Allosteric kidney-type glutaminase (GLS) inhibitors with a mercaptoethyl linker

A series of allosteric kidney-type glutaminase (GLS) inhibitors possessing a mercaptoethyl (SCH₂CH₂) linker were synthesized in an effort to further expand the structural diversity of chemotypes derived from bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES), a prototype allosteric inhibitor of GLS. BPTES analog 3a with a mercaptoethyl linker between the two thiadiazole rings was found to potently inhibit GLS with an IC₅₀ value of 50 nM. Interestingly, the corresponding derivative with an n-propyl (CH₂CH₂CH₂) linker showed substantially lower inhibitory potency (IC₅₀ = 2.3 μM) while the derivative with a dimethylsulfide (CH₂SCH₂) linker showed no inhibitory activity at concentrations up to 100 μM, underscoring the critical role played by the mercaptoethyl linker in the high affinity binding to the allosteric site of GLS. Additional mercaptoethyl-linked compounds were synthesized and tested as GLS inhibitors to further explore SAR within this scaffold including derivatives possessing a pyridazine as a replacement for one of the two thiadiazole moiety.     

Photostabilization of phycocyanin from Spirulina platensis modified by formaldehyde

Spirulina platensis contain variety of pigments, such as chlorophylls, carotenoids, and phycocyanin. Phycocyanin (PC) exists in abundance, but due to its instability, the utilization of this pigment is still very limited. In this study, the PC was modified using formaldehyde crosslinks yielding phycocyanin-formaldehyde (PC-F), and its photostability was evaluated. The PC-F formation was designated by the distinctive alterations of the maximum absorption to 611 nm, which was 10 nm blue-shifted than those of the PC. Additionally, the sharp peaks of FTIR spectra at 1636 nm for CO and at 1019 nm for COC, suggesting the interaction of phycocyanin with formaldehyde. The PC-F showed stabilization improvement up to 1.53-folds after 300 mins of yellow light exposure than those of PC. Contrary to yellow light irradiation, a severe decrease of PC-F absorbance was observed reach to 4.9-folds under UV-B irradiation. The poor stability of PC-F upon white light and UV-A irradiation were indicated by the decline of PC-F absorbance up to 1.72 and 1.80, respectively. Moreover, the present study suggests that the modification of phycocyanin by formaldehyde crosslink can increase photostability upon yellow light irradiation.     

The catalytic mechanism of sulfoxide synthases

Sulfoxide synthases are non-heme iron enzymes that catalyze oxidative carbonsulfur bond formation in the biosynthesis of thiohistidines such as ergothioneine and ovothiol. The catalytic mechanism of these enzymes has been studied by protein crystallography, steady-state kinetics, non-natural amino acid incorporation and computational modeling. This review discusses the current status of this research and also highlights similarities between the CS bond forming activity of sulfoxide synthases with that of synthetic coordination compounds.     

Preparation and antioxidant study of silver nanoparticles of Microsorum pteropus methanol extract

This study reports a preparation of silver nanoparticles (SNPs) using Microsorum pteropus methanol extract, as a new approach in the development of therapeutic strategies against diseases caused by oxidative stress, reactive oxygen, and nitrogen species. During the effort of extraction and isolation from M. pteropus, X-ray single-crystal structural analysis of sucrose was succeeded. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide scavenging assay were used to confirm the antioxidant potential. Preparation of SNPs was confirmed by ultraviolet–visible (UV–Vis) spectra with peaks between 431 and 436 nm. Infrared (IR) analysis showed OH, NH functional groups of alcohol, phenol, amine, and aliphatic CH stretching vibrations of hydrocarbon chains of the synthesized nanoparticles. The antioxidant properties of the SNPs significantly showed DPPH reduction with an IC₅₀ value of 47.0 µg/mL and hydrogen peroxide scavenging activity with an IC₅₀ value of 35.8 µg/mL, and hence, indicating their capability to eliminate potentially damaging oxidants involved in oxidative stress and their related diseases.     

