Fenton oxidation treatment of oxytetracycline fermentation residues: Harmless performance and bioresource properties.

The pharmaceutical factories of oxytetracycline (OTC) massively produce OTC fermentation residues (OFRs). The high content of residual OTC and antibiotic resistance genes in OFRs must to be considered and controlled at an acceptable level. This study therefore investigated the applicability of Fenton oxidation in OTC degradation and resistant gene inactivation of OFRs. The results revealed that Fe2+ as catalyzer could very rapidly activate H2O2 to produce HO•, leading to instantaneous degradation of OTC. The optimum conditions for OTC removal were 60 mM H2O2 and 140 mg/L Fe2+ under pH 7. After Fenton oxidation treatment, the release of water-soluble polysaccharides, NO3-N, and PO4-P was enhanced, whereas for proteins and NH3-N were reduced. Three soluble fluorescence components (humic, tryptophan-like, and humic acid-like substances) were identified through fluorescence spectra with parallel factor analysis, and their reduction exceeded 50% after Fenton oxidation. There were twelve intermediates and three degradation pathways of OTC in OFRs during Fenton process. According to toxicity prediction, the comprehensive toxicity of OTC in OFRs was alleviated via Fenton oxidation treatment. In addition, Fenton oxidation showed the ability to reduce antibiotic resistance genes and mobile genetic elements, and even tetO, tetG, intI1, and intI2 were eliminated completely. These results suggested that Fenton oxidation treatment could be an efficient strategy for removing OTC and resistance genes in OFRs.

Study on the preparation and activity of intelligent response poly(lactic-co-glycolic acid)-ss-polyethylene glycol copolymer micelles.

Amphiphilic polymer micellar carriers are the most commonly used nanocarriers for oral delivery of hydrophobic drugs because their hydrophilic shell can avoid the recognition of the reticuloendothelial system (RES), has excellent drug-carrying capacity, and protect the drug from inactivation in the gastrointestinal fluid. The polymer micelle shell can enter cancer cells by endocytosis, and autophagy in cells, degradation by lysosomal pathway, so as to release drugs, prolong the circulation time of drugs in vivo, and then achieve the effect of drug sustained release. In this study, the glutathione-responsive PLGA-ss-PEG loaded paclitaxel (PTX) micelles (PLGA-ss-PEG-PTX) were developed for anticancer therapy. With its long-term circulation and EPR (enhanced permeability and retention) effect, and the micelle had disulfide bond, which could be used as the recognition group of tumor microenvironment, so that the PLGA-ss-PEG-PTX could specifically accumulate at the tumor site, so as to produce better anti-tumor effect. The PLGA-ss-PEG-PTX was formulated by the emulsification method in this study. The drug loading was about 21.54%, the entrapment efficiency was about 94.2%, and the particle size range was about 90 nm with narrow particle size distribution. Cytotoxicity and embryonic toxicity experiments were carried out using mouse lung cancer cells (LLC) and zebrafish fertilized eggs. It was proved that the low concentration of blank micelles had little cytotoxicity, but high concentration of blank micelles had adverse effects on zebrafish embryonic development, resulting in embryonic malformation. The uptake of drugs by cancer cells was studied by a high connotation cell imaging analysis system. The experiments showed that the drug molecules encapsulated in micelles could achieve higher uptake by cells compared with free drug molecules. In addition, in the in vivo evaluation experiment of drugs, the PLGA-ss-PEG-PTX could significantly enhance the therapeutic effect of the PTX, improve its water solubility, and improve its oral bioavailability.

Machine Learning Enhanced Spectrum Recognition Based on Computer Vision (SRCV) for Intelligent NMR Data Extraction.

A machine learning enhanced spectrum recognition system called spectrum recognition based on computer vision (SRCV) for data extraction from previously analyzed 13C and 1H NMR spectra has been developed. The intelligent system was designed with four function modules to extract data from three areas of NMR images, including 13C and 1H chemical shifts, the integral, and the range of the shift values. During this study, three machine learning models were pretrained for number recognition, which is the key procedure for NMR data extraction. The k nearest neighbor (kNN) method was selected with optimized k (k = 4), which displayed a 100% recognition rate. Subsequently, the performance of SRCV was tested and validated to have high accuracy with a short processing time (11-21 s) for each NMR spectral image. Our spectrum recognizer enables high-throughput 13C and 1H NMR data extraction from abundant spectra in the literature and has the potential to be used for spectral database construction. In addition, the system may be applicable to be developed for data import to computer-assisted structure elucidation systems, which would automate this procedure significantly. SRCV can be accessed in GitHub (https://github.com/WJmodels/SRCV).

