Search

Based on flexible construction and broad bioactivity of ferulic acid, a series of novel α,β-unsaturated amide derivatives bearing α-aminophosphonate moiety were designed, synthesized and systematically evaluated for their antiviral activity. Bioassay results indicated that some compounds exhibited good antiviral activities against cucumber mosaic virus (CMV) and tobacco mosaic virus (TMV) in vivo. Especially, compound g18 showed excellent curative and protective activities against CMV, with half-maximal effective concentration (EC50) values of 284.67μg/mL and 216.30μg/mL, which were obviously superior to that of Ningnanmycin (352.08μg/mL and 262.53μg/mL). Preliminary structure-activity relationships (SARs) analysis revealed that the introduction of electron-withdrawing group at the 2-position or 4-position of the aromatic ring is favorable for antiviral activity. Present work provides a promising template for development of potential inhibitor of plant virus.

A series of novel 1,3,4-oxadiazole/thiadiazole-chalcone conjugates were synthesized and their in vitro and in vivo antiviral activities were evaluated via microscale thermophoresis method and half-leaf method, respectively. The in vitro results indicated that compounds 7g, 7l, 8h, and 8l displayed good antiviral activity against TMV, with the binding constant values of 5.93, 6.15, 6.02, and 5.04μM, respectively, which were comparable to that of Ninnanmycin (6.78μM) and even better than that of Ribavirin (99.25μM). The in vivo results demonstrated that compounds 7g, 7l, 8h, and 8l exhibited remarkable anti-TMV activity with the EC50 values of 33.66, 33.97, 33.87 and 30.57µg/mL, respectively, which were comparable to that of Ningnanmycin (36.85µg/mL) and superior to that of Ribavirin (88.52µg/mL). Interestingly, the trend of antiviral activity in vivo was consistent with the in vitro results.

A series of novel chalcone derivatives that contain the 1,1-dichloropropene moiety was designed and synthesized. Bioactivity assays showed that most of the target compounds exhibited moderate to good antiviral activity against tobacco mosaic virus (TMV) at 500 μg/mL. Among the target compounds, compound 7h showed the highest in vivo inactivation activity against TMV with the EC 50 and EC 90 value of 45.6 and 327.5 μg/mL, respectively, which was similar to that of Ningnanmycin (46.9 and 329.4 μg/mL) and superior to that of Ribavirin (145.1 and 793.1 μg/mL). Meanwhile, the microscale thermophoresis and fluorescence spectroscopy experiments showed that the compound 7h had a strong interaction with the tobacco mosaic virus coat protein.

In this paper, a variety of novel 1,3,4-oxadiazole derivatives possessing diamides were synthesized and tested for their antibacterial and antiviral activity. Preliminary antibacterial assays indicated that some intermediates and title compounds displayed excellent inhibition effects against plant pathogens Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas axonopodis pv. citri (Xac). Further studies revealed that compound H15 exhibited the strongest activities against Xoo and Xac with minimal EC50 values of 0.7 and 5.9 μg/mL, respectively. Antiviral bioassays suggested that some of these structures displayed appreciable curative activities and moderate protective effects against tobacco mosaic virus (TMV) in vivo. Among them, compound H8 exerted the best chemotherapeutic effect against TMV with the curative rate of 60.0% at 500 µg/mL, which was comparable with those of commercial agricultural antiviral agent ningnanmycin (54.2%). Given their significant biological activities, this kind of compound could serve as new leading compounds in the study of antibacterial and antiviral chemotherapy.

A series of vanillin derivatives incorporating a bis(2-hydroxyethyl)dithioacetal moiety was designed and synthesized via a facile method. A plausible reaction pathway was proposed and verified by computational studies. Bioassay results demonstrated that target compounds possessed good to excellent activities against potato virus Y (PVY) and cucumber mosaic virus (CMV), of which, compound 6f incorporating a bis(2-hydroxyethyl)dithioacetal moiety, exhibited the best curative and protection activities against PVY and CMV in vivo, with 50% effective concentration values of 217.6, 205.7 μg/mL and 206.3, 186.2 μg/mL, respectively, better than those of ribavirin (848.0, 808.1 μg/mL and 858.2, 766.5 μg/mL, respectively), dufulin (462.6, 454.8 μg/mL and 471.2, 465.4 μg/mL, respectively), and ningnanmycin (440.5, 425.3 μg/mL and 426.1, 405.3 μg/mL, respectively). Current studies provide support for the application of vanillin derivatives incorporating bis(2-hydroxyethyl)dithioacetal as new antiviral agents.

To find new lead compounds with high biological activity, a series of novel 4-methyl-1,2,3-thiadiazole-5-carboxaldehyde benzoyl hydrazone derivatives were designed and synthesized. Their structures were confirmed by 1 H NMR, 13 C NMR, IR spectrum and elemental analysis. Preliminary bioassay indicated that the title compounds exhibited moderate to strong fungicidal activity against six fungi in vitro at 50 μg/mL. Moreover, some of the title compounds exhibited good curative activity against TMV in vivo at 500 μg/mL. The structure-activity relationship analysis of compounds against Valsa mali showed that compounds containing halogen at the para position on phenyl exhibited the best activity. Especially compound 8k showed broad spectrum fungicidal activities against Valsa mali, Botrytis cinerea, Pythium aphanidermatum, Rhizoctonia solani, Fusarium moniliforme and Alternaria solani with the EC 50 values of 8.20, 24.42, 15.80, 40.53, 41.48, and 34.16 μg/mL, respectively.