Phyto-fabricated ZnO nanoparticles from Canthium dicoccum (L.) for antimicrobial,anti-tuberculosis and antioxidant activity

Bioactivity exhibited by nanoparticles has been interesting for researchers globally. The phytogenic synthesis of zinc oxide nanoparticles (ZnO-NPs) has been an eco-friendly approach due to its low toxicity and biological potential. In this pretext, the present study has been conducted. The bacterial inhibition by ZnO-NPs could be attributed to its high specific surface charge and reactive oxygen species generation. The present study states the phyto-fabrication of ZnO-NPs employing aqueous leaf extract of Canthium dicoccum (L.). The synthesized nanoparticles (NPs) displayed characteristic excitation at 293 nm. The dynamic light scattering (DLS) analysis revealed an average 33 nm size of ZnO-NPs. The FT-IR functional groups CH stretch, CH bend, aromatic CN stretch, and CO stretch were observed in phyto-fabricated ZnO-NPs. Results obtained from antibacterial activities inferred that ZnO-NPs were most effective against Bacillus subtilis, least sensitive to Staphylococcus aureus. The minimum inhibitory concentration (MIC) was observed in the range 78.12 to 625 μg mL⁻¹ which was further confirmed by bacterial cell viability test. The Anti-TB activity by Alamar Blue Dye test revealed phyto-fabricated ZnO-NPs inhibited M. tuberculosis at 25 μg mL⁻¹. The result of the antioxidant activity of the DPPH method was dose-dependent. The application of ZnO-NPs as potential antibacterial applications could be envisioned.     

Synchrotron Fourier-Transform Infrared Microspectroscopy: Characterization of in vitro polarized tumor-associated macrophages stimulated by the secretome of inflammatory and non-inflammatory breast cancer cells

Studies suggested that the pathogenesis of inflammatory breast cancer (IBC) is related to inflammatory manifestations accompanied by specific cellular and molecular mechanisms in the IBC tumor microenvironment (TME). IBC is characterized by significantly higher infiltration of tumor-associated macrophages (TAMs) that contribute to its metastatic process via secreting many cytokines such as TNF, IL-6, IL-8, and IL-10 that enhance invasion and angiogenesis. Thus, there is a need to first understand how IBC-TME modulates the polarization of TAMs to better understand the role of TAMs in IBC. Herein, we used gene expression signature and Synchrotron Fourier-Transform Infrared Microspectroscopy (SR-μFTIR) to study the molecular and biochemical changes, respectively of in vitro polarized TAMs stimulated by the secretome of IBC and non-IBC cells. The gene expression signature showed significant differences in the macrophage's polarization-related genes between stimulated TAMs. FTIR spectra showed absorption bands in the region of 1700–1500 cm^?1 attributed to the amide I ν(C=O), & ν_AS (CN), δ (NH), and amide II ν(CN), δ (NH) proteins bands. Moreover, three peaks of different intensities and areas were detected in the lipid region of the νCH₂ and νCH₃ stretching modes positioned within the 3000–2800 cm^?1 range. The PCA analysis for the second derivative spectra of the amide regions discriminates between stimulated IBC and non-IBC TAMs. This study showed that IBC and non-IBC TMEs differentially modulate the polarization of TAMs and SR-μFTIR can determine these biochemical changes which will help to better understand the potential role of TAMs in IBC.     

Time-resolved FTIR difference spectroscopy for the study of quinones in the A1 binding site in photosystem I: Identification of neutral state quinone bands

Infrared absorption bands associated with the neutral state of quinones in the A₁ binding site in photosystem I (PSI) have been difficult to identify in the past. This problem is addressed here, where time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study PSI with six different quinones incorporated into the A₁ binding site. (P700⁺A₁⁻ – P700A₁) and (A₁⁻ – A₁) FTIR difference spectra (DS) were obtained for PSI with the different quinones incorporated, and several double-difference spectra (DDS) were constructed from the DS. From analysis of the DS and DDS, in combination with density functional theory based vibrational frequency calculations of the quinones, the neutral state bands of the incorporated quinones are identified and assigned. For neutral PhQ in the A₁ binding site, infrared absorption bands were identified near 1665 and 1635 cm⁻¹, that are due to the C₁O and C₄O stretching vibrations of the incorporated PhQ, respectively. These assignments indicate a 30 cm⁻¹ separation between the C₁O and C₄O modes, considerably less than the ~80 cm⁻¹ found for similar modes of PhQ⁻. The C₄O mode downshifts due to hydrogen bonding, so the suggestion is that hydrogen bonding is weaker for the neutral state compared to the anion state, indicating radical-induced proton dynamics associated with the quinone in the A₁ binding site in PSI.     

