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The cationic nature of heptamethine cyanines gives them the capacity to form aggregates with salts by electrostatic interactions. In this work, NaCl promoted J-aggregate formation of aza-coating heptamethine cyanines is explored. NaCl can induce the N-benzyloxycarbonyl Cy-CO

Despite increasing awareness of the biological impacts of long-chain fatty acyl-CoA esters (LCACoAs), our knowledge about the subcellular distribution and regulatory functions of these acyl-CoA molecules is limited by a lack of methods for detecting LCACoAs in living cells. Here, we report development of a genetically encoded fluorescent sensor that enables ratiometric quantification of LCACoAs in living cells and subcellular compartments. We demonstrate how this FadR-cpYFP fusion "LACSer sensor" undergoes LCACoA-induced conformational changes reflected in easily detectable fluorescence responses, and show proof-of-concept for real-time monitoring of LCACoAs in human cells. Subsequently, we applied LACSer to investigate how disruption of ACSL enzymes differentially reduces cytosolic and mitochondrial LCACoA levels, and show how genetic disruption of an acyl-CoA binding protein (ACBP) alters mitochondrial accumulation of LCACoAs. Thus, our LACSer sensor achieves spatiotemporally precise detection of dynamic changes in endogenous LCACoA levels in living cells and yields mechanistic insights about metabolism and cellular regulation .

Herbicide resistance has become one of the foremost problems in crop production worldwide. New herbicides are required to manage weeds that have evolved resistance to the existing herbicides. However, relatively few herbicides with new modes of action (MOAs) have been discovered in the past two decades. Therefore, the discovery of new herbicides (i.e., new chemical classes or MOAs) remains a primary but ongoing strategy to overcome herbicide resistance and ensure crop production. In this mini-review, starting with the inherent characteristics of the target proteins and the inhibitor structures, we propose two strategies for the rational design of new herbicides and one computational method for the risk evaluation of target mutation-conferred herbicide resistance. The information presented here may improve the utilization of known targets and inspire the discovery of herbicides with new targets. We believe that these strategies may trigger the sustainable development of herbicides in the future. © 2021 Society of Chemical Industry.

Intron-containing genes have the ability to generate multiple transcript isoforms by splicing, thereby greatly expanding the eukaryotic transcriptome and proteome. In eukaryotic cells, precursor mRNA (pre-mRNA) splicing is performed by a mega-macromolecular complex defined as a spliceosome. Among its splicing components, U1 small nuclear ribonucleoprotein (U1 snRNP) is the smallest subcomplex involved in early spliceosome assembly and 5'-splice site recognition. Its central component, named U1-70K, has been extensively characterized in animals and yeast. Very few investigations on U1-70K genes have been conducted in plants, however. To this end, we performed a comprehensive study to systematically identify 115 U1-70K genes from 67 plant species, ranging from algae to angiosperms. Phylogenetic analysis suggested that the expansion of the plant U1-70K gene family was likely to have been driven by whole-genome duplications. Subsequent comparisons of gene structures, protein domains, promoter regions and conserved splicing patterns indicated that plant U1-70Ks are likely to preserve their conserved molecular function across plant lineages and play an important functional role in response to environmental stresses. Furthermore, genetic analysis using T-DNA insertion mutants suggested that Arabidopsis U1-70K may be involved in response to osmotic stress. Our results provide a general overview of this gene family in Viridiplantae and will act as a reference source for future mechanistic studies on this U1 snRNP-specific splicing factor.

