Synthesis, Structural Characterization and Biological Activity of Functionalized Derivatives of Gum Arabic, Pullulan and Levan Polysaccharides

U okviru ove doktorske disertacije uraĎena je hemijska derivatizacija polisaharida biljnog i mikrobnog porekla u cilju dobijanja novih funkcionalizovanih polimera. Polisaharidi gumiarabika, pululan i levan korišćeni su za sintezu dve grupe konjugata. U prvom delu ovog rada raĎene su oksidativne transformacije polisaharida sa ciljem povećanja njihove reaktivnosti. Tretiranjem polisaharida natrijum-perjodatnim reagensom u vodenom rastvoru uvedene su reaktivne aldehidne grupe u polimerni niz glikana. Perjodatnom oksidacijom gumiarabike i pululana u kontrolisanim uslovima dobijeni su polialdehidni derivati, a variranjem koncentracija polisaharida i oksidacionog sredstva, kao i reakcionog vremena, dobijeni su uzorci različitog stepena oksidacije. Kuplovanjem ovako dobijenih polialdehida gumiarabike i pululana sa polienskim antibioticima u adekvatnim reakcionim uslovima sintetisane su hemijske formulacije nistatina i amfotericina B, sa ciljem povećanja rastvorljivosti ovih antibiotika u vodi. Ispitivanjem antifungalne aktivnosti sintetisanih konjugata dokazano je zadržavanje antimikrobne aktivnosti kuplovanih antibiotika. U drugom delu ovog rada raĎena je hemijska derivatizacija polisaharida pululana i levana kuplovanjem molekula reaktivne antrahinonske boje Remazol Brilliant Blue R za polisaharidne nizove, u baznim uslovima. Sintetisani proizvodi su upotrebljeni kao hromogeni supstrati za odreĎivanje aktivnosti enzima koji selektivno hidrolizuju glikozidne veze karakteristične za ciljne polisaharide, kao i za „screening” mikroorganizama na odreĎenu enzimsku aktivnost direktnom selekcijom na agarnim podlogama...Within the scope of this Doctoral Dissertation the chemical derivatization of polysaccharides of plant and microbial origin was done for the purpose of getting new functionalized polymers. Polysaccharides gum Arabic, pullulan and levan were used for the synthesis of two groups of conjugates. The first section of this paper deals with the oxidative transformation of the polysaccharides aiming to increase their reactivity. By treating the polysaccharides with sodium periodate reagent in aqueous solution the reactive aldehyde groups are introduced into the polymer chain of glycan. Periodate oxidation of gum Arabic and pullulan under the controlled conditions resulted in formation of polyaldehide derivatives, and with the varying concentrations of polysaccharides and oxidizing agent as well as the reaction rate, samples with various levels of oxidation were obtained. By coupling gum Arabic and pullulan polyaldehide, formed in such way, with polyene antibiotics under the adequate reaction conditions, chemical formulations of nystatin and amphotericin B have been synthesized, with the purpose of increasing solubility of these antibiotics in water. The investigation of antifungal activites of the synthesized conjugate has proved that the antimicrobial activity of the coupled antibiotics has been preserved. The second section of this paper describes the chemical derivatization of pullulan and levan polysaccharides by coupling molecules of the reactive Remazol Brilliant Blue R antraquinone dye to polysaccharide chains, under base conditions. Synthesized products were used as chromogenic substrates for the determination of the enzyme activity that selectively hydrolize glycosidic linkages which are typical for the target polysaccharides, as well as for the screening of microorganisms for the specific enzyme activity through direct selection in agar substrates..

Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

The objective of this study was to investigate the hydrodynamics and the gas-liquid mass transfer coefficient of an external-loop airlift reactor (ELAR). The ELAR was operated in three cases: different inlet velocities of fluids, different alcohols solutions (water, 0.5% methanol, 0.5% ethanol, 0.5% propanol and 0.5% butanol) and different concentration of methanol in solutions (0%, 0.5%, 1%, 2% and 5%). The influence of superficial gas velocity and various diluted alcohol solutions on hydrodynamics and the gas-liquid mass transfer coefficient of the ELAR was studied. Experimentally, the gas hold-up, liquid velocities and volumetric mass transfer coefficient values in the riser and the downcomer were obtained from the literature source. A computational fluid dynamics (CFD) model was developed, based on two-phase flow, investigating different liquids regarding surface tension, assuming the ideal gas flow, applying the finite volume method and Eulerian-Eulerian model. The volumetric mass transfer coefficient was determined using the CFD and artificial neural network model. The effects of liquid parameters and gas velocity on the characteristics of the gas-liquid mass transfer were simulated. These models were compared with the appropriate experimental results. The CFD model successfully simulates the influence of different alcohols regarding the number of C-atoms on hydrodynamics and mass transfer

Ankrd1-mediated signaling is supported by its interaction with zonula occludens-1

The muscle ankyrin repeat protein Ankrd1 is localized in a mechanosensory complex of the sarcomeric I-band. It is involved in signaling pathways activated in response to mechanical stretch. It also acts as a transcriptional cofactor in the nucleus, playing an important role in cardiogenesis and skeletal muscle differentiation. To investigate its regulatory function in signaling we employed protein array methodology and identified 10 novel Ankrd1 binding partners among PDZ domain proteins known to act as platforms for multiprotein complex assembly. The zonula occludens protein-1 (ZO-1) was chosen for further analysis since its interaction with Ankrd2 had already been demonstrated. Both Ankrd2 and Ankrd1 have similar functions and localize in the same regions. We confirmed the interaction of Ankrd1 with ZO-1 protein and determined their subcellular distribution in HeLa cells, showing their colocalization in the cytoplasm. Our findings corroborate the role of Ankrd1 in intracellular signaling

Influence of Cannabis sativa L. on guaiacol peroxidase activity in Ambrosia artemisiifolia L.