BACKGROUND Ferulic acid and quinazoline derivatives possess good antiviral activities. In order to develop novel compounds with high antiviral activities, a series of ferulic acid ester derivatives containing quinazoline were synthesized and evaluated for their antiviral activities. RESULTS Bioassays indicated that some of the compounds exhibited good antiviral activities in vivo against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). One of the compounds demonstrated significant curative and protective activities against TMV and CMV, with EC50 values of 162.14, 114.61 and 255.49, 138.81 mg L−1, respectively, better than those of ningnanmycin (324.51, 168.84 and 373.88, 272.70 mg L−1). The values of q2 and r2 for comparative molecular field analysis and comparative molecular similarity index analysis in the TMV (0.508, 0.663 and 0.992, 0.930) and CMV (0.530, 0.626 and 0.997, 0.981) models presented good predictive abilities. CONCLUSION Some of the title compounds demonstrated good antiviral activities. Three-dimensional quantitative structure–activity relationship models revealed that the antiviral activities depend on steric and electrostatic properties. These results could provide significant structural insights for the design of highly active ferulic acid derivatives. © 2017 Society of Chemical Industry

To understand the antibacterial mechanism of the new bactericide 2-(methylsulfonyl)-5- (4-fluorobenzyl)-1, 3, 4-oxadiazole (Generic name: Fubianezuofeng), we performed label-free quantitative proteomics analysis of the response of Xanthomonas axonopodis pv. citri (Xac) strain 29-1 to Fubianezuofeng. A total of 1133 proteins were identified in the treatment and control groups. Upon treatment with the 1/2 minimum inhibitory concentration (MIC), 339 proteins were found to be differentially expressed (fold changes>1.5, p

The research in the field of asymmetric carbene organic catalysis has primarily focused on the activation of carbon atoms in non-aromatic scaffolds. Here we report a reaction mode of carbene catalysis that allows for aromatic aldehyde activation and remote oxygen atom functionalization. The addition of a carbene catalyst to the aldehyde moiety of 2-hydroxyl aryl aldehyde eventually enables dearomatization and remote OH activation. The catalytic process generates a type of carbene-derived intermediate with an oxygen atom as the reactive centre. Inexpensive achiral urea co-catalyst works cooperatively with the carbene catalyst, leading to consistent enhancement of the reaction enantioselectivity. Given the wide presence of aromatic moieties and heteroatoms in natural products and synthetic functional molecules, we expect our reaction mode to significantly expand the power of carbene catalysis in asymmetric chemical synthesis., Selective functionalization of aromatic compounds is important in synthetic chemistry. Here the authors report an N-heterocyclic carbene-catalysed approach for enantioselectively converting ortho-hydroxyaldehydes to cyclic products, via activation of both phenol and aldehyde groups.

A series of novel trans-ferulic acid derivatives containing a chalcone moiety were designed and synthesized to induce plant resistance. Antiviral activities of the compounds were evaluated. Bioassay results demonstrated that compounds F3, F6, F17, and F27 showed remarkable curative, protective, and inactivating activities against tobacco mosaic virus (TMV). With a 50% effective concentration (EC50) value of 98.78 μg mL–1, compound F27 exhibited the best protective activity compared with trans-ferulic acid (328.6 μg mL–1), dufulin (385.6 μg mL–1), and ningnanmycin (241.3 μg mL–1). This protective ability was associated with potentiation of defense-related enzyme activity and activation of photosynthesis of tobacco at an early stage. This notion was confirmed by up-regulated expression of stress responses and photosynthesis regulating proteins. This work revealed that F27 can induce resistance and enhance plant tolerance to TMV infection. Hence, F27 can be considered as a novel activator for inducing plant ...

Diacylhydrazine-based fluorescent probes are designed for selective detection of copper(II) and sulphide with two modes. The probes can not only be decomposed into rhodamine B by Cu2+, but can also be tuned to construct Cu ensembles for selective detection of sulphide.

To find new antiviral agents, novel chalcone derivatives containing a purine moiety were designed and synthesized by combining bioactive substructures. The antiviral activities of the derivatives against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV) were evaluated. Results showed that most of the derivatives showed antiviral activities. Compounds 3n and 3p exhibited excellent curative, protective and inactivation activities against TMV, with the EC50 values of 452.4, 416.2, 241.2 and 438.7, 418.6, 261.7 µg•mL−1, respectively, which were better than those of ribavirin (585.8, 436.0 and 268.7 µg•mL−1). Compounds 3n and 3p showed remarkable curative and protective activities against CMV. Compound 3n showed a moderate affinity to TMV coat protein, with binding constant Ka and Kd values of 1.5 × 104 L•mol−1 and 79.8 µmol•L−1, respectively. These findings provided an important structural insight for further designs of highly active chalcone derivatives and a basis for further study on their mechanism of action.

