Total Synthesis of Lobatamides A and C

The total synthesis of lobatamides A (1 a) and C (1 c) via a common bislactone intermediate is reported. The allylic aryl moiety including a trisubstituted Z-olefin was constructed by hydroboration of a 1,1-disubstituted allene and subsequent Migita-Kosugi-Stille coupling. Although the seco acid proved to be highly unstable even in the presence of weak bases, Zhao macrolactonization under acidic conditions via the α-acyloxyenamide successfully provided the common bislactone intermediate. Hydrozirconation-iodination of the terminal alkyne and subsequent copper-mediated coupling with primary amides proceeded successfully in the presence of the sensitive bislactone framework. The developed synthetic route enables the late-stage installation of enamide side chains, which are crucial structures for V-ATPase inhibition.

Unlocking the Metalation Applications of TMP-powered Fe and Co(II) Bis(amides): Synthesis, Structure and Mechanistic Insights

Typified by LiTMP and TMPMgCl.LiCl, (TMP = 2,2,6,6-tetramethylpiperidide), s-block metal amides have found widespread applications in arene deprotonative metalation. On the contrary transition metal amides lack sufficient basicity to activate these substrates. Breaking new ground in this field, here we present the synthesis and full characterisation of earth abundant transition metals M(TMP)2 (M= Fe, Co). Uncovering a new reactivity profile towards fluoroarenes these amide complexes can promote direct M-H exchange processes regioselectively using one or two of their basic amide arms. Remarkably even when using perfluorinated substrate, selective CH-metalation occurs leaving C-F bonds intact. Their kinetic basicity can be boosted by LiCl or (nBu)4NCl additives which enables formation of kinetically activated ate species. Combining spectroscopic and structural studies with DFT calculations, mechanistic insights have been gained on how these low polarity metalation processes take place. M(TMP)2 can also be used to access ferrocene and cobaltocene by direct deprotonation of cyclopentadiene and to undergo efficient CO2 insertion of both amide groups under mild reaction conditions.

Novel Cyclopenta[c]pyridine Derivatives Based on Natural Cerbinal as Potential Agrochemical Anti-TMV Agents and Insecticides

Based on natural cerbinal, a series of novel 4-bit modified cyclopenta[c]pyridine derivatives containing a substituted amide or ester moiety were designed and synthesized for the first time. Their structures were systematically characterized by NMR and high-resolution mass spectra (HRMS). The anti-TMV activities, such as protection, inactivation, and curative effects in vivo, were evaluated methodically. The lethal activities of the target compounds against the agriculturally common pests Plutella xylostella larvae and Aphis laburni kaltenbach were evaluated by the immersion method. The bioassay results indicated that most of the target compounds exhibited good to excellent anti-TMV activity levels, good lethal activity against P. xylostella larvae at 600 μg/mL, and greater insecticidal activities against A. laburni Kaltenbach compared to the plant-derived insecticide rotenone. The binding mode of cerbinal and cyclopenta[c]pyridine derivatives 4b, 4p, and 4v with the TMV protein was studied with a molecular docking method, which indicated that the functional group of the 2- and 4-positions is vital for anti-TMV activity. The systematic research provides strong evidence that these novel 4-bit modified cyclopenta[c]pyridine derivatives could become potential agrochemical insecticides and anti-TMV agents.

Synthesis, Crystal Structures, Genotoxicity, and Antifungal and Antibacterial Studies of Ni(II) and Cd(II) Pyrazole Amide Coordination Complexes

In this study, we synthesized two coordination complexes based on pyrazole-based ligands, namely 1,5-dimethyl-N-phenyl-1H-pyrazole-3-carboxamide (L1) and 1,5-dimethyl-N-propyl-1H-pyrazole-3-carboxamide (L2), with the aim to investigate bio-inorganic properties. Their crystal structures revealed a mononuclear complex [Ni(L1)2](ClO4)2 (C1) and a dinuclear complex [Cd2(L2)2]Cl4 (C2). Very competitive antifungal and anti-Fusarium activities were found compared to the reference standard cycloheximide. Additionally, L1 and L2 present very weak genotoxicity in contrast to the observed increase in genotoxicity for the coordination complexes C1 and C2.

Photoredox Catalytic Access to N,O-Acetals from Enamides by Means of Electron-Poor Perylene Bisimides

N,O-acetals are found as structural motifs in natural products and are important synthetic precursors for N-acylimines as building blocks in organic synthesis for C-C-bond formation and amines. For the synthesis of N,O-acetals, an acid-, base- and metal-free catalytic method is reported applying N,N-di-(2,6-diisopropyl)-1,7-dicyano-perylen-3,4,9,10-tetracarboxylic acid imide and N,N-di-(2,6-diisopropyl)-1,6,7,12-tetrabromo-2,5,8,11-tetracyano-perylen-3,4,9,10-tetracarboxylic acid imide as extremely electron-deficient photocatalysts. The first perylene bisimide highly selectively photocatalyzes the formation of the N,O-acetals as products in high yields, and the second and more electron-deficient perylene bisimide allows these reactions without thiophenol as an H-atom transfer reagent. Calculated electron density maps support this. The reaction scope comprises different substituents at the nitrogen of the enamides and different alcohols as starting material. Dehydroalanines are converted to non-natural amino acids which shows the usefulness of this method for organic and medicinal chemistry.

N-Phenylnorbornenesuccinimide derivatives, agricultural defensive, and enzymatic target selection

BACKGROUND

Faced with the need to develop new herbicides with modes of action different to those observed for existing agrochemicals, one of the most promising strategies employed by synthetic chemists involves the structural modification of molecules found in natural products. Molecules containing amides, imides, and epoxides as functional groups are prevalent in nature and find extensive application in synthesizing more intricate compounds due to their biological properties. In this context, this paper delineates the synthesis of N-phenylnorbornenesuccinimide derivatives, conducts biological assays, and carries out in silico investigation of the protein target associated with the most potent compound in plant organisms. The phytotoxic effects of the synthesized compounds (2-29) were evaluated on Allium cepa, Bidens pilosa, Cucumis sativus, Sorghum bicolor, and Solanum lycopersicum.

RESULTS

Reaction of endo-bicyclo[2.2.1]hept-5-ene-3a,7a-dicarboxylic anhydride (1) with aromatic amines led to the N-phenylnorbornenesuccinic acids (2-11) with yields ranging from 75% to 90%. Cyclization of compounds (2-11) in the presence of acetic anhydride and sodium acetate afforded N-phenylnorbornenesuccinimides (12-20) with yields varying from 65% to 89%. Those imides were then subjected to epoxidation reaction to afford N-phenylepoxynorbornanesuccimides (21-29) with yields from 60% to 90%. All compounds inhibited the growth of seedlings of the plants evaluated. Substance 23 was the most active against the plants tested, inhibiting 100% the growth of all species in all concentrations. Cyclophilin was found to be the enzymatic target of compound 23.

CONCLUSION

These findings suggest that derivatives of N-phenylnorbornenesuccinimide are promising compounds in the quest for more selective and stable agrochemicals. This perspective reinforces the significance of these derivatives as potential innovative herbicides and emphasizes the importance of further exploring their biological activity on weeds. © 2024 Society of Chemical Industry.