Agricultural research is increasingly focused on finding alternative, biological methods of pest control. It is known that many plant species have allelopathic properties and allelopathy may be one of the mechanisms of biological weed control in the future. Allelopathic substances responsible for biochemical interactions between plants are secondary metabolites of plants. Unlike many pesticides on natural bases present on the market, the number of preparations based on allelochemicals with herbicidal action is insufficient. Therefore, it is necessary to investigate the influence of allelochemicals on weed plant species. Cannabis sativa L., as a type of confirmed allelopathic properties, has a significant impact on cultivated and weed plant species. Finding allelopathic substances that would have negative effect on A. artemisiifolia L. is very important due to its invasiveness. Changes in guaiacol peroxidase activity are one of the indicators of oxidative stress in plants produced by allelochemicals

Efficient synthesis and detailed thermal studies of zinc phthalocyanine

A facile and efficient, one step synthesis of macrocyclic molecule zinc phthalocyanine (ZnPc), was proposed. Dark violet crystals of ZnPc dye were obtained in high boiling point solvent of dimethylformamide (DMF) in the presence of 2,2,6,6-tetramethylpiperidine (TMP) as a catalyst. Detailed thermogravimetric and kinetic analysis revealed high thermal stability of the investigated compound

Deciphering the reward-related impulsivity domains in rats: The big data study of historical control

Impulsivity is a lack of ability to control own impulses, and encompasses many subdomains. The variable-delay-to-signal (VDS) paradigm is behavioral procedure for assessing motor impulsivity and delay intolerance in rats, but it was unclear whether all parameters contributed to these domains. Therefore, the aim of this study was to uncover the relationship between impulsivity parameters in a large cohort. VDS adapted to a touchscreen environment was used to assess impulsivity in adult Sprague-Dawley rats. After 1 week of training, animals were tested in a 3-stage testing protocol. The first stage included 20 trials with 6s inter-trial interval (ITI6si) that suggested motor impulsivity. The second stage, with 60 randomly distributed trials of ITI9s or 15s, was interpreted as delay intolerance, whereas for the last stage (ITI6sf), which is similar to the first stage, it was unclear to which type of impulsivity it was associated. Principal component analysis (PCA) was used to determine the different behavioral domains. The results of 132 controls from 11 independent VDS experiments were analyzed. Based on the cumulative variance explained, scree plot, and eigenvalues, the main components were extracted whereby varimax rotation was used on factor loadings to extract the components. PCA with varimax rotation was performed in R studio. PCA revealed that 96.45% of the variance could be explained by 3 principal components (PCs). After varimax rotation, loadings for ITI9s and ITI15s were 0.8189 and 0.9419, respectively, for rotated PC1 (RC1), loading for ITI6sf was 0.9482 for RC2, and loading for 6si was 0.9183 for RC3. In the VDS paradigm, 3 different impulsivity domains could be determined. In addition to motor impulsivity and delay intolerance, it is suggested that reflection impulsivity can also be assessed as learning-based impulsivity.Book of abstract: 4th Belgrade Bioinformatics Conference, June 19-23, 202

Utilization of Sugar Beet Pulp as Biosorbent for Molassigenic Metal Ions: Kinetic Study of Batch Biosorption

The sugar industry is facing problems with high amount of molassigenic metal ions remained after the purification step in sugar juice. In this investigation the application of unmodified sugar beet pulp as a weak monofunctional cation-exchange biosorbent for molassigenic metal ions (Na+, K+ and Ca2+) removal from the alkalized sugar juice was studied. The batch biosorption experiments were performed at temperature (70 °C) and pH (10.5) of alkalized sugar juice similar to industrial conditions. The highest removal efficiency was noticed for divalent Ca2+ (30.2%), while monovalent Na+ and K+ ions were removed with 10.9 and 9.1% efficiency, respectively. Biosorption equilibrium was established in 90 min for all tested metals. Sugar beet pulp characterization from the perspective of cation-exhange material was conducted. The structure of the biosorbent and an insight of the functional groups were also characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The biosorption data were analyzed using four non-linear kinetic (pseudo-first order, pseudo-second order and Elovich) and diffusion models (Weber-Morris). The time course data of biosorption processes fitted well to the pseudo-first and the pseudo-second-order kinetic models indicating ion-exchange and chemisorption as dominant mechanisms for metal ions removal from the alkalized juice. HNO3 as a desorption reagent showed the highest average molassigenic metal ions desorption efficiency (54.4%). Utilization of sugar beet biomass as cation-exchange material imposes as a potential solution for more successful sugar juice purification