The phytohormone abscisic acid (ABA) is the best‐known stress signaling molecule in plants. ABA protects sessile land plants from biotic and abiotic stresses. The conserved pyrabactin resistance/pyrabactin resistance‐like/regulatory component of ABA receptors (PYR/PYL/RCAR) perceives ABA and triggers a cascade of signaling events. A thorough knowledge of the sequential steps of ABA signaling will be necessary for the development of chemicals that control plant stress responses. The core components of the ABA signaling pathway have been identified with adequate characterization. The information available concerning ABA biosynthesis, transport, perception, and metabolism has enabled detailed functional studies on how the protective ability of ABA in plants might be modified to increase plant resistance to stress. Some of the significant contributions to chemical manipulation include ABA biosynthesis inhibitors, and ABA receptor agonists and antagonists. Chemical manipulation of key control points in ABA signaling is important for abiotic and biotic stress management in agriculture. However, a comprehensive review of the current knowledge of chemical manipulation of ABA signaling is lacking. Here, a thorough analysis of recent reports on small‐molecule modulation of ABA signaling is provided. The challenges and prospects in the chemical manipulation of ABA signaling for the development of ABA‐based agrochemicals are also discussed., Small molecules that can manipulate abscisic acid (ABA) signaling events are designed, developed, and evaluated. The ABA‐mediated stress adaptive responses of plants are mimicked by small molecules, and the ABA biosynthesis and catabolism events are altered by inhibitors. This approach is a novel way to gain chemical control over plant stress by using safer ABA‐based agrochemicals.

BACKGOUND Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first common enzyme in the biosynthetic pathway leading to the branched-chain amino acids in plants and a wide range of microorganisms. With the long-term and wide application of AHAS inhibitors, weed resistance is becoming a global problem, which leads to an urgent demand for novel inhibitors to antagonize both wild-type and resistant AHAS. RESULTS Pyrimidinyl-Salicylic acid derivatives, as one of the main classes of commercial AHAS herbicides, show potential anti-resistant bioactivity to wild-type and P197L mutant. In current work, a series of novel 2-benzoyloxy- 6-pyrimidinyl salicylic acid derivatives were designed through fragment-based drug discovery (FBDD). Fortunately, the newly synthesized compounds showed a good inhibitory activity against both wild-type and P197L mutant. Some compounds not only had a lower resistance factor value, but also showed an excellent inhibitory activity against wild type AHAS and P197L mutant. Furthermore greenhouse experiments showed compound 11 m displayed almost 100% inhibition against both wild-type and high-resistant Descurainia sophia at the dosage of 150 g.ai/ha. CONCLUSION The present work indicated that the 2-benzoyloxy- 6-pyrimidinyl salicylic acid motif was well worth further optimization. And compound 11 m can be used as a potential anti-resistant AHAS herbicide which requires further research.

The model eukaryotic yeast Saccharomyces cerevisiae has proven a useful model system in which prion biogenesis and elimination are studied. Several yeast prions exist in budding yeast and a number of studies now suggest that these alternate protein conformations may play important roles in the cell. During the last few years cellular factors affecting prion induction, propagation and elimination have been identified. Amongst these, proteins involved in the regulation of the actin cytoskeleton and dynamic membrane processes such as endocytosis have been found to play a critical role not only in facilitating de novo prion formation but also in prion propagation. Here we briefly review prion formation and maintenance with special attention given to the cellular processes that require the functionality of the actin cytoskeleton.

BACKGROUND 4-Hydroxyphenylpyruvate dioxygenase (HPPD) (EC 1.13.11.27) has been identified as one of the most promising target sites for herbicide discovery. To discover novel HPPD inhibitors with high herbicidal activity and improved crop selectivity, a series of novel triketone-containing quinazoline-2,4-dione derivatives possessing a variety of substituents at the N-1 position of the quinazoline-2,4-dione ring were designed and synthesised. RESULTS The results of in vitro tests and greenhouse experiments indicated that some analogues showed good HPPD inhibitory activity, with promising broad-spectrum herbicidal activity at a rate of 150 g AI ha−1. Most surprisingly, compound 11 h, 1-ethyl-6-(2-hydroxy-6-oxocyclohex-1-enecarbonyl)-3-(o-tolyl)quinazoline-2,4(1H,3H)-dione, showed the highest HPPD inhibition activity, with a Ki value of 0.005 μM, about 2 times more potent than mesotrione (Ki = 0.013 μM). Further greenhouse experiments indicated that compounds 11d and 11 h displayed strong and broad-spectrum post-emergent herbicidal activity even at a dosage as low as 37.5 g AI ha−1, which was superior to mesotrione. More importantly, compounds 11d and 11 h were safe for maize at a rate of 150 g AI ha−1, and compound 11d was safe for wheat as well. CONCLUSION The present work indicated that the triketone-containing quinazoline-2,4-dione motif could be a potential lead structure for further development of novel herbicides. © 2014 Society of Chemical Industry

