scholarly journals Sulfonated (1→6)-β-d-Glucan (Lasiodiplodan)

2019 ◽  
Vol 57 (4) ◽  
pp. 490-502
Author(s):  
Gabrielle Cristina Calegari ◽  
Santos Vidiany Aparecida Queiroz ◽  
Aneli M. Barbosa-Dekker ◽  
Cleverson Busso ◽  
Robert F. H. Dekker ◽  
...  
Keyword(s):  
Morphological Changes ◽  
High Thermal Stability ◽  
Ftir Analysis ◽  
Cytotoxic Potential ◽  
Antioxidant Power ◽  
Removal Capacity ◽  
Mutant Strains ◽  
Stretching Vibration ◽  
Symmetrical Vibration ◽  
Derivatives Of

Sulfonated derivatives of lasiodiplodan (LAS-S) with different degrees of substitution (1.61, 1.42, 1.02 and 0.15) were obtained and characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal and solubility analyses. Antimicrobial, antioxidant and cytotoxic potential were also assessed. The sulfonation was confirmed by FTIR analysis with specific bands at 1250 cm–1 (S=O, strong asymmetrical stretching vibration) and at 810 cm–1 (C-O-S, symmetrical vibration associated with the C-O-SO3 group) in the sulfonated samples. SEM demonstrated that sulfonation promoted morphological changes on the surface of the biopolymer with heterogeneous fibrillary structures appearing along the surface following chemical modification. LAS-S showed high thermal stability, with mass loss due to oxidation at temperatures close to 460 °C. Sulfonation increased the solubility of LAS, and in addition, increased the antimicrobial activity, especially against Candida albicans (fungicidal) and Salmonella enterica Typhimurium (bacteriostatic). Native lasiodiplodan (LAS-N) showed higher OH˙ removal capacity, while LAS-S had higher ferric ion reducing antioxidant power (FRAP) potential. LAS-N and LAS-S did not demonstrate lethal cytotoxicity against wild and mutant strains of Saccharomyces cerevisiae. Samples with higher degree of substitution (1.42 and 1.61) showed lower potential to induce oxidative stress.

Infrared spectra and substituent effects in 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones

1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Wave Number ◽  
Vibrational Coupling ◽  
Wave Numbers ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
The Relationship ◽  
Derivatives Of ◽  
Effect Of Structure

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

scholarly journals Mouse-Colonizing Helicobacter pylori SS1 Is Unusually Susceptible to Metronidazole Due to Two Complementary Reductase Activities

2000 ◽  
Vol 44 (11) ◽  
pp. 3127-3132 ◽  
Author(s):  
Jin-Yong Jeong ◽  
Douglas E. Berg
Keyword(s):  
Helicobacter Pylori ◽  
Kanamycin Resistance ◽  
Phenotypic Traits ◽  
Insertion Mutant ◽  
Low Concentrations ◽  
Mutant Strains ◽  
Resistance Markers ◽  
Clinically Significant ◽  
H Pylori ◽  
Derivatives Of

ABSTRACT In most strains of Helicobacter pylori, mutational inactivation of the rdxA (HP0954) gene, which encodes a nitroreductase that converts metronidazole (MTZ) from a harmless prodrug to a mutagenic and bacteriocidal product, is sufficient to make this pathogen resistant to clinically significant levels of MTZ. Here we report that SS1, a strain with the special ability to colonize mice, is unusual in being susceptible to very low concentrations of MTZ (0.5 μg/ml) and in being especially difficult to mutate to MTZ resistance (Mtzr). These phenotypic traits were traced to expression in this strain of the normally quiescent H. pylori frxAgene (HP0642, an rdxA paralog) along with rdxA. Transformation tests using rdxA::camand frxA::kan insertion mutant DNAs, with selection solely for the chloramphenicol and kanamycin resistance markers, and sequence analyses of frxA in spontaneous Mtzr derivatives of rdxA null mutant strains each showed that the development of Mtzr in SS1 required inactivation of both rdxA and frxA. Inactivation of either gene alone left SS1 susceptible to MTZ, although it was readily mutable from an MTZ-susceptible to an Mtzrphenotype. Reverse transcriptase PCR tests showed that frxAmRNA was at least 10-fold more abundant in SS1 than in reference strain 26695. It is proposed that these reductases play primarily nutritional roles during bacterial growth.