Simple and inexpensive polyhalides (CCl4 and C2Cl6 ) have been found to be effective and versatile oxidants in removing electrons from Breslow intermediates under N-heterocyclic carbene (NHC) catalysis. This oxidative reaction involves multiple single-electron-transfer (SET) processes and several radical intermediates. The α, β, and γ-carbon atoms of aldehydes and enals could be readily functionalized. Given the low cost of the oxidants and the broad applicability of the reactions, this study is expected to greatly enhance the feasibility of oxidative NHC catalysis for large-scale applications. Also this new SET radical process with polyhalides as single-electron oxidants will open a new avenue in the development of NHC-catalyzed radical reactions. Accepted version We acknowledge financial support from the National Natural Science Foundation of China (No. 21132003; No. 21472028), Singapore National Research Foundation (NRF-NRFI2016-06), the Ministry of Education of Singapore (MOE2013-T2-2-003), Nanyang Technological University (NTU, Singapore), China's Ministry of Education, Thousand Talent Plan, Guizhou Province Returned Oversea Student Science and Technology Activity Program, Science and Technology of Guizhou Province, and Guizhou University.

In our previous work, a series of novel benzothiazepine derivatives containing pyridine moiety were successfully synthesized through chalcone 1,3-dipolar cycloaddition and determined their antiviral activity against tobacco mosaic virus (TMV). Bioassay results indicated that most of these target compounds exhibited improved curative, protection, and inactivation activity in vivo than the commercial agent ningnanmycin. Particularly, compound 3m exhibited marked curative activity against TMV, with an EC50 value of 352.2 μM, which was even better than that of ningnanmycin. The compound was identified as the most promising candidate for inhibiting plant virus and an excellent compound with antiviral activities against TMV. Structure–activity relationship experiment indicated that the 1,5-benzothiazepine moiety is crucial for potent anti-TMV activity.

Tobacco mosaic virus (TMV) is an important plant virus that can cause considerable crop loss. Our group synthesized a series of enantiomeric α-aminophosphonate derivatives with high anti-TMV activities. The activity of (R)-diphenyl-1-(4-methylbenzothiazole-2-amino)-1-(thiphene-2-yl)-methylphosphonate (Q-R) was found to be superior to that of (S)-diphenyl-1-(4-methyl benzothiazole-2-amino)-1-(thiphene-2-yl)-methylphosphonate (Q-S). However, the mechanism for inhibition of the R-isomer (Q-R) of infection activity is not clear. Thus, we studied the interactions between Q-R and Q-S and TMV by using TMV coat proteins (CP) as a potential target for fluorescence spectroscopy, isothermal titration calorimetry, microscale thermophoresis, and molecular docking. Arg90 was found to play a major role in the interaction of Q-R with TMV CP, as demonstrated by the interaction experiments and the results of molecular modeling. The substitution of arginine with glycine resulted in a mutant that was significantly less sensitive to Q-R. These results indicate that Q-R undermines the structural stability of the TMV R90G virus particle by binding with Arg90, eventually leading to the loss of the virus' ability for infection.

A series of chiral thioureas derived from quinine were tested as catalysts in the enantioselective Michael additions of nitromethane to α,β-unsaturated ketones containing pyridine. The best results were obtained with the bifunctional catalyst prepared from 3,5-di(trifluoromethyl)-aniline under solvent-free conditions. This thiourea promoted the reaction with high enantioselectivities and chemical yields for aryl ketones. The origins of enantioselectivity were further investigated via experiment and computation. Meanwhile, the products from our reaction showed potent antibacterial activities against rice bacterial leaf blight, with the S-enantiomer performing much better than the R-enantiomer. Given the promising bioactivity of this class of molecules, our work is expected to offer important applications in developing future generations for drug design.

Through tuning and optimizing the phenyl substituents and alkyl length, a series of pyridinium-functionalized amphiphiles possessing potent antibacterial activity toward three types of plant pathogenic bacteria were obtained. Investigations on the inhibition effect of substituents on the phenyl ring towards the bioactivity suggested that the substitutional group was not the crucial factor for the bioactivity. In comparison, the antibacterial effects could be significantly enhanced with increasing the length of alkyl chains. Among these amphiphiles, 6c, 6f, 6h, 6i, 6k, 6l, 6n, and 6q exhibited remarkable inhibition activities against the three pathogenic bacteria with the half-maximal effective concentration (EC50) values within 0.128–1.98 µg/mL. Furthermore, the minimum EC50 values against the pathogens Xanthomonas oryzae pv. oryzae and Xanthomonas axonopodis pv. citri could reach to 0.128 and 0.403 µg/mL, respectively, which were decreased about four times than those of our previous results. Given their simple synthesis and biocidal antibacterial activity, this kind of amphiphiles could be developed as promising bactericides against plant bacterial diseases.