Background Pyridalyl is a highly active insecticide against lepidopterous larvae, with a novel chemical structure not related to any other existing insecticide. To discover new pyridalyl analogues with high activity against resistant pests, a series of 1,1-dichloropropene derivatives bearing structurally diverse substituted heterocycle rings in place of the pyridine ring of pyridalyl were designed and synthesised. Results All of the title compounds were confirmed by (1)H NMR, (13)C NMR and high-resolution mass spectra. Two representative compounds (Ic and IIa) were further characterised by X-ray diffraction analysis. In addition, bioassays showed that most of the newly synthesised compounds displayed good insecticidal activity against Prodenia litura. Further determination of LD50 values and field trials identified compound IIa as the most promising candidate, which produced a much better 14 day control effect against diamondback moths and longer duration of efficacy than pyridalyl, indicating its potential for further development as a new insecticide for the control of lepidopteran insects. Conclusion Compound IIa has great potential for further development as a new insecticide for the control of lepidopteran insects.

Succinate-ubiquinone oxidoreductase (SQR, EC 1.3.5.1), also known as mitochondrial respiratory complex II or succinate dehydrogenase (SDH), catalyzes the oxidation of succinate to fumarate as part of the tricarboxylic acid cycle. SQR has been identified as a novel target of a large family of agricultural fungicides. However, the detailed mechanism of action between the fungicides and SQR is still unclear, and the bioactive conformation of fungicides in the SQR binding pocket has not been identified. In this study, the kinetics of porcine SQR inhibition by ten commercial carboxamide fungicides were measured, and noncompetitive inhibition was observed with respect to succinate, DCIP, and cytochrome c, while competitive inhibition was observed with respect to ubiquinone. With the aim to uncover the binding conformation of these fungicides, molecular docking, molecular dynamics simulation, and molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) calculations were then performed. The excellent correlation (r(2) =0.94) between the calculated (ΔGcal ) and experimental (ΔGexp ) binding free energies indicates that the obtained docking conformation could be the bioactive conformation. The acid moiety of carboxamide fungicides inserts into the ubiquinone binding site (Q-site) of SQR, forming van der Waals (vdW) interactions with C_R46, C_S42, B_I218, and B_P169, while the amine moiety extends to the mouth of the Q-site, forming vdW interactions with C_W35, C_I43, and C_I30. The carbonyl oxygen atom of the carboxamide forms hydrogen bonds with B_W173 and D_Y91. These findings provide valuable information for the design of more potent and specific inhibitors of SQR.

Antimycin and cyazofamid are specific inhibitors of the mitochondrial respiratory chain and bind to the Qi site of the cytochrome bc1 complex. With the aim to understand the detailed molecular inhibition mechanism of Qi inhibitors, we performed a comparative investigation of the inhibitory kinetics of them against the porcine bc1 complex. The results showed that antimycin is a slow tight-binding inhibitor of succinate-cytochrome c reductase (SCR) with Ki = 0.033 ± 0.00027 nm and non-competitive inhibition with respect to cytochrome c. Cyazofamid is a classical inhibitor of SCR with Ki = 12.90 ± 0.91 μm and a non-competitive inhibitor with respect to cytochrome c. Both of them show competitive inhibition with respect to substrate DBH2 . Further molecular docking and quantum mechanics calculations were performed. The results showed that antimycin underwent significant conformational change upon the binding. The energy barrier between the conformations in the crystal and in the binding pocket is ~13.63 kcal/mol. Antimycin formed an H-bond with Asp228 and two water-bridged H-bonds with Lys227 and His201, whereas cyazofamid formed only one H-bond with Asp228. The conformational change and the different hydrogen bonding network might account for why antimycin is a slow tight-binding inhibitor, whereas cyazofamid is a classic inhibitor.