LiCl-promoted amination of ß-methoxy amides (γ-lactones).

An efficient and mild method has been developed for the amination of ß-methoxy amides (γ-lactones) including natural products michelolide, costunolide and parthenolide derivatives by using lithium chloride in good yields. This reaction is applicable to a wide range of substrates with good functional group tolerance. Mechanism studies show that the reactions undergo a LiCl promoted MeOH elimination from the substrates to form the corresponding α,ß-unsaturated intermediates followed by the Michael addition of amines.

Design, Synthesis, and Biological Evaluation of Amidobenzimidazole Derivatives as Stimulator of Interferon Genes (STING) Receptor Agonists.

Stimulator of interferon genes (STING) is an endoplasmic reticulum-localized adaptor protein (STING receptor) that has been shown to be activated by binding to natural cyclic dinucleotide (CDN) ligands and plays a vital role in innate immune sensing of exogenous or endogenous DNA, which then induces type I interferons and other cytokines. In this paper, we described a series of amidobenzimidazole STING agonists with high potency for the STING receptor and presented the relevant structure-activity relationships (SARs). The relative potencies of compounds 16g, 24b, and 24e were measured by a STING competition binding assay. A more thorough study of the effect on the STING signaling pathway demonstrated that three compounds, 16g, 24b, and 24e, significantly increased the protein levels and mRNA levels of IFN-ß, CXCL10, and IL-6, and 24b as a representative compound effectively triggered the phosphorylation of STING, TBK1, and IRF3 in both human peripheral blood mononuclear cells (hPBMCs) and WT THP-1 cells. In addition, compound 24b demonstrated impressive antitumor efficacy in mice with established syngeneic colon tumors by intravenous administration. Furthermore, the pharmacokinetic profile of compound 24b was fully evaluated.

Machine Learning Models Based on Molecular Fingerprints and an Extreme Gradient Boosting Method Lead to the Discovery of JAK2 Inhibitors.

Developing Janus kinase 2 (JAK2) inhibitors has become a significant focus for small-molecule drug discovery programs in recent years because the inhibition of JAK2 may be an effective approach for the treatment of myeloproliferative neoplasm. Here, based on three different types of fingerprints and Extreme Gradient Boosting (XGBoost) methods, we developed three groups of models in that each group contained a classification model and a regression model to accurately acquire highly potent JAK2 kinase inhibitors from the ZINC database. The three classification models resulted in Matthews correlation coefficients of 0.97, 0.94, and 0.97. Docking methods including Glide and AutoDock Vina were employed to evaluate the virtual screening effectiveness of our classification models. The R2 of three regression models were 0.80, 0.78, and 0.80. Finally, 13 compounds were biologically evaluated, and the results showed that the IC50 values of six compounds were identified to be less than 100 nM. Among them, compound 9 showed high activity and selectivity in that its IC50 value was less than 1 nM against JAK2 while 694 nM against JAK3. The strategy developed may be generally applicable in ligand-based virtual screening campaigns.

Structure-based analysis and biological characterization of imatinib derivatives reveal insights towards the inhibition of wild-type BCR-ABL and its mutants.

To reveal insights into the inhibition of BCR-ABL and its mutants, structure-based computing methods, such as docking, molecular dynamics (MD) simulation, the molecular mechanics generalized born surface area (MMGBSA), and biological characterizations, were employed to analyze two main pharmacophore zones and two related regions of imatinib derivatives. The hydrophobic and halogen interactions formed by the trifluoromethyl, as well as T-shaped π-π interactions formed by the pyrimidine, were confirmed. For the imatinib derivatives, the impacts of the amide moiety (region A) and the pyridine (region B) on the formed interactions were explored. To reveal insights into the inhibition of BCR-ABL mutants, the bioactivities of imatinib, nilotinib and flumatinib against BCR-ABL mutants were evaluated, and a point mutant (Y253F) of BCR-ABL was simulated. The results of our structure-based analysis and biological characterization of imatinib derivatives towards the inhibition of wild-type BCR-ABL and its mutants may provide new ideas for the design of imatinib analogs with potent activity.