scholarly journals Overproduction of Penicillin-Binding Protein 2 and Its Inactive Variants Causes Morphological Changes and Lysis in Escherichia coli

2007 ◽  
Vol 189 (14) ◽  
pp. 4975-4983 ◽  
Author(s):  
Blaine A. Legaree ◽  
Calvin B. Adams ◽  
Anthony J. Clarke
Keyword(s):  
Escherichia Coli ◽  
Signal Sequence ◽  
Morphological Changes ◽  
Binding Protein ◽  
Penicillin Binding Protein ◽  
Prolonged Incubation ◽  
Lytic Transglycosylases ◽  
E Coli ◽  
Derivatives Of

ABSTRACT Penicillin-binding protein 2 (PBP 2) has long been known to be essential for rod-shaped morphology in gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa. In the course of earlier studies with P. aeruginosa PBP 2, we observed that E. coli was sensitive to the overexpression of its gene, pbpA. In this study, we examined E. coli overproducing both P. aeruginosa and E. coli PBP 2. Growth of cells entered a stationary phase soon after induction of gene expression, and cells began to lyse upon prolonged incubation. Concomitant with the growth retardation, cells were observed to have changed morphologically from typical rods into enlarged spheres. Inactive derivatives of the PBP 2s were engineered, involving site-specific replacement of their catalytic Ser residues with Ala in their transpeptidase module. Overproduction of these inactive PBPs resulted in identical effects. Likewise, overproduction of PBP 2 derivatives possessing only their N-terminal non-penicillin-binding module (i.e., lacking their C-terminal transpeptidase module) produced similar effects. However, E. coli overproducing engineered derivatives of PBP 2 lacking their noncleavable, N-terminal signal sequence and membrane anchor were found to grow and divide at the same rate as control cells. The morphological effects and lysis were also eliminated entirely when overproduction of PBP 2 and variants was conducted with E. coli MHD79, a strain lacking six lytic transglycosylases. A possible interaction between the N-terminal domain of PBP 2 and lytic transglycosylases in vivo through the formation of multienzyme complexes is discussed.

Double Schiff bases derivatives of chitosan by selective C-6 and C-2 oxidation mediated by 5-fluorosalicylaldehyde aniline by TG-GC-MS and TG-FTIR analysis

2020 ◽  
Vol 50 (17) ◽  
pp. 2617-2628
Author(s):  
Ida Malarselvi Rajkumar ◽  
Deepika Asaithambi ◽  
Ramachandra Raja Chidambaram ◽  
Priscilla Rajkumar
Keyword(s):  
Schiff Bases ◽  
Ftir Analysis ◽  
Derivatives Of

FTIR Analysis to Study Chemical Changes in Wool Following a Sulfitolysis Treatment

1997 ◽  
Vol 67 (6) ◽  
pp. 397-401 ◽  
Author(s):  
P. Erra ◽  
N. Gómez ◽  
L. M. Dolcet ◽  
M. R. Juliá ◽  
D. M. Lewis ◽  
...  
Keyword(s):  
Chemical Method ◽  
Fiber Surface ◽  
Industrial Processes ◽  
Attenuated Total Reflectance ◽  
Ftir Analysis ◽  
Rapid Estimation ◽  
Total Reflectance ◽  
Second Derivatives ◽  
Stretching Vibration ◽  
Wool Keratin