Marine Streptomyces-Derived Novel Alkaloids Discovered in the Past Decade

Natural alkaloids originating from actinomycetes and synthetic derivatives have always been among the important suppliers of small-molecule drugs. Among their biological sources, Streptomyces is the highest and most extensively researched genus. Marine-derived Streptomyces strains harbor unconventional metabolic pathways and have been demonstrated to be efficient producers of biologically active alkaloids; more than 60% of these compounds exhibit valuable activity such as antibacterial, antitumor, anti-inflammatory activities. This review comprehensively summarizes novel alkaloids produced by marine Streptomyces discovered in the past decade, focusing on their structural features, biological activity, and pharmacological mechanisms. Future perspectives on the discovery and development of novel alkaloids from marine Streptomyces are also provided.

Broad Spectrum Enantioselective Amide Bond Synthetase from Streptoalloteichus hindustanus

The synthesis of amide bonds is one of the most frequently performed reactions in pharmaceutical synthesis, but the requirement for stoichiometric quantities of coupling agents and activated substrates in established methods has prompted interest in biocatalytic alternatives. Amide Bond Synthetases (ABSs) actively catalyze both the ATP-dependent adenylation of carboxylic acid substrates and their subsequent amidation using an amine nucleophile, both within the active site of the enzyme, enabling the use of only a small excess of the amine partner. We have assessed the ability of an ABS from Streptoalloteichus hindustanus (ShABS) to couple a range of carboxylic acid substrates and amines to form amine products. ShABS displayed superior activity to a previously studied ABS, McbA, and a remarkable complementary substrate specificity that included the enantioselective formation of a library of amides from racemic acid and amine coupling partners. The X-ray crystallographic structure of ShABS has permitted mutational mapping of the carboxylic acid and amine binding sites, revealing key roles for L207 and F246 in determining the enantioselectivity of the enzyme with respect to chiral acid and amine substrates. ShABS was applied to the synthesis of pharmaceutical amides, including ilepcimide, lazabemide, trimethobenzamide, and cinepazide, the last with 99% conversion and 95% isolated yield. These findings provide a blueprint for enabling a contemporary pharmaceutical synthesis of one of the most significant classes of small molecule drugs using biocatalysis.

Dual contrast CEST MRI for pH-weighted imaging in stroke

PURPOSE

pH enhanced (pHenh ) CEST imaging combines the pH sensitivity from amide and guanidino signals, but the saturation parameters have not been optimized. We propose pHdual as a variant of pHenh that suppresses background signal variations, while enhancing pH sensitivity and potential for imaging ischemic brain injury of stroke.

METHODS

Simulation and in vivo rodent stroke experiments of pHenh MRI were performed with varied RF saturation powers for both amide and guanidino protons to optimize the contrast between lesion/normal tissues, while simultaneously minimizing signal variations across different types of normal tissues. In acute stroke, contrast and volume ratio measured by pHdual imaging were compared with an amide-CEST approach, and perfusion and diffusion MRI.

RESULTS

Simulation experiments indicated that amide and guanidino CEST signals exhibit unique sensitivities across different pH ranges, with pHenh producing greater sensitivity over a broader pH regime. The pHenh data of rodent stroke brain demonstrated that the lesion/normal tissue contrast was maximized for an RF saturation power pair of 0.5 μT at 2.0 ppm and 1.0 μT at 3.6 ppm, whereas an optimal contrast-to-variation ratio (CVR) was obtained with a 0.7 μT saturation at 2.0 ppm and 0.8 μT at 3.6 ppm. In acute stroke, CVR optimized pHenh (i.e., pHdual ) achieved a higher sensitivity than the three-point amide-CEST approach, and distinct patterns of lesion tissue compared to diffusion and perfusion MRI.

CONCLUSION

pHdual MRI improves the sensitivity of pH-weighted imaging and will be a valuable tool for assessing tissue viability in stroke.

Synthesis of a Cyclic Hexaamide Consisting of a Brominated m-Phenylene Repeating Unit

Aiming to synthesize a cyclic hexaamide, 4-bromo-3-(isobutylamino)benzoic acid was subjected to self-condensation reactions in the presence of either dichlorotriphenylphosphorane in 1,1,2,2-tetrachloroethane or tetrachlorosilane in pyridine. However, instead of the targeted cyclic hexaamide, the cyclic triamide and the cyclic tetraamide were obtained. The cyclic hexaamide was successfully synthesized via the self-condensation of the dimer, which was synthesized in five steps from 4-bromo-3-(isobutylamino)benzoic acid. A thorough screening of the self-condensation conditions was performed to improve the yield of the target macrocycle. In addition, the linear hexamer was synthesized by stepwise deprotection and condensation, and its cyclization afforded the cyclic hexaamide in good yield.

Diacetyl strategy for synthesis of NHAc containing glycans: enhancing glycosylation reactivity via diacetyl imide protection

The presence of NHAc groups in the substrates (both glycosyl donors and acceptors) significantly reduced the reactivity of glycosylation. This decrease was attributed to the NHAc groups forming intermolecular hydrogen bonds by the NHAc groups, thereby reducing molecular mobility. Hence, a diacetyl strategy involving the temporary conversion of NHAc to diacetyl imide (NAc2) was developed for the synthesis of NHAc-containing glycans. This strategy has two significant advantages for oligosaccharide synthesis. The NAc2 protection of NHAc substantially enhances the rate of glycosylation reactions, resulting in improved yields. Moreover, NAc2 can be readily reverted to NHAc by the simple removal of one acetyl group under mild basic conditions, obviating the necessity for treating the polar amino group. We have achieved the efficient synthesis of oligosaccharides containing GlcNHAc and N-glycans containing sialic acid using the diacetyl strategy.

Synthesis, antibacterial and antifungal activity of myricetin derivatives containing piperidine and amide fragments

BACKGROUND

Continuous use of synthetic bactericides and fungicides is causing pathogens to develop resistance, resulting in increased use of pesticides and affecting food security. The green pesticides derived from natural products could reduce or avoid 'pesticide hazards' caused by synthetic pesticides as a result of their unique mechanism of action. Therefore, it is of great significance to create green pesticides with novel structures.

RESULTS

Herein, 30 novel myricetin derivatives containing piperidine and amide fragments were designed and synthesized using active group splicing. Among them, compound Z30 had excellent inhibitory effect against Xanthomonas oryzae pv. Oryzae (Xoo) with the half effective concentration (EC50 ) of 2.7 μg mL-1 . Compound Z26 not only exhibited better antibacterial activity against Xaxonopodis pv. Citri (Xac) with EC50 of 3.9 μg mL-1 , but also displayed higher antifungal activity against Rhizoctonia solani (Rs) with EC50 of 8.3 μg mL-1 . In vivo experiments proved that Z30 against bacterial blight of rice and Z26 against rice blast exhibits significant protective and curative effect. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Z26 and Z30 could change the integrity of cell wall and membrane of pathogen Xoo, Xac and Rs, resulting in cytoplasmic leakage and eventually death. Enzymatic assay, molecular docking and molecular dynamics simulations (MDs) indicated that Z26 could be used as a potential succinate dehydrogenase inhibitor (SDHI).

CONCLUSION

Z26 and Z30 significantly reduced the pathogenicity of the pathogens, which provided a new idea and direction for the development of green pesticides. © 2023 Society of Chemical Industry.

