Synthesis of New Derivatives of Berberine Canagliflozin and Study of Their Antibacterial Activity and Mechanism.

The isoquinoline alkaloid berberine, derived from Coptidis rhizoma, exhibits antibacterial, hypoglycemic, and anti-inflammatory properties. Canagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor. We synthesized compounds B9OC and B9OBU by conjugating canagliflozin and n-butane at the C9 position of berberine, aiming to develop antimicrobial agents for combating bacterial infections worldwide. We utilized clinically prevalent pathogenic bacteria, namely Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, to investigate the antibacterial efficacy of B9OC. This was accomplished through the determination of the MIC80 values, analysis of bacterial growth curves, evaluation of biofilm formation using crystal violet staining, assessment of impact on bacterial proteins via SDS-PAGE analysis, and observation of alterations in bacterial morphology utilizing field emission scanning electron microscopy. Meanwhile, the ADMET of compound B9OC was predicted using a computer-aided method. The findings revealed that B9OC exhibited lower minimal inhibitory concentrations against all three bacteria compared to berberine alone or in combination with canagliflozin. The minimal inhibitory concentrations (MICs) of B9OC against the three experimental strains were determined to be 0.035, 0.258, and 0.331 mM. However, B9OBu exhibited a lower level of antimicrobial activity compared to berberine. The compound B9OC exhibits a broad spectrum of antibacterial activity by disrupting the integrity of bacterial cell walls, leading to cellular rupture and the subsequent degradation of intracellular proteins.

Dioxane Bridge Formation during the Biosynthesis of Spectinomycin Involves a Twitch Radical S-Adenosyl Methionine Dehydrogenase That May Have Evolved from an Epimerase.

Spectinomycin is a dioxane-bridged, tricyclic aminoglycoside produced by Streptomyces spectabilis ATCC 27741. While the spe biosynthetic gene cluster for spectinomycin has been reported, the chemistry underlying construction of the dioxane ring is unknown. The twitch radical SAM enzyme SpeY from the spe cluster is shown here to catalyze dehydrogenation of the C2' alcohol of (2'R,3'S)-tetrahydrospectinomycin to yield (3'S)-dihydrospectinomycin as a likely biosynthetic intermediate. This reaction is radical-mediated and initiated via H atom abstraction from C2' of the substrate by the 5'-deoxyadenosyl radical equivalent generated upon reductive cleavage of SAM. Crystallographic analysis of the ternary Michaelis complex places serine-183 adjacent to C2' of the bound substrate opposite C5' of SAM. Mutation of this residue to cysteine converts SpeY to the corresponding C2' epimerase mirroring the opposite phenomenon observed in the homologous twitch radical SAM epimerase HygY from the hygromycin B biosynthetic pathway. Phylogenetic analysis suggests a relatively recent evolutionary branching of putative twitch radical SAM epimerases bearing homologous cysteine residues to generate the SpeY clade of enzymes.

Radical S-Adenosyl Methionine Enzyme BlsE Catalyzes a Radical-Mediated 1,2-Diol Dehydration during the Biosynthesis of Blasticidin S.

The biosynthesis of blasticidin S has drawn attention due to the participation of the radical S-adenosyl methionine (SAM) enzyme BlsE. The original assignment of BlsE as a radical-mediated, redox-neutral decarboxylase is unusual because this reaction appears to serve no biosynthetic purpose and would need to be reversed by a subsequent carboxylation step. Furthermore, with the exception of BlsE, all other radical SAM decarboxylases reported to date are oxidative in nature. Careful analysis of the BlsE reaction, however, demonstrates that BlsE is not a decarboxylase but instead a lyase that catalyzes the dehydration of cytosylglucuronic acid (CGA) to form cytosyl-4'-keto-3'-deoxy-d-glucuronic acid, which can rapidly decarboxylate nonenzymatically in vitro. Analysis of substrate isotopologs, fluorinated analogues, as well as computational models based on X-ray crystal structures of the BlsE·SAM (2.09 Å) and BlsE·SAM·CGA (2.62 Å) complexes suggests that BlsE catalysis likely proceeds via direct elimination of water from the CGA C4' α-hydroxyalkyl radical as opposed to 1,2-migration of the C3'-hydroxyl prior to dehydration. Biosynthetic and mechanistic implications of the revised assignment of BlsE are discussed.