Adaptive management of estuarine resource utilization and wetland conservation based on multi-temporal remote sensing: A case study of Minjiang Estuary,China

Adaptive management of estuarine resource utilization and wetland conservation (ERU&WC) have both socioeconomic and ecological implications because estuaries involve plentiful navigation, aquaculture, wetland, and land-reclamation resources but are featured with complexity and vulnerability of hydrodynamics, morphodynamics, and ecological processes. To achieve positive synergistic effects and prevent disasters by optimizing the allocation of estuarine space to various activities and biological habitats, there is a need to track the estuarine evolutionary trajectories and demarcate the spatial function subareas. However, estuarine field data acquisition is time-consuming, spatially limited, expensive, and there are some areas not accessible due to shallowness or moving sand bars. This paper presents an exact estuarine morphodynamics acquisition and evolution analysis based on multi-temporal remote sensing images, with Minjiang Estuary, China as a case study. The imageries with high tide level (1995, 2017) and low tide level (1995, 2002, 2010, and 2017) were chosen to track the changes of coastline, tidal flat, channel, sand bar, sand island, wetland vegetation, and the spatial heterogeneity of Minjiang Estuary, and the results show visually the section of shoreline change, the pattern of TCSS change and the part of tidal flat vegetation change, which are the fundamental data for demarcating the spatial function subareas. Also, the adaptive management rule was explored, and the schematic diagram of the estuarine morphodynamic evolution process and the framework of ERU&WC adaptive management were outlined. The research result will provide technical support and theoretical guidance for the management of other estuarine environments.     

NADP-dependent glutamate dehydrogenases in a dimorphic zygomycete Benjaminiella poitrasii: Purification,characterization and their evaluation as an antifungal drug target

BackgroundIt has been reported that the genes coding for NADP-dependent glutamate dehydrogenases (NADP-GDHs) showed a cause-effect relationship with Yeast-Hypha (YH) reversible transition in a zygomycete Benjaminiella poitrasii. As YH transition is significant in human pathogenic fungi for their survival and proliferation in the host, the NADP-GDHs can be explored as antifungal drug targets.MethodsThe yeast-form specific BpNADPGDH I and hyphal-form specific BpNADPGDH II of B. poitrasii were purified by heterologous expression in E. coli BL-21 cells and characterized. The structural analogs of L-glutamate, dimethyl esters of isophthalic acid (DMIP) and its derivatives were designed, synthesized and screened for inhibition of NADP-GDH activity as well as YH transition in B. poitrasii, and also in human pathogenic Candida albicans strains.ResultsThe BpNADPGDH I and BpNADPGDH II were found to be homo-hexameric proteins with native molecular mass of 282 kDa and 298 kDa, respectively and subunit molecular weights of 47 kDa and 49 kDa, respectively. Besides the distinct kinetic properties, BpNADPGDH I and BpNADPGDH II were found to be regulated by cAMP-dependent- and Calmodulin (CaM) dependent- protein kinases, respectively. The DMIP compounds showed a more pronounced effect on H-form specific BpNADPGDH II and inhibited YH transition as well as growth in B. poitrasii and C. albicans strains.ConclusionThe present study will be useful to design and develop antifungal drugs against dimorphic human pathogens using glutamate dehydrogenase as a target.SignificanceGlutamate dehydrogenases can be explored as a target against human pathogenic fungi.     

Synthesis and antileishmanial activity of fluorinated rhodacyanine analogues: The ‘fluorine-walk’ analysis

In a search for potent antileishmanial drug candidates, eighteen rhodacyanine analogues bearing fluorine or perfluoroalkyl substituents at various positions were synthesized. These compounds were tested for their inhibitory activities against Leishmania martiniquensis and L. orientalis. This ‘fluorine-walk’ analysis revealed that the introduction of fluorine atom at C-5, 6, 5′, or 6′ on the benzothiazole units led to significant enhancement of the activity, correlating with the less negative reduction potentials of the fluorinated analogues confirmed by the electrochemical study. On the other hand, CF₃ and OCF₃ groups were found to have detrimental effects, which agreed with the poor aqueous solubility predicted by the in silico ADMET analysis. In addition, some of the analogues including the difluorinated species showed exceptional potency against the promastigote and axenic amastigote stages (IC₅₀ = 40–85 nM), with the activities surpassing both amphotericin B and miltefosine.     

Green synthesis of silver nanoparticles using aqueous rhizome extract of Zingiber officinale and Curcuma longa: In-vitro anti-cancer potential on human colon carcinoma HT-29 cells

This study was aimed to analyze the anti-cancer activity of silver nanoparticles (AgNPs) synthesized using aqueous plant extracts from the rhizome of Curcuma longa and Zingiber officinale. Synergistic aqueous extract of rhizome of C. longa and Z. officinale was used to green synthesis of AgNPs. Characterization of AgNPs was performed using UV–visible spectroscopy, FTIR, X-ray diffraction, TEM, and SEM analyses. Anti-cancer activity of AgNPs against human colon carcinoma (HT-29) cells was tested using MTT assay. UV–Visible spectroscopy analysis indicated the surface plasmon resonance (SPR) sharp peak at 350–430 nm wavelength that corresponds to the production of AgNPs. FTIR analysis reveals that existence of carboxyl (CO) and amine (NH) functional groups in the AgNPs. The X-ray diffraction analysis confirms four spectral peaks at 111, 200, 220, and 311. SEM analysis showed that AgNPs are in a spherical shape with a size of 42–61 nm and TEM analysis showed particle size are ranged between 20–51 nm. Anti-cancer study reveals that AgNPs had shown cytotoxicity against HT-29 cells at the concentrations ranged from 25 to 500 μg/mL and IC₅₀ at 150.8 µg/mL. This study concludes that AgNPs synthesized using rhizome of Z. officinale and C. longa possesses potential anti-cancer activity.     