Reaction of Amino Acids with Ferrate(VI): Impact of the Carboxylic Group on the Primary Amine Oxidation Kinetics and Mechanism

Ferrate (Fe(VI)) is a novel oxidant that can be used to mitigate disinfection byproduct (DBP) precursors. However, the reaction of Fe(VI) with organic nitrogen, which is a potential precursor of potent nitrogenous DBPs, remains largely unexplored. The present work aimed to identify the kinetics and products for the reaction of Fe(VI) with primary amines, notably amino acids. A new kinetic model involving ionizable intermediates was proposed and can describe the unusual pH effect on the Fe(VI) reactivity toward primary amines and amino acids. The Fe(VI) oxidation of phenylalanine produced a mixture of nitrile, nitrite/nitrate, amide, and ammonia, while nitroalkane was an additional product in the case of glycine. The product distribution for amino acids significantly differed from that of uncarboxylated primary amines that mainly generate nitriles. A general reaction pathway for primary amines and amino acids was proposed and notably involved the formation of imines, the degradation of which was affected by the presence of a carboxylic group. In comparison, ozonation led to higher yields of nitroalkanes that could be readily converted to potent halonitroalkanes during chlor(am)ination. Based on this study, Fe(VI) can effectively mitigate primary amine-based, nitrogenous DBP precursors with little formation of toxic halonitroalkanes.

Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells

Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10-5 S cm-1 upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10-6 S cm-1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.

tuberculosis: experimental, biological and computational investigations

Tuberculosis (TB) is a treatable contagious disease that continuously kills approximately 2 million people yearly. Different oxazoline/amide derivatives were synthesized, and their anti-tuberculosis activity was performed against different strains of Mtb. This study designed the anti-Mtb compounds based on amide and oxazoline, two different structural moieties. The compounds were further synthesized and characterized by spectral techniques. Their anti-Tb activity was evaluated against strain (M. tuberculosis: H37Rv). Selectivity and binding affinity of all synthesized compounds (2a-2e, 3a-3e) against PanK in Mtb were investigated through molecular docking. Molecular dynamics simulation studies for the promising compounds 2d and 3e were performed for 100 ns. The stability of these complexes was assessed by calculating the root mean square deviation, solvent-accessible surface area, and gyration radius relative to their parent structures. Additionally, free energy of binding calculations were performed. Among all synthesized compounds, 2d and 3e had comparable antitubercular activity against standard drug, validated by their computational and biological study.

lacryma-jobi

Phytochemical investigation of the seeds of Coix lacryma-jobi var. lacryma-jobi resulted in the isolation of eight compounds, including two new structures, coixdines A-B (1-2) and six known compounds (3-8). The structures of these compounds were determined by 1 D and 2 D NMR spectra referring to the literatures, together with HR-MS analysis. Coixdine A and B are first examples of spermidine skeleton in genus Coix. In the present paper, all compounds were evaluated for the cytotoxicity against two cancer cell lines (CT-26 and BxPC-3) in vitro, and none of the compounds exhibited obvious cytotoxic activity. The present investigation suggests that these amides seem to be of great chemotaxonomic value for C. lacryma-jobi.

Synthesis and Characterization of Organo-Soluble Polyimides Based on Polycondensation Chemistry of Fluorene-Containing Dianhydride and Amide-Bridged Diamines with Good Optical Transparency and Glass Transition Temperatures over 400 °C

Polymeric optical films with light colors, good optical transparency and high thermal resistance have gained increasing attention in advanced optoelectronic areas in recent years. However, it is somewhat inter-conflicting for achieving the good optical properties to the conventional thermal resistant polymers, such as the standard aromatic polyimide (PI) films, which are well known for the excellent combined properties and also the deep colors. In this work, a series of wholly aromatic PI films were prepared via the polycondensation chemistry of one fluorene-containing dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (FDAn) and several aromatic diamines with amide linkages in the main chain, including 9,9-bis [4-(4-aminobenzamide)phenyl]fluorene (FDAADA), 2,2'-bis(trifluoromethyl)-4,4'-bis[4-(4-aminobenzamide)] biphenyl (ABTFMB), and 2,2'-bis(trifluoromethyl)-4,4'-bis[4-(4-amino-3-methyl)benzamide] biphenyl (MABTFMB). The derived FLPI-1 (FDAn-FDAADA), FLPI-2 (FDAn-ABTFMB) and FLPI-3 (FDAn-MABTFMB) resins showed good solubility in the polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO). The solution-processing FDAn-PI films exhibited good optical transmittance over 80.0% at a wavelength of 500 nm (T500), yellow indices (b*) in the range of 1.01-5.20, and haze values lower than 1.0%. In addition, the FDAn-PI films showed low optical retardance with optical retardation (Rth) values in the range of 31.7-390.6 nm. At the same time, the FDAn-PI films exhibited extremely high glass transition temperatures (Tg) over 420 °C according to dynamic mechanical analysis (DMA) tests. The FDAn-PI films showed good dimensional stability at elevated temperatures with linear coefficients of thermal expansion (CTE) in the range of (31.8-45.8) × 10-6/K.

Hierarchical K-means clustering method for accelerated Lorentzian estimation (KALE) in chemical exchange saturation transfer-magnetic resonance imaging quantification

Background

Quantification of in vivo chemical exchange saturation transfer (CEST) magnetic resonance signals is challenging due to contamination from coexisting effects, including the direct water effect and asymmetric magnetization transfer. Fitting-based analysis allows the calculation of multiple types of signals from the line shape of Z-spectra. However, the conventional voxelwise method has several drawbacks, including its long computation time and its susceptibility to image noise and Z-spectra oscillations, and it is difficult to determine the initial fitting parameters.

Methods

Herein, we propose a K-means clustering method for accelerated Lorentzian estimation (KALE) in CEST quantification. Briefly, voxels in CEST images are clustered into K groups according to their Z-spectra characteristics. A 'groupwise' fitting process is then performed with preset initial values, yielding a set of fitted spectra and fitted parameters for each group. With the updated initial values, each group is further clustered into subgroups, and groupwise fitting is performed again. This hierarchical K-means clustering and parameter updating process continues until the pixel number or intensity error meets the termination criteria. Voxelwise fitting could be further conducted to improve the quantification images (termed voxel-K) by utilizing the previous groupwise KALE results as the initial values (termed group-K).

Results

Incorporated with Lorentzian difference (LD) quantification, KALE was first optimized and evaluated on 5 healthy human brain datasets at 3 Tesla. Compared with traditional voxel-by-voxel LD quantification, the computation times of group-K and voxel-K were significantly reduced by ~85% and ~70%, respectively (P<0.001). Furthermore, the group-K images exhibited better denoising performance than traditional LD and voxel-K. KALE was further validated on six ischemic rat brains acquired at 7 Tesla, with both LD_group-K and LD_voxel-K displaying almost identical contrast maps with traditional voxelwise maps. When incorporated with the five-pool Lorentzian fitting (LF), KALE exhibited an improved contrast-to-noise ratio (CNR) for amplitude maps of each pool [P=0.003, 0.015, 0.047, and 0.047 for amide, nuclear Overhauser effect (NOE), magnetic transfer (MT) and guanidine amine, respectively] and improved fitting goodness (P=0.033).

Conclusions

KALE quantification provides comparable or even superior contrast maps to traditional voxelwise fitting, with significantly reduced computation time. The 'smart' and hierarchical voxel-clustering and parameter updating process of KALE may facilitate more preclinical and clinical CEST applications.

