Influence of Solvents on the Oxidation Kinetics of Aldehydic Group Compounds by Diethylammonium Chloro-chromate

The redox studies of some compounds containing aldehydic functional groups by diethyl ammonium chloro-chromate (DEACC) in dimethyl sulfoxide leading a product forming to acid of correspondimg order. Reactions are found to be in unit order with oxidant while a fractional order (less than unity) was found w.r.t. reductants. The redox reactions are influenced with acid, the acid dependence is governed by this equation: kobs = a + b[H+].. When isomeric form of aldehyde, that is Me-CDO is oxidised with the same oxidant it was observed a considerable K.I.E. (Deuterium effect; kH/kD = 05.69 at 298 K). The reaction of Acetaldehyde was done in various non aqueous medium, soluble or miscible in DMSO. The effect of solvent is studied fitting our data in the solvent model of Taft's and Swain's applied for this purpose.. Rate constants are correlating very well with already reported Taft’s values of *; further the reaction constants are negative in nature. Suitable mechanism involving are proposed with transfer of hydride ion..

Synthetic Approaches and Biological Significance of Oxazolone Moieties: A Review

Oxazolone is a five-membered heterocyclic compound which is also known as azlactone. It contains one oxygen and one nitrogen as heteroatoms, which exist in five isomeric forms, according to the carbonyl group's location and the double bonds such as: 5 (4)-oxazolones, 5 (2) – oxazolones, 2 (3)-oxazolones, 4 (5)-oxazolones, and 2 (5)-oxazolones. 5 (4)-oxazolones is the most important heterocyclic moiety among all isomeric form of oxazolones. It is classified into two classes: saturated and unsaturated oxazolones. It is synthesized by various synthetic routes. Oxazolones are reported to exhibit various pharmacological activities such as antimicrobial, anti-inflammatory, anticancer, anti-HIV, antiangiogenic, anticonvulsant, sedative, cardiotonic, antidiabetic activity, etc.

Phenylisoxazole-3/5-Carbaldehyde Isonicotinylhydrazone Derivatives: Synthesis, Characterization, and Antitubercular Activity

Eight new phenylisoxazole isoniazid derivatives, 3-(2′-fluorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (1), 3-(2′-methoxyphenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (2), 3-(2′-chlorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (3), 3-(3′-clorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (4), 3-(4′-bromophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (5), 5-(4′-methoxiphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (6), 5-(4′-methylphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (7), and 5-(4′-clorophenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (8), have been synthesized and characterized by FT-IR, 1H-NMR, 13C-NMR, and mass spectral data. The 2D NMR (1H-1H NOESY) analysis of 1 and 2 confirmed that these compounds in acetone-d6 are in the trans(E) isomeric form. This evidence is supported by computational calculations which were performed for compounds 1–8, using DFT/B3LYP level with the 6-311++G(d,p) basis set. The in vitro antituberculous activity of all the synthesized compounds was determined against the Mycobacterium tuberculosis standard strains: sensitive H37Rv (ATCC-27294) and resistant TB DM97. All the compounds exhibited moderate bioactivity (MIC = 0.34–0.41 μM) with respect to the isoniazid drug (MIC = 0.91 μM) against the H37Rv sensitive strain. Compounds 6 (X = 4′-OCH3) and 7 (X = 4′-CH3) with MIC values of 12.41 and 13.06 μM, respectively, were about two times more cytotoxic, compared with isoniazid, against the resistant strain TB DM97.

A Novel UPLC-MS/MS Method Identifies Organ-Specific Dipeptide Profiles

Background: Amino acids have a central role in cell metabolism, and intracellular changes contribute to the pathogenesis of various diseases, while the role and specific organ distribution of dipeptides is largely unknown. Method: We established a sensitive, rapid and reliable UPLC-MS/MS method for quantification of 36 dipeptides. Dipeptide patterns were analyzed in brown and white adipose tissues, brain, eye, heart, kidney, liver, lung, muscle, sciatic nerve, pancreas, spleen and thymus, serum and urine of C57BL/6N wildtype mice and related to the corresponding amino acid profiles. Results: A total of 30 out of the 36 investigated dipeptides were detected with organ-specific distribution patterns. Carnosine and anserine were most abundant in all organs, with the highest concentrations in muscles. In liver, Asp-Gln and Ala-Gln concentrations were high, in the spleen and thymus, Glu-Ser and Gly-Asp. In serum, dipeptide concentrations were several magnitudes lower than in organ tissues. In all organs, dipeptides with C-terminal proline (Gly-Pro and Leu-Pro) were present at higher concentrations than dipeptides with N-terminal proline (Pro-Gly and Pro-Leu). Organ-specific amino acid profiles were related to the dipeptide profile with several amino acid concentrations being related to the isomeric form of the dipeptides. Aspartate, histidine, proline and serine tissue concentrations correlated with dipeptide concentrations, when the amino acids were present at the C- but not at the N-terminus. Conclusion: Our multi-dipeptide quantification approach demonstrates organ-specific dipeptide distribution. This method allows us to understand more about the dipeptide metabolism in disease or in healthy state.

