Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
316
result(s) for
"Jin, Hong-Lin"
Sort by:
Oxidation of difluorocarbene and subsequent trifluoromethoxylation
As a versatile intermediate, difluorocarbene is an electron-deficient transient species, meaning that its oxidation would be challenging. Herein we show that the oxidation of difluorocarbene could occur smoothly to generate carbonyl fluoride. The oxidation process is confirmed by successful trifluoromethoxylation,
18
O-trifluoromethoxylation, the observation of AgOCF
3
species, and DFT calculations.
Difluorocarbene is a versatile and efficient intermediate for fluorine incorporation. Here, the authors show that difluorocarbene can be oxidized to carbonyl fluoride and this process is confirmed in
18
O-trifluoromethoxylation reactions, by observation of AgOCF
3
species and theory.
Journal Article
BrCF2CN for photocatalytic cyanodifluoromethylation
Considering the unique electronic properties of the CF
2
and the CN groups, the CF
2
CN group has significant potential in drug and agrochemical development, as well as material sciences. However, incorporating a CF
2
CN group remains a considerable challenge. In this work, we disclose a use of bromodifluoroacetonitrile (BrCF
2
CN), a cost-effective and readily available reagent, as a radical source for cyanodifluoromethylation of alkyl alkenes, aryl alkenes, alkynes, and (hetero)arenes under photocatalytic conditions. This protocol demonstrates an exceptionally broad substrate scope and remarkable tolerance to various functional groups. Notably, the cyanodifluoromethylation of alkynes predominantly provides sterically hindered alkenes, a thermodynamically unfavorable outcome, and (hetero)arene C-H bonds are directly amenable to cyanodifluoromethylation without pre-functionalization.
Considering the unique electronic properties of the CF2 and the CN groups, the CF2CN group has significant potential in drug and agrochemical development, as well as material sciences. Here, the authors report bromodifluoroacetonitrile (BrCF2CN) as a radical source for cyanodifluoromethylation of alkyl alkenes, aryl alkenes, alkynes, and (hetero)arenes under photocatalytic conditions.
Journal Article
Contemporary synthetic strategies in organofluorine chemistry
Fluorinated molecules have a wide range of applications and are used as medicines, agrochemicals and refrigerants and in smartphone liquid crystal displays, photovoltaic solar cells, Teflon tapes and the coatings of textiles and buildings. Fluorination and fluoroalkylation — incorporation of a trifluoromethyl, difluoromethyl or monofluoromethyl group — are the major strategies used for the construction of carbon–fluorine bonds and fluorinated carbon–carbon bonds, respectively. The past two decades have witnessed a rapid growth in fluorination and fluoroalkylation methods thanks to the development of new reagents and catalysts. This Primer aims to provide an overview of state-of-the-art strategies in fluorination, trifluoromethylation, difluoromethylation and monofluoromethylation, with an emphasis on using C–H functionalization, although other strategies for fluorination and fluoroalkylation are also discussed. Further landmark achievements are expected in the fields of fluorination and fluoroalkylation as organofluorine compounds are used increasingly in everyday applications.This Primer describes contemporary fluorination and fluoroalkylation reactions in chemical synthesis. The authors describe the main fluorination and fluoroalkylation reactions. The many applications of these reactions in pharmaceuticals, imaging agents and agriculture are discussed, along with the history and future of synthetic organofluorine chemistry.
Journal Article
Nucleophilic arylation with tetraarylphosphonium salts
Organic phosphonium salts have served as important intermediates in synthetic chemistry. But the use of a substituent on the positive phosphorus as a nucleophile to construct C–C bond remains a significant challenge. Here we report an efficient transition-metal-free protocol for the direct nucleophilic arylation of carbonyls and imines with tetraarylphosphonium salts in the presence of caesium carbonate. The aryl nucleophile generated from phosphonium salt shows low basicity and good nucleophilicity, as evidenced by the successful conversion of enolizable aldehydes and ketones. The reaction is not particularly sensitive to water, shows wide substrate scope, and is compatible with a variety of functional groups including cyano and ester groups. Compared with the arylmetallic reagents that are usually moisture sensitive, the phosphonium salts are shelf-stable and can be easily handled.
Carbon based nucleophiles often are synthetically limited by the high basicity/reactivity of the starting materials. Here, the authors show that tetraarylphosphonium salts can be induced to act as C-aryl nucleophiles for the addition to carbonyls and imines.