Controlling Phase Conversion of Cu-Sb-Se Nanoparticles through the Use of an Amide Base

The family of copper antimony selenides is important for renewable energy applications. Several phases are accessible within narrow energy and compositional ranges, and tunability between phases is not well-established. Thus, this system provides a rich landscape to understand the phase transformations that occur in hot-injection nanoparticle syntheses. Rietveld refinements on X-ray diffraction patterns model anisotropic morphologies to obtain phase percentages. Reactions targeting the stoichiometry of CuSbSe₂ formed Cu₃SbSe₃ before decomposing to thermodynamically stable CuSbSe₂ over time. An amide base was added to balance cation reactivity and directly form CuSbSe₂. Interestingly, Cu₃SbSe₃ remained present but converted to CuSbSe₂ more rapidly. We propose that initial Cu₃SbSe₃ formation may be due to the selenium species not being reactive enough to balance the high reactivity of the copper complex. The unexpected effect of a base on cation reactivity in this system provides insight into the advantages and limitations for its use in other multivalent systems.

Design, synthesis, antifungal activity and molecular docking of ring-opened pimprinine derivative containing (thio)amide structure

BACKGROUND

To obtain new environmentally friendly fungicides, we used the natural product pimprinine as the lead compound, and designed and synthesized two series of ring-opening derivatives of pimprinine containing amide/thioamide. We then studied their antifungal activity against six common plant pathogenic fungi in vitro.

RESULTS

Most of the target compounds have good antifungal activity against six important plant pathogenic fungi in vitro. At a concentration of 50 μg ml-1 , compound 3o showed prominent antifungal effects on Alternaria solani and Rhioctornia solani, with inhibition rates of 91.8% and 97.4%, and a 50% effective concentration (EC50 ) of 6.2255 and 0.6969 μg ml-1 respectively. The EC50 of compound 3o against Alternaria solani was significantly lower than that of boscalid (13.0380 μg ml-1 ) and flutriafol (11.9057 μg ml-1 ). In addition, compound 3o had good antifungal activity against Sclerotinia sclerotiorum, cucumber powdery mildew, cucumber Botrytis cinerea and Phytophthora capsici in vivo; the antifungal activity of compound 3o against cucumber Botrytis cinerea is 91.7%. At the same time, docking results for highly active compound 3o with the presumed target succinate dehydrogenase and the molecular docking prediction scores of all compounds further indicate its possible antifungal activity mechanism.

CONCLUSION

The designed and optimized derivative 3o of ring-opening pimprinine has good antifungal activity and can be used as a new antifungal drug for further research. © 2023 Society of Chemical Industry.

7 tricks for 7 T CEST: Improving the reproducibility of multipool evaluation provides insights into the effects of age and the early stages of Parkinson's disease

The objective of the current study was to optimize the postprocessing pipeline of 7 T chemical exchange saturation transfer (CEST) imaging for reproducibility and to prove this optimization for the detection of age differences and differences between patients with Parkinson's disease versus normal subjects. The following 7 T CEST MRI experiments were analyzed: repeated measurements of a healthy subject, subjects of two age cohorts (14 older, seven younger subjects), and measurements of 12 patients with Parkinson's disease. A slab-selective, B 1 + -homogeneous parallel transmit protocol was used. The postprocessing, consisting of motion correction, smoothing, B 0 -correction, normalization, denoising, B 1 + -correction and Lorentzian fitting, was optimized regarding the intrasubject and intersubject coefficient of variation (CoV) of the amplitudes of the amide pool and the aliphatic relayed nuclear Overhauser effect (rNOE) pool within the brain. Seven "tricks" for postprocessing accomplished an improvement of the mean voxel CoV of the amide pool and the aliphatic rNOE pool amplitudes of less than 5% and 3%, respectively. These postprocessing steps are: motion correction with interpolation of the motion of low-signal offsets (1) using the amide pool frequency offset image as reference (2), normalization of the Z-spectrum using the outermost saturated measurements (3), B 0 correction of the Z-spectrum with moderate spline smoothing (4), denoising using principal component analysis preserving the 11 highest intensity components (5), B 1 + correction using a linear fit (6) and Lorentzian fitting using the five-pool fit model (7). With the optimized postprocessing pipeline, a significant age effect in the amide pool can be detected. Additionally, for the first time, an aliphatic rNOE contrast between subjects with Parkinson's disease and age-matched healthy controls in the substantia nigra is detected. We propose an optimized postprocessing pipeline for CEST multipool evaluation. It is shown that by the use of these seven "tricks", the reproducibility and, thus, the statistical power of a CEST measurement, can be greatly improved and subtle changes can be detected.

Amide- and bis-amide-linked highly potent and broadly active antifungal agents for the treatment of invasive fungal infections- towards the discovery of pre-clinical development candidate FC12406

Most fungal infections are common, localized to skin or mucosal surfaces and can be treated effectively with topical antifungal agents. However, while invasive fungal infections (IFIs) are uncommon, they are very difficult to control medically, and are associated with high mortality rates. We have previously described highly potent bis-guanidine-containing heteroaryl-linked antifungal agents, and were interested in expanding the range of agents to novel series so as to reduce the degree of aromaticity (with a view to making the compounds more drug-like), and provide broadly active high potency derivatives. We have investigated the replacement of the central aryl ring from our original series by both amide and a bis-amide moieties, and have found particular structure-activity relationships (SAR) for both series', resulting in highly active antifungal agents against both mold and yeast pathogens. In particular, we describe the in vitro antifungal activity, absorption, distribution, metabolism and elimination (ADME) properties, and off-target properties of FC12406 (34), which was selected as a pre-clinical development candidate.

BAHD Company: The Ever-Expanding Roles of the BAHD Acyltransferase Gene Family in Plants

Plants' ability to chemically modify core structures of specialized metabolites is the main reason why the plant kingdom contains such a wide and rich array of diverse compounds. One of the most important types of chemical modifications of small molecules is the addition of an acyl moiety to produce esters and amides. Large-scale phylogenomics analyses have shown that the enzymes that perform acyl transfer reactions on the myriad small molecules synthesized by plants belong to only a few gene families. This review is focused on describing the biochemistry, evolutionary origins, and chemical ecology implications of one of these families-the BAHD acyltransferases. The growth of advanced metabolomic studies coupled with next-generation sequencing of diverse plant species has confirmed that the BAHD family plays critical roles in modifying nearly all known classes of specialized metabolites. The current and future outlook for research on BAHDs includes expanding their roles in synthetic biology and metabolic engineering.

Optimization of Osthole in the Lactone Ring as an Agrochemical Candidate: Synthesis, Characterization, and Pesticidal Activities of Osthole Amide/Ester Derivatives and Their Effects on Morphological Changes of Mite Epidermis

Structural modification of natural products is one of the important ways in the discovery of novel pesticides. Based on a diversity-oriented synthesis strategy, herein, two series of amide/ester derivatives (52 compounds) were obtained by opening the lactone of osthole. Interestingly, the effect of different concentrations of aq. sodium hydroxide on the ratio of two isomers (cis- and trans-2) was investigated, and a magical phenomenon of ultraviolet (UV) light irradiation on intertransformation of two isomers (cis- and trans-2) was observed. Against Mythimna separata, when compared with the precursor osthole, compounds 4b, 4l, 5l, 5m, 7h, 7l, and 7m displayed more pronounced growth inhibitory activity with the final mortality rates of 62.0-68.9%. Compounds 4b, 4i, and 5m showed 5.7-6.6 times stronger acaricidal activity against Tetranychus cinnabarinus than osthole, and notably, control effects of compounds 4i and 5m were 2.4- and 2.7-fold that of osthole in the management of T. cinnabarinus in the greenhouse. Scanning electron microscopy (SEM) images of the epidermis of 5m-treated T. cinnabarinus indicated that compound 5m can destroy the mite cuticle layer. Compounds 4b and 5m can be used as leads to further explore more promising pesticidal agents.