Kelarutan Lignin Kayu Cepat Tumbuh dalam Ekstraksi Alkali

The dissolution of wood lignin in the alkali solution were analyzed for two fast growing species, sengon (Paraserianthes falcataria) dan leda (Eucalyptus deglupta). Wood samples were extracted in 1% sodium hydroxide solution in cold and hot temperatures for 24 and 1 h, respectively. Extractable substances content, permanganate consumption (expressed as assumed lignin content) were analyzed from the filtrates, lignin content and diastereomeric of β-O-4 structure were analyzed from the wood residue after alkali extraction. The extracted substances from both of wood in hot alkali was higher than in cold alkali solution, although the time of cold alkali extraction was much longer that hot alkali extraction. Assumed lignin content in the extract was quite high in both samples which were 34.4-42.9% and 35.5-39.8% including 2,15-2,29% dan 1,04-1,32% of lignin for cold and hot alkali extraction, respectively. The changes in stereo isomeric form, erythro and threo, of β-O-4 structure of lignin in wood residue indicated that partial depolimerization of lignin was takec place during alkali treatment.

Isomeric Forms of Biologically Active 2-Aminopyrimidinium Picrate Through Intrinsic Reaction Coordinate Analysis and Spectroscopic Measurements

In the present study, the isomeric forms of a biologically active 2-Aminopyrimidinium picrate cocrystal were investigated using spectroscopic investigation and Density functional theory (DFT) calculations. The vibrational assignments of IR and Raman peaks were predicted and the experimental IR and Raman spectra of the condensed phase of 2-Aminopyrimidinium picrate were compared with the simulated one. The intrinsic reaction coordinate (IRC) analysis was performed on all the possible reaction pathways to identify the isomeric forms of 2APP and transition state (TS) geometry. From the IRC analysis, a relatively stable form (named as isomer 2) has been identified in addition to the existing isomeric form (isomer 1) in the crystalline packing of 2APP. The presence of non-covalent interactions within the isomeric forms of 2APP was investigated with the help of quantum topological atoms in molecules (QTAIM) analysis. Reactivity descriptors and charge delocalization from lone pair to acceptor entities of both the isomers were predicted to validate the interactions present and to understand the charge distribution within the molecule.

Molecular Properties of Bare and Microhydrated Vitamin B5–Calcium Complexes

Pantothenic acid, also called vitamin B5, is an essential nutrient involved in several metabolic pathways. It shows a characteristic preference for interacting with Ca(II) ions, which are abundant in the extracellular media and act as secondary mediators in the activation of numerous biological functions. The bare deprotonated form of pantothenic acid, [panto-H]−, its complex with Ca(II) ion, [Ca(panto-H)]+, and singly charged micro-hydrated calcium pantothenate [Ca(panto-H)(H2O)]+ adduct have been obtained in the gas phase by electrospray ionization and assayed by mass spectrometry and IR multiple photon dissociation spectroscopy in the fingerprint spectral range. Quantum chemical calculations at the B3LYP(-D3) and MP2 levels of theory were performed to simulate geometries, thermochemical data, and linear absorption spectra of low-lying isomers, allowing us to assign the experimental absorptions to particular structural motifs. Pantothenate was found to exist in the gas phase as a single isomeric form showing deprotonation on the carboxylic moiety. On the contrary, free and monohydrated calcium complexes of deprotonated pantothenic acid both present at least two isomers participating in the gas-phase population, sharing the deprotonation of pantothenate on the carboxylic group and either a fourfold or fivefold coordination with calcium, thus justifying the strong affinity of pantothenate for the metal.

Rapid amplitude-modulation of a diarylethene photoswitch: en route to contrast-enhanced fluorescence imaging

A water soluble diarylethene derivative displaying exceptionally bright fluorescence in the open isomeric form has been used for emission amplitude-modulation. We apply this scheme in fluorescence microscopy, aiming to suppress undesired background.

The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient

Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.

Antibacterial and Anti-Inflammatory Activity of an Antimicrobial Peptide Synthesized with D Amino Acids

The peptide SET-M33 is a molecule synthesized in tetra-branched form which is being developed as a new antibiotic against Gram-negative bacteria. Its isomeric form with D amino acids instead of the L version (SET-M33D) is also able to kill Gram-positive bacteria because of its higher resistance to bacterial proteases (Falciani et al., PLoS ONE, 2012, 7, e46259). Here we report the strong in vitro activity of SET-M33D (MIC range 0.7–6.0 µM) against multiresistant pathogens of clinical interest, including Gram-positives Staphylococcus aureus, Staphylococcus saprophyticus, and Enterococcus faecalis, and various Gram-negative enterobacteriaceae. SET-M33D antibacterial activity is also confirmed in vivo against a MRSA strain of S. aureus with doses perfectly compatible with clinical use (5 and 2.5 mg/Kg). Moreover, SET-M33D strongly neutralized lipopolysaccharide (LPS) and lipoteichoic acid (LTA), thus exerting a strong anti-inflammatory effect, reducing expression of cytokines, enzymes, and transcription factors (TNF-α, IL6, COX-2, KC, MIP-1, IP10, iNOS, NF-κB) involved in the onset and evolution of the inflammatory process. These results, along with in vitro and in vivo toxicity data and the low frequency of resistance selection reported here, make SET-M33D a strong candidate for the development of a new broad spectrum antibiotic.