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) is one of the most significant targets for a large family of inhibitors that may be used as herbicide, bactericide, fungicide, or photosensitizing activator to treat cancer through photodynamic therapy (PDT). Molecular docking and CoMFA were combined in a multistep framework with the ultimate goal of identifying important factor contributing to the activity of PPO inhibitors. As a continuation of the previous research work on the development of new PPO inhibitors, the bioassay results indicated that good PPO inhibitors were discovered in all of the three chemical series with IC50 values ranging from 0.010 to 0.061 µmol·L−1. Using the crystal structure of tobacco mitochondrial PPO (mtPPO) as template, all the compounds were docked into the enzyme active site. The docking pose of each compound was subsequently used in a receptor-based alignment, leading to the development of a significant CoMFA model with r2 value of 0.98 and q2 (cross validation r2) value of 0.63. This novel multistep framework gives insight into the structural characteristics for the binding of inhibitors, and it can be extended to other classes of PPO inhibitors. In addition, the simplicity of the proposed approach may be particularly applicable in virtual screening procedures.

Gibberellins (GAs) are phytohormones essential for many developmental processes in plants. In this work, fundamental mechanism of hormone perception by receptor GID1 has been studied by performing computational simulations, revealing a new GA-binding channel of GID1 and a novel hormone perception mechanism involving only one conformational state of GID1. The novel hormone perception mechanism demonstrated here is remarkably different from the previously proposed/speculated mechanism [Murase et al., Nature 2008, 456, 459] involving two conformational states ("OPEN" and "CLOSED") of GID1. According to the new perception mechanism, GA acts as a "conformational stabilizer," rather than the previously speculated "allosteric inducer," to induce the recognition of protein DELLA by GID1. The novel mechanistic insights obtained in this study provide a new starting point for further studies on the detailed molecular mechanisms of GID1 interacting with DELLA and various hormones and for mechanism-based rational design of novel, potent growth regulators that target crops and ornamental plants.

A palladium-catalyzed carbonylative coupling of aryl iodides with a (trifluoromethyl)copper reagent has been developed. A wide range of substrates have been transformed into their corresponding trifluoromethyl ketones in good to excellent yields under mild conditions with high efficiency and excellent functional-group compatibility. Preliminary mechanistic investigations suggest that the transmetallation of an acylpalladium intermediate with the (trifluoromethyl)copper reagent seems to be involved in the catalytic cycle. Notably, this report represents one of the few studies on carbonylative coupling with organocopper reagents.

A mild and facile approach to the title compounds, which are of interest in natural product and medicinal chemistry, becomes optimal in the presence of HClO4.

A new efficient method for the synthesis of functionalized 4-methyl-6-bulkyarylsalicylates via a microwave-promoted Suzuki cross-coupling is presented.

Strobilurins are one of the most important natural products with fungicidal activities and well known for their novel action mode, broad fungicidal spectrum, lower toxicity against mammalian cells, and environmentally benign characteristics. Design and syntheses of strobilurin analogues therefore have attracted great attention in the field of agrochemistry. Previously, we successfully developed a new molecular design method of pharmacophore-linked fragment virtual screening (PFVS) and discovered a lead compound (E)-methyl-2-(2-(((3-(imino-(phenyl)methyl)phenyl)thio)methyl)phenyl)-3-methoxyacrylate (1). To discover new strobilurin analogues with higher fungicidal activity, the structural modification of compound 1 was carried out guided by bioisosterism. A series of benzophenone derivatives 2a–2j were synthesized, among which compound 2j with a Ki value of 1.89 nmol/L was identified as the most promising inhibitor of porcine cytochrome bc1 complex, 157-fold improved binding affinity compared to the commercially available bc1 inhibitor Azoxystrobin (AZ). In addition, most of the new compounds displayed excellent fungicidal activity against Sphaerotheca fuliginea at the concentration of 200 µmol/L. The present work indicates that strobilurin analogues containing benzophenone side chains may be the ideal leads for future fungicide discovery.