The Indenyl Effect: Accelerated C-H Amidation of Arenes via Ind*Rh(III) Nitrene Transfer Catalysis

Investigations into C-H amidation reactions catalysed by cationic half-sandwich d6 metal complexes revealed that the indenyl-derived catalyst [Ind*RhCl2]2 significantly accelerated the directed ortho C-H amidation of benzoyl silanes using 1,4,2-dioxazol-5-ones. Ring slippage involving a haptotropic η5 to η3 rearrangement of the indenyl complex proposedly enables ligand substitution at the metal centre to proceed via associative, rather than dissociative pathways, leading to significant rate and yield enhancements. Intriguingly, this phenomenon appears specific for C-H amidation reactions involving weakly coordinating carbonyl-based directing groups with no acceleration observed for the corresponding reactions involving strongly coordinating nitrogen-based directing groups.

2-(3-Methyl-2-oxoquinoxalin-1-yl)-N-(4-methyl-phen-yl)acetamide

The quinoxaline moiety in the title mol-ecule, C₁₈H₁₇N₃O₂, is not quite planar and the p-tolyl group is rotationally disordered over two nearly equally populated sets of sites. In the crystal, N-H⋯O and C-H⋯O hydro-gen bonds form chains extending along the b-axis direction. Due to the disorder of the p-tolyl rings, short C⋯C distances are observed between adjacent chains.

DeepCEST 7 T: Fast and homogeneous mapping of 7 T CEST MRI parameters and their uncertainty quantification

PURPOSE

In this work, we investigated the ability of neural networks to rapidly and robustly predict Lorentzian parameters of multi-pool CEST MRI spectra at 7 T with corresponding uncertainty maps to make them quickly and easily available for routine clinical use.

METHODS

We developed a deepCEST 7 T approach that generates CEST contrasts from just 1 scan with robustness against B₁ inhomogeneities. The input data for a neural feed-forward network consisted of 7 T in vivo uncorrected Z-spectra of a single B₁ level, and a B₁ map. The 7 T raw data were acquired using a 3D snapshot gradient echo multiple interleaved mode saturation CEST sequence. These inputs were mapped voxel-wise to target data consisting of Lorentzian amplitudes generated conventionally by 5-pool Lorentzian fitting of normalized, denoised, B₀ - and B₁ -corrected Z-spectra. The deepCEST network was trained with Gaussian negative log-likelihood loss, providing an uncertainty quantification in addition to the Lorentzian amplitudes.

RESULTS

The deepCEST 7 T network provides fast and accurate prediction of all Lorentzian parameters also when only a single B₁ level is used. The prediction was highly accurate with respect to the Lorentzian fit amplitudes, and both healthy tissues and hyperintensities in tumor areas are predicted with a low uncertainty. In corrupted cases, high uncertainty indicated wrong predictions reliably.

CONCLUSION

The proposed deepCEST 7 T approach reduces scan time by 50% to now 6:42 min, but still delivers both B₀ - and B₁ -corrected homogeneous CEST contrasts along with an uncertainty map, which can increase diagnostic confidence. Multiple accurate 7 T CEST contrasts are delivered within seconds.

Chemical exchange saturation transfer MRI detects myelin changes in cuprizone mouse model at 3T

Chemical exchange saturation transfer (CEST) sensitively detects molecular alterations in the brain, such as relayed nuclear Overhauser effect (rNOE) CEST contrast at -3.5 ppm representing aliphatic protons in both lipids and proteins, and CEST contrast at 3.5 ppm correlating with amide proton in proteins. Myelin is rich in lipids and proteins, and therefore CEST can be explored as a biomarker for myelin pathology, which could contribute to the diagnosis and prognosis of multiple sclerosis (MS). In the current study, we investigate the specificity of aliphatic rNOE and the amide pool in myelin detection using the cuprizone (CPZ) mouse model, which recapitulates the demyelination and remyelination of MS. In this study, preclinical 3T MRI was performed in 19 male C57BL/6 mice. Mice in the normal control (NC) group (n = 9) were fed a normal diet for the whole course, while mice in the CPZ group (n = 10) were fed with CPZ for 10 weeks, followed by 4 weeks with a normal diet. The CEST contrast of rNOE (-3.5 ppm) and amide (3.5 ppm) in brain regions of the corpus callosum (CC) and the caudate putamen were compared. Statistical differences between the groups were calculated using two-way ANOVA. We observed significantly decreased rNOE (NC: 4.85% ± 0.09%/s vs. CPZ: 3.88% ± 0.18%/s, p = 0.007) and amide pool (NC: 3.20% ± 0.10%/s vs. CPZ: 2.46% ± 0.16%/s, p = 0.02) in the CC after 8 weeks on CPZ diet (p < 0.05). Moreover, the rNOE in the CPZ group recovered to a level comparable with the NC group at week 14 (p = 0.39), while amide remained at a level as low as that for the NC group (p = 0.051). Significant rNOE and amide changes, validated by immunohistochemistry results for demyelination and remyelination, demonstrate the huge potential of CEST for revealing myelin pathology, which has implications for MS identification at the clinical field strength of 3T.

Cobalt-catalyzed Enantioselective Hydrogenation of Trisubstituted Carbocyclic Olefins: An Access to Chiral Cyclic Amides

The enantioselective hydrogenation of cyclic enamides has been achieved using an earth-abundant cobalt-bisphosphine catalyst. Using CoCl2/(S,S)-Ph-BPE, several trisubstituted carbocyclic enamides were reduced with high activity and excellent enantioselectivity (up to 99%) to the corresponding saturated amides. The methodology can be extended to the synthesis of chiral amines by base hydrolysis of the hydrogenation products. Preliminary mechanistic investigations reveal the presence of a high spin cobalt (II) species in the catalytic cycle. We propose that the hydrogenation of the carbon-carbon double bond proceeds via a sigma-bond-metathesis pathway.

Reshuffle Bonds by Ball Milling: A Mechanochemical Protocol for Charge-Accelerated Aza-Claisen Rearrangements

This study presents the development of a mechanochemical protocol for a charge-accelerated aza-Claisen rearrangement. The protocol waives the use of commonly applied transition metals, ligands, or pyrophoric Lewis acids, e.g., AlMe₃. Based on (heterocyclic) tertiary allylamines and acyl chlorides, the desired tertiary amides were prepared in yields ranging from 17% to 84%. Moreover, the same protocol was applied for a Belluš-Claisen-type rearrangement resulting in the synthesis of a 9-membered lactam without further optimization.

Nickel-Catalyzed Aminocarbonylation of Aryl Iodides with 1 atm CO

Reported here is a nickel-catalyzed aminocarbonylation of aromatic iodides with (hetero)aryl anilines and alkyl amines under atmospheric CO pressure. The reaction features with broad substrate scope with excellent functional group tolerance, providing an expedient method for the construction of amide analogues. Notably, amino alcohols can be selectively transformed into the corresponding amides successfully without interfering the hydroxyl group under the current standard conditions.

