Organic Reactions Enabled by Mechanical Force-Induced Single Electron Transfer.

Mechanochemical reactions, achieved through milling, grinding, or other mechanical actions, have emerged as a solvent-free alternative to traditional solution-based chemistry. Mechanochemistry not only provides the opportunity to eliminate bulk solvent use, reducing waste generation, but also unveils a new reaction strategy which enables the realization of reactions previously inaccessible in solution. While the majority of organic reactions facilitated by mechanical force traditionally follow two-electron transfer pathways similar to their solution-based counterparts, the field of mechanochemically induced single-electron transfer (SET) reactions has witnessed rapid development. This review outlines examples of mechanochemical reactions facilitated by the SET process, focusing on the reagents that initiate SET, thereby positioning mechanochemistry as a burgeoning field within the realm of single-electron chemistry.

Mechanical-Force-Induced Non-spontaneous Dehalogenative Deuteration of Aromatic Iodides Enabled by Using Piezoelectric Materials as a Redox Catalyst.

The development of green and efficient deuteration methods is of great significance for various fields such as organic synthesis, analytical chemistry, and medicinal chemistry. Herein, we have developed a dehalogenative deuteration strategy using piezoelectric materials as catalysts in a solid-phase system under ball-milling conditions. This non-spontaneous reaction is induced by mechanical force. D2O can serve as both a deuterium source and an electron donor in the transformation, eliminating the need for additional stoichiometric exogenous reductants. A series of (hetero)aryl iodides can be transformed into deuterated products with high deuterium incorporation. This method not only effectively overcomes existing synthetic challenges but can also be used for deuterium labelling of drug molecules and derivatives. Bioactivity experiments with deuterated drug molecule suggest that the D-ipriflavone enhances the inhibitory effects on osteoclast differentiation of BMDMs in vitro.

Triphasic Hydroxysilylation of Alkenes by Mechanically Piezoelectric Catalysis.

The 1,2-hydroxysilylation of alkenes is crucial for synthesizing organosilicon compounds which are key intermediates in material science, pharmaceuticals, and organic synthesis. The development of strategies employing hydrogen atom transfer pathways is currently hindered by the existence of various competing reactions. Herein, we reported a novel mechanochemical strategy for the triphasic 1,2-hydroxysilylation of alkenes through a single-electron-transfer pathway. Our approach not only circumvents competitive reactions to enable the first-ever 1,2-hydroxysilylation of unactivated alkenes but also pioneers the research in mechanic force-induced triphasic reactions under ambient conditions. This gentle method offers excellent compatibility with various functional groups, operates under simple and solvent-free conditions, ensures rapid reaction time. Preliminary mechanistic investigations suggest that silylboronate can be transformed to a silicon radical by highly polarized Li2TiO3 particles and oxygen under ball-milling condition.

Palladium-Catalyzed Carbonylative Hiyama-Denmark Reaction toward the Synthesis of Aryl Carbonyl-Containing Oxindoles.

A palladium-catalyzed domino Heck cyclization/carbonylative Hiyama-Denmark cross-coupling reaction between alkene-tethered aryl iodides and silylcarboxylic acids is presented. This reaction proceeds well without toxic carbon monoxide (CO) gas and has good functional group tolerance, providing an alternative access to carbonyl-containing oxindoles. In this transformation, silylcarboxylic acids play a dual role as a CO source and a nucleophile.

Characterization of structural and functional properties of soy protein isolate and sodium alginate interpenetrating polymer network hydrogels.

BACKGROUND: This study used enzymatic and Ca2+ cross-linking methods to prepare edible soy protein isolate (SPI) and sodium alginate (SA) interpenetrating polymer network hydrogels to overcome the disadvantages of traditional interpenetrating polymer network (IPN) hydrogels, such as poor performance, high toxicity, and inedibility. The influence of changes in SPI and SA mass ratio on the performance of SPI-SA IPN hydrogels was investigated. RESULTS: Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure of the hydrogels. Texture profile analysis (TPA), rheological properties, swelling rate, and Cell Counting Kit-8 (CCK-8) were used to evaluate physical and chemical properties and safety. The results showed that, compared with SPI hydrogel, IPN hydrogels had better gel properties and structural stability. As the mass ratio of SPI-SA IPN changed from 1:0.2 to 1:1, the gel network structure of hydrogels also tended to be dense and uniform. The water retention and mechanical properties of these hydrogels, such as storage modulus (G'), loss modulus (G"), and gel hardness increased significantly and were greater than those of the SPI hydrogel. Cytotoxicity tests were also performed. The biocompatibility of these hydrogels was good. CONCLUSIONS: This study proposes a new method to prepare food-grade IPN hydrogels with mechanical properties of SPI and SA, which may have strong potential for the development of new foods. © 2023 Society of Chemical Industry.