Sclerotiorin, a chlorine-containing azaphilone-type natural product, was first isolated from Penicillium sclerotiorum and has been reported to exhibit weak fungicidal activity. Optimization of the substituents at the 3- and 5-positions of the sclerotiorin framework was investigated with the aim of discovering novel fungicides with improved activity. The design of sclerotiorin analogues involved replacing the diene side chain with a phenyl group or an aromatic- or heteroaromatic-containing aliphatic side chain. The designed compounds were synthesized by cycloisomerization and subsequent oxidation of suitable 2-alkynylbenzaldehydes, in which a variety of substituents were introduced using a Sonogashira coupling reaction. The structures of these newly prepared compounds were confirmed by 1H and 13C NMR spectroscopy, HRMS and single-crystal X-ray analysis. The antifungal activity of the synthesized compounds was evaluated against seven phytopathogenic species. Compounds 3, 9g and 9h were found to have a broad spectrum of fungicidal activity, and these structurally simpler products can be recognized as lead compounds for further optimization.

A novel three-component reaction of o-bromobenzaldehyde, terminal alkynes and tert-butyl amine has been established, which proceeded smoothly to give 3-substituted isoquinolines in good yields in the presence of palladium/copper catalysts under microwave irradiation.

Objective: Study of the nutrition pathway for lumbar intervertebral disk cartilage of normal goats. Methods: Four lumbar intervertebral disks from each of eight 24-month-old goats (32 disks) were studied. After the goats had been anesthetized, signal intensity changes in the regions of interest (ROI) were observed by dynamic contrast enhanced magnetic resonance scanning. Before and after enhancement at the time points of 0, 5, 10, and 30 mins, and 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 hs, the ROI signal intensity was measured, and the time-signal intensity curve and peak times analyzed. Results: Signal intensity in the vertebral bodies reached a peak at 0 min and decreased quickly thereafter. Signal intensity in the cartilage endplate zones reached the first peak at 30 mins and then went down slightly before increasing to a second peak at 2 hs. Signal intensity in the nuclei pulposus was negative within 5 mins, increased slowly to a peak at 2 hs, and declined thereafter. Conclusion: Nutrient metabolism of the lumbar intervertebral disks of normal goats occurs mainly through the cartilage end-plate pathway.

In order to search for novel fungicides with high activity, a series of 2-heteroaryl-4-chromanones were designed and synthesized via bioisosterism substitution. The structures of all new compounds were confirmed by spectroscopic methods and microanalyses. Preliminary bioassays indicated that some compounds showed fungicidal activity against Rhizoctonia solani, Fusarium oxysporum, Physalospora piricola and Cercospora beticola.

A novel series of 1-(4-chlorophenyl)-4-{[5-(alkylthio)-4-phenyl-4H-1,2,4-triazol-3-yl]methyl}-1,4-dihydro-5H-tetrazol-5-ones 6a-y were synthesized in good to excellent yields and their structures were identified by 1H nmr, 13C nmr, ms and elemental analysis. Determining the X-ray crystallography of compound 6j indicated that there were strong intermolecular hydrogen bonds in the stacking interactions. The bioassay results showed that compound 6k exhibited good insecticidal activities against T cinnabarinus at the dosage of 250 mg.L−1. To our knowledge, this is the first report about the insecticidal activity of tetrazolinone derivatives.