Chalcogenide glasses possess novel optical property in infrared range, which make them ideal candidates for photonic devices by laser direct writing. Precisely control of the refractive index manipulation in the material is the key to achieve high quality optical devices. In this work, diffraction gratings in chalcogenide As

Novel purine nucleoside derivatives containing a sulfonamide moiety were prepared, as well as their antiviral activities against potato virus Y (PVY), cucumber mosaic virus (CMV), and tobacco mosaic virus (TMV) were evaluated. The antiviral mechanisms of the compounds were investigated. Results showed that most of the compounds had good antiviral activities. Compound

A series of α-haloacetophenones and analogues were synthesized. The bioassays show that some target compounds have good antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac) and Meloidogyne incognita (M. incognita). Especially, the compound 24 has good in vitro and in vivo antibacterial activities against Xoo, the EC50 value, curative and protection activities are 0.09 mg/L, 48.9%, and 52.3%, respectively, which are better than the thiodiazole copper and bismerthiazol. Meanwhile, the compound 24 has good in vitro antibacterial activity against Xac, and has an EC50 value of 1.6 mg/L. Moreover, the compound 19 exhibits good nematicidal activity M. incognita, with the LC50 value of 1.0 mg/L, which is better than the positive control avermectin. In addition, the compound 24 can inhibit the formation of extracellular polysaccharide and biofilm of Xoo, and change the permeability of cell membrane. α-haloacetophenone and analogues have the advantages of simple structure, high efficiency, broad spectrum of biological activity, and can be used as antibacterial agents and nematicides or lead compounds in the future.

The fungal pathogen

Target validation of current drugs remains the major challenge for target-based drug discovery, especially for agrochemical discovery. The bactericide 0 represents a novel lead structure and has shown potent efficacy against those diseases that are extremely difficult to control, such as rice bacterial leaf blight. However, no detailed target analysis of this bactericide has been reported. Here, we developed a panel of 0-derived probes 1-6, in which a conservative modification (alkyne tag) was introduced to keep the antibacterial activity of 0 and provide functionality for target identification via click chemistry. With these cell-permeable probes, we were able to discover dihydrolipoamide S-succinyltransferase (DLST) as an unprecedented target in living cells. The probes showed good preference for DLST, especially probe 1, which demonstrated distinct selectivity and reactivity. Also, we reported 0 as the first covalent DLST inhibitor, which has been used to confirm the involvement of DLST in the regulation of energy production.

The present work designed and synthesized a series of dithioacetal derivatives containing dioxyether, as well as evaluated their antiviral activities against tobacco mosaic virus (TMV). Bioassays demonstrated that the target compounds showed excellent anti-TMV activities in vivo and in vitro . Compound 24c has excellent anti-TMV activities, and its curative, protective and inactivating activities for TMV were 50.9%, 58.9% and 81.8%, respectively, which are obviously superior to those of ribavirin (50.2%, 41.3% and 69.5%, respectively). Moreover, the EC 50 of the inactivating activities of the anti-TMV of compound 24c is 67.9 mg/L, which is superior to that of ribavirin (149.5 mg/L). Transmission electron microscopy showed that compound 24c caused great damage to the morphology of TMV particles, causing fracture and bending. Molecule docking model revealed that this compound formed five conventional hydrogen bonds with the active sites of amino acids GLN57, ASN73, TYR139, and SER138. Furthermore, the test results of Fluorescence titration and microscale thermophoresis showed that compound 24c has a strong binding force with TMV coat protein (TMV CP), with an association constant ( K a ) of 1.04×10 5 L/mol and dissociation constant ( K d ) of 1.6 ± 0.6 μ M. These results indicate that the dithioacetal derivatives containing dioxyether are worthy of further research and development as novel antiviral agents.

Tomato chlorosis virus (ToCV) is a newly reported plant virus that has rapidly spread to all parts of the world, resulting in a serious decline in tomato quality and yield due to the lack of effective control agents. In this study, the ToCV coat protein (ToCVCP) was expressed and purified in Escherichia coli, and a series of novel glucopyranoside derivatives containing a dithioacetal moiety was designed and synthesized. The binding affinity of these compounds to ToCVCP was determined using microscale thermophoresis. Results revealed that compounds 6b and 8a interacted with ToCVCP with Kd values of 0.12 and 0.21 μM, respectively. Quantitative reverse transcription polymerase chain reaction was used to evaluate the anti-ToCV activity of 6b and 8a in vivo, and both significantly reduced the expression level of ToCVCP gene in tomato compared with commercial antivirus agents. This study provides an efficient and convenient screening method for anti-ToCV agents and reliable support for the development of novel agrochemicals for ToCV.

The emergence and widespread occurrence of plant bacterial diseases that cause global production constraints have become major challenges to agriculture worldwide. To promote the discovery and development of new bactericides, imidazole-labeled 1,3,4-oxadiazole thioethers were first fabricated by integrating the crucially bioactive scaffolds of the imidazole motif and 1,3,4-oxadiazole skeleton in a single molecular architecture. Subsequently, a superior antibacterial compound A6 was gradually discovered possessing excellent competence against plant pathogens Xanthomonas oryzae pv oryzae and Xanthomonas axonopodis pv citri with EC50 values of 0.734 and 1.79 μg/mL, respectively. These values were better than those of commercial agents bismerthiazol (92.6 μg/mL) and thiodiazole copper (77.0 μg/mL). Further modifying the imidazole moiety into the imidazolium scaffold led to the discovery of an array of potent antibacterial compounds providing the corresponding minimum EC50 values of 0.295 and 0.607 μg/mL against the two strains. Moreover, a plausible action mechanism for attacking pathogens was proposed based on the concentration dependence of scanning electron microscopy, transmission electron microscopy, and fluorescence microscopy images. Given the simple molecular structures, easy synthetic procedure, and highly efficient bioactivity, imidazole (or imidazolium)-labeled 1,3,4-oxadiazole thioethers can be further explored and developed as promising indicators for the development of commercial drugs.