Enantioselective Intermolecular Radical Amidation and Amination of Benzylic C-H Bonds via Dual Copper and Photocatalysis.

A method for direct access to enantioenriched benzylic amides and carbamate-protected primary benzylamines by C-H functionalization is reported. The C-H substrate is used as limiting reagent with only a small excess of the unactivated amide or carbamate nucleophile. The enantioselective intermolecular dehydrogenative C-N bond formation is enabled by a combination of a chiral copper catalyst, a photocatalyst, and an oxidant, and it takes place under mild conditions, which allow for a broad substrate scope. The method is compatible with late-stage C-H functionalization, and it provides easy access to 15 N-labeled amides and amines starting from cheap 15 NH4 Cl.

Mechanochemical Synthesis of Aryl Fluorides by Using Ball Milling and a Piezoelectric Material as the Redox Catalyst.

Aryl fluorides are important structural motifs in many pharmaceuticals. Although the Balz-Schiemann reaction provides an entry to aryl fluorides from aryldiazonium tetrafluoroborates, it suffers from drawbacks such as long reaction time, high temperature, toxic solvent, toxic gas release, and low functional group tolerance. Here, we describe a general method for the synthesis of aryl fluorides from aryldiazonium tetrafluoroborates using a piezoelectric material as redox catalyst under ball milling conditions in the presence of Selectfluor. This approach effectively addresses the aforementioned limitations. Furthermore, the piezoelectric material can be recycled multiple times. Mechanistic investigations indicate that this fluorination reaction may proceed via a radical pathway, and Selectfluor plays a dual role as both a source of fluorine and a terminal reductant.

Determination of the regulatory network and function of the lysR-type transcriptional regulator of Lactiplantibacillus plantarum, LpLttR.

BACKGROUND: Lactiplantibacillus plantarum has various healthcare functions including the regulation of immunity and inflammation, reduction of serum cholesterol levels, anti-tumor activity, and maintenance of the balance of intestinal flora. However, the underlying metabolic and regulatory mechanisms of these processes remain unclear. Our previous studies have shown that the LysR type transcriptional regulator of L. plantarum (LpLttR) regulates the biotransformation of conjugated linoleic acids (CLAs) through the transcriptional activation of cla-dh (coding gene for CLA short-chain dehydrogenase) and cla-dc (coding gene for CLA acetoacetate decarboxylase). However, the regulatory network and function of LpLttR have not yet been characterized in L. plantarum. RESULTS: In this study, the regulatory role of LpLttR in various cellular processes was assessed using transcriptome analysis. The deletion of LpLttR had no evident influence on the bacterial growth. The transcriptome data showed that the expression of nine genes were positively regulated by LpLttR, and the expression of only two genes were negatively regulated. Through binding motif analysis and molecular interaction, we demonstrated that the regulatory region of the directly regulated genes contained a highly conserved sequence, consisting of a 15-base long box and rich in AT. CONCLUSION: This study revealed that LpLttR of L. plantarum did not play a global regulatory role similar to that of the other transcriptional regulators in this family. This study broadens our knowledge of LpLttR and provides a theoretical basis for the utilization of L. plantarum.

Rabeprazole plus amoxicillin dual therapy is equally effective to bismuth-containing quadruple therapy for Helicobacter pylori eradication in central China: A single-center, prospective, open-label, randomized-controlled trial.

BACKGROUND: Antibiotic resistance emerges as a major issue for Helicobacter pylori (H. pylori) treatment. High-dose dual therapy has recently shown encouraging results in H. pylori eradication, but it has yet to be validated in this H. pylori highly infected area; it is also not known if this concept can be extended to antibiotics other than amoxicillin, and factors that affect the eradication. We investigate if rabeprazole plus amoxicillin or furazolidone regimens could be a first-line therapy for H. pylori eradication, and factors that affect the curing rate. METHODS: This is a single-center, prospective, open-label, randomized-controlled trial. Naive patients (n=292) were randomly treated with bismuth-containing quadruple therapy (BQT), rabeprazole plus amoxicillin (RADT), or furazolidone (RFDT) groups. RADT and FADT use three times daily regimens. H. pylori diagnosis and eradication were determined and confirmed by 13 C-urea breath test. RESULTS: In per-protocol (PP) analysis, H. pylori eradication rate was 91.2% in BQT group, 89.6% in RADT, and 51.0% in RFDT group. In intention-to-treat (ITT) analysis, infection was eradicated in 86.7% of patients in BQT group, 85.8% in RADT, and 48.1% in RFDT groups, respectively. Noninferiority was confirmed between BQT and RADT groups. The incidence of side effects in BQT group was significantly higher than that in RADT group. Successful eradication was associated with lower body surface area (BSA) and low body mass index (BMI) in BQT group. Smoking and high BSA index reduced H. pylori eradication rate in RADT group. CONCLUSIONS: Rabeprazole-amoxicillin dual therapy is equally effective to the bismuth-containing quadruple therapy for H. pylori eradication with fewer side effects and saves use of one antibiotic per each treatment. Successful eradication is also associated with low BSA and non-smoking condition, which deserves future stratified analysis for refinement and optimization.