One-Pot Synthesis of O-Heterocycles or Aryl Ketones Using an InCl3/Et3SiH System by Switching the Solvent.

An efficient one-pot synthesis of O-heterocycles or aryl ketones has been achieved using Et3SiH in the presence of InCl3 via a sequential ionic hydrogenation reaction by switching the solvent. This methodology can be used to construct C-O bonds and to prepare conjugate reduction products, including chromans, tetrahydrofurans, tetrahydropyrans, dihydroisobenzofurans, dihydrochalcones, and 1,4-diones in a facile manner. In addition, a novel plausible mechanism involving a conjugate reduction and a tandem reductive cyclization was verified by experimental investigations.

A Computational Approach to the Study of the Binding Mode of S1P1R Agonists Based on the Active-Like Receptor Model.

Sphingosine-1-phosphate receptor 1 (S1P1R), a member of the G protein-coupled receptor (GPCR) family, is an attractive protein target for the treatment of autoimmune diseases, and a diverse array of S1P1R agonists have been developed. Rational drug design based on S1P1R remains challenging due to the limited information available on the binding mode between S1P1R and its agonists. In this work, the active-like state of S1P1R was modeled via Gaussian accelerated molecular dynamics (GaMD) based on its inactive form, which was further validated by docking studies with two representative S1P1R agonists. Moreover, with the usage of the induced active-like state, the binding mode between S1P1R and its agonists was studied through molecular dynamics simulations and MM-GBSA calculations. The results of those studies indicated that four groups of binding site residues were the major contributors to the ligand and receptor interactions. In addition, this model was verified by five chemically similar compounds synthesized in-house and 1145 known S1P1R agonists collected from the BindingDB database. The elucidation of the key binding characteristics will further complete the cognition of S1P1R, which can guide the rational design of novel S1P1R agonists.

Identification and Structure-Activity Relationship (SAR) of potent and selective oxadiazole-based agonists of sphingosine-1-phosphate receptor (S1P1).

Agonism of S1P1 receptor has been proven to be responsible for peripheral blood lymphopenia and elicts the identification of various S1P1 modulators. In this paper we described a series of oxadiazole-based S1P1 direct-acting agonists disubstituted on terminal benzene ring, with high potency for S1P1 receptor and favorable selectivity against S1P3 receptor. In addition, two representative agents named 16-3b and 16-3g demonstrated impressive efficacy in lymphocyte reduction along with reduced effect on heart rate when orally administered. Furthermore, these compounds have been shown to possess desired pharmacokinetic (PK) and physicochemical profiles. The binding mode between 16-3b and the activated S1P1 model was also studied.

Diversity-Oriented Synthesis of Heterocycles: Al(OTf)3-Promoted Cascade Cyclization and Ionic Hydrogenation.

An efficient and facile method has been developed for the diversity-oriented synthesis of heterocycles. Hexahydrophenoxazines, tetrahydroquinolines, indolines, hexahydrocarbazoles, and lactones were conducted via Al(OTf)3-promoted cascade cyclization and ionic hydrogenation. Furthermore, this protocol was utilized to smoothly prepare piracetam and its key intermediate as well.

A Series of Enthalpically Optimized Docetaxel Analogues Exhibiting Enhanced Antitumor Activity and Water Solubility.

A dual-purpose strategy aimed at enhancing the binding affinity for microtubules and improving the water solubility of docetaxel led to the design and synthesis of a series of C-2- and C-3'-modified analogues. Both aims were realized when the C-3' phenyl group present in docetaxel was replaced with a propargyl alcohol. The resulting compound, 3f, was able to overcome drug resistance in cultured P-gp-overexpressing tumor cells and showed greater activity than docetaxel against drug-resistant A2780/AD ovarian cancer xenografts in mice. In addition, the considerably lower hydrophobicity of 3f relative to both docetaxel and paclitaxel led to better aqueous solubility. A molecular model of tubulin-bound 3f revealed novel hydrogen-bonding interactions between the propargyl alcohol and the polar environment provided by the side chains of Ser236, Glu27, and Arg320.