Sulfitolysis of wool keratin is important to many industrial processes, including shrink resistance, setting, and bleaching; its extent therefore requires rapid estimation. Currently, time consuming chemical analysis is used to convert the cysteine-S-sulfonate to cysteine and then to measure total cysteine colorimetricaily. Using ftir and the attenuated total reflectance (atr) method, our experiments quantify the relative amount of cysteine-S-sulfonate on the wool fiber surface. The cysteine-S-sulfonate (Bunte salt) shows a strong symmetrical stretching vibration at 1022 cm−1; working in the absorbance mode and taking second derivatives to enhance resolution allows changes in the amount of Bunte salt to be followed. The keratin Bunte salt is stable to acid but labile in alkali; a treatment with ammonium thioglycolate at pH 7.6 completely removes the Bunte salt. Results show the same trend as those obtained using the classical chemical method.

scholarly journals Synthesis of Four-arms Star-shaped PCL-b-PEG as a Potential Amphiphilic Hydrogel

2021 ◽  
Vol 18 (1) ◽  
pp. 101
Author(s):  
Wafiuddin Ismail ◽  
Wan Khartini Wan Abdul Khodir ◽  
Shafida Abd Hamid ◽  
Rusli Daik
Keyword(s):  
1H Nmr ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Ring Opening Polymerization ◽  
Gas Permeation ◽  
High Thermal Stability ◽  
Ftir Analysis ◽  
Star Shaped Polymer ◽  
Weight Analysis ◽  
Tga Analysis

Hydrogel formulations have drawbacks in delivering hydrophobic drugs which can affect its efficiency. Introducing amphiphilic system into hydrogel can overcome this limitation and increase hydrogel effectiveness as a drug cargo. In this study, four arms star-shaped block copolymers with polyethylene glycol (PEG) as hydrophilic block and polycaprolactone (PCL) as hydrophobic block were synthesized via a combination of ring-opening polymerization (ROP) and Steglich esterification. The structures were confirmed by 1H-NMR and FTIR analysis. The polydispersity index (PDI) indices from gas permeation chromatography (GPC) were 1.3 to 1.6 suggesting controlled polymerisation reaction occurred. Average molecular weight analysis, Mn based on 1H-NMR are close to the theoretical value. However, there is a slight difference of Mn between GPC and proton analysis due to the ability of GPC determining Mn for the star-shaped polymer. Both star-shaped polymers possesses high thermal stability (>350 °C) based on thermal decomposition study using TGA analysis. The presence of PEG had increased the hydrophilicity and solubility of the PCL in the hydrogel since an opaque homogeneous formulation form when using the amphiphilic star-shaped polymer. The pH (7.25 ± 0.03) and viscosity (9330 cP) of the formulation are set within the compatibility and suitable for human skin and topical application.

scholarly journals Reliable and Sophisticated Techniques to Evaluate LDPE Degraded Compounds by Streptomyces werraensis SDJM

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
N. Deepika ◽  
R. Jaya Madhuri
Keyword(s):  
Weight Loss ◽  
Structural Changes ◽  
Morphological Changes ◽  
Field Trials ◽  
Sem Analysis ◽  
Modern World ◽  
Ftir Analysis ◽  
Test Results ◽  
Laboratory Test Results ◽  
The World

The modern world in the present era made life miserable due to extensive usage of plastic. Low-density polyethylene (LDPE) is widely consumed in every part of the world starting from baby products to garbage bags. Humans and animals are affected due to the usage and disposal of LDPE in the environment. To safeguard the environment from deleterious effects, biodegradation of LDPE was studied by isolating a potent Streptomyces werraensis SDJM strain from garbage soil. The degradation assessment was performed to identify the LDPE degraded compounds such as octane, decane, tetracosane, hexacosane, dotriacontene, tetratiacontene, tridecone, tetracontane, and pentacosane, using a sophisticated technique - liquid chromatography-mass spectroscopy (LCMS). The end product of LDPE biodegradation, carbon dioxide was measured by the GCMS-SPME technique. Field trials in garbage soil for a period of three months reveal 71.26% weight loss compared to laboratory test results where the weight loss was 60.05%. The morphological changes and structural changes of the polymer in fields were assessed by SEM analysis and FTIR analysis after one month of incubation. The test results in field trials were promising and convincing to overcome the LDPE pollution in presence of S.werraensis SDJM strain.