Chemical Constituents of the Deep-Sea-Derived Penicillium citreonigrum MCCC 3A00169 and Their Antiproliferative Effects.

Six new citreoviridins (citreoviridins J-O, 1-6) and twenty-two known compounds (7-28) were isolated from the deep-sea-derived Penicillium citreonigrum MCCC 3A00169. The structures of the new compounds were determined by spectroscopic methods, including the HRESIMS, NMR, ECD calculations, and dimolybdenum tetraacetate-induced CD (ICD) experiments. Citreoviridins J-O (1-6) are diastereomers of 6,7-epoxycitreoviridin with different chiral centers at C-2-C-7. Pyrenocine A (7), terrein (14), and citreoviridin (20) significantly induced apoptosis for HeLa cells with IC50 values of 5.4 µM, 11.3 µM, and 0.7 µM, respectively. To be specific, pyrenocine A could induce S phase arrest, while terrein and citreoviridin could obviously induce G0-G1 phase arrest. Citreoviridin could inhibit mTOR activity in HeLa cells.

LysR Family Regulator LttR Controls Production of Conjugated Linoleic Acid in Lactobacillus plantarum by Directly Activating the cla Operon.

Conjugated linoleic acids (CLAs) have attracted more attention as functional lipids due to their potential physiological activities, including anticancer, anti-inflammatory, anti-cardiovascular disease, and antidiabetes activities. Microbiological synthesis of CLA has become a compelling method due to its high isomer selectivity and convenient separation and purification processes. In Lactobacillus plantarum, the generation of CLA from linoleic acids (LAs) requires the combination of CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC), which are separately encoded by cla-hy, cla-dh, and cla-dc. However, the regulatory mechanisms of CLA synthesis remain unknown. In this study, we found that a LysR family transcriptional regulator, LTTR, directly bound to the promoter region of the cla operon and activated the transcription of cla-dh and cla-dc. The binding motif was also predicted by bioinformatics analysis and verified by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting assays. The lttR overexpression strain showed a 5-fold increase in CLA production. Moreover, we uncovered that the transcription of lttR is activated by LA. These results indicate that LttR senses LA and promotes CLA production by activating the transcription of cla-dh and cla-dc. This study reveals a new regulatory mechanism in CLA biotransformation and provides a new potential metabolic engineering strategy to increase the yield of CLA.IMPORTANCE Our work has identified a novel transcriptional regulator, LTTR, that regulates the production of CLA by activating the transcription of cla-dh and cla-dc, essential genes participating in CLA synthesis in Lactobacillus plantarum This study provides insight into the regulatory mechanism of CLA synthesis and broadens our understanding of the synthesis and regulatory mechanisms of the biosynthesis of CLA.

Whole family-based Helicobacter pylori eradication is a superior strategy to single-infected patient treatment approach: A systematic review and meta-analysis.