Bifunctional N-heterocyclic carbene catalyzed [3+4] annulation of enals and aurones.

Bifunctional N-heterocyclic carbenes with a free hydroxy group are demonstrated as efficient catalysts for the [3+4] annulation of enals with aurones to give the corresponding benzofuran-fused ε-lactones in good yields with good diastereoselectivities and excellent enantioselectivities. Control experiments reveal that the [3+4] cycloadducts are kinetically favored and could be transformed to the thermodynamically favored [3+2] cycloadducts with a non-bifunctional NHC catalyst.

Organocatalytic [4 + 2] cyclocondensation of α,ß-unsaturated acyl chlorides with imines: highly enantioselective synthesis of dihydropyridinone and piperidine derivatives.

The cinchona alkaloid-catalyzed [4 + 2] cyclocondensation of α,ß-unsaturated acyl chlorides with imines is developed to give the corresponding substituted dihydropyridinones in good yields with high to excellent enantioselectivities. Reduction of the dihydropyridinones gave highly optically active substituted tetrahydropyridinone and piperidine derivatives.

Catalytic [4+2] cyclization of α,ß-unsaturated acyl chlorides with 3-alkylenyloxindoles: highly diastereo- and enantioselective synthesis of spirocarbocyclic oxindoles.

Cinchona alkaloids were used as Lewis base catalysts in the title reaction. The [4+2] cyclization of α,ß-unsaturated acyl chlorides with electron-deficient alkenes derived from oxindole gave the corresponding spirocarbocyclic oxindoles.

Radical-scavenging activity and mechanism of resveratrol-oriented analogues: influence of the solvent, radical, and substitution.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene, 3,5,4'-THS) is a well-known natural antioxidant and cancer chemopreventive agent that has attracted much interest in the past decade. To find a more active antioxidant and investigate the antioxidative mechanism with resveratrol as the lead compound, we synthesized 3,5-dihydroxy-trans-stilbene (3,5-DHS), 4-hydroxy-trans-stilbene (4-HS) 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-3-methoxy-trans-stilbene (3-MeO-4-HS), 4-hydroxy-4'-methoxy-trans-stilbene (4'-MeO-4-HS), 4-hydroxy-4'-methyl-trans-stilbene (4'-Me-4-HS), 4-hydroxy-4'-nitro-trans-stilbene (4'-NO(2)-4-HS), and 4-hydroxy-4'-trifluoromethyl-trans-stilbene (4'-CF(3)-4-HS). The radical-scavenging activity and detailed mechanism of resveratrol and its analogues (ArOHs) were investigated by the reaction kinetics with galvinoxyl (GO(*)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) radicals in ethanol and ethyl acetate at 25 degrees C, using UV-vis spectroscopy. It was found that the reaction rates increase with increasing the electron-rich environment in the molecules, and the compound bearing o-dihydroxyl groups (3,4-DHS) is the most reactive one among the examined resveratrol analogues. The effect of added acetic acid on the measured rate constant for GO(*)-scavenging reaction reveals that in ethanol that supports ionization solvent besides hydrogen atom transfer (HAT), the kinetics of the process is partially governed by sequential proton loss electron transfer (SPLET). In contrast to GO(*), DPPH(*) has a relatively high reduction potential and therefore enhances the proportion of SPLET in ethanol. The relatively low rate constants for the reactions of ArOHs with GO(*) or DPPH(*) in ethyl acetate compared with the rate constants in ethanol prove that in ethyl acetate these reactions occur primarily by the HAT mechanism. The contribution of SPLET and HAT mechanism depends on the ability of the solvent to ionize ArOH and the reduction potential of the free radical involved. Furthermore, the fate of the ArOH-derived radicals, i.e., the phenoxyl radicals, was investigated by the oxidative product analysis of ArOHs and GO(*) in ethanol. The major products were dihydrofuran dimers in the case of resveratrol, 4,4'-DHS, and 4-HS and a dioxane-like dimer in the case of 3,4-DHS. It is suggested from the oxidative products of these ArOHs that the hydroxyl group at the 4-position is much easier to subject to oxidation than other hydroxyl groups, and the dioxane-like dimer is formed via an o-quinone intermediate.