Rice bacterial leaf blight and leaf streak are two important bacterial diseases of rice, which can result in yield loss. Currently, effective antimicrobials for rice bacterial diseases are still lacking. Thus, to develop highly effective and low-risk bactericides, 31 novel 1,3,4-oxadiazole derivatives containing a cinnamic acid moiety were designed and synthesized. Bioassay results demonstrated that all compounds exhibited good antibacterial activities in vitro. Significantly, compounds 5r and 5t showed excellent antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc), with the 50% effective concentration (EC50) values of 0.58 and 0.34, and 0.44 and 0.20 &mu, g/mL, respectively. These compounds were much better than thiodiazole copper (123.10 and 161.52 &mu, g/mL) and bismerthiazol (85.66 and 110.96 &mu, g/mL). Moreover, compound 5t had better protective and curative activities against rice bacterial leaf blight and leaf streak than thiodiazole copper and bismerthiazol in vivo. Simultaneously, the in vivo efficacy of the compounds was demonstrated by real-time quantitative PCR to quantify bacterial titers. In addition, a three-dimensional quantitative structure&ndash, activity relationship model was created and presented good predictive ability. This work provides support for 1,3,4-oxadiazole derivatives containing a cinnamic acid moiety as a potential new bactericide for rice bacterial diseases.

A series of novel amide derivatives containing 1,3,4-thiadiazole moiety were synthesized and their bioactivities were evaluated. The compound 34 exhibited good nematocidal activities against Meloidogyne incognita in vitro and in vivo, the LC50 value and control effect were 6.5 mg/L and 83.3%, respectively. Meanwhile, it exhibited exciting antibacterial activities against Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. citri, and Ralstonia solanacearum, the EC50 values were 0.4, 6.7 and 5.1 mg/L, respectively, which were better than positive controls. The curative and protection activities under the greenhouse conditions of compound 34 against rice bacterial blight were 47.9 and 55.8%, respectively. The structure-activity relationship were analyzed in detail.

Femtosecond laser pulse of 800 nm wavelength and 150 fs temporal width ablation of As2S3 chalcogenide glasses is investigated by pump-probing technology. At lower laser fluence (8.26 mJ/cm2), the surface temperature dropping to the melting point is fast (about 43 ps), which results in a clean hole on the surface. As the laser fluence increases, it takes a longer time for lattice temperature to cool to the melting point at high fluence (about 200 ps for 18.58 mJ/cm2, about 400 ps for 30.98 mJ/cm2). The longer time of the surface heating temperature induces the melting pool in the center, and accelerates material diffusing and gathering surrounding the crater, resulting in the peripheral rim structure and droplet-like structure around the rim. In addition, the fabricated long periodic As2S3 glasses diffraction gratings can preserve with high diffraction efficiency by laser direct writing technology.

Plant immune activators can protect crops from plant virus pathogens by activating intrinsic immune mechanisms in plants and are widely used in agricultural production. In our previous work, we found that curcumin analogs exhibit excellent biological activity against plant viruses, especially protective activity. Inspired by these results, the active substructure of pentadienone and quinazoline were spliced to obtain curcumin analogs as potential exogenously induced resistant molecule. Bioassay results showed that compound A13 exhibited excellent protective activity for tobacco to against Tobacco mosaic virus (TMV) at 500 &mu, g/mL, with a value of 70.4 &plusmn, 2.6% compared with control treatments, which was better than that of the plant immune activator chitosan oligosaccharide (49.0 &plusmn, 5.9%). The protective activity is due to compound A13 inducing tobacco resistance to TMV, which was related to defense-related enzymes, defense-related genes, and photosynthesis. This was confirmed by the up-regulated expression of proteins that mediate stress responses and oxidative phosphorylation.

Hydrolysis and photolysis kinetics of Fubianezuofeng (FBEZF) in water were investigated in detail. The hydrolysis half-lives of FBEZF depending on pH, initial concentration, and temperature were (14.44 d at pH = 5, 1.60 d at pH = 7), (36.48 h at 1.0 mg L&minus, 1, 38.51 h at 5.0 mg L&minus, and 31.51 h at 10.0 mg L&minus, 1), and (77.02 h at 15 &deg, C, 38.51 h at 25 &deg, 19.80 h at 35 &deg, and 3.00 h at 45 &deg, C), respectively. The photolysis half-life of FBEZF in different initial concentrations were 8.77 h at 1.0 mg L&minus, 1, 8.35 h at 5.0 mg L&minus, 1, and 8.66 h at 10.0 mg L&minus, 1, respectively. Results indicated that the degradation of FBEZF followed first-order kinetics, as the initial concentration of FBEZF only had a slight effect on the UV irradiation effects, and the increase in pH and temperature can substantially accelerate the degradation. The hydrolysis Ea of FBEZF was 49.90 kJ mol&minus, 1, which indicates that FBEZF belongs to medium hydrolysis. In addition, the degradation products were identified using ultra-high-performance liquid chromatography coupled with an Orbitrap high-resolution mass spectrometer. One degradation product was extracted and further analyzed by 1H-NMR, 13C-NMR, 19F-NMR, and MS. The degradation product was identified as 2-(4-fluorobenazyl)-5-methoxy-1,3,4-oxadiazole, therefore a degradation mechanism of FBEZF in water was proposed. The research on FBEZF can be helpful for its safety assessment and increase the understanding of FBEZF in water environments.