Journal Article
Resistance of Lepidopteran Egg Parasitoids, Trichogramma japonicum and Trichogramma chilonis, to Insecticides Used for Control of Rice Planthoppers
Trichogramma wasps are commonly used as biocontrol agents to manage lepidopteran rice pests in rice fields. However, lepidopteran pests synergistically occur with rice planthoppers which are not targeted by Trichogramma. The use of Trichogramma parasitoids in field-based pest control efforts is greatly affected by the application of insecticides targeting planthoppers. As such, insecticide-resistant strains of Trichogramma are urgently needed for the incorporation of these beneficial natural enemies into integrated pest management programs in rice agroecosystems. In the present study, Trichogramma japonicum Ahmead (Hymenoptera: Trichogrammitidae) and Trichogramma chilonis Ishii (Hymenoptera:Trichogrammitidae) were treated with sublethal doses of four insecticides which target rice planthoppers, to generate tolerant strains in the laboratory. The resistance rate of T. japonicum to imidacloprid was the highest (17.8-folds) after 10 successive treatments and experienced 2.5, 4.72, and 7.41-fold increases in tolerance to thiamethoxam, buprofezin, and nitenpyram, respectively. Tolerance of T. chilonis to imidacloprid, thiamethoxam, buprofezin, and nitenpyram were 8.8, 6.9, 4.43, and 5.67-fold greater, respectively. The emergence and deformity (without spreading wings or short wings) rates of T. japonicum and T. chilonis gradually recovered with an increased exposure time of treatments. The fecundity of T. japonicum treated with thiamethoxam was significantly higher than that of the control and T. chilonis treated with thiamethoxam and nitenpyra. Our results demonstrate that screening for insecticide-tolerant/resistant Trichogramma strains was feasible, especially in the pairing of T. japonicum and imidacloprid, which could provide a valuable biological control tool that can be combined with traditional chemical control strategies for use in IPM of rice agroecosystems.
Journal Article
Chemical Constituents of Caesalpinia decapetala (Roth) Alston
The current study targets the chemical constituents of Caesalpinia decapetala (Roth) Alston and investigates the bioactivities of the isolated compounds. Fourteen known compounds were isolated using column chromatography, and structural identification was performed by physical and spectral analyses. The biological activities of the compounds were also evaluated by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and 2,2-diphenlyl-1-picrylhydrazyl (DPPH) assays. Emodin (6), baicalein (9), and apigenin (12) displayed antitumor activities against the MGC-803 cell line, while quercetin (2), rutin (5), baicalein (9), and epicatechin (13) showed stronger DPPH scavenging activities compared with ascorbic acid. Andrographolide (1), quercetin (2), bergenin (4), rutin (5), emodin (6), betulin (7), baicalein (9), polydatin (10), salicin (11), and apigenin (12), were obtained from C. decapetala (Roth) Alston for the first time.
Journal Article
OsProT1 and OsProT3 Function to Mediate Proline- and γ-aminobutyric acid-specific Transport in Yeast and are Differentially Expressed in Rice (Oryza sativa L.)
BackgroundProline (Pro) and γ-aminobutyric acid (GABA) play important roles in plant development and stress tolerance. However, the molecular components responsible for the transport of these molecules in rice remain largely unknown.ResultsHere we identified OsProT1 and OsProT3 as functional transporters for Pro and GABA. Transient expression of eGFP-OsProTs in plant protoplasts revealed that both OsProT1 and OsProT3 are localized to the plasma membrane. Ectopic expression in a yeast mutant demonstrated that both OsProT1 and OsProT3 specifically mediate transport of Pro and GABA with affinity for Pro in the low affinity range. qRT-PCR analyses suggested that OsProT1 was preferentially expressed in leaf sheathes during vegetative growth, while OsProT3 exhibited relatively high expression levels in several tissues, including nodes, panicles and roots. Interestingly, both OsProT1 and OsProT3 were induced by cadmium stress in rice shoots.ConclusionsOur results suggested that plasma membrane-localized OsProT1 and OsProT3 efficiently transport Pro and GABA when ectopically expressed in yeast and appear to be involved in various physiological processes, including adaption to cadmium stress in rice plants.