A new amide from the marine sponge Haliclona baeri

A new amide, baeriamide (1), along with nine known diketopiperazines (2-10), was isolated from the marine sponge Haliclona baeri. Their structures were identified by the means of UV, IR, MS and NMR. The absolute configuration of 1 was established by Marfey's method and comparing the specific optical rotation with the known compound HCO-Val-Gly methyl ester. Compound 1 was derived from dehydration of formylated L-valine with γ-amino-butanoic acid methyl ester. Compounds 2-10 were isolated from the genus of Haliclona for the first time. The absolute confirmation of 7 was confirmed first by the means of single-crystal X-ray diffraction. The cytotoxic, antibacterial, antiviral and antifouling activities of these compounds were also tested. However, none of them exhibited significant bioactivities.

Discovery of 4-aminoindole carboxamide derivatives to curtail alpha-synuclein and tau isoform 2N4R oligomer formation

Alzheimer's disease (AD) is a multifactorial, chronic neurodegenerative disease characterized by the presence of extracellular β-amyloid (Aβ) plaques, intraneuronal neurofibrillary tangles (NFTs), activated microglial cells, and an inflammatory state (involving reactive oxygen species production) in the brain. NFTs are comprised of misfolded and hyperphosphorylated forms of the microtubule-binding protein tau. Interestingly, the trimeric form of the 2N4R splice isoform of tau has been found to be more toxic than the trimeric 1N4R isoform in neuron precursor cells. Few drug discovery programs have focused on specific tau isoforms. The present drug discovery project is centered on the anti-aggregation effect of a series of seventeen 4- or 5-aminoindole carboxamides on the 2N4R isoform of tau. The selection of the best compounds was performed using α-synuclein (α-syn). The anti-oligomer and -fibril activities of newly synthesized aminoindole carboxamide derivatives were evaluated with biophysical methods, such as thioflavin T fluorescence assays, photo-induced cross-linking of unmodified proteins, and transmission electron microscopy. To evaluate the reduction of inclusions and cytoprotective effects, M17D neuroblastoma cells expressing inclusion-forming α-syn were treated with the best amide representatives. The 4-aminoindole carboxamide derivatives exhibited a better anti-fibrillar activity compared to their 5-aminoindole counterparts. The amide derivatives 2, 8, and 17 exerted anti-oligomer and anti-fibril activities on α-syn and the 2N4R isoform of tau. At a concentration of 40 μM, compound 8 reduced inclusion formation in M17D neuroblastoma cells expressing inclusion-prone αSynuclein3K::YFP. Our results demonstrate the potential of 4-aminoindole carboxamide derivatives with regard to inhibiting the oligomer formation of α-syn and tau (2N4R isoform) for further optimization prior to pre-clinical studies.

[Development of Unactivated Bond Cleavage Reactions Under Mild Conditions Based on Stabilization of Addition Intermediates]

Cleavage of unactivated bonds, such as amides, often requires challenging reaction conditions with strong acids and bases, and the tolerance of functional groups is limited. Therefore, the development of cleavage reactions for unactivated bonds under mild reaction conditions is essential. Herein, I report our recent developments in the cleavage of unactivated bonds under mild conditions. We achieved cleavage of unactivated amides, carbamates, ureas, and esters, as well as chemoselective cleavage of directing groups. Furthermore, we conducted mechanistic studies and found that these reactions proceed through the stabilization of addition intermediates.

(Carbazol-9-ido-κN)di-chlorido-(η5:η1-2,3,4,5-tetra-methyl-penta-fulvene)tantalum(V)

The reaction of (η⁵:η¹-2,3,4,5-tetra-methyl-penta-fulvene)tantalum(V) dicarbazolide chloride (1) with etheric HCl results in the formation of the title compound (2), [Ta(C₁₀H₁₄)(C₁₂H₈N)Cl₂]. The Ta^V atom has a distorted tetra-hedral coordination environment in a three-legged piano-stool fashion. The conformation of the penta-fulvene exocyclic C atom to the three other ligands is staggered and not eclipsed, as found in the crystal structure of 1. Inter-molecular inter-actions include π-π stacking, H⋯π inter-actions and weak C-H⋯Cl hydrogen bonds.

Progress in C-C and C-Heteroatom Bonds Construction Using Alcohols as Acyl Precursors

Acyl moiety is a common structural unit in organic molecules, thus acylation methods have been widely explored to construct various functional compounds. While the traditional Friedel-Crafts acylation processes work to allow viable construction of arylketones under harsh acid conditions, recent progress on developing acylation methods focused on the new reactivity discovery by exploiting versatile and easily accessible acylating reagents. Of them, alcohols are cheap, have low toxicity, and are naturally abundant feedstocks; thus, they were recently used as ideal acyl precursors in molecule synthesis for ketones, esters, amides, etc. In this review, we display and discuss recent advances in employing alcohols as unusual acyl sources to form C-C and C-heteroatom bonds, with emphasis on the substrate scope, limitations, and mechanism.

Antifungal active ingredient from the twigs and leaves of Clausena lansium Lour. Skeels (Rutaceae)

Two novel amides, named clauphenamides A and B, and twelve other known compounds were isolated from the twigs and leaves of Clausena lansium Lour. Skeels (Rutaceae). Their structures were elucidated on the basis of extensive spectroscopic analysis and comparison with data reported in the literature. Clauphenamide A (1) featured in the unit of N-2-(4,8-dimethoxyfuro [2,3-b]quinolin-7-yl)vinyl, and clauphenamide B (2) was a unprecedented N-phenethyl cinnamide dimer. Other known compounds belong to pyrrolidone amides (3 and 4), furacoumarins (7-10), simple coumarins (11-14), lignan (5) and sesquiterpene (6). Compounds 5, 6, 10 and 12 were separated from the genus (Clausena) for the first time, while 13 was isolated in the species (C. lansium) for the first time. The antifungal activities of the isolated compounds were assayed. As a result, at the concentration of 100 μg/ml, compared with the control (chlorothalonil, inhibition rate of 83.67%), compounds 1 and 2 were found to exhibit moderate antifungal activity against B. dothidea with inhibition rates of 68.39% and 52.05%, respectively. Compounds 11-14 also exhibited moderate activity against B. dothidea and F. oxysporum, with inhibition rates greater than 40%. In addition, compared with the control (chlorothalonil, inhibition rate of 69.02%), compounds 11-14 showed strong antifungal activity to P. oryzae, with inhibition rates greater than 55%. Among them, compound 14 has the strongest antifungal activity against P. oryzae, and the inhibition rate (65.44%) is close to that of the control chlorothalonil. Additionally, the structure-activity relationships of the separated compounds are also discussed preliminarily in this paper.

Does Urea Preferentially Interact with Amide Moieties or Nonpolar Sidechains? A Question Answered Through a Judicious Selection of Model Systems

The transfer model suggests that urea unfolds proteins mainly by increasing the solubility of the amide backbone, probably through urea-induced increase in hydrogen bonding. Other studies suggest that urea addition increases the magnitude of solvent-solute van der Waals interactions, which increases the solubility of nonpolar sidechains. More recent analyses hypothesize that urea has a similar effect in increasing the solubility of backbone and sidechain groups. In this work, we compare the effects of urea addition on the solvation of amides and alkyl groups. At first, we study the effects of urea addition upon solvent hydrogen bonding acidity and basicity through the perturbation in the fluorescence spectrum of probes 1-AN and 1-DMAN. Our results demonstrate that the solvent's hydrogen bonding properties are minimally affected by urea addition. Subsequently, we show that urea addition does not perturb the intra-molecular hydrogen bonding in salicylic acid significantly. Finally, we investigate how urea preferentially interacts with amide and alkyl groups moieties in water by comparing the effects of urea addition upon the solubility of acetaminophen and 4-tertbutylphenol. We show that urea affects amide and t-butyl solubility (lowers the transfer free energy of both amide (backbone) and alkyl (sidechain) groups) in a similar fashion. In other words, preferential interaction of urea with both moieties contributes to protein denaturation.