Investigations on unconventional hydrogen bonds in RNA binding proteins: The role of CH⋯OC interactions

We have investigated the roles played by CH⋯OC interactions in RNA binding proteins. There was an average of 78 CH⋯OC interactions per protein and also there was an average of one significant CH⋯OC interaction for every 6 residues in the 59 RNA binding proteins studied. Main chain–Main chain (MM) CH⋯OC interactions are the predominant type of interactions in RNA binding proteins. The donor atom contribution to CH⋯OC interactions was mainly from aliphatic residues. The acceptor atom contribution for MM CH⋯OC interactions was mainly from Val, Phe, Leu, Ile, Arg and Ala. The secondary structure preference analysis of CH⋯OC interacting residues showed that, Arg, Gln, Glu and Tyr preferred to be in helix, while Ala, Asp, Cys, Gly, Ile, Leu, Lys, Met, Phe, Trp and Val preferred to be in strand conformation. Most of the CH⋯OC interacting polar amino acid residues were solvent exposed while, majority of the CH⋯OC interacting non polar residues were excluded from the solvent. Long and medium-range CH⋯OC interactions are the predominant type of interactions in RNA binding proteins. More than 50% of CH⋯OC interacting residues had a higher conservation score. Significant percentage of CH⋯OC interacting residues had one or more stabilization centers. Sixty-six percent of the theoretically predicted stabilizing residues were also involved in CH⋯OC interactions and hence these residues may also contribute additional stability to RNA binding proteins.     

Deuterium Raman imaging for lipid analysis

Raman microscopy has been used to deduce information about the distributions of endogenous biomolecules without exogenous labeling. Several functional groups, such as alkynes (CC), nitriles (CN), and carbon-deuterium (C–D) bonds, have been employed in recent years as Raman tags to detect target molecules in cells. In this article, we review some recent advances in applications using deuterated fatty acids for lipid analysis, such as investigation of tumor-selective cytotoxicity of γ-linolenic acid (GLA), simultaneous two-color imaging of stearate and oleate using deuterated and protonated alkynes, Raman hyperspectral imaging, and analyses of the physical properties of lipids through spectral unmixing of the C–D vibrational frequencies. In addition, we review some advanced methods for observing intracellular metabolic activities, such as de novo lipogenesis from deuterium-labeled precursors.     

Precursor De13.1 from Conus delessertii defines the novel G gene superfamily

Peptide de13a was previously purified from the venom of the worm-hunting cone snail Conus delessertii from the Yucatán Channel, México. This peptide has eight cysteine (Cys) residues in the unique arrangement CCCCCCCC, which defines the cysteine framework XIII (“” represents one or more non-Cys residues). Remarkably, δ-hydroxy-lysine residues have been found only in conotoxin de13a, which also contains an unusually high proportion of hydroxylated amino acid residues. Here, we report the cDNA cloning of the complete precursor De13.1 of a related peptide, de13b, which has the same Cys framework and inter-Cys spacings as peptide de13a, and shares high protein/nucleic acid sequence identity (87%/90%) with de13a, suggesting that both peptides belong to the same conotoxin gene superfamily. Analysis of the signal peptide of precursor De13.1 reveals that this precursor belongs to a novel conotoxin gene superfamily that we chose to name gene superfamily G. Thus far superfamily G only includes two peptides, each of which contains the same, distinctive Cys framework and a high proportion of amino acid residues with hydroxylated side chains.     