Catalytic transfer hydrogenation (CTH) reactions are efficient transformation routes to upgrade biobased chemicals. Herein, we report a facile and template-free route to synthesize a series of heterogeneous nitrogen-containing alkyltriphosphonate–metal hybrids with enhancive Lewis acid and base sites, and their catalytic activity in converting biomass-derived carbonyl compounds to corresponding alcohols in 2-propanol. Particularly, a quantitative yield of furfuryl alcohol (FFA) was obtained from furfural (FUR) over organotriphosphate–zirconium hybrid (ZrPN) under mild conditions. The presence of Lewis basic sites adjacent to acid sites with an appropriate base/acid site ratio (1:0.7) in ZrPN significantly improved the yield of FFA. Mechanistic studies for the transformation of FUR to FFA with ZrPN in 2-propanol-d8 evidently indicate CTH reaction proceeding via a direct intermolecular hydrogen transfer route. It was also found that ZrPN could catalyze isomerization of C3–C6 aldoses to ketoses involving int...

Carbene-catalyzed reaction of carboxylic esters has the potential to offer effective synthetic solutions that cannot be readily achieved by using the more conventional aldehyde-type substrates. Here we report the first carbene-catalyzed dynamic kinetic resolution of α,α-disubstituted carboxylic esters with up to 99:1 er and 99% yield. The present study clearly illustrates the unique power of carbene-catalyzed reactions of readily available and easy to handle carboxylic esters. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

The asymmetric synthesis of enantiomerically pure α-aminophosphonates with high and bioselective activities is a challenge. Here, we report that both enantiomers of α-aminophosphonates bearing the N-benzothiazole moiety can be prepared in high yields (up to 99%) and excellent enantioselectivities (up to 99% ee) by using chiral thiourea organocatalysts. Evaluation of the antiviral activities of our reaction products against cucumber mosaic virus (CMV) led to promising hits with high and selective biological activities, wherein (R)-enantiomers exhibit higher biological activities than the corresponding (S)-enantiomers. Especially, compound (R)-3b with excellent anti-CMV activity (curative activity, 72.3%; protection activity, 56.9%; and inactivation activity, 96.9%) at 500 μg/mL emerged as a potential inhibitor of the plant virus. The difference in the selective bioactivity could be affected by the combination mode of the three-dimensional space between the enantiomers of α-aminophosphonate and cucumber mosaic virus coat protein (CMV-CP) via florescence spectroscopy and molecular docking.

A series of novel purine derivatives containing 1,4-pentadien-3-one moiety were designed and synthesized. The optimal conditions for the synthesis of the target compounds E 1 –E 25 were as follows: solvent, DMF; catalyst, KOH; temperature, 40 °C; time, 2 h; and molar equivalent of A:D:Catalyst, 1:0.8:1.2. Antiviral bioassays indicated that compounds E 1 , E 3 , E 5 , E 7 , E 18 , and E 19 showed excellent protection activities, with EC50 values of 188.9, 194.6, 125.2, 134.1, 137.8, and 195.4 µg/mL, respectively, which were better than that of Ningnanmycin (271.2 μg/mL). To the best of our knowledge, this study is the first report on the design, synthesis, and antiviral activity of novel purine derivatives containing 1,4-pentadien-3-one moiety.

Benzocoumarin is an important structural motif widely found in natural products and synthetic molecules. Traditional methods for the synthesis of benzocoumarins and their derivatives require multiple steps, typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal‐catalyzed coupling or carbon‐hydrogen bond activation reactions starting with pre‐existing aryl frameworks in the substrates. Here we report a new strategy for the green and rapid access to benzocoumarins and their derivatives. Our method uses readily available unsaturated aldehydes and coumarins as the substrates and air as the green oxidant. The overall reaction proceeds through a formal [4+2] process to construct a new benzene ring and thus to afford benzocoumarins in essentially a single step. No metal catalysts were used; no toxic or expensive reagents were involved. The power of our new approach is further demonstrated in a concise formal total synthesis of cannabinol, a bioactive natural product. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

In this study, thirty 1,3,4-oxadiazole sulfone derivatives containing 3,4-dichloroisothiazolamide moiety were designed and synthesized, and their antibacterial activities were evaluated. Bioassay results showed that some compounds exhibited excellent antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) in vitro and in vivo. Notably, the EC50 values of compounds 2 and 3 against Xoo were 0.79 and 0.85 μg/mL, respectively, which were superior to those of the control agents isotianil, bismerthiazol, and thiodiazole copper. In addition, in vivo antibacterial activities revealed that the compound 2 at 50 μg/mL possessed protective and curative activities of 43.99% and 41.06% against Xoo, respectively, which were better than positive controls. Furthermore, the preliminary mechanism study disclosed that compound 2 exhibited effective antibacterial activity against Xoo by inhibiting the formation of extracellular polysaccharides from Xoo, increasing cell permeability, and changing the shape of cells. This study suggested that 1,3,4-oxadiazole sulfone derivatives containing 3,4-dichloroisothiazolamide moiety displayed excellent antibacterial activity and could be further explored and developed as commercial pesticides.