A one-pot liquid-phase combinatorial synthesis of 2-(4-oxo-4H-1-benzopyran-3-yl)-4-thiazolidinones bearing diverse substituents at the 3-position under microwave irradiation was successfully performed using 3-formyl chromone, primary amine, and mercaptoacetic acid as reactants. Compared to an identical library generated by conventional parallel synthesis, the microwave-assisted parallel synthesis approach dramatically decreased the reaction time from an average of 9 h to 5 min, and substantially increased the product yields. The coupling of microwave technology with liquid-phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:381–389, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20309

Indole represents one of the most important privileged scaffolds in drug discovery. Indole derivatives have the unique property of mimicking the structure of peptides and to bind reversibly to enzymes, which provide tremendous opportunities to discover novel drugs with different modes of action. There are seven indole-containing commercial drugs in the Top-200 Best Selling Drugs by US Retail Sales in 2012. There are also an amazing number of approved indole-containing drugs in the market as well as compounds currently going through different clinical phases or registration statuses. This review focused on the recent development of indole derivatives as antiviral agents with the following objectives: 1) To present one of the most comprehensive listings of indole antiviral agents, drugs on market or compounds in clinical trials; 2) To focus on recent developments of indole compounds (including natural products) and their antiviral activities, summarize the structure property, hoping to inspire new and even more creative approaches; 3) To offer perspectives on how indole scaffolds as a privileged structure might be exploited in the future.

Iminophosphorane 1 reacted with an aromatic isocyanate to unexpectedly give a mixture of carbodiimides 2, 3 and 4 through both the normal and the abnormal aza-Wittig reactions. 3-Aminoimidazolone 10 was obtained from the reaction of hydrazine hydrate with carbodiimide 2. Reaction of 10 with triphenyphosphane, hexachloroethane and triethylamine produced iminophosphorane 11 in good yield. A tandem aza-Wittig reaction of iminophosphorane 11 with isocyanate or CS2 generated 3,5-dihydro-6H-imidazo[1,2-b]-1,2,4-triazol-6-ones 13 or 15 in satisfactory yield. Carbodiimides 18, obtained from normal aza-Wittig reactions of vinyl iminophosphorane 17 with aromatic isocyanates, reacted with hydrazine to give 2-arylamino-3-amino-4H-imidazol-4-ones 20. One-pot reactions of 2-arylamino-3-amino-4H-imidazol-4-ones 20 with isocyanates (or acyl chlorides), triphenyphosphane, hexachloroethane and triethylamine produced 3,5-dihydro-6H-imidazo[1,2-b]-1,2,4-triazol-6-ones 22 (or 23) in good yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The equilibrium geometries, electronic structures, and electrostatic potentials of a series of substituted phenyl triazolinones of protoporphyrinogen oxidase (PPO) inhibitors have been investigated by using the density functional theory (DFT) method. The quantum chemical descriptors, highest occupied molecular orbital and lowest unoccupied molecular orbital energy gap (ΔE), weighted electrophilic, and nucleophilic atomic frontier electron density (F and F), and net atomic charge (QA), were computed at the same DFT level. Based on these precise quantum chemical descriptors, a quantitative structure–activity relationships study has been carried out and shown that Q, F, F, and ΔE of individual molecules are most likely to be responsible for the in vitro biological activity and greenhouse preemergence activity of phenyl triazolinones. The ability to quite accurately predict the biological activity of phenyl triazolinones by using DFT-based QSAR can be expected to help facilitate the design of additional substituted phenyl triazolinones as PPO inhibitors with good biological activity. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1827–1832, 2004

Pyrazoles and their derivatives are important heterocycles found in nature and present in numerous bioactive compounds. In contrast to 3 or 5-aryl pyrazole, the preparation of 4-aryl pyrazole is fairly rare. Utilizing microwave irradiation, the synthesis of 4-substituted-arylpyrazole via Suzuki cross-coupling has been developed with a wide range of substrates. The remarkable advantages of this method are mild reaction conditions, simple operation, high yield, and short reaction time. Product structures were identified by MS, 1H NMR, 13C NMR, and elemental analysis.

Isatin (1H-indole-2,3-dione, ) was first obtained by Erdman and Laurent in 1841 as a product from the oxidation of indigo by nitric and chromic acids.1 Since then, isatin and its derivatives have b...

The improved microwave assisted Suzuki cross-coupling of aryl iodides (I) with boronic acids followed by deprotection produces various thiosalicylates.

The two-step procedure gives access to the title compounds starting from iodo salicylate (I) and a broad variety of arylboronic acids within a very short time and good to excellent yields.