Inhibitions of monoamine oxidases and acetylcholinesterase by 1-methyl, 5-phenyl substituted thiosemicarbazones: Synthesis,biochemical, and computational investigations

A series of eleven 1-methyl, 5-phenyl substituted thiosemicarbazones (MT1–MT11) with the phenyl ring substitutions were prepared and investigated for their inhibitory activities against monoamine oxidases (MAOs) and acetylcholinesterase (AChE). [4-(dimethylamino) phenyl]methylidene}-N-methylhydrazine-1-carbothioamide (MT5) inhibited MAO-B potently with an IC₅₀ of 8.77 μM. Potencies for MAO-B increased in the order N(CH₃)₂ in MT5 > OCH₃ in MT3 > Br in MT9. Most of the 11 compounds weakly inhibited AChE by <30% at 10 μM. MT5 competitively inhibited MAO-B and K_i value was 6.58 ± 0.064 μM. Reversibility experiments showed MT5 also reversibly inhibited MAO-B. MTT assays revealed that MT5 and MT3 were non-toxic to normal VERO cell lines with IC₅₀ values of 191.96 and 187.04 μg/mL, respectively. From the molecular docking, MT5 binding was found to be stabilized by hydrogen bonding to the non-bonding electron of the terminal N-methyl group with Cys172 (binding energy = −7.01 kcal/mol) of MAO-B. The molecular dynamics further predicted that MT5 had a major π–π hydrophobic interaction with Tyr326 of MAO-B, suggesting that it plays an important role in the stabilization of protein-ligand interaction.These results documents that MT5 is a moderately selective, reversible, and competitive inhibitor of MAO-B with low cytotoxic profile.     

Restriction of RecG translocation by DNA mispairing

BackgroundThe RecG DNA helicase plays a crucial role in stalled replication fork rescue. We have recently discovered that interaction of RecG with single-strand DNA binding protein (SSB) remodels RecG, allowing it to spontaneously translocate upstream of the fork. Based on these findings, we hypothesized that mispairing of DNA could limit such translocation of RecG.MethodsHere, we used atomic force microscopy (AFM) to directly test this hypothesis and investigate how sensitive RecG translocation is to different types of mispairing.ResultsWe found that a CC mispairing, at a distance of 30 bp from the fork position, prevents translocation of RecG over this mispairing. A G-bulge, placed at the same distance, also has a similar blocking efficiency. However, a CC mispairing, 10 bp away from the fork, does not prevent RecG translocation beyond 10 bp distance, but decreases complex yield. Modeling of RecG-DNA complexes show that 10 bp distance from the fork is within the binding footprint of RecG on DNA.ConclusionsOur results suggest that the RecG translocation upstream of the replication fork is limited by mispairings in the parental arm of the replication fork.General significanceThese findings led us to propose dual functions for RecG, in which the thermally driven translocation of RecG can be a mechanism for the additional control of the DNA paring in which RecG can detect the lesions in front of the replication fork, adding to the fidelity of the DNA replication machinery.     

Ultrasound assisted rapid synthesis of mefenamic acid based indole derivatives under ligand free Cu-catalysis: Their pharmacological evaluation

An improved and rapid synthesis of mefenamic acid based indole derivatives has been achieved via the ligand free Cu-catalyzed coupling-cyclization method under ultrasound irradiation. This simple, straightforward and inexpensive one-pot method involved the reaction of a terminal alkyne derived from mefenamic acid with 2-iodosulfanilides in the presence of CuI and K₂CO₃ in PEG-400. The reaction proceeded via an initial CC bond formation (the coupling step) followed by CN bond formation (the intramolecular cyclization) to afford the mefenamic acid based indole derivatives in good to acceptable yields. Several of these compounds showed inhibition of PDE4 in vitro and the SAR (Structure Activity Relationship) within the series is discussed. The compound 3d has been identified as a promising and selective inhibitor of PDE4B (IC₅₀ = 1.34 ± 0.46 µM) that showed TNF-α inhibition in vitro (IC₅₀ = 5.81 ± 0.24 µM) and acceptable stability in the rat liver microsomes.     

Estimation of the content of lipids composing endothelial lipid droplets based on Raman imaging

Lipid droplets (LDs) are dynamic organelles involved in intracellular lipid metabolism, and the biogenesis of LDs in endothelium is triggered by the excess of lipids in the environment. In this paper we present the methodology aimed to define the composition of endothelial LDs formed upon stimulation with oleic acid (OA) in two models: endothelial cells cultured in vitro and in isolated blood vessel ex vivo. The biochemical composition of LDs was determined using Raman imaging, followed by the lipid unsaturation calibration analysis and modelling of spectral bands based on individual spectra of selected lipids. Among LDs formed in response to OA in vitro or ex vivo conditions there were two types of LDs; those with more unsaturated (average number of CC bonds equalled 1.40) or saturated (average number of CC bonds equalled 0.95) lipids. The modelling of endothelial LDs composition revealed the OA represented a major component of LDs (80.6–91.3%) with an important content of arachidonic acid (8.7–19.4%). In conclusion, endothelial LDs consist of exogenous oleic acid uptaken from the extracellular space, and the endogenous arachidonic acid released from plasma membranes.