Emulsion stability is a key physical characteristic in the preparation and use of emulsions. In this study, the interaction forces between two droplets in different solutions were measured by a modified DCAT21 tensiometer equipped with a high-frequency digital camera which can capture the droplets coalesce process and correspondingly force curves at the same time. The results indicate that for pure surfactant solution, only when the concentration exceeds the critical micelle concentration, sufficient surfactant molecules are adsorbed on the oil-water interface to form a high-strength interface film, so as to prevent droplet coalescence and improve the emulsion stability. However, for pesticide solution, the active ingredient with a certain surface activity will reduce the interfacial tension of the solution. We also found that the active ingredient and surfactant molecules exhibit competitive adsorption in the same phase and mixed adsorption in different phases, which have different effects on the emulsion stability. This study compared the stability of the pure surfactant solution and pesticide solution through microscopic observed the change of force and the coalescence phenomenon in the dynamic process of droplet contact which can advance our understanding of the mechanism of the emulsion stability.

On the basis of the active substructure combination principle, 24 novel synthesis of novel bis-sulfoxide derivatives bearing acylhydrazone and benzothiazole moieties as potential antibacterial agents were designed and synthesized. The bioactivity assay results showed that many compounds had significant in vitro inhibitory effects against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas citri pv. citri (Xac). Notably, compound 4b had the best in vitro antibacterial activity against Xoo at an half-maximal effective concentration value of 11.4 μg/mL, which was superior to those of thiodiazole copper (TDC) and bismerthiazol (BMT). Compared with TDC and BMT, compound 4b was more effective in vivo controlling rice bacterial leaf blight with curative and protection activities of 42.5% and 40.3%, respectively. In addition, compound 4b can influence biofilm formation, inhibit extracellular polysaccharide production, and ultimately reduce the pathogenicity of Xoo. All the results indicated that bis-sulfoxide derivatives bearing acylhydrazone and benzothiazole moieties can be used for the development of small-molecule pesticides with high antibacterial activity.

A polysaccharide DNPE6(11) was purified from Dendrobium nobile Lindl. (D. nobile Lindl.). Its structural characteristic, antiviral activity, and preliminary mechanism were studied. The structural characteristic analysis indicated that DNPE6(11) was a novel homogenous heteropolysaccharide from D. nobile Lindl. Bioactivity assays indicated that DNPE6(11) possessed outstanding curative and inactivating activities against cucumber mosaic virus, which were superior to chitosan oligosaccharide and lentinan. Additionally, DNPE6(11) exhibited notable protective activity against potato virus Y, which was better than Ningnanmycin. Furthermore, the preliminary mechanism study found that DNPE6(11) cannot accumulate salicylic acid to induce systemic acquired resistance, but had a strong binding capacity for cucumber mosaic virus coat protein. Therefore, DNPE6(11) could be considered as a promising antiviral agent to study in the future.

Seventy-two novel 1,3,4-oxadiazole thioether derivatives containing different flexible-chain moieties were designed and synthesized. The nematicidal activities of all the title compounds were evaluated, and some compounds showed excellent nematicidal activities against citrus nematodes. The compounds 15, 16, 18, 27, 41, 42, 44, 53, and 71 had the mortality to citrus nematodes of 92.5, 93.7, 90.3, 91.5, 92.6, 92.8, 93.5, 91.3, and 91.0% at the concentration of 100 mg/L, which were better than the control agent of avermectin (85.9%). After the test concentration was reduced to 50 mg/L, the nematicidal activities of the compounds 16, 42, 44, 53, and 71 were still superior to avermectin (65.1%), with the mortality of 72.3, 71.3, 70.6, 71.1, and 73.9%, respectively. The LC50 values of the compounds 16, 42, 44, 53, and 71 were 16.3, 18.8, 20.8, 17.5, and 14.7 mg/L, which were better than the commercial positive control agent of avermectin (24.8 mg/L). Meanwhile, the qualitative and quantitative analysis of the pesticide-likeness shows that compound 71 exhibits the potential insecticide-likeness. This work indicates that novel 1,3,4-oxadiazole thioether derivatives containing flexible-chains deserve further research as potential nematicides to protect citrus crops in the future.

Thirty-five novel chromone derivatives containing dithioacetal moiety were designed, synthesized, and their anti-TMV activities were evaluated through half-leaf method. The results showed compound c23 illustrates highly curative, protective and inactivating activities against TMV at 500 mg/L, with the values of 68.8%, 58.8%, 86.0% respectively, which were superior to that of Ribavirin (42.3%, 49.8%, 68.4%, respectively) and similar to that of Ningnanmycin (59.4%, 52.4%, 88.4%, respectively). The EC50 value of inactivating activities of compound c23 is 9.3 mg/L, which was better than that of Ribavirin (135.2 mg/L), and equivalent to that of Ningnanmycin (8.8 mg/L). Furthermore, compound c23 can destroy the integrity of TMV-CP, resulting in reduced infectivity of TMV. Meanwhile, compound c23 can combine with TMV protein coat and hydrolyze TMV protein coat to impact the process of self-assembling of TMV, with the association constant (Kd) 4.5 mg/L. This finding suggests that chromone derivatives containing dithioacetal moiety can be used as new antiviral agent.