In an attempt to discover novel compounds with high herbicidal activity and low toxicity, a series of novel 1,2,4-triazolo[1,5-a]pyrimidine derivatives, α-(5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine-2-thio)acetamides 3 and α-(5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine-2-sul-fonyl)acetamides 4, have been designed and synthesized by a three-step synthetic route. The structures of all compounds prepared were confirmed by elemental analyses and by 1H NMR and mass spectroscopy. The results of preliminary bioassay indicate that the title compounds possess good herbicidal activity against rape (Brassica campestris L.) and barnyardgrass (Echinochloca crusgalli L.) © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:491–496, 2001

For the purpose of better understanding the molecular mechanism of action of sulfonylurea and sulfonamide herbicides, the quantitative relationship between their structure and herbicidal activity against rape, Brassica campestris L, was analysed using physicochemical parameters and regression analysis and comparative molecular field analysis (CoMFA). The results showed that the structure–activity relationships of the two sets of compounds were identical, which suggested that the two different sets of compounds affect a common region of the receptor site. The CoMFA results were consistent with those derived from traditional QSAR analysis. Combining the traditional QSAR analysis with the CoMFA results, we can conclude that the variations in the herbicidal activity of the two sets of ALS inhibitors were governed dominantly by the three-dimensional steric and electrostatic field parameters of molecules participating in the interaction with the receptor site and there is apparently an optimum electronic property (Σσ or pKa) for the molecules to fit the receptor. © 1999 Society of Chemical Industry

The synthesis of a broad range of thioether substituted flavonoids from the corresponding flavonoid chlorides is described.

An efficient one-pot synthesis of polyhydroxyalkyl-substituted pyrroles from 1,2-cyclopropa-3-pyranones with primary amines is reported. With 10% of InBr3 as the catalyst, both aryl- and alkylamines as well as various 1,2-cyclopropa-3-pyranones are well tolerated. This method is highly appealing because of its one-pot process, mild reaction conditions, substrate simplicity, and broad substrate scope.

On the basis of the principle of combination of active structural moieties, a modified and efficient synthetic method for three series of novel indole-based 1,3,4-oxadiazoles is described. Bioassays conducted at Syngenta showed that several of the synthesized compounds exhibit higher antifungal activity than pimprinine, the natural product which inspired this synthesis. Two main structural alterations were found to broaden the spectrum of biological activity in most cases. Compounds 3g, 6c, 6e, 6h, 9d, 9e, 9h and 9m (Fig. 1) were identified as the most active on the biological assays, and will be studied further.

Electronic and steric modifications have only small effects on the reactions of 4-iodoisatins with aryl- and alkenyl boronic acids.

Unsaturated glycosides containing various C-1 alkoxy groups smoothly undergo glycosidation reactions with arylamines such as (II) using either InI3 or InBr3 as the catalyst.

Pimprinine is used as the parent structure to carry out optimization with the aim of discovering synthetic analogues which possess simpler structures and improved fungicidal effects.

The cytochrome bc(1) complex (complex III, cyt bc(1)) is an essential component of cellular respiration. Cyt bc(1) has three core subunits that are required for its catalytic activity: cytochrome b, cytochrome c(1), and the Rieske iron-sulfur protein (ISP). Although most fungicides inhibit this enzyme by binding to the cytochrome b subunit, resistance to these fungicides has developed rapidly due to their widespread application. Resistance is mainly associated with mutations in cytochrome b, the only subunit encoded by mitochondrial DNA. Recently, the flexibility and motion of the ISP and its essential role in electron transfer have received intense attention; this leads us to propose a new classification of cyt bc(1) inhibitors (three types of Q(o) inhibitors) that mobilize, restrict, or fix the rotation of the ISP. Importantly, the strengths of the ISP-inhibitor interactions correlate with inhibitor activity and the development of resistance to Q(o) inhibitors, thereby offering clues for designing novel cyt bc(1) inhibitors with high potency and a low risk of resistance.