Study on synthesis and bioactivity of biotinylated emodin.

A novel compound biotinylated emodin was synthesized by a two-step acyl chloride method which connects the biotin to emodin with esterification reaction. The product was characterized with ultraviolet-visible spectrophotometry, fourier transform infrared and high-performance liquid chromatography tandem mass spectrometry techniques. Its antibacterial activity against Staphylococcus aureus CMCC 26003 was investigated, and the emodin- and biotinylated emodin-caused antibacterial mechanism was proposed. It was shown that the product was isolated and activity of emodin was remained. These results indicated that our study provides a kind of chemosynthesis method under mild conditions and a strong molecular tool for investigating the emodin-binding protein.

Mechanistic Insights from the Crystal Structure and Computational Analysis of the Radical SAM Deaminase DesII.

Radical S-adenosyl-L-methionine (SAM) enzymes couple the reductive cleavage of SAM to radical-mediated transformations that have proven to be quite broad in scope. DesII is one such enzyme from the biosynthetic pathway of TDP-desosamine where it catalyzes a radical-mediated deamination. Previous studies have suggested that this reaction proceeds via direct elimination of ammonia from an α-hydroxyalkyl radical or its conjugate base (i.e., a ketyl radical) rather than 1,2-migration of the amino group to form a carbinolamine radical intermediate. However, without a crystal structure, the active site features responsible for this chemistry have remained largely unknown. The crystallographic studies described herein help to fill this gap by providing a structural description of the DesII active site. Computational analyses based on the solved crystal structure are consistent with direct elimination and indicate that an active site glutamate residue likely serves as a general base to promote deprotonation of the α-hydroxyalkyl radical intermediate and elimination of the ammonia group.

Adaptive control for downhole nuclear magnetic resonance excitation.

Nuclear magnetic resonance (NMR) measurements are performed with the pulse sequence and acquisition parameters set by the operator, which cannot be adjusted in real time according to sample characteristics. In one acquisition cycle, usually thousands of high-power pulses are transmitted and thousands of echo points are acquired. The power consumption cause the RF amplifier to overheat, and large amounts of acquired data may be invalid. Therefore, the optimization of excitation and acquisition processes is necessary to improve measurement efficiency. We explore a scheme for the real-time measurement of the samples by adaptively regulating the pulse sequence, which adapts the variable TE pulse sequence as the reconnaissance mode. The appropriate pulse sequence and reasonable parameters (NE, TE) can be selected according to the relaxation characteristics of the samples.This adaptive control strategy has great significance in guiding both dynamic and static measurements, and it is especially suitable for occasions where low magnetic field gradients and diffusion terms can be ignored. We also design a test circuit for adaptive control, which has the function of automatic parameter adjustment. By adjusting parameters such as the number of refocusing pulses, echo spacing, etc., the effective measurement of the samples can be achieved in practice.

Phytoecdysteroids from Dianthus superbus L.: Structures and anti-neuroinflammatory evaluation.