Synthese von α-Arylacrylamiden via Lewis Base vermitteltem Aryl/Wasserstoff-Austausch

Hierin stellen wir eine neue Methode für die Synthese von α‐Arylacrylamiden vor. Die Reaktion basiert auf der Nutzung polarer S‐zu‐C Arylwanderungen, induziert durch einen Lewis‐basischen Organokatalysator. Im Unterschied zu zuvor publizierten radikalischen Arylwanderungen von Sulfonylacrylamiden, ermöglicht dieser polare Prozess eine darauffolgende Eliminierung, wodurch in Summe ein formaler Aryl/Wasserstoff‐Austausch unter Ausscheidung von SO2 stattfindet. Die vorgestellte Reaktion ist selektiv für elektronenarme aromatische Gruppen, während eine Vielfalt von Substituenten am Stickstoff und an der β‐Position toleriert werden, und erzeugt nützliche Bausteine für Folgereaktionen wie Zykloadditionen und Zyklisierungen. Der Reaktionsmechanismus wurde mithilfe quantenchemischer Berechnungen erforscht, die die unerwartete Rolle der Lewis Base in mehreren Schlüsselschritten darlegten.

Harmicens, Novel Harmine and Ferrocene Hybrids: Design, Synthesis and Biological Activity

Cancer and malaria are both global health threats. Due to the increase in the resistance to the known drugs, research on new active substances is a priority. Here, we present the design, synthesis, and evaluation of the biological activity of harmicens, hybrids composed of covalently bound harmine/β-carboline and ferrocene scaffolds. Structural diversity was achieved by varying the type and length of the linker between the β-carboline ring and ferrocene, as well as its position on the β-carboline ring. Triazole-type harmicens were prepared using Cu(I)-catalyzed azide-alkyne cycloaddition, while the synthesis of amide-type harmicens was carried out by applying a standard coupling reaction. The results of in vitro biological assays showed that the harmicens exerted moderate antiplasmodial activity against the erythrocytic stage of P. falciparum (IC50 in submicromolar and low micromolar range) and significant and selective antiproliferative activity against the MCF-7 and HCT116 cell lines (IC50 in the single-digit micromolar range, SI > 5.9). Cell localization experiments showed different localizations of nonselective harmicene 36 and HCT116-selective compound 28, which clearly entered the nucleus. A cell cycle analysis revealed that selective harmicene 28 had already induced G1 cell cycle arrest after 24 h, followed by G2/M arrest with a concomitant drastic reduction in the percentage of cells in the S phase, whereas the effect of nonselective compound 36 on the cell cycle was much less pronounced, which agreed with their different localizations within the cell.

Construction, Pesticidal Activities, Control Effects, and Detoxification Enzyme Activities of Osthole Ester/Amide Derivatives

Pesticide research and development has entered an era of safety, efficiency, and environmental friendliness. Discovery of effective active products directly or indirectly from plant secondary metabolites as pesticide candidates has been one of the current research focuses. Herein, two series of new ester and amide derivatives were prepared by structural modifications of a natural coumarin-type product osthole at its C-4' position. Their structures were characterized by IR, mp, ¹H NMR, and HRMS. Confirmation of steric configuration of seven compounds was based on single-crystal analysis. Against Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), (2'E)-3'-ethoxycarbonylosthole (4b) and (2'E)-3'-(n)hexyloxycarbonylosthole (4e) exhibited 3.2 and 3.1 times acaricidal activity of osthole, and particularly, they also showed 2.4 and 2.2 times control efficiency on the 5th day of osthole. Against Aphis citricola Van der Goot (Homoptera: Aphididae), (2'E)-3'-(p-CF₃)benzyloxycarbonylosthole (4w), (2'E)-3'-benzylaminocarbonylosthole (5f), and (2'E)-3'-phenylethylaminocarbonylosthole (5g) showed 1.9-2.1-fold aphicidal activity of osthole. Furthermore, the changes in two detoxification enzyme [carboxylesterase (CarE) and glutathione S-transferase (GST)] activities over time in treated T. cinnabarinus were investigated. These results can pave the foundation for future design and preparation of osthole derivatives as botanical agrochemicals.

cloacae and MRSA and Its Validation via a Computational Approach

N-(4-bromophenyl)furan-2-carboxamide (3) was synthesized by the reaction furan-2-carbonyl chloride (1) and 4-bromoaniline (2) in the presence of Et₃N in excellent yields of 94%. The carboxamide (3) was arylated by employing triphenylphosphine palladium as a catalyst and K₃PO₄ as a base to afford N-(4-bromophenyl)furan-2-carboxamide analogues (5a-i) in moderate to good yields (43–83%). Furthermore, we investigated the in vitro anti-bacterial activities of the respective compounds against clinically isolated drug-resistant bacteria A. baumannii, K. pneumoniae, E. cloacae and S. aureus. The molecule (3) was found to be the most effective activity against these bacteria, particularly NDM-positive bacteria A. baumannii as compared to various commercially available drugs. Docking studies and MD simulations further validated it, expressing the active site and molecular interaction stability.

Overview of Chemistry and Therapeutic Potential of Non-Nitrogen Heterocyclics as Anticonvulsant Agents

Epilepsy is a chronic neurological disorder, characterized by the predisposition of unprovoked seizures affecting the neurobiological, psychological, cognitive, economic, and social wellbeing of the patient. As per the 2019 report by World Health Organization, it affects nearly 80% of the population, which comes from middle to low-income countries. It has been suggested that 70% of such cases can be treated effectively if properly diagnosed. It is one of the most common neurological diseases affecting 50 million people globally. Most of the antiepileptic drugs used in clinical practice are only 60-80% effective in controlling the disease. These drugs suffer from serious drawbacks of non-selectivity and toxicity that limit their clinical usefulness. Hence, there is a need to search for safe, potent, and effective anti-epileptic drugs. One of the emerging strategies to discover and develop selective and non-toxic anticonvulsant molecules focuses on the design of non-nitrogen heterocyclic compounds (NNHC). Drugs such as valproic acid, gabapentin, viagabatrin, fluorofelbamate, tiagabine, progabide, pregabalin, gamma amino butyric acid (GABA), etc. do not contain a nitrogen heterocyclic ring but are as effective anticonvulsants as conventional heterocyclic nitrogen compounds. This review covers the various classes of NNHC which have been developed in the recent past as anticonvulsants along with their chemistry, percentage yield, structure-activity relationship and biological activity. The most potent compound in each series has been identified for comparative studies, for further structural modification and to improve the pharmacokinetic profile. Various optimized synthetic pathways and diverse functionalities other than nitrogen-containing rings discussed in the article may help medicinal chemists to design safe and effective anticonvulsant drugs in near future.