A novel thermostable YtnP lactonase from Stenotrophomonas maltophilia inhibits Pseudomonas aeruginosa virulence in vitro and in vivo

Infections caused by multidrug-resistant pathogens are one of the biggest challenges facing the healthcare system today. Quorum quenching (QQ) enzymes have the potential to be used as innovative enzyme-based antivirulence therapeutics to combat infections caused by multidrug-resistant pathogens. The main objective of this research was to describe the novel YtnP lactonase derived from the clinical isolate Stenotrophomonas maltophilia and to investigate its antivirulence potential against multidrug-resistant Pseudomonas aeruginosa MMA83. YtnP lactonase, the QQ enzyme, belongs to the family of metallo-β-lactamases. The recombinant enzyme has several advantageous biotechnological properties, such as high thermostability, activity in a wide pH range, and no cytotoxic effect. High-performance liquid chromatography analysis revealed the activity of recombinant YtnP lactonase toward a wide range of N-acyl-homoserine lactones (AHLs), quorum sensing signaling molecules, with a higher preference for long-chain AHLs. Recombinant YtnP lactonase was shown to inhibit P. aeruginosa MMA83 biofilm formation, induce biofilm decomposition, and reduce extracellular virulence factors production. Moreover, the lifespan of MMA83-infected Caenorhabditis elegans was prolonged with YtnP lactonase treatment. YtnP lactonase showed synergistic inhibitory activity in combination with gentamicin and acted additively with meropenem against MMA83. The described properties make YtnP lactonase a promising therapeutic candidate for the development of next-generation antivirulence agents

Quality assessment of 3D-printed cereal-based products

The process of three-dimensional (3D) printing is of greatest interest to food science and engineering community because it offers numerous opportunities for innovative food design, new product formulations and personalized nutrition. Of particular interest are food inks based on cereal flours or starches, whose unique rheological properties make them suitable for 3D printing, typically with an extrusion-based printer. While the factors that influence the success of food printing are well addressed, the terminology and methods used to evaluate the process and product features are miscellaneous. Therefore, this research work aims at providing an overview of the most commonly used parameters and methods for evaluation of the extrusion-based 3D printing process and the resulting cereal-based foods. Physical and sensory methods that are successfully used for the quality assessment of the ink and the printed raw objects, as well as the post-processed products are here reviewed and outlined. The properties of inks, usually determined with dynamic rheological tests, are linked to various aspects of printing quality whereas the physical properties of printed raw forms are usually evaluated by image analysis combined with mathematical calculations. Microscopy analysis is undertaken to study the microstructure of both the raw objects and the end-products, while texture analysis and sensory evaluation of final product are performed both by a panel and instrumentally. We provide details of the tests, but also emphasize the need to standardize the procedures and terminology in order to avoid misunderstandings and multiple variations of similar methods. This review provides a basis for further development and standardization of the methodology for quality assessment of 3D-printed cereal-based foods.info:eu-repo/semantics/publishedVersio

Highly selective anticancer activity of core shell particles based on hydroxyapatite, chitosan lactate and different androstane derivatives

Hybrid systems based on nano hydroxyapatites (HAp) are the subject of numerous studies in preventive and regenerative medicine. Special interests are directed towards the creation of a system based on HAp for use in a nano-oncology. The main objective of this research is directed towards the creation of a system with cytotoxic properties towards the cancer cells with the same time, minimum side effects. Carriers base on core shell of HAp/chitosan-poly(D,L)-lactide-coglycolide (PLGA) loaded with androstane-based cancer inhibitor could be seen as promising drug delivery platforms for selective cancer therapies. In this study we utilize an emulsification process and freeze drying to load the composite particles based on HAp nanocarrier, chitosane (Ch), PLGA and chitosan oligosaccharide lactate (ChOL) with 17β-hydroxy-17α-picolyl-androst-5-en-3β-acetate (A) and 3β,17β-dihydroxy-16-hydroxymino-androst-5-en (B), a chemotherapeutic derivatives of androstane. The picolyl androstane derivatives showed high potency in the cell inhibitors of hormone-dependent cancers (lung, prostate and colon cancer; adeno and cervix carcinoma; etc.). 1H NMR, 13C NMR and high-resolution time-of-flight mass spectrometry (MS) techniques confirmed the intact structure of the derivatives A and B. The thermogravimetric and differential thermal analysis (TGA, DTA) coupled with mass spectrometry was used to qualitatively confirm the drug loading process. FT-IR, XRD, AFM and DSC techniques have confirmed the success of androstane (A and B) loading process in core shell particles base on nano hydroxyapatite. All the synthesized particles were found to be spherical in shape with a uniform size distribution from d50=167 to d50=231 nm. Highly selective anticancer activity was noted towards the human lung carcinoma (A549) by A loaded HAp/Ch-PLGA and towards the human breast adenocarcinoma (MDA-MB-231) by B loaded HAp/ChOL. The obtained results of the DET and MTT tests were in agreement