Six undescribed C27-phytoecdysteroid derivatives, named superecdysones A-F, and ten known analogs were extracted from the whole plant of Dianthus superbus L. Their structures were identified by extensive spectroscopy, mass spectrometric methods, chemical transformations, chiral HPLC analysis, and the single-crystal X-ray diffraction analysis. Superecdysones A and B possess a tetrahydrofuran ring in the side chain and superecdysones C-E are rare phytoecdysones containing a (R)-lactic acid moiety, whereas superecdysone F is an uncommon B-ring-modified ecdysone. Notably, based on the variable temperature (from 333 K to 253 K) NMR experiments of superecdysone C, the missing carbon signals were visible at 253 K and assigned. The neuroinflammatory bioassay of all compounds were evaluated, and 22-acetyl-2-deoxyecdysone, 2-deoxy-20-hydroxyecdysone, 20-hydroxyecdysone, ecdysterone-22-O-benzoate, 20-hydroxyecdysone-20,22-O-R-ethylidene, and acetonide derivative 20-hydroxyecdysterone-20, 22-acetonide significantly suppressed the LPS-induced nitric oxide generation in microglia cells (BV-2), with IC50 values ranging from 6.9 to 23.0 µM. Structure-activity relationships were also discussed. Molecular docking simulations of the active compounds confirmed the possible mechanism of action against neuroinflammations. Furthermore, none compounds showed cytotoxicity against HepG2 and MCF-7. It is the first report about the occurrence and anti-neuroinflammatory activity of the phytoecdysteroids in the genus Dianthus. Our findings demonstrated that ecdysteroids may be used as potential anti-inflammatory drugs.

Novel biotin-linked amphiphilic calix[4]arene-based supramolecular micelles as doxorubicin carriers for boosted anticancer activity.

Supramolecular carrier-mediated chemotherapy is a highly attractive strategy for targeted drug delivery. In this study, four novel biotin-linked calix[4]arenes BPCA1-BPCA4 have been rationally designed to construct nano-complex with doxorubicin. The in vitro and in vivo assessments reveal that BPCA4-DOX with excellent stability are capable of affording significantly superior anti-tumor activity and lower side effects.

Design of a new LWD NMR tool with high mechanical reliability.

Nuclear magnetic resonance (NMR) provides useful information for formation evaluation on pore size and pore volume. Depending on field operations, there are two types of borehole NMR: wireline logging and logging-while-drilling (LWD). The latter type is more convenient. But due to the high mechanical failure risk caused by insufficient mechanical strength of the tool and vibrations during measurement, the quality of LWD NMR measurements are severely affected. In this paper, to enable high reliability and vibration tolerance, we propose a new design and implement a new LWD NMR tool, whose features includes a double hollow cylindric magnet (DHCM) structure and a solenoid-optimized antenna. The DHCM structure greatly reduces the proportion of the magnet in the cross-section of the tool without reducing B0 field strength. Thus, the mechanical strength and the reliability of the tool is greatly improved. The antenna is improved by optimizing the parameters of each coil of the solenoid for finding the generated B1 distribution best matching B0. The new design has a saddle sensing area in the axial and radial plane with a width greater than 50 mm, which is wide enough to ensure the validity of the T2 measurement under strong vibrations. We had demonstrated that this new tool performs well when TE = 0.6 ms, ensuring the measurement richness is suitable for LWD prospecting for unconventional oil and gas reservoirs. Besides, this design is suitable for that in slim holes.

Toxic effects of copper on antioxidative and metabolic enzymes of the marine gastropod, Onchidium struma.

The goals of this study were to evaluate the acute and sublethal toxicity of copper (Cu(2+)) on the marine gastropod, Onchidium struma, and to examine the utility of enzymatic parameters as indicators of Cu(2+) exposure. In a semistatic renewal test, the 96-hour median lethal concentration of Cu(2+) for O. struma, 74.80 mg/L, was higher than that for other intertidal species. The activities of the antioxidative enzymes, Cu/Zn superoxide dismutase (Cu/Zn-SOD) and catalase (CAT), and those of the metabolic enzymes-acid phosphatase (ACP), alkaline phosphatase (AKP), glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) -in both hepatopancreas and muscle were determined after a 1-week exposure to Cu(2+) (range 1.35 to 4.20 mg/L). The activities of both Cu/Zn-SOD and CAT were higher in hepatopancreas than muscle. In addition, there was a negative correlation between Cu(2+) concentration and Cu/Zn-SOD activity in hepatopancreas, whereas a positive correlation was observed for CAT activity. Concentration-dependent changes in ACP and AKP activity showed a similar trend in hepatopancreas, increasing then decreasing and, finally, a slight increase. In contrast, ACP activity was positively correlated with Cu(2+) across the concentration range tested. In both hepatopancreas and muscle, both GOT and GPT were activated by lower concentrations of Cu(2+) and inhibited at higher concentrations.