Synthesis and Evaluation of Small Molecule Disruptors of the Aha1/Hsp90 Complex for the Reduction of Tau Aggregation

KU-177 was recently shown to disrupt interactions between Hsp90 and Aha1 in vitro. Subsequent studies in recombinant thioflavin T (ThT) assays demonstrated that KU-177 ablates Aha1-driven enhancement of Hsp90-dependent tau aggregation, which was confirmed by TEM. Using KU-177 as a lead compound, derivatives of KU-177 were synthesized and evaluated for their ability to disrupt Aha1/Hsp90 interactions and inhibit P301L tau aggregation. Preliminary structure-activity relationships were revealed, which led to the identification of a new lead compound that contains a cis-like amide bond. The new lead compounds retain the ability to disrupt Aha1/Hsp90 interactions in SH-SY5Y and SK-BR-3 cells without direct inhibition of Hsp90, providing a new scaffold for subsequent drug discovery efforts.

Mechanical Properties of Amide Functionalized CNT/NBR at Different Temperatures: A Molecular Dynamics Study

A comprehensive study on the mechanical properties of a pure carbon nanotube (PCNT)/nitrile butadiene rubber (NBR) composite and an amide-functionalized carbon nanotube (CONH₂-CNT)/nitrile butadiene rubber (NBR) composite was carried out using molecular dynamics (MDs) simulations at different temperatures. The effects of temperature on the mechanical properties, fractional free volume (FFV), MSD, dipole autocorrelation function, number of hydrogen bonds of PCNT composites, and functionalized CNT composites were analyzed and compared, and the pull-out behavior of the composites under different condition temperatures was simulated. The enhancement mechanism of the interface interaction between the functionalized carbon nanotubes and the NBR matrix was explained from an atomic point of view. The results show that, due to the existence of hydrogen bonds, higher interfacial binding energies were formed between PCNT and NBR, and FFVs and MSDs were restricted at each temperature, with the mechanical properties of the composites being improved by 5.02-25.93%.

Renoprotective activity of a new amide and a new hydroxycinnamic acid derivative from the fresh roots of Rehmannia glutinosa

A new amide, named rehmagluamide (1), and a new hydroxycinnamic acid derivative, named nepetoidin F (2), together with six known compounds, 2'-O-methyluridine (3), puroglutamic acid (4), biliverdic acid (5), peterolactam (6), nicotinic acid (7), nicotinamide (8), were isolated from the fresh roots of Rehmannia glutinosa. All the structures of compounds were identified by the interpretation of their spectroscopic data and comparison with those reported in the literatures. The protective effects of compounds 1-7 on normal rat kidney tubule epithelioid (NRK-52e) cells injury induced by LPS were investigated. The results indicated that compounds 1, 2, and 7 exhibited protective effects against LPS-induced NRK 52e cells injury.

A Selective Single Step Amidation of Polyfluoroarenes

This chemistry establishes a method for the synthesis of per- and poly-fluoroaryl acid amides, utilizing nucleophilic aromatic substitution. Traditionally, such amides are constructed in a two-step process, namely, ammonolysis and then N-acylation. Herein, good yields of N-polyfluoroaryl acid amides were achieved in a single step under mild reaction conditions. Key to achieving optimal yields is the use of two equivalents of the nucleophile. In addition, the mechanism of the reaction is discussed which has implications for other related nucleophilic substitutions.

Mapping intracellular pH in tumors using amide and guanidyl CEST-MRI at 9.4 T

PURPOSE

In principle, non-invasive mapping of the intracellular pH (pH_i ) in vivo is possible using endogenous chemical exchange saturation transfer (CEST)-MRI of the amide and guanidyl signals. However, the application for cancer imaging is still impeded, as current state-of-the-art approaches do not allow for simultaneous compensation of concomitant effects that vary within tumors. In this study, we present a novel method for absolute pH_i mapping using endogenous CEST-MRI, which simultaneously compensates for concentration changes, superimposing CEST signals, magnetization transfer contrast, and spillover dilution.

THEORY AND METHODS

Compensation of the concomitant effects was achieved by a ratiometric approach (i.e. the ratio of one CEST signal at different B₁ ) in combination with the relaxation-compensated inverse magnetization transfer ratio MTR_Rex and a separate first-order polynomial-Lorentzian fit of the amide and guanidyl signals at 9.4 T. Calibration of pH values was accomplished using in vivo-like model suspensions from porcine brain lysates. Applicability of the presented method in vivo was demonstrated in n = 19 tumor-bearing mice.

RESULTS

In porcine brain lysates, measurement of pH was feasible over a broad range of physiologically relevant pH values of 6.2 to 8.0, while being independent of changes in concentration. A median pH_i of approximately 7.2 was found in the lesions of 19 tumor-bearing mice.

CONCLUSION

The presented method enables non-invasive mapping of absolute pH_i values in tumors using CEST-MRI, which was so far prevented by concomitant effects. Consequently, pre-clinical studies on pH_i changes in tumors are possible allowing the assessment of pH_i in vivo as a biomarker for cancer diagnosis or treatment monitoring.

New Deoxycholic Acid Derived Tyrosyl-DNA Phosphodiesterase 1 Inhibitors Also Inhibit Tyrosyl-DNA Phosphodiesterase 2

A series of deoxycholic acid (DCA) amides containing benzyl ether groups on the steroid core were tested against the tyrosyl-DNA phosphodiesterase 1 (TDP1) and 2 (TDP2) enzymes. In addition, 1,2,4- and 1,3,4-oxadiazole derivatives were synthesized to study the linker influence between a para-bromophenyl moiety and the steroid scaffold. The DCA derivatives demonstrated promising inhibitory activity against TDP1 with IC₅₀ in the submicromolar range. Furthermore, the amides and the 1,3,4-oxadiazole derivatives inhibited the TDP2 enzyme but at substantially higher concentration. Tryptamide 5 and para-bromoanilide 8 derivatives containing benzyloxy substituent at the C-3 position and non-substituted hydroxy group at C-12 on the DCA scaffold inhibited both TDP1 and TDP2 as well as enhanced the cytotoxicity of topotecan in non-toxic concentration in vitro. According to molecular modeling, ligand 5 is anchored into the catalytic pocket of TDP1 by one hydrogen bond to the backbone of Gly458 as well as by π–π stacking between the indolyl rings of the ligand and Tyr590, resulting in excellent activity. It can therefore be concluded that these derivatives contribute to the development of specific TDP1 and TDP2 inhibitors for adjuvant therapy against cancer in combination with topoisomerase poisons.

2-(Piperidin-4-yl)acetamides as Potent Inhibitors of Soluble Epoxide Hydrolase with Anti-Inflammatory Activity

The pharmacological inhibition of soluble epoxide hydrolase (sEH) has been suggested as a potential therapy for the treatment of pain and inflammatory diseases through the stabilization of endogenous epoxyeicosatrienoic acids. Numerous potent sEH inhibitors (sEHI) have been developed, however many contain highly lipophilic substituents limiting their availability. Recently, a new series of benzohomoadamantane-based ureas endowed with potent inhibitory activity for the human and murine sEH was reported. However, their very low microsomal stability prevented further development. Herein, a new series of benzohomoadamantane-based amides were synthetized, fully characterized, and evaluated as sEHI. Most of these amides were endowed with excellent inhibitory potencies. A selected compound displayed anti-inflammatory effects with higher effectiveness than the reference sEHI, TPPU.