exchange capacity, organic matter, and pH. Vegetable garden with elevated Pb and Cd had recognizable risk factors such as older, painted structures on adjacent houses and closer proximity to arterial roads with higher frequency traffic.

Effects of sulfation and the environment on the structure of chondroitin sulfate studied via Raman optical activity.

Glycosaminoglycans are linear carbohydrate polymers with essential roles in many biological processes. Chondroitin sulfate (CS) is one of them, omnipresent in living organisms as an important structural component of cartilage. It provides much of its resistance to compression. Despite its biological importance, little is still known about the relation of the CS structure to chemical composition and interaction with the environment. We therefore measured Raman and Raman optical activity (ROA) spectra of five CS samples of different biological origin and variously sulfated CS building blocks (GlcA, GalNAc, and basic disaccharide units) in a wide frequency range between 200 cm-1 and 1800 cm-1 and analyzed them with respect to specific structure marker bands. We show that ROA spectroscopy is sensitive to the conformational stability and rigidity of pyranose rings of saccharides, the orientation of sugar hydroxyl groups and the secondary structure of the CS's backbone. The CS secondary structure has been found to be quite stable, with a minor variation as a reaction to physicochemical parameters (concentration, pH, temperature, and the presence of cations). Larger changes were observed under chemical changes (sulfation) of the CS chain. ROA spectroscopy thus exhibited useful potential to study the structure of similar biopolymers.

Investigation of chemical composition of meat using spatially off-set Raman spectroscopy.

Spatially off-set Raman spectroscopy (SORS) offers non-invasive chemical characterisation of the sub-surface of various biological tissues as it permits the assessment of diffusely scattering samples at depths of several orders of magnitude deeper than conventional Raman spectroscopy. Chemicals such as glycogen, glucose, lactate and cortisol are predictors of meat quality, however detection of these chemicals is limited to the surface of meat using conventional Raman spectroscopy as their concentration is higher within the tissue. Here, we have used SORS to detect spectral bands for glycogen, lactate, glucose and cortisol beneath the surface of meat tissue by spiking. To our knowledge, this is the first report on this method for potential application in meat quality analysis. We further validate our SORS spectral results using chemometric analysis to determine chemical-specific spectral characteristics suitable for chemical identification. The chemometric analysis clearly shows distinction of spiked metabolites into four distinct groups, even for such chemically similar compounds as glucose, glycogen and lactate.

Solution Structure of Mannobioses Unravelled by Means of Raman Optical Activity.

Structural analysis of carbohydrates is a complicated endeavour, due to the complexity and diversity of the samples at hand. Herein, we apply a combined computational and experimental approach, employing molecular dynamics (MD) and density functional theory (DFT) calculations together with NMR and Raman optical activity (ROA) measurements, in the structural study of three mannobiose disaccharides, consisting of two mannoses with varying glycosidic linkages. The disaccharide structures make up the scaffold of high mannose glycans and are therefore important targets for structural analysis. Based on the MD population analysis and NMR, the major conformers of each mannobiose were identified and used as input for DFT analysis. By systematically varying the solvent models used to describe water interacting with the molecules and applying overlap integral analysis to the resulting calculational ROA spectra, we found that a full quantum mechanical/molecular mechanical approach is required for an optimal calculation of the ROA parameters. Subsequent normal mode analysis of the predicted vibrational modes was attempted in order to identify possible marker bands for glycosidic linkages. However, the normal mode vibrations of the mannobioses are completely delocalised, presumably due to conformational flexibility in these compounds, rendering the identification of isolated marker bands unfeasible.

Antibacterial Properties of Graphene Oxide-Copper Oxide Nanoparticle Nanocomposites.

The resistance of pathogenic bacteria toward traditional biocidal treatment methods is a growing concern in various settings, including that of water treatment and in the medical industry. As such, advanced antibacterial technologies are needed to prevent infections, against which current antibiotics are failing. This study introduces copper oxide nanoparticles (CuONPs) doped in graphene oxide (GO) as a potential pathogenic bacterial treatment. The aim of the study was to evaluate the antibacterial properties of the GO-CuONP hybridized material against pathogenic Escherichia coli ATCC 8739 (E. coli) and Salmonella typhimurium ATCC 14028 (S. typhimurium). GO was synthesized using a modified Hummer's method and doped with 40% w/w CuONPs using a series of thermal chemical reactions. The resulting hybrids were then characterized using scanning electron microscopic (SEM) and spectroscopic studies. These studies revealed that the hybrid material was considerably altered by the inclusion of CuONPs. The live and dead bacteria attached to the GO-CuONP material were detected using confocal laser scanning microscopy (CLSM). The antibacterial activity assay of the GO-CuONP material was conducted using a standard plate count method. Importantly, the GO-CuONP nanocomposite was determined to be an effective antibacterial nanomaterial, significantly inhibiting the growth of both E. coli and S. typhimurium bacteria compared to that observed on the pristine GO material. This study suggests that GO-CuONP composites are a promising high-efficacy antibacterial nanomaterial.

Lactoferrin: Structure, function, denaturation and digestion.

Lactoferrin (LF) is a multifunctional protein occurring in many biological secretions including milk. It possesses iron binding/transferring, antibacterial, antiviral, antifungal, anti-inflammatory and anti-carcinogenic properties. These functional properties intimately depend on the structural integrity of LF especially its higher order conformation. LF is primarily extracted from bovine milk and it is subsequently added into many commercial products such as nutritional supplements, infant formula, cosmetics and toothpaste. LF is sensitive to denaturation induced by temperature and other physicochemical stresses. Hence, the extraction, powder formation processes of LF and processing parameters of LF-containing products have to be optimized to minimise its undesired denaturation. This review documents the advances made on structure-function relationships and discusses the effectiveness of methods used to preserve the structure of LF during thermal processing. Oral delivery, as the most convenient way for administering LF, is also discussed focusing on digestion of LF in oral, gastric and intestinal stages. The effectiveness of methods used to deliver LF to intestinal digestion stage in structurally intact form is also compared. Altogether, this work comprehensively reviews the fate of LF during thermal processing and digestion, and suggests suitable means to preserve its structural integrity and functional properties. Scope of review The manuscript aims at providing a comprehensive review of the latest publications on four aspects of LF: structural features, functional properties, nature and extent of denaturation and gastrointestinal digestion. It also analyses how these publications benefit food and pharmaceutical industries.

Optically Active Vibrational Spectroscopy of α-Aminoisobutyric Acid Foldamers in Organic Solvents and Phospholipid Bilayers.

Helical α-aminoisobutyric acid (Aib) foldamers show great potential as devices for the communication of conformational information across phospholipid bilayers, but determining their conformation in bilayers remains a challenge. In the present study, Raman, Raman optical activity (ROA), infrared (IR) and vibrational circular dichroism (VCD) spectroscopies have been used to analyze the conformational preferences of Aib foldamers in solution and when interacting with bilayers. A 310 -helix marker band at 1665-1668 cm-1 in Raman spectra was used to show that net helical content increased strongly with oligomer length. ROA and VCD spectra of chiral Aib foldamers provided the chiroptical signature for both left- and right-handed 310 -helices in organic solvents, with VCD establishing that foldamer screw-sense was preserved when the foldamers became embedded within bilayers. However, the population distribution between different secondary structures was perturbed by the chiral phospholipid. These studies indicate that ROA and VCD spectroscopies are valuable tools for the study of biomimetic structures, such as artificial signal transduction molecules, in phospholipid bilayers.