BACKGROUND: Two critical concerns during Helicobacter pylori (H. pylori) eradication are the successful eradication and recurrence. It is debatable whether whole family-based H. pylori treatment regimen might have any advantage over single-infected patient treatment approach in increasing eradication rate and reducing recurrence rate. We conduct systematic review and meta-analysis to compare the efficacy of these two treatment regimens in order to provide clinical practice a better option for H. pylori eradication. METHODS: Randomized controlled trials evaluating H. pylori eradication and recurrence in whole family-based treatment group (WFTG) versus single-infected patient treatment group (SPTG) were collected from published literature up to July 2020 from common databases. Pooled results were analyzed using either fixed-effect or random-effect model. Results were expressed as the odds ratio (OR) and 95% confidence interval (CI). RESULTS: A total of 1751 relevant articles were identified, and 12 studies were eligible for analysis. Among them: (a) Eight articles including 1198 patients were selected to analyze H. pylori eradication rate, pooled result showed that eradication rate of WFTG was higher than that of SPTG (OR=2.93; 95% CI 1.68-5.13). Stratified analysis showed that H. pylori eradication rate in WFTG were higher over SPTG in children subgroup, but had no difference in spouse subgroup. (b) Six studies including 881 patients were analyzed for recurrence rate between the two groups, pooled analysis showed that the overall recurrence rate of WFTG was lower than that of SPTG (OR=0.3; 95% CI 0.19-0.48). Stratified analysis showed that the recurrence rate in WFTG was lower over SPTG at 6, 12, 18, and more than 24 months post-treatment subgroups. CONCLUSION: Whole family-based H. pylori treatment can partially increase eradication rate and reduce recurrence rate over single-infected patient treatment approach, the results provide clinical practice a novel notion for H. pylori eradication and infection prevention.

Recent Research Advances in Small Regulatory RNAs in Streptococcus.

Small non-coding RNAs (sRNAs) are a class of regulatory RNAs 20-500 nucleotides in length, which have recently been discovered in prokaryotic organisms. sRNAs are key regulators in many biological processes, such as sensing various environmental changes and regulating intracellular gene expression through binding target mRNAs or proteins. Bacterial sRNAs have recently been rapidly mined, thus providing new insights into the regulatory network of biological functions in prokaryotes. Although most bacterial sRNAs have been discovered and studied in Escherichia coli and other Gram-negative bacteria, sRNAs have increasingly been predicted and verified in Gram-positive bacteria in the past decade. The genus Streptococcus includes many commensal and pathogenic Gram-positive bacteria. However, current understanding of sRNA-mediated regulation in Streptococcus is limited. Most known sRNAs in Streptococcus are associated with the regulation of virulence. In this review, we summarize recent advances in understanding of the functions and mechanisms of sRNAs in Streptococcus, and we discuss the RNA chaperone protein and synthetic sRNA-mediated gene regulation, with the aim of providing a reference for the study of microbial sRNAs.

Anti-Food Allergic Compounds from Penicillium griseofulvum MCCC 3A00225, a Deep-Sea-Derived Fungus.

Ten new (1-10) and 26 known (11-36) compounds were isolated from Penicillium griseofulvum MCCC 3A00225, a deep sea-derived fungus. The structures of the new compounds were determined by detailed analysis of the NMR and HRESIMS spectroscopic data. The absolute configurations were established by X-ray crystallography, Marfey's method, and the ICD method. All isolates were tested for in vitro anti-food allergic bioactivities in immunoglobulin (Ig) E-mediated rat basophilic leukemia (RBL)-2H3 cells. Compound 13 significantly decreased the degranulation release with an IC50 value of 60.3 µM, compared to that of 91.6 µM of the positive control, loratadine.

Reasons for the differences in biotransformation of conjugated linoleic acid by Lactobacillus plantarum.

Conjugated linoleic acid (CLA) has attracted a great deal of attention for its functions in weight loss, regulation of metabolism, and antioxidant capabilities. Many microorganisms, including rumen bacteria, propionic acid bacilli, and Lactobacillus, have CLA biotransformation ability. The CLA production capability of different species is different, as are those different strains of the same species. However, the reasons for this discrepancy remain unclear. In this study, 14 strains of Lactobacillus plantarum were found, through gas chromatography-mass spectrometry analysis, to be capable of converting linoleic acid to CLA. The transcriptional levels of CLA-related genes in the high- (AR195, WCFS1, and AR488) and low-yield strains (AR176, AR269, and AR611) were analyzed using real-time quantitative PCR. The transcriptional levels of cla-hy, cla-dh, and cla-dc in AR195 were the lowest in the exponential phase, but it had the highest CLA yield. Correlation analysis showed no correlation between CLA yield and the transcription level of these genes in the exponential phase. The results showed that a high transcriptional level in the exponential phase of cla-hy, cla-dh, and cla-dc did not necessarily lead to high CLA production. Investigation of the transcription level in different growth phases showed that the CLA biotransformation abilities of Lactobacillus plantarum strains significantly depended on the transcriptional maintenance of cla-hy, cla-dh, and cla-dc. We observed a correlation between CLA production and increased levels of cla-hy transcription, but a prerequisite is needed: the transcription of cla-dh and cla-dc should be upregulated and maintained a high transcriptional level during the platform period. This study provides a new strategy for screening high CLA-producing strains. It also lays a theoretical foundation for regulating CLA biotransformation and increasing the yield of CLA.