Journal Article
S-9-PAHSA ameliorates cognitive decline in a type 2 diabetes mouse model by inhibiting oxidative stress and apoptosis via CAIII modulation
S-palmitic acid-9-hydroxy stearic acid (SP), a newly characterized endogenous lipid with multifaceted biological activities, is poised to shed light on its potential in diabetes-related cognitive disorder (DRCD). This study aims to uncover the effects of SP on DRCD and the underlying mechanisms.
C57BL/6 mice were fed with high-fat diet for 5 months to induce type 2 diabetes mellitus (T2DM). Subsequently, they received bilateral hippocampal injections of adeno-associated virus (AAV) carrying carbonic anhydrase III (CAIII) shRNA or control shRNA. Following one-month treatment with SP or vehicle, cognitive function was assessed using the Morris water maze and Y-maze tests. Oxidative stress and apoptosis were measured by Enzyme-linked Immunosorbent Assay (ELISA), and hippocampal neuronal morphology was examined through HE, Nissl, or NeuN staining. RNA sequencing (RNA seq), cell viability, tetramethylrhodamine ethyl ester (TMRE) staining, and mitoSOX assays were also performed in cultured PC12 cells.
Our findings demonstrated that CAIII played a pivotal role in enhancing cognitive function in T2DM mice by improving spatial memory. SP ameliorated hippocampal injury by CAIII-mediated AMPK/Sirt1/PGC1α pathway, Bcl-2/Bax ratio elevation, and cleaved-Caspase 3 reduction. CAIII participated in various biological processes in the effects of SP on PC12 cells, including cell viability, lactate dehydrogenase (LDH) release, antioxidant enzymes, the maintenance of mitochondrial membrane potential, and the reduction of mitochondrial reactive oxygen species (ROS).
Our study revealed that CAIII was integral to the effects of SP on DRCD, suggesting its potential as a therapeutic target for DRCD.
Journal Article
S‐9‐PAHSA's neuroprotective effect mediated by CAIII suppresses apoptosis and oxidative stress in a mouse model of type 2 diabetes
Background With the rapidly increasing prevalence of metabolic diseases such as type 2 diabetes mellitus (T2DM), neuronal complications associated with these diseases have resulted in significant burdens on healthcare systems. Meanwhile, effective therapies have remained insufficient. A novel fatty acid called S‐9‐PAHSA has been reported to provide metabolic benefits in T2DM by regulating glucose metabolism. However, whether S‐9‐PAHSA has a neuroprotective effect in mouse models of T2DM remains unclear. Methods This in vivo study in mice fed a high‐fat diet (HFD) for 5 months used fasting blood glucose, glucose tolerance, and insulin tolerance tests to examine the effect of S‐9‐PAHSA on glucose metabolism. The Morris water maze test was also used to assess the impact of S‐9‐PAHSA on cognition in the mice, while the neuroprotective effect of S‐9‐PAHSA was evaluated by measuring the expression of proteins related to apoptosis and oxidative stress. In addition, an in vitro study in PC12 cells assessed apoptosis, oxidative stress, and mitochondrial membrane potential with or without CAIII knockdown to determine the role of CAIII in the neuroprotective effect of S‐9‐PAHSA. Results S‐9‐PAHSA reduced fasting blood glucose levels significantly, increased insulin sensitivity in the HFD mice and also suppressed apoptosis and oxidative stress in the cortex of the mice and PC12 cells in a diabetic setting. By suppressing oxidative stress and apoptosis, S‐9‐PAHSA protected both neuronal cells and microvascular endothelial cells in in vivo and in vitro diabetic environments. Interestingly, this protective effect of S‐9‐PAHSA was reduced significantly when CAIII was knocked down in the PC12 cells, suggesting that CAIII has a major role in the neuroprotective effect of S‐9‐PAHSA. However, overexpression of CAIII did not significantly enhance the protective effect of S‐9‐PAHSA. Conclusion S‐9‐PAHSA mediated by CAIII has the potential to exert a neuroprotective effect by suppressing apoptosis and oxidative stress in neuronal cells exposed to diabetic conditions. Furthermore, S‐9‐PAHSA has the capability to reduce fasting blood glucose and LDL levels and enhance insulin sensitivity in mice fed with HFD. S‐9‐PAHSA has the potential to exert neuroprotective effects mediated by CAIII via suppressing apoptosis and oxidative stress in neuronal cells exposed to diabetic conditions. Furthermore, it has the capability to reduce fasting blood glucose and LDL and enhance insulin sensitivity in mice with a high‐fat diet.
Journal Article