Fingerprinting bacterial chromosomal DNA with restriction endonuclease EcoRI: comparison of Rhizobium spp. and identification of mutants

1979 ◽  
Vol 25 (7) ◽  
pp. 803-807 ◽  
Author(s):  
Jonathan R. Mielenz ◽  
L. E. Jackson ◽  
F. O'Gara ◽  
K. T. Shanmugam
Keyword(s):  
Restriction Endonuclease ◽  
Dna Cleavage ◽  
Rhizobium Trifolii ◽  
Chromosomal Dna ◽  
Mutant Strains ◽  
Restriction Endonuclease Ecori ◽  
Endonuclease Ecori ◽  
Cellular Dna ◽  
Derivatives Of ◽  
Japonicum Strain

Total cellular DNA from Rhizobium trifolii, R. meliloti, and R. japonicum strains 110 and 117 were prepared. DNA fragments generated with restriction endonuclease EcoRI from these DNA samples were compared in agarose gels after electrophoresis. DNA cleavage patterns generated from R. japonicum strain 110, R. trifolii, and R. meliloti were clearly distinguishable from each other. Restriction endonuclease cleavage patterns of DNA from R. japonicum strain 110 and presumptive R. trifolii mutant strains that nodulate soybean were found to be similar. Rhizobium trifolii mutant strains were also lysed by a phage specific for R. japonicum strain 110. These results show that "R. trifolii mutant strains" are indeed derivatives of R. japonicum strain 110 and not R. trifolii.

scholarly journals Phenolic Fingerprinting, Antioxidant, and Deterrent Potentials of Persicaria maculosa Extracts

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3054 ◽  
Author(s):  
Luisa Quesada-Romero ◽  
Carlos Fernández-Galleguillos ◽  
Jan Bergmann ◽  
María-Eugenia Amorós ◽  
Felipe Jiménez-Aspee ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Antioxidant Capacity ◽  
Macrosiphum Euphorbiae ◽  
Total Phenolic ◽  
Phenolic Profile ◽  
Antioxidant Power ◽  
Aerial Parts ◽  
Ferric Reducing Antioxidant Power ◽  
First Time ◽  
Derivatives Of

Persicaria maculosa (Polygonaceae) (known as lady’s thumb) is an annual morphologically variable weed that is widely distributed in Chile. The purpose of this study was to investigate the antifeedant potential of methanolic (MeOH), ethanolic (EtOH), and dichloromethane (DCM) extracts from the aerial parts of this plant collected in the Valparaíso and Curicó provinces (Chile) and relate this activity to the antioxidant capacity and the presence of phenolic compounds in the extracts. A phenolic profile based on HPLC-ESI-MS/MS allowed the identification of 26 phenolic compounds, most of them glycosyl derivatives of isorhamnetin, quercetin, and kaempferol. In addition, the total phenolic content (TP), total flavonoids (TF), and antioxidant activity measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide anion scavenging (O2−), ferric-reducing antioxidant power (FRAP), and cupric-reducing antioxidant capacity (CUPRAC) of the extracts are reported. The antifeedant potentials of the plant extracts were tested against Epilachna paenulata, Pseudaletia adultera, Macrosiphum euphorbiae, and Diaphorina citri insects for the first time. The activity against the aphid M. euphorbiae was significant for the DCM extracts of plants from Valparaíso and Curicó (settling % = 23% ± 4% and 23% ± 5%, respectively). The antifeedant activities against the beetle E. paenulata and the lepidoptera P. adultera were significant for Valparaíso extracts, especially when tested against E. Paenulata (IFP = 1.0 ± 0.0). Finally, the MeOH and EtOH extracts from Valparaíso plants reduced the diet consumption of the psilid D. citri (p < 0.05). The results showed that P. maculosa is a good source of flavonoids with some antioxidant capacities and has potential interest as botanical eco-friendly alternative with deterrent activity.

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