Multipoint Cauchy method (MCM) is presented to investigate the refractive index and dispersion for each of Ge20Sb15Se65 and Ge28Sb12Se60 chalcogenide thin films at any wavelength in the transmission spectrum based on the regional approach method and Cauchy fitting. We theoretically calculate and compare the refractive index and dispersion curves obtained by using six different models. The results show that the most accurate results are obtained by the MCM. Two Ge—Sb—Se films are prepared by magnetron sputtering experimentally, and transmission spectrum curves are measured by Fourier infrared spectrometer, the noise is removed by segmental filtering and then the refractive index, dispersion, absorption coefficient, and optical band gap of the two films ina range of 500–2500 nm are obtained by the MCM. The results show that the refractive index of Ge28Sb12Se60 film is larger than that of Ge20Sb15Se65 film, which is caused by the higher polarizability and density of the former. The refractive indexes of both films decrease with wavelength increasing, so the long waves travel faster than short waves in the two films. The optical band gap of Ge28Sb12Se60 film (1.675 eV) is smaller than that of Ge20Sb15Se65 film (1.729 eV), and the corresponding wavelengths of the two are 740.3 nm and 717.2 nm. Finally, the microstructures of the two films are characterized by Raman spectra, and the reasons why the two chalcogenide films have different optical properties are explained from the bonding properties between the atoms.

Rice stripe virus (RSV) is naturally transmitted by the small brown planthopper and infects plants of the family Poaceae. Under laboratory conditions, RSV can infect Nicotiana benthamiana by mechanical inoculation, providing a useful system to study RSV–plant interactions. Measurements of CO2 assimilation ability and PSII photochemical efficiency showed that these were both reduced in N. benthamiana plants infected by RSV. These plants also had decreased expression of the N. benthamiana Phosphoribulokinases (NbPRKs), the key gene in the Calvin cycle. When the NbPRKs were silenced using the TRV-Virus Induced Gene Silencing system, the plants had decreased CO2 assimilation ability, indicating that the downregulated expression of NbPRKs contributes to the reduced CO2 assimilation ability of RSV-infected plants. Additionally, NbPRKs-silenced plants were more resistant to RSV. Similarly, resistance was enhanced by silencing of either N. benthamiana Rubisco small subunit (NbRbCS) or Phosphoglycerate kinase (NbPGK), two other key genes in the Calvin cycle. Conversely, transgenic plants overexpressing NbPRK1 were more susceptible to RSV infection. The results suggest that a normally functional Calvin cycle may be necessary for RSV infection of N. benthamiana.

Pesticide spray droplets can damage ecological environments and negatively affect biodiversity if they reach nontarget areas. Effective retention of pesticide droplets on plant surfaces is an important challenge. In this study, a high-speed camera was utilized to visualize the bounce behavior of droplets of different pesticide solutions on rice leaf surfaces. We explored the addition of surfactants (SAAs) to different pesticide solutions and altered a pesticide solution system to prevent or regulate droplet bounce behavior. Experimental results indicate that the addition of SAAs to a pesticide solution can inhibit the bouncing of droplets on rice leaf surfaces. Additionally, a water-in-oil (EO) emulsion not only can significantly inhibit droplet rebound on a superhydrophobic surface, but also can quickly and automatically spread pesticide droplets to maximize the wetting area. Therefore, this work effectively improves the utilization of pesticides and reduces environmental pollution.

Femtosecond (fs) laser-induced functional microstructure in transparent chalcogenide film has potential application value in the field of novel infrared micro-nano photonic devices. Refractive index and thickness control of the film are crucial to manufacture infrared photonic devices. However, the changes of the refractive index and thickness induced by fs laser are too tiny to be characterized. In this condition, we designed and developed a method for studying the influencing factors of small refractive index changes induced by fs laser irradiation process. We obtained 64 different modified regions in chalcogenide film by using the laser direct writing technology. The transmission spectra of these fs laser-modified regions were recorded by use of micro-FTIR spectrometer. The refractive index and thickness of the transparent film before and after irradiation were calculated by an improved Swanepoel method. The dependence of the refractive index variation and the photo-expansion in the chalcogenide film on irradiation parameters (laser power and stage translational speed) was obtained quantitatively for the first time as far as our knowledge. The results show that the transparent chalcogenide film exhibits expansion and decreasing refractive index after fs laser irradiation. The transition threshold from non-thermal to thermal has been estimated for the Ge20Sb15Se65 film to be ~15.6 GW/cm2. There is a linear relationship between refractive index change and photo-expansion around the threshold. Raman spectroscopy analysis of the modified area suggests that the change of refractive index and thickness may be due to the reduction in glass network connectivity of the Ge-based film induced by fs laser.

A series of pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety were synthesized, characterised, and evaluated for their activity against tobacco mosaic virus (TMV). Biological assays indicated that several of the derivatives exhibited significant activity against TMV. In particularly, compounds 5y and 5aa displayed excellent inactivating activity against TMV, with half maximal effective concentration (EC50) values of 70.3 and 53.65 μg/mL, respectively, which were much better than that of ribavirin (150.45 μg/mL), and 5aa was superior to ningnanmycin (EC50 = 55.35 μg/mL). Interactions of compounds 5y and 5aa with TMV coat protein (TMV-CP) were investigated using microscale thermophoresis and molecular docking. Compounds 5y and 5aa displayed strong binding capability to TMV-CP with dissociation constant (Kd) values of 22.6 and 9.8 μM, respectively. These findings indicate that pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base may be potential antiviral agents.