A new side-looking downhole magnetic resonance imaging tool.

In general, only the depth information can be acquired using the centralized downhole NMR tools. The radial profile information is equally important to the depth. Improving the pad tools, also called side-looking tools, is the appropriate direction for solving this problem. The side-looking downhole measurement can provide depth and radially resolved information of the reservoir. In this research a new side-looking tool which includes main magnets and pre-polarized magnets has been designed and built. The pre-polarized magnets in both sides are used to adjust the homogeneity of magnetic field along the length direction of the instrument and polarize the samples when the tool is moving up and down along the borehole with a speed up to 500 m/h. A winding coil with several frequencies corresponding to different depths has been designed to match the static magnetic field. The sensitive region of this tool is about one-third of a hollow cylinder at every frequency which gives a side-looking image of the borehole wall. We have demonstrated that this new side-looking tool behaves well with an echo time short to 0.25 ms, which ensures the richness and accuracy of the measurements. Such a new side-looking tool is suitable for the detection of unconventional reservoirs.

Two different one-dimensional Cd(II) halide coordination polymers constructed through bridging carboxylate ligands.

Two cadmium halide complexes, catena-poly[[chloridocadmium(II)]-di-µ-chlorido-[chloridocadmium(II)]-bis[µ2-4-(dimethylamino)pyridin-1-ium-1-acetate]-κ(3)O:O,O';κ(3)O,O':O], [CdCl2(C9H12N2O2)]n, (I), and catena-poly[1-cyanomethyl-1,4-diazoniabicyclo[2.2.2]octane [[dichloridocadmium(II)]-µ-oxalato-κ(4)O(1),O(2):O(1'),O(2')] monohydrate], {(C8H15N3)[CdCl2(C2O4)]·H2O}n, (II), were synthesized in aqueous solution. In (I), the Cd(II) cation is octahedrally coordinated by three O atoms from two carboxylate groups and by one terminal and two bridging chloride ligands. Neighbouring Cd(II) cations are linked together by chloride anions and bridging O atoms to form a one-dimensional zigzag chain. Hydrogen-bond interactions are involved in the formation of the two-dimensional network. In (II), each Cd(II) cation is octahedrally coordinated by four O atoms from two oxalic acid ligands and two terminal Cl(-) ligands. Neighbouring Cd(II) cations are linked together by oxalate groups to form a one-dimensional anionic chain, and the water molecules and organic cations are connected to this one-dimensional zigzag chain through hydrogen-bond interactions.

Isostructural organic-inorganic hybrid compounds: triethylcholine tribromidocadmate and triethylcholine tribromidomercurate.

In order to search for new anionic architectures and develop useful organic-inorganic hybrid materials in halometallate systems, two new crystalline organic-inorganic hybrid compounds have been prepared, i.e. catena-poly[triethyl(2-hydroxyethyl)azanium [[bromidocadmate(II)]-di-µ-bromido]], {(C8H20NO)[CdBr3]}n, (1), and catena-poly[triethyl(2-hydroxyethyl)azanium [[bromidomercurate(II)]-di-µ-bromido]], {(C8H20NO)[HgBr3]}n, (2), and the structures determined by X-ray diffraction analysis. The compounds are isostructural, crystallizing in the space group P21/n. The metal centres are five-coordinated by bromide anions, giving a slightly distorted trigonal-bipyramidal geometry. The crystal structures consist of one-dimensional edge-sharing chains of MBr5 trigonal bipyramids, between which triethylcholine counter-cations are intercalated. O-H···Br hydrogen-bonding interactions are present between the cations and anions.