Single-plasmid systems based on CRISPR-Cas9 for gene editing in Lactococcus lactis.

Lactococcus lactis is a food-grade lactic acid bacterial species that is widely used in food and medical industries. Due to its relatively small genome and simple metabolism, L. lactis is commonly engineered to produce large quantities of recombinant proteins. The most common single-gene knockout strategy in L. lactis involves RecA-dependent homologous double-crossover recombination, which is relatively time-consuming and laborious. In this study, a precise and efficient genome-editing plasmid for L. lactis NZ9000 genome engineering, pLL, was established based on clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology. By studying the effects of different single guide RNA (sgRNA) promoters, the efficiency of gene deletion was optimized. For LLNZ_02045 (ldh), gene deletion efficiency of up to 50% was achieved. Effective sequential gene deletion of LLNZ_11240 (upp) and LLNZ_04580 (upp1) was also demonstrated using this tool. Additionally, the gene that encodes for uracil phosphoribosyltransferase was identified using this system. Similar robust gene deletion efficiencies of sgRNA that targeted different regions of a single gene suggested that gene deletion was not affected by the location of sgRNA binding. Thus, our study established a new gene-editing tool that may allow further investigation and understanding of the L. lactis NZ9000 genome.

High-efficiency transformation of Streptococcus thermophilus using electroporation.

BACKGROUND: Streptococcus thermophilus, one of the most important lactic acid bacteria, is widely used in food fermentation, which is beneficial to improve food quality. However, the current genetic transformation systems are inefficient for S. thermophilus S-3, which hinders its further study. RESULTS: We developed three electroporation transformation methods for S. thermophilus S-3, and optimized various parameters to enhance the transformation efficiency up to 1.3 × 106 CFU/µg DNA, which was 32-fold higher than that of unoptimized. Additionally, transcriptional analysis showed that a series of competence genes in S. thermophilus S-3 were remarkedly up-regulated after optimization, indicating that improvement of transformation efficiency was attributed to the expression level of competence genes. Furthermore, to prove their potential, expression of competence genes (comEA, cbpD and comX) were employed to increase transformation efficiency. The maximum transformation efficiency was obtained by overexpression of comEA, which was 14-fold higher than that of control. CONCLUSION: This is the first report of competence gene expression for enhancing transformability in S. thermophilus, which exerts a positive effect on the development of desirable characteristics strains. © 2021 Society of Chemical Industry.

Design and Applications of a SO2 Surrogate in Palladium-Catalyzed Direct Aminosulfonylation between Aryl Iodides and Amines.

A new SO2 surrogate is reported that is cheap, bench-stable, and can be accessed in just two steps from bulk chemicals. Essentially complete SO2 release is achieved in 5 minutes. Eight established sulfonylation reactions proceeded smoothly by ex situ formation of SO2 by utilizing a two-chamber system in combination with the SO2 surrogate. Furthermore, we report the first direct aminosulfonylation between aryl iodides and amines. Broad functional group tolerance is demonstrated, and the method is applicable to pharmaceutically relevant substrates, including heterocyclic substrates.

Nickel-Catalyzed Intramolecular Desulfitative C-N Coupling: A Synthesis of Aromatic Amines.

A nickel-catalyzed intramolecular C-N coupling reaction via SO2 extrusion is presented. The use of a catalytic amount of BPh3 allows the transformation to take place under much milder conditions (60 °C) than previously reported C-N coupling reactions by CO or CO2 extrusion (160-180 °C). In addition, this method displays good functional group tolerance and versatility, as it can be applied to the synthesis of dialkyl aryl amines, alkyl diaryl amines, and triaryl amines. The robustness of the desulfitative C-N coupling is demonstrated by three high-yielding gram-scale reactions.

CRISPR-Cas-mediated gene editing in lactic acid bacteria.

The high efficiency, convenience and diversity of clustered regular interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems are driving a technological revolution in the gene editing of lactic acid bacteria (LAB). Cas-RNA cassettes have been adopted as tools to perform gene deletion, insertion and point mutation in several species of LAB. In this article, we describe the basic mechanisms of the CRISPR-Cas system, and the current gene editing methods available, focusing on the CRISPR-Cas models developed for LAB. We also compare the different types of CRISPR-Cas-based genomic manipulations classified according to the different Cas proteins and the type of recombineering, and discuss the rapidly evolving landscape of CRISPR